Disaster Risk Management
for the Historic City of Patan, Nepal
Final Report of the Kathmandu Research Project

March, 2012
Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University, Kyoto, Japan
Institute of Engineering,Tribhuvan University,Kathmandu, Nepal

Final Report of the Kathmandu Research Project
Disaster Risk Management for the Historic City of Patan, Nepal
Rits-DMUCH (Research Center for Disaster Mitigation of Urban Cultural Heritage),
Ritsumeikan University, Kyoto, Japan
IoE (Institute of Engineering),
Tribhuvan University,Kathmandu, Nepal
This work was supported in part by Global COE Program ”Global COE for Education, Researchand Development of Strategy on Disaster Mitigation of Cultural Heritage and Historic Cities”,
MEXT, Japan.
Date of Publication: March 2012
Published by: Rits-DMUCH
Research Center for Disaster Mitigation of Urban Cultural Heritage, Ritsumeikan University
Komatsubarakita-Machi, Kita-Ku, Kyoto, 603-8341 Japan
Tel: +81-75-467-8801
Edited by: Rohit Jigyasu, Naoko Itaya
All illustration and diagrams have been taken from the respective presentations. Where possible
credit has been given.

PREFACE
Global Center of Excellence (GCoE) for Education, Research and Development of Strategy on
Disaster Mitigation of Cultural Heritage and Historic Cities was established in 2008 to implement
advanced education and research for the protection of cultural heritage and historic cities that havethem and to develop these concepts on an international scale. One of the goals of GCoE program isresearch and development of universally practical, applicable technologies for mitigating the effects
of disasters on cultural heritage.
Under this program, the Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University, Kyoto and the Institute of Engineering, Tribhuvan University, Kathmandu,
Nepal initiated a collaborative research project, established in spirit through the Memorandum ofUnderstanding signed in 2009. The research aims at formulating comprehensive risk mitigation
planning strategies for historic urban area of Lalitpur (Patan), which is located within the core areaof one of the seven World Heritage Sites of Kathmandu Valley, Patan Durbar Square.
As part of this research project, researchers from cultural heritage and disaster management
fields from both the institutions have undertaken joint research activities within two broad areas –assessment of structural safety of traditional buildings and disaster mitigation planning of thehistoric area. Various activities undertaken as part of this research project include field surveys
aimed at mapping, documentation, interviews, workshops, experiments as well as laboratory
analysis.
The research outcomes of the both groups are integrated to develop the disaster management
plan and the risk mitigation proposal for the historic urban areas aimed at saving human lives aswell as cultural heritage in the event of an earthquake that may strike the area in the near future.
We would like to congratulate all those who have been involved in this important research
project for their hard work and dedication that has led to this outstanding work that would
contribute immensely towards reducing disaster risks to our irreplaceable cultural heritage in theWorld.

Kenzo Toki
Director,
Research Center for Disaster Mitigation of
Urban Cultural Heritage,
Ritsumeikan University,
Kyoto, Japan

Bharat Pahari
Dean,
Institute of Engineering,
Tribhuvan University,
Pulchowk Campus, Lalitpur,
Kathmandu, Nepal

CONTENTS
Preface
1 Introduction………………………………………………… 1

1-1 Seismic activity in Nepal………………………………………………… 3
1-2 History and construction system of traditional buildings in Kathmandu Valley …………… 6

2. Seismic Hazard Assessment………………………………………………… 9

2-1 Earthquake sources and recurrences
2-1.1 Earthquake catalogue and recurrences………………………………………………… 9………………………………………………

…11

2-1.2 Attenuation of Ground motion…………………………………………………12…………………………………………………14
2-2 Probabilistic seismic hazard analysis
2-2.1 Earthquake densities…………………………………………………142-2.2 Maximum magnitude…………………………………………………16…………………………………………………16
2-3 Probabilistic spectra
2-4 Simulation of Ground Motions…………………………………………………18
2-4.1 Deaggregation of hazard…………………………………………………18
2-4.2 Duration and envelope function…………………………………………………19
2-4.3 Design earthquakes…………………………………………………20
2-5. Local Soil Effects…………………………………………………23
2-5.1 Soil Profile Data Acquisition and Interpolation ………………………….……..……………23
2-5.2 Characterization of the Soil…………………………………………………24(1) Estimation of Shear wave velocity(2) Density of Soil Strata
2-5.3 One Dimensional Site Response Analysis …………………………………………………25

3. Structural Analysis of Traditional Brick Masonry Buildings………………………………37

3-1 Present situation of Traditional Brick Masonry Buildings in Patan …………..…………………37
3-1.1 Structural Design and Construction…………………………………………………37
3-1.2 Method of Repair…………………………………………………41(1) Concept of Repair…………………………………………………42(2) Concept of Restoration…………………………………………………42(3) Strengthening Concept…………………………………………………43
3-1.3 Present Situation of Buildings…………………………………………………43(1) Traditional brick masonry buildings in original form ……………………………………44(2) Traditional brick masonry buildings with modifications ………………………………44…………………………………………………45(3) Buildings with modern features
3-2 Structural Analysis of Traditional Brick Masonry Buildings (Case study) ……………………47
3-2.1 Structural Survey of Traditional and Historical Buildings …………………………………47
3-2.2 Experimental verification for Element of Reinforced Technology ……………………52(1) Non-Destructive Tests (NDT)…………………………………………………52i

(2) Schmidt Rebound Hammer Test…………………………………………………52…………………………………………………56(3) Ultrasonic Pulse Velocity Test
3-2.3 Experimental investigation and Structural Analysis of Traditional Brick Masonry
Buildings…………………………………………………60(1) Material properties of historical masonry building ….……………………………………60a) Elastic wave tomographyb) Measurement by Pocket AEc) Micro tremor measurementd) H/V Spectrume) Natural frequency of buildingf) Transfer function and damping(2) Laboratory Tests on Material properties of Traditional Masonry Buildings ……78a) Compression testingb) Shear testc) Combined shear and compression(3) Structural analysis of historical masonry building ………………………………………………84

3-2.4 Simulation of Building Collapse…………………………………………………89…………………………………………………89(1) Introduction(2)Analytical Method…………………………………………………89a) Basic conceptb) Spring constant of each elementc) Modeling of elastic behaviord) Modeling of failure phenomenae) Modeling of contact and recontact between elementsf) Restoring and contact forces acting at each elementg) Structural dampingh) Equations of motioni) Critical time intervalj) Modeling of bricks and mortar(3)Analysis outline…………………………………………………97a) Target historic masonry buildingb) Analytical modelc) Verification of analytical modeld) Input ground acceleratione) Analytical cases………………………………………………100(4) Simulation resultsa) Input ground acceleration with the occurrence probability of 40% in 50 yearsb) Input ground acceleration with the occurrence probability of 10% in 50 yearsc) Input ground acceleration with the occurrence probability of 5% in 50 years(5) Conclusions………………………………………………104
3-3 Damage Potential of Buildings in Case Study Area ………………………………………………107
3-3.1 Characteristics of Traditional Brick Masonry Buildings ………………..…………………107
3-3.2 Classification of Building Type for Traditional Brick Masonry ……………..…………109
3-3.4 Characteristics of RC Buildings………………………………………..………113
3-3.5 Development of Seismic Risk Evaluation method …………………………….…..………116(1) Classification of Reinforced Concrete Buildings ………………………………………116(2) Fragility Analysis of RC Buildings………………………………………..………118
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(3) Fragility Analysis of the traditional brick masonry buildings ………………..………123………………………………………..………127(4) Vulnerability in the line of EMS-98
3-3.6 Application of Risk Evaluation methods to Case Study Area …………………………135(1) Jhatapo area………………………………………………135(2) Complete enumeration………………………………………………136(3) Seismic risk evaluation………………………………………………137a) Analytical modelingb) Damage indexc) Damage index function and fragility curve(4) Results………………………………………………140a) Estimated damage indexb) Damage index functionc) Fragility curved) Reinforcement using ring beams(5) Conclusions………………………………………………146

4. Analysis of Heritage Values, Vulnerabilities and Resources for Emergency Response…………………………………………………… 147

4-1 Reading Heritage Values of the Historic City of Patan in Kathmandu Valley ………….……147
4-1.1 Reading Urban Cultural Heritage of Patan………………………………………………147(1) History, legends and symbolic values of the city of Patan ……………………………148(2) Built Heritage Elements………………………………………………150a) Templesb) Baha-Bahic) Sattald) Patie) Chiba and Othersf) Residential Buildingsg) Inscription………………………………………………153(3) Streetsa) Main Streetb) Alleyways and Underpass(4) Squares………………………………………………154(5) Society………………………………………………154
4-1.2 Reading Traditional Urban Water Systems ………………………………………………155(1) History and Historicity………………………………………………156(2) Elements of the urban water supply system ………………………………………………157a) Pondsb) Wellc) Hiti(3) Water in Cultural Practices of Patan………………………………………………158(4) The Technology of Hiti………………………………………………161(5) Defunct Status of the Traditional Water system in Patan……………………………162
4-1.3 History and Traditional Knowledge of Disasters ……………………..…………………164iii

4-2 Assessment of Heritage Values in Case Study Area ………………………………………………169………………………………………………169
4-2.1 Purpose of Heritage Value Assessment
4-2.2 The Target Area………………………………………………169………………………………………………170
4-2.3 Overall Methodology
4-2.4 Attributes for Assessing Values………………………………………………171
4-2.5 Indicators for Assessment of Heritage Values of Attributes …………..………………173(1) Historic Value………………………………………………173………………………………………………173(2) Aesthetic Values(3) Architectural Value………………………………………………174………………………………………………176(4) Artistic Value(5) Socio-religious values of living heritage (livingness value) ………………………177………………………………………………179(6) Ecological Values(7) Resource Value for Disaster Mitigation and Response ………………………………179(8) Assessing HeritageValues of Traditional Open Spaces and Routes ………………179
4-2.6 Assessment of Heritage Values of Attributes ………………………………………………180
4-2.7 Indicators for Prioritization of Attributes for Disaster Mitigation ……………………183
4-3 Assessment of Resources for Disaster Mitigation and Response ……………………..………185
4-3.1 Survey for Evacuation Planning………………………………………………185(1) Research of courtyard and courtyard entrance as evacuation route ………………185a) Layoutb) Residents workshop on risk of courtyard entrance blockage with DIGc) Risk analysis of courtyard entrancesd) Application to Jhatapo as a case study(2) Challenges and Countermeasures for Disaster Mitigation …………………………187(3) Analysis of results………………………………………………188a) Analysis of Fires Sectionb) Analysis of Evacuation Sectionc) Analysis of Rescue Sectiond) Analysis of evacuation training
4-3.2 Survey for Firefighting(1) Current condition of the public firefighting capacity ……………………………………190(2) Assessing the effectiveness of Hiti: traditional water resource in Kathmandu………………………………………………191
Valleya) Effective amount as a water resource for firefightingb) Method of the simple measurementc) Results of the investigation(3) Assessing the inaccessibility of the fire engine ……………………………………………192a) Method of the measurement and the assessmentb) Results of the investigation(4) Assessing difficult areas for firefighting ………………………………………………193a) Concept of difficult areas for firefightingb) Method of assessmentc) Results of the risk identification
4-3.3 Survey for Community activities………………………………………………195(1) Research of Community around the Hiti ………………………………………………195a) Purpose of Researchb) Selection of 4 Hiti(s) as research targets
iv

(2) Challenges and Countermeasures for Disaster Mitigation ……………..……………196a) Interview Researchb) Outline of community around the Hitic) Introduction of water supply system with Hiti
4-4 Current Status and Issues concerning disaster management of cultural heritage in Nepal………………………………………………………198

4-4.1 Current Status and Issues confronting Cultural Heritage protection and managementin Nepal and Kathmandu valley in particular………………………………………………198(1) Legal provisions for the classification of monuments …..……………………………198(2) Protection of urban cultural heritage besides monuments …………………………198………………………………………………199(3) Lalitpur Sub-Metropolitan City
4-4.2 Current Status and issues concerning the impact of existing Urban policies andplanning on Core and Buffer zones of the Patan World Heritage Site…………………………………………………………200

4-4.3 The existing role of Central Government, army, municipality, owners andresidentsfor disaster risk management of urban cultural heritage ……………..……………201………………………………………………201(1) Central Government Level(2) Army and Police………………………………………………201(3) Municipality………………………………………………201………………………………………………202(4) Earthquake Safety Section(5) Challenges………………………………………………203

5. Disaster Risk Management Proposals………………………………………………205

5-1 Structural Reinforcement of Traditional Buildings and Open Spaces …………………………205
5-1.1 Strengthening of buildings………………………………………………207
5-1.2 Strengthening of open space and underpass ………………………………………………209
5-2 Utilization of Cultural Heritage for Evacuation and Rescue ………………….…………………212………………………………………………212
5-2.1 Summary
5-2.2 Preparedness for Evacuation………………………………………………212(1) Grounds of temples with functions as primary refuges …………………………………212(2) Traditional urban structure that hinders the accessibility to primary refuge areas…………………………………………………213

5-2.3 Preparation of evacuation plan “from Houses to Pattis and Sattels” (1st step) ……213(1) Disussion with local residents on available evacuation routes through Disaster
Imagination Game (DIG)…..……………………………………………213(2) Calculation of the number of evacuees passing through the courtyards and accesspaths………………………………………………214(3) Selection of prioritized courtyard and access path to bereinforced for seismic
safety………………………………………………215
5-2.4 Preparedness of “Pattis and Sattels” for Rescue Activities (2nd step)…………215(1) Establishing storage areas for rescue and salvage equipments in Patis and Sattels…..………………………………………………215(2) Enhancing functions of Guthi(s)…..……………………………………………215(3) Utilization of Cultural Heritage in the Daily Milieu for Supporting Evacuation
and Rescue…..……………………………………………216v

5-2.5 Preparation of evacuation plan “from Paties and Sattels to Squares” (3rd step) …217…..……………………………………………217(1) Recent condition of Evacuation Sites(2) Strategy for Preparation of alternative evacuation site …………………………………218a) Recomended complementary evacuation site: the Durbar Squareb) Selection and repairment of evacuation routes to the Durbar Squarec) Repair and reinforcement of the monuments in the Durbar Square

5-3 Improvement of Firefighting Capacity by Utilizing Cultural Properties ……………………221………………………………………………221
5-3.1 Summary
5-3.2 Challenges for Firefighting in World Heritage core and buffer area of Patan …..221(1) Current condition of the public firefighting capacity ……………………………………221(2) Assessing the effectiveness of Hiti: traditional water network in Kathmandu
Valley………………………………………………222(3) Narrow streets that make firefighting difficult ……………………………………………222(4) Identification of difficult areas for firefighting …………………………………………222
5-3.3 Challenges for eliminating Difficult Areas for Firefighting ……………………………223(1) Security of water supply for firefighting ………………………………………………223(2) Securing accessibility for the fire engine ………………………………………………223
5-3.4 Improvement of Disaster Preparedness with Residents, Communities and theMunicipality………………………………………………225

Acknowledgment………………………………………………227

Authors List………………………………………………228

Appendix………………………………………………231

Damage Potential of Buildings in Case Study Area………………………………………………233
Appendix A: Sample of Building Survey FormAppendix B: Building survey results/ Traditional brick masonry buildings ………………………234
Appendix C: Building survey results/ Reinforced concrete buildings ………………………………236
Assessment of Heritage Values in Case Study Area
Appendix D: Assessment of Heritage Values for Buildings ……………………………….………….....237
Appendix E: Assessment of Heritage Values for Components ……………………………………....…239
Appendix F: Assessment of Heritage Values for Open Spaces …………………………………………242vi

1. Introduction
The Kathmandu Valley, accommodating the capital city, and being the cultural, commercial andpolitical center of Nepal, lies in a highly seismically vulnerable zone. All the major earthquakes ofpast centuries have badly affected the valley. Some of the major earthquakes have even devastatedits cities. The Kathmandu Valley is well known for its traditional historical buildings andmonumental structures, most of them built in the Medieval Period of Nepal. The rich history,
importance and original peculiarity of arts and architecture of these structures have made their sites
listed in the World Heritage by UNESCO. Protection of these structures against major earthquakes
has been one of the major concerns in the conservation of the cultural heritage.
The Kathmandu Valley is situated in the middle of the country at an elevation of about 1300 m
above sea level. The valley, surrounded by high hills of average elevation ranging from 2100 m to2765 m, has maximum sizes of 25 km and 20 km, respectively in the east - west and north - south
directions. According to the history of the origin of Nepal, the valley to the boundaries of which thethen Nepal was limited, used to be a large lake before the accumulated water was drained off.
Kathmandu Valley has been considered as an in-filled basin formed during the Quaternary period,
mainly by the rising of the Mahabharat Lekh, the mountain range forming the southern boundary of
the Valley.
Geographically, the Kathmandu Valley, is considered as an in-filled basin, and has sedimentdeposits of different layers varying from one part to another. If the valley is identified as highly
seismic due to its geographical location, geological and seismo-tectonic reasons, its different parts
have different seismic effects due to considerable variation in soil conditions.
The Kathmandu Valley has three major cities of historical importance. All three cities ofKathmandu, Lalitpur and Bhaktapur accommodate many monument zones. The cultural heritage ofKathmandu Valley represents the art, architecture and civilization of the country. The everincreasing population, uncontrolled planning, indiscriminate reconstruction and the haphazard
development have an adverse impact on the historic-cultural heritage of the valley, in the meantime,
substantially increasing the seismic risk factor of the valley. In view of the need of conservation of
the heritage sites with clusters of heritage structures, old and new traditional buildings, and with anobjective of mitigating the disaster risk due to possible earthquakes in future, the development ofearthquake disaster risk management plan for the valley has become an issue of utmost importance.
In order to establish such a disaster risk mitigation plan for the historic urban areas, acomprehensive risk assessment of them considering the risk to inhabitants, properties as well as
heritage values needs to be carried out. As a part of the risk mitigation planning measure, apart frombuilding an awareness of vulnerabilities as well as capacities, it is important to establish social andfinancial programs to address them.
With an aim to develop a comprehensive risk mitigation strategy for historic urban areas ofKathmandu Valley, the Research Centre of Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University (Rits-DMUCH), Kyoto, Japan in collaboration with the Institute ofEngineering (IOE), Tribhuvan University, Kathmandu, Nepal has undertaken the research. The
collaborative research was initiated under the IOE – Rits-DMUCH Collaborative Research Project,established in spirit with the Memorandum of Understanding signed in 2009. The research is aimed
at formulating comprehensive risk mitigation planning strategies for historic urban area of Lalitpur(Patan), which is located within the core area of one of the seven World Heritage Sites ofKathmandu Valley, Patan Durbar Square (Fig.1.1).

1

Fig.1.1 Patan Durbar Square core and buffer zone

The historic urban areas, in general, consist basically of two components: existing traditional
structures, and the community with open spaces and service (life) lines. Accordingly the research is
divided into two broad groups of scope – structural assessment of traditional buildings and disastermitigation planning of the area. The research outcomes of the both groups are integrated to develop
the disaster management plan and the risk mitigation proposal for the historic areas. The major
components of the overall research are outlined in Fig.1.2.

Fig. 1.2 Research components of disaster risk management of historical urban areas21-1. Seismic activity in Nepal
Hari Ram Parajuli
Prem Nath Maskey
Junji Kiyono

Nepal lies in a high seismic risk zone. It has a long history of destructive earthquakes. All the
major earthquakes of past centuries have badly affected the urban areas including the Kathmandu
Valley; some have even devastated its cities. A major earthquake of magnitude 8.4 in Richter Scalein the year 1934 ( The Great Bihar – Nepal Earthquake) had destroyed many areas of the country,
especially large parts of Kathmandu Valley, with a considerable loss of lives and property, although
its epicenter was located far off from the Valley, about 240 km in the eastern Nepal. Prior to thisalso, there have been historical records of large earthquakes in years 1253, 1407, 1681, 1803, 1824,
1833 and 1835. The first major earthquake in Nepal, ever recorded in the documents, dates back to1253 and is estimated to have had a Richter magnitude of 7.7. The history indicates theconsiderable damage made by the earthquake of 26 August 1833. This earthquake is believed tohave its epicenter close to Kathmandu within or close to the inferred rupture zone of the Bihar
Nepal earthquake of 1934. The earthquake of Richter magnitude 6.6 occurred in August 1988 with
its epicenter at Udayapur, 165 km away to the southeast from Kathmandu, had destroyed many
parts of eastern Nepal with some damages in the Kathmandu Valley. The recent earthquake of
September 18, 2011 of Richter magnitude of 6.8 with the epicenter at the border with Sikkim and its
shaking effects in many parts of Nepal is the latest event of the seismic activity in Nepal. These
historic earthquakes have established the active seismicity of Nepal a long time ago (Fig.1.3).

Fig.1.3: Seismicity map of Nepal. Source: 1). Note: Each circle represents a recorded earthquake. Most of Nepal’searthquakes are relatively shallow (≤ 33 Km depth) and located near the estimated boundary between the India Eurasian Plates.
3

Earthquake records in Nepal since 1253 indicate that Nepal was hit by at least 20 large
earthquakes of, the last major earthquake being that of 2011 (Table 1.1) with various digress ofdamage.
Table 1.1: Historical earthquakes in Nepal. source: 2), 3),4)
Year (A.D.)
1255

1260
1408
1681
1767
1810
1823
1833

DeathsEstimated magnitude around 7.7 in
Richter scale. One third of the total
population of Kathmandu were
killed including Abahya Malla , theKing of Kathmandu valley
Many people died, famine after theearthquake
Many people died
Many people died
No record available on deaths
Many lives were lost particularly in
Bhaktapur
No record of deaths
Estimated magnitude 7.7, 414
people died in the vicinity of the
Kathmandu valley

1834
1837

No good record available
No good record available

1869
1897
1917(1918?)
1934

No good record available
No good record available
No record deaths
Estimated Magnitude 8.3 (epicenter,eastern Nepal). 8,519 people diedout of which 4,296 died in
Kathmandu valley alone

1936
1954
1966
1980

No good record available
No good record available
24 people died
Magnitude 6.5 (epicenter far
western Nepal). 103 people died
Magnitude 6.5 (epicenter in SE
Nepal). 721 people died
Magnitude 6.9 (epicenter in NE
Nepal). 11 people died in Nepal

1988
2011

Damages
A lot of damages to residential buildings andtemples

A lot of damages to residential buildings andtemples
A lot of damages to temples, residentialbuildings, fissures developed in the groundA lot of damages to residential buildings
No record available on damage
A lot of damages to buildings and temples
Some damage to houses
Nearly 4040 houses destroyed in Kathmandu,
Bhaktapur, and Patan in the valley andadjoining Banepa and a total of 18,000
buildings damaged in the whole country.
Many buildings collapsed
No damage in Nepal recorded but greatly
affected Patna and other parts of Bihar, India.
No good record available
No good record available
No record on damage
Over 200,000 buildings and temples etc
damaged out of which nearly 81 thousandcompletely destroyed in the country. Max
Intensity X. 55,000 building affected in
Kathmandu (12,397 completely destroyed).
No good record available
No good record available
1,300 houses collapsed
12, 817 buildings completely destroyed, 2,500
66,382 buildings collapsed or seriously
Damages in rural houses

In view of the geographical location of the country, seismotectonic characteristics of the region,and the geotechnical condition, it has long been established that Nepal is very much susceptible tolarge earthquake risks. Bilham et al 4) has indicated that there lies a seismic gap of 500-800 km
between the epicenters of the great 1934 Bihar Nepal earthquake and the 1905 Kangra earthquake
and this gap has not experienced major earthquakes for the last two centuries. It indicates that adevastating earthquake is inevitable in the long term and it is most likely to occur in the near future.
The seismicity of Nepal is basically attributed to the seismo-tectonic activities in the region.
Nepal is located at the boundary between seismically active Indian and Tibetan tectonic plates,
which are moving towards each other with about a relative movement of about 20 mm or so per
annum. The continued tectonic activities beneath the Himalayan region attribute to the buildup of
tectonic stresses accompanying the interpolate collision, and leads to the accumulation of strains4and the abrupt failure of rock in the earth’s crust along Major fault systems. The major fault
systems are recognized as lying parallel to the axis of Himalayan range and consist of Indus Suture
Zone (ISZ), the Main Central Thrust (MCT), the Main Boundary Thrust (MBT), and the Himalayan
Frontal Fault (HFF). Of these major faults, the Main Boundary Thrust (MBT) separating the SubHimalayas from the Lesser Himalayas, and the Main Central Thrust (MCT), separating the Lesser
Himalayas from the Higher/Tethyan Himalayas have been identified as the crucial faults in theseismicity of the region. The Main Boundary Thrust (MBT) is the most active major fault system.
The tectonically young Himalayas and the continued tectonic activities have made the wholecountry of Nepal and the surrounding area seismically lying in a very active zone. Fig. 1.4 presents
the distribution of the active faults in Nepal.

Fig. 1.4 Active fault distribution in Nepal ( Source: 5)During a study recently conducted, five faults, at various locations and of different lengths andnature, within the valley itself have been identified as active. Some faults located within 20 to 50
km away from the Kathmandu Valley have been found as active, capable of generating anearthquake of magnitude from 6.9 to 7.1 Richter scale. Any earthquake along these faults will beaffecting the Valley also.
The features of the active faults within and in the vicinity of the valley indicate that they could
be the sources of strong ground motion and surface rupture. Accordingly, apart from the primaryseismic hazard, any earthquake may result into three main types of secondary seismic hazards,
namely, surface fault rupture, soil liquefaction and earthquake-induced landslide in the Valley. The
report describing the effects of The Bihar - Nepal Earthquake of 1934 suggests the occurrence ofwidespread liquefaction, development of fissures in roads and paddy fields with ejection of waterfrom them. The susceptibility of the soil condition of the valley to liquefaction during an earthquake
is strongly evidenced by the description.
Different studies carried out earlier suggest that one of the major factors influencing the level ofground motion within Kathmandu Valley is the site amplification due to unconsolidated sediments.
The northern and north-eastern part of the valley, in general, if are characterized by the site
amplification similar to that of surface bed rock conditions, the central part of the valley has arelative amplification factor of 4 to 7 as compared to sites in the northern part. The maximum
amplification is believed to be confined to certain belt in the southern part of the valley where thehigh intensity was reported after the Great Earthquake of 1934.

5

1-2. History and construction system of traditional buildings in Kathmandu Valley
Prem Nath Maskey

The prominent settlements of the Kathmandu Valley date back to the beginning of the Malla
Period (13th to 18th centuries), and have remained in the compact forms that were established then.
All the important structures created in that period represent the high status of art, architecture andculture, and thus possess the heritage value. These are traditional dwelling houses as well as
numerous structures related with public services and religion. Apart from traditional dwellinghouses, built in brick masonry, as a perfect part of the town planning, the cities of the Valley arefound liberally interspersed and beautified with religious structures. These are different types oftemples, viharas, chaityas, and water conduits. The massive palaces with peculiar architecture anddecorative facades, public squares with places of rest and gathering (Sattals and Patis), public places
for travellers are other monumental structures of importance. These historical structures, all withsuitable forms of architecture, and full of arts exhibiting their craftsmanship and architecture in thebest manner, represent today the culture and civilization of the country. It is evident from the studyof these structures that the basic concept of seismic resistance design (performance against lateralloading) was well understood, and the best available materials and technology were utilized in theconstruction of the temples and other structures of public importance including dwelling houses.
Out of these monumental and traditional structures, the tiered temples are not only common but also
possess very peculiar to the Valley. A tiered temple, representing the best of the original Nepali
style structure, is usually a structure with diminishing dimensions having a series of pyramidal roofs.
Such tiered temples, as well as other historical structures are constructed with basic materials like,brick, rich mud mortar, timber and stone.
The traditional building style of the Kathmandu Valley is represented by the Newar style 6).
The style of these houses is more than 2 centuries old making the houses historic monuments, someof these houses are master pieces of the builders’ art.6).
In general, the traditional building has a basic unit of brick-walled rectangle of about 6m widthand of variable length. The lengths range from a minimum of 1.5 m to 15 meters, although 4 to 8
meters is the general feature. The buildings, typically, are three stories high with a half storey for an
attic. However, two and four storeyed buildings are not uncommon. The four storeyed buildings aremostly in the core area of the cities with relatively better economic standard, while the two storeyedbuildings are mostly distributed in the city areas with poorer economy. In most of the localities, thebuildings are joined end to end, paralleling the streets. Mostly in the community, these buildings areconnected with each other in orthogonal directions forming a courtyard, with one or more accessgateways in the ground floor to the street.
The structural system of the traditional buildings is based on the load bearing unreinforced brickmasonry in mud mortar. Typically, the walls usually consist of three different vertical layers ofmasonry, with a total width varying from 45 to 75cm. The outer face is made of a wythe of burnt
brick, locally known as ma apa. For the main front of important buildings or temples, a special
wedge-shaped brick (daci apa) is employed quite often to create a veneer-like façade. The taper ofthese bricks results in a varying thickness of the mortar joint from the front to the back. The innerface of the wall is made of one wythe of burnt or even unburnt brickwork (kaci apa). Only rarely dothose thick walls consist of continuous solid brickwork. The bricks are traditionally laid in mud
mortar. The special clay for the mortar is obtained from specified places, where the plastic clay istaken from the deposit after digging for a depth of more than 3m. Commonly, all bricks of the outer6face are laid as runners, so that there is no or only little bonding between the different leafs. Cross
walls are often simply butt jointed with no interlocking at all.
Frequently timber arcades replace a part of the masonry walls at the ground floor to provide
better access to shops or storage space. Here, wooden pillars set above stone piers support a larger
spandrel beam on which the upper wall portion is resting. Frames for wall openings such as doors
and windows are pieced together from many wooden elements, joined with sophisticatedconnections. The preassembled free-standing frames are placed on the brickwork and thereafter
integrated into the masonry wall.
The foundations of the buildings are typically shallow and often have a depth of about 150 cm
below ground level. These foundations are often slightly stepped, and the width of the footing isabout 75 cm. The base is generally formed by a few layers of large pebbles or broken stones. This isfollowed by the usual brickwork, which continues into the upper structure. No damp proofing wasused in traditional masonry structures.
The floors are generally timber floors. The timber floors are supported by closely spaced timber
joists with a layer of terra cotta tiles or wooden planks. This subfloor is topped with a 10cm thickcover of fine yellow clay. The joists rest on continuous wooden wall plates that are embedded in themasonry. The wedge like wooden pegs are provided at the ends of the timber joists at their supports,
normally wall plates or walls, making them the shear-locks to prevent possible horizontal
dislodgement. The floor heights of the buildings are about 2.20m.
The roofs in the traditional buildings are double-pitched roofs covered with the local ceramicroof tiles. The roof structure is based on timber rafters or rarely on timber trusses supported on thewalls. The roofs normally have wide projections, indicating the most prominent feature of the
traditional buildings of the Kathmandu Valley. These roofs, which typically protrude more than one
meter from the façade; in the case of larger buildings and temples this can be more than 2 meters.
The traditional buildings are characterized by a limited numbers and sizes of openings for doors
and windows, which are tied with the walls by timber ties at strategic levels. Almost all the door
and window frames are provided with double frames. All the decorative members also function as
important structural elements. Timber is extensively used in windows, doors and almost all thestructural elements other than brick walls.
The traditional architecture and construction of the buildings of the Kathmandu Valley Malla
were extensively developed during the Malla Period (1200-1768 A.D.). The numerous monumental
structures and historical buildings were constructed in this Medieval Period. All these different
types of structures have their own distinct character and utility, however, these have a common
feature of traditional materials and technology. These structures were built with the best materials
available with the best workmanship and knowledge available at the time of their construction.
However, the basic materials like bricks and mud mortar, as known, have limited strengths towithstand earthquake excitation, making vulnerable to earthquake excitation.
The traditional building architecture of the Kathmandu valley remained relatively unchanged
from the 16th century until the beginning of westernization in the middle of the last century. Other
building types, such as palaces, monasteries, houses for priests or merchants, and shrines are similar
in terms of building materials and construction principles, although different in size and splendor 6)
7).
The style of the traditional buildings of the Kathmandu Valley did not change much in the
periods following the Malla Period. During the early part of the Shah Period (1768 A.D.- to date),
particularly during the period of (1806-1837A.D.), the then Prime Minister Bhimsen Thapa first
introduced the exotic architecture of European style in the Kathmandu Valley. During the Rana
Period (1846-1951 A.D.), the then powerful rulers introduced the neo-classical architecture during
in a large scale in the Kathmandu Valley. The introduction of these new architectural styles is7

apparent in the construction of new palaces and residences of the elite group only. The influence ofthe exotic European style of architecture and the neo classical architecture in the common
traditional building is not remarkable except for some forms of the traditional elements and thebuilding materials. The influence in the traditional buildings of the Kathmandu Valley can beassessed by looking at the three main types of buildings in terms of the finish of their facades. The
original and the oldest or medieval style of a common traditional building are characterized by ahorizontal window style with square latticed openings (decorative Sajhya of the Malla style). About
two hundred years ago the lattice window style started to change towards a more vertical form, andthe Sajhya became less ornamented (the Shah style). Before the end of the century the windows
started being lighter and larger, resulting into French windows, making the height of the windows
almost one story high, and the latticed form of window and so the Sajhya disappeared (the Ranastyle). The increase in the opening sizes and removal of the latticed structures in the frames, as theresults of the changes, decrease the lateral stiffness and the shear areas of the walls, making the
traditional buildings more vulnerable to the seismic excitations.

References
1)
2)
3)
4)
5)
6)
7)

USGS http://earthquake.usgs.gov/earthquakes/world/nepal/seismicity.php
UN/UNCHS: Seismic hazard mapping and risk assessment for Nepal. Unpublished Report submitted to His Majesty’s
government of Nepal, Ministry of Housing and Physical Planning, 1993.
Pandey, M.R. and Molnar, P.: The distribution of intensity of the Bihar-Nepal earthquake of 15 January 1934 and bounds on theextent of the rupture zone, Jour. Nepal Geol. Soc., Vol. 5(1), pp. 22-44, 1988.
Bilham, R.P, Bodin, P. and Jackson, M.: Entertaining great earthquakes in Western Nepal: Historic inactivity and geodetic testfor development of strain. Journal of Nepal Geological Society, 11, 73-78, 1995.
Upreti, B.N., Kumahara, Y. and Nakata, T.: Paleoseismological study in the Nepal Himalaya – present status, Proceedings ofthe Korea-Nepal Joint symposium on slope stability and landslides, April, 1, pp. 1-9, 2007.
Slusser, M.: Nepal Mandala, Princeton, Princeton University Press, 1982.
Hutt, M.: Nepal Gartmore, Kiscadale Publications, 1994.

8

2. Seismic Hazard Assessment
Hari Ram Parajuli
Prem Nath Maskey
Junji Kiyono

2-1. Earthquake sources and recurrences
The collision of India into Asia, 50 million years ago, caused Eurasian plate to crumble up andoverride the Indian plate 1). After collision, the slow convergence of two plates over millions ofyears pushed up the Himalayas and the Tibetan plateau to their present heights. The Himalayas,
approximately two thousand two hundred kilometers long, is the youngest and fragile geology, andhigh rise mountain in the world extends from west to the east of the northern part of Nepal. It iscalled Nepal Himalaya and approximately one thousand kilometers in length. Within the narrow
width of Nepal (Fig. 2.1), three fault systems, Main Central Thrust (MCT), Main Boundary Thrust(MBT) and Himalayan Frontal Thrust (HFT), pass east to west throughout the length of Nepal.

Fig. 2.1a Geological map of Nepal

Fig. 2.1b North-South cross section of Nepal showing depth and faulting systems. Source: 2)

9Along the sides of these three greater fault systems and in the Tibetan Himalayan region, ninety
two small faults have been identified 3). Most of these faults might have formed during past 10
million years and lie in the interface of Indian and Tibetan plate. The geology of Nepal is also
differed by the great faults. The southern part is plane with soft alluvium deposits, the middle part is
low rise mountains and northern part is high rise rocky mountains. The convergence of two plates
has caused many earthquakes in the past with moment magnitude greater than M8 4,5), whichindicates a high rate of deformation and seismicity in the region necessitating urgent need ofseismic hazard estimation and mitigation.
Some studies have also been done for Kathmandu and for Nepal. Hazard curve and risk
consistent response spectrum was obtained by Maskey and Datta 6) for typical location ofKathmandu valley. Free field ground motion accelerations were obtained considering the soil
linearity and non linearity. As a part of preparation of national building code of Nepal, seismic
hazard mapping and risk assessment for Nepal 3) was carried out under the ministry of housing andphysical planning of Nepal, the output of which is the most specific document addressing theseismic hazard issue of Nepal. It has identified ninety two smaller faults within and around Nepal.
The whole area has been divided into three sub zones depending on the earthquake density obtained
from available and assumed earthquakes, however, details have not been provided on what basis
earthquake data was considered. Seismic hazard assessment has been estimated considering both
historical data and assigned characteristic earthquakes after subdividing it into twenty one smallzones. It has assigned different coefficients for magnitude frequency relationship to the identified
ninety two smaller faults, though details have not been given. BECA 3) further divides the wholestudy area into small area sources, assigns the different maximum magnitudes for each region, but
none of areas has maximum magnitude greater than M8, whereas three earthquakes in excess of M8
have already occurred and one of which is also included in their catalogue. Distribution ofearthquake densities in different sub-zones has not been well explained. Division of big area into
three types of zones and considering uniform distribution of earthquakes within the zone smears out
the earthquakes into greater area and the hazard estimates on that basis will result always a low
value. Other issue on that study is attenuation law. It has used Kawashima et al. 7) equation. Large
numbers of studies on developing attenuation laws have been done since then. Investigations
regarding tectonic slip between Tibetan and Indian plates, earthquake size scaling relations havebeen done on this decade. JICA 8) undertook a comprehensive study for disaster mitigation ofKathmandu valley. It has pointed out that risk at Kathmandu is so high that great earthquake may
occur any time. If an earthquake occurs, damage scenario would be worst and Kathmandu valley
cannot be functioning as capital city. Recently, probabilistic seismic hazard assessment 9, 10) for
Kathmandu considering intra-plate rate observed from GIS information has been done.
Major issues such as advances in the development of ground motion equations, investigation ofmagnitude scaling of earthquakes in the Himalayan region, and confirmation of location and size ofthe great 1505 earthquake, have been done after BECA 3). Thus, a seismic hazard estimate
addressing these issues has been presented here. This study covers formation of earthquake
catalogue merging the data from various sources, development of magnitude frequency relationshipat various locations of the rectangular grids and estimation of probabilistic peak ground and spectral
accelerations at various natural periods of the structures.

10

2-1.1 Earthquake catalogue and recurrences
The historical earthquake data within 300 km radius around Nepal, area enclosed by 26.5-30.5N
latitude and 80-89E longitude through 2009 was collected. The earthquake catalogue was formed
merging the data from U.S. Geological Survey, National earthquake Information Centre (NEIC) 11),
BECA 3), Pant 12), Ambraseys and Douglas 13), Ambraseys and Jackson 5). The earthquakes data
have been reported in terms of different magnitudes and or intensity scales. To make uniformity, alldata were converted to moment magnitude as per Hank and Kanamori 14), using various
relationships as proposed by McGuire 15) and scaling relationship for Himalayan region by
Ambraseys and Douglas 13). The plot of these earthquake data with the faults is presented in Fig.
2.2.
The usual practice for seismic hazard analysis is to allocate the earthquakes to the nearest faults,
rearrange the data into various magnitude groups and year intervals, develop recurrence
relationships, calculate mean rate of exceedence. However, the faults are so close and it is difficult
to judge which earthquake belongs to which fault. The other point is there are two categories offaults- greater fault systems (MFT, MBT, MCT, and STDS-Fig. 2.1) and smaller faults, 92 in
numbers as defined in BECA 3). The smaller faults has been said to be part of greater one, however,they might be multiple rupture segments of greater fault systems. If only the historical earthquake isconsidered, on the one hand, it is difficult to allocate them in the fault being close to multiple faults
and on the other hand, some of the faults are empty, and some of them hold only few numbers ofdata which is insufficient to define the recurrence relationship for individual faults.

32
31
30
China
Latitude

29

Nepal
*

28

*

27
26
25
24
76

M4-M5
M5-M6
M6-M7
M7-M8
M>8
78

India
80

82

84
Longitude

86

88

Fig. 2.2 Historical earthquakes (points) and faults (line)

11

90

92

Number of earthquakes (M>m) per year

10

1

Lo g(N/Y)= 3.60-0.76M
10

10

10

10

0

-1

-2

-3

3

4

5

6

M agnitude

7

8

9

Fig. 2.3 Magnitude - frequency relationship

From engineering prospective, peak ground or spectral acceleration and time history of groundmotions at a particular site are necessary and important for design of new and strengthening ofexisting structures rather than detailing individual small faults. Thus, whole area is divided into
grids and cells at intervals of 0.5 and 1.0 degrees in latitude and longitude respectively. Centre ofeach cell is considered a site. All the earthquakes with magnitude greater than M4 within the radiusof 300km from each site are grouped in the range with a 0.5M interval. Earthquake data are notuniformly distributed, only few records available in the early periods are followed by increasing
numbers of records towards the end. In order to do completeness analysis of data as proposed by
Stepp 16), events are grouped according to small intervals of time. Each range of magnitude isjudged separately, and the rate of occurrences of earthquakes exceeding certain magnitude iscalculated for all the sites. A total of 197earthquake events with magnitude greater than M4 were
found. Considering the lower threshold magnitude M5, and maximum magnitude M8.8 (Lave et al2005) 30), and with 50% intra plate slip magnitude frequency relationship was developed (Fig. 2.3)
following Stepp 1972 29)
It is found that the slope of the recurrence relationship, represented by b value is almost unity
for the eastern side of Nepal, whereas the value is higher for the western part of Nepal. This means
sufficient data are available for the eastern part, while for the western side, either earthquake data is
missing or big quake may occur soon as the intra plate slip deficits exist in the region as suggested
by Bilham 17).

2-1.2 Attenuation of Ground motion
Ground motion attenuation relations so far developed, can be categorized into few groups, theseare for shallow crustal earthquakes in active regions, shallow crustal earthquakes in stable regions
and subduction zones focusing America and Japan where large earthquake database is available.

12

No earthquake attenuation relations have been developed so far for the Himalayan region
specifically because of unavailability of adequate earthquake data. Hence the available empirical
relationships developed for other regions are reviewed for the suitability according to the tectonic
conditions of Nepal. Out of these attenuation relationships, the equations for subduction zone
developed by Crouse 18), Fukushima and Tanaka 19), Molas and Yamazaki 20), Youngs et al. [21),Gregor et al. 22), Atkinson and Boore 23)], Atkinson and Boore 24), Kanno et al. 25), and Zhao et
al. 26), which support the tectonics, geology and faulting systems of Nepal are studied.
Youngs et al. 21) has been developed from worldwide seismic environment including Crouse18) catalogue. Zhao et al 26) relation uses Fukushima and Tanaka 19), and Molas and Yamazaki20) and is derived from Japanese earthquake database. Kanno et al. 25) relationship has also beendeveloped based on Japanese catalogue adding shallow crustal earthquakes from outside Japan.
Atkinson and Boore 23) compiled the database of both Youngs and Crouse, added many recent
earthquakes data from Japan through 2001, formed four times bigger database for subduction zone
events and developed new ground motion relationship. Gregor et al. 22) relationship also has beendeveloped for Cascadia subduction zone. Both attenuation equations have focused on Cascadia fault
geometry and ground motion parameter is estimated based on the fault distances. Based on theevaluation of these relationships in relation with the tectonic environment of Nepal, five attenuation
laws developed by Youngs et al. 21), Gregor et al. 22), Atkinson and Boore 23), Kanno et al. 25)
and Zhao et al. 26) are selected for this study. Among these, the relationship proposed by Atkinson
and Boore 23) predicts the lowest, whereas Zhao et al. 26) predicts the highest value. It is uncertainthat in any future earthquake the ground motion will attenuate according to any particularattenuation relationship. Thus, seismic hazard for the region is estimated considering all the fiveattenuation laws giving equal weight.
In subduction zones, there is possibility of occurring both interface and intra-plate earthquakes.
None of the past earthquakes in the Himalayan regions has been categorized as interface or intraplate earthquake. Regarding the information available in the region, there is shallow angle thrustfaults which is very similar situation of subduction interface earthquakes as in other parts of theworld. For intra-plate, earthquakes are basically categorized by deep focus and volcanic activities.
So, subduction interface ground motion relations are considered in this study.

13

2-2. Probabilistic seismic hazard analysis
For a site, an area of 600km x 600km is considered as the seismic source, and it is further
divided into smaller sub-areas or cells of 10km x 10km size. The distances between the centres of
the cells and the site are determined. Only the cells within a radius of 300km from the site areconsidered for the earthquake recurrence relationship. The annual mean rate of occurrence of theground motion intensity parameter (PGA) exceeding a certain value of intensity parameter isdetermined by equation 1.
Ns y   i*i 1

  P Y  y | m , r f m  f r dmdr
*

M min

Mi

Ri

(2.1)

Where, Ns is number of sources in the region,

i

M min

 expi  i mmin  is total rate of exceedence of threshold magnitude (M=5.0 is taken in thisstudy), with α = 2.303a, β = 2.303b.



P Y  y * | m , r is the conditional probability that chosen acceleration exceeded for a given

magnitude (M) and distance (R), andfMi (m) and fRi (r) are probability density functions of magnitude and distance respectively.
Here, M and m are used as the random variable and the specific value for magnitude respectively.
The probability density function for Gunterberg-Richter law with lower and upper boundmagnitudes is expressed asf M m   exp  m  mmin 
1  exp  mmax  mmin (2.2)

Since the recurrence relation is developed for 300km square area, it is applicable for all the cells
around the site. However, the earthquake data is not uniformly distributed over whole area (Fig. 2).
Higher concentration exists in the narrow zone along MCT, MBT than Tibetan Himalayan andlower concentration is in the southern alluvium.

2-2.1 Earthquake densities
Earthquake density is simply the number of earthquakes per unit area. However, the size ofearthquake makes major influence in terms of effects. The effect of a single big event would be far
greater than thousands of smaller events. Thus, activity rate based upon size of earthquake iscalculated using Kernel estimation method Woo 27). Considering the total rate around theparticular site as unity, the fraction of the activity rate, which is earthquake density here, for all thesources around the site, is calculated based on the numbers and sizes of the earthquakes from the
nearby cells. The mean activity rate λ(m,x), at a cell is taken as a kernel estimation sum considering
the contribution of N events inversely weighted by its effective return period which satisfies thecondition (eqn. 3), can be obtained from equations 2.3 to 2.6.
r  hm j 
14

(2.3)

N

 m , x i  K m j , r j 

j 1

(2.4)

T r j  D   h m j K m , r  j   2h m j   r j 

2 D

(2.5)

h m j   H exp Cm j (2.6)

 m , x i

(2.7)

i  N  m, x 
s

i

i 1

Where, K(m,x) is the kernel function, T(r) is the return period of the event located at a distanceof r, h(m) is the kernel band width scaling parameter shorter for smaller magnitude and vice-versa,
which may be regarded as the fault length given by Chen et. al. 28) and D is the fractal dimension,
taken as 1.7. H and C are constants equal to 1.45 and 0.64. From Fig. 2.2, we can see that the
distribution of earthquakes are not only uneven, none of the data has fallen near some faults. The
faults are geological evidences of sources of earthquakes, even though, earthquakes data may nothave fallen in short time span. Thus the activity rate may be based partly on the geological andpartly on the historical data as suggested by Woo 27), and the density of each cell is calculated from
eqn. 2.7. The earthquake densities are illustrated in Fig. 2.4, in which the historical earthquakes andfaults as well as the densities calculated from earthquake data, and faults individually, andcombination of both are shown. For each fault, an equivalent earthquake represented by its
maximum magnitude as given by Wells and Coppersmith 29) was assigned to calculate the density.

0
20

40 0

29.5

Latitude

0
20

400

29

4

0
50

200

0
30

0
20

30

40

0
30 0

30 0

30
0

30.5

30 0

28.5

40
0

20 0

10 0

300

0
20

27.5

30 0

500

28

30 0

0
50

0
40

27
100

26.5

83

20
0

84
85
Longitude

86

87

0
30

82

30 0

20

81

0
40

88

Fig. 2.4 PGA soft soil (5% damping and 10% in 50 years).

The densities calculated from the historical earthquakes are higher around the regions where
great earthquakes have occurred in the past, whereas the densities calculated from maximum

15

magnitude of fault are higher around the faults which account for the future possibilities ofoccurrences even though there might not be the records of historical earthquakes and combinationof two accounts, both past history and future possibilities.
The magnitude is divided into 0.1M and distance into 10km intervals. Nm and Nr are the total
numbers of magnitude and distance bins. Thus, the mean rate of occurrences can be obtained by eqn.
(2.8).
Ns

Nr Nm

 y     i*i  1 j 1 k  1

M min

 i P Y  y * | m , r P M  m P R  r m r(2.8)

2-2.2 Maximum magnitude
In the seismic hazard assessment another important parameter is maximum magnitude. In theearthquake catalogue, maximum earthquake size is M8.2. However, recent study by Lave et al.
2005 30) has shown that big earthquakes of magnitude M8.8 must have occurred in the same area
where 1934 Nepal-Bihar earthquake occurred. Though, it still requires further investigation todetermine its exact size and location, it give there is possibility of bigger earthquake. Thus, in thisstudy, maximum earthquake is considered as M8.8.

2-3. Probabilistic spectra
The mean rate of exceedence of peak ground accelerations and the spectral accelerations arecalculated using all five attenuation laws. Assuming the occurrence of earthquake according to the
Poisson’s process, the accelerations for three probabilities of exceedence in 50 years are calculatedwith all the five attenuation laws for each sites, and the integrated value was obtained giving equal
weights to each of the attenuation laws. The peak ground acceleration corresponding to 10 % ofprobability of exceedence in 50 years (475 years return period) in soft soil condition for 5%
damping obtained at various sites is plotted in Fig.2.4. The values shown in the contours are in gals.
PGA for distribution is higher around Kathmandu than in other parts of the country (Fig. 2.4). The
PGA of 500 gals near Kathmandu, 400 gals in the western part and around 300 gal in the rest part ofthe country are obtained from the calculations.
2.5
PSHA RT 1000 yrs.
PSHA RT 475 yrs.
PSHA RT 100 yrs.

2

BECA 1993 RT 1000 yrs.
BECA 1993 RT 475 yrs.
BECA 1993 RT 100 yrs.

PGA (g)

1.5

1

0.5

0

0

0.5

1

1.5
Periods (secs.)2

2.5

Fig. 2.5 Comparison of spectra for Kathmandu.

163

To compare the results, the highest values (soil group 2) from BECA 3) from among the three
types of soil conditions are taken and the results obtained from this study are plotted together in Fig.
2.5.
The purpose of using return period 100 (39% in 50 years-100 RT yrs.-Fig 5), 475 (10% in 50
years- 475 RT –Fig. 2.5) and 1000 (4.85% in 50 years-1000 RT yrs.-Fig. 2.5) years is to makeclarity with BECA 3). In the plot the values in the horizontal axis are natural periods in seconds andin the vertical axis accelerations are in the fraction of g (acceleration due to gravity).
In Fig. 2.4, higher concentration around Kathmandu can be seen than other part of the country
illustrating the highest risk. However, in the western part, the PGA seems lower. The reason might
be more historical earthquake records are available in the central part than other areas. Kathmandu
has very soft soil and ground motions would have been amplified very much than in other places
and the people would have though earthquake occurred near or in the Kathmandu which might be
the case all the earthquake records centered near Kathmandu. This kind of misinterpretation is very
likely because similar case happened in 1934 earthquake. Because soft alluvium deposit in theGanges plain, heavy damage occurred in Bihar and earthquake was supposed to occur in Bihar asenvisaged by Rana 4) in the beginning. But, it was relocated at 10km south of Mount Everest later.
However, relocation of earthquakes within few kilometers does not make any significant
differences in hazard estimates. The recent investigations of Bilham 17) based upon the GIS revealthat there is a big seismic gap especially in the western part of Nepal Himalaya. The available
earthquake data support only one third of its slip rate. There are many possible alternate
explanations for that. Earthquakes may have gone missing, the slip between the two plates may beaseismic that could die out without producing any earthquakes or earthquake may occur in near
future. Thus, despite the smaller value obtained from the analysis, for design and code
implementation purpose, it is better to consider similar values as obtained for the area around
Kathmandu.
In the Fig. 2.5, the peaks are not aligning in the same axis. This means that different attenuation
laws estimate different peak values of spectral acceleration at different periods. Any specificattenuation law is developed based upon its own hypothesis and tectonic environment. They havedifferent earthquake database, use different distances such as distance from site to faults surface,epicentre, hypocentre, rupture location etc. The depth has also significant effect on the functional
form of attenuation law. Thus, slight differences in the results by different attenuation laws are
obvious. Almost all of the recent attenuation laws developed for subduction zones have used depth
and interface and intra-plate events as separate variables in the equations which have not been usedin Kawashima et al. 7) equation.
The site soil classifications also give significant effects to the results. As the period of vibration
increases the contributions of bigger events go on increasing. BECA 3) does not consider events ofearthquakes whose magnitude is greater than M8, thus it may be the other reason for not aligning
the peaks. BECA 3) has increased earthquakes data by 2.5 times and has distributed the density
uniformly in subzones. This may be the cause for difference in results.

17

2-4. Simulation of Ground Motions
2-4.1 Deaggregation of hazard
The main advantage of probabilistic seismic hazard analysis (PSHA) over other representationsof earthquake threats is it integrates over all possible earthquake occurrences and ground motions to
calculate a combined probability of exceedence that incorporate relative frequencies of occurrenceof different earthquakes. The disadvantage of PSHA is that the concept of a design earthquake islost. There is no single event in terms of magnitude and distance that can be identified as
dominating the hazard. However, significant earthquakes are defined from deaggregation of mean
rate of exceedence 31,32,33). It reallocates the total contribution of mean rate of exceedence interms of magnitudes and distances. Then, distance and magnitude of significant earthquake isdefined on the basis of highest contribution in deaggregation matrix. This earthquake is also called
design earthquake. Acceleration history is developed on the basis of the magnitude and distance.
But, a single earthquake never represents the whole return period or alternately, the same
earthquake never becomes dominant for structures with different natural periods. Thus, as analternate method, a procedure to simulate earthquake ground motions which satisfy whole return
period is presented. The simulation process requires target spectra, thus, for the study, probabilistic
spectra developed for Kathmandu is taken as target. At first, all the contributions in response
acceleration are relocated into corresponding distance and magnitude cells. As an example, thedeaggregation of the peak ground acceleration for 10% probability of exceedence in 50 years isshown in Fig. 2.6. Considering the distance, magnitude and weight of each cells duration ofearthquake ground motion is estimated which is explained in next section.

Contribution (%)

0.04
0.03
1 M(5.0-5.5)
2 M(5.6-6.0)
3 M(6.1-6.5)
4 M(6.6-7.0)
5 M(7.1-7.5)
6 M(7.6-8.0)
7 M(8.1-8.5)
8 M(8.6-9.0)

0.02
0.01
0
0
100
Distance (km) 200

300 MagnitudeFig. 2.6 Deaggregation of hazard for peak ground acceleration 10% probability of exceedences in 50 years18

2-4.2 Duration and envelope function
The duration of the earthquake can be calculated from the magnitude and the epicentral distance.
It means, each earthquake should have separate duration. A probabilistic spectrum consists of many
earthquakes. Even within duration span acceleration amplitudes are not uniform. Thus total duration(TD) is divided into three parts as shown in Fig.2.7. In the first part up to TB, acceleration will be
ascending, between TB to TC, it is much effective and after TC, it starts descending. TB and TC are
calculated using equations 2.9 to 2.10 following Osaki 34) and TD is calculated using equation 11
following Kemption and Stewart 35) . It is significant duration which is defined as the time interval
across which 5 to 95% of total energy is dissipated.
TB  0.12  0.04M  7 TD

(2.9)

Tc  0.50  0.04M  7 TD

(2.10)  expb  b M  6  13

1
2



1.5 M 16.05
10
  c r  c sln TD  ln  21

4.9.10 6 





(2.11)

where, b1, b2, c1, c2 are coefficients equal to 2.79, 0.82, 1.91, 0.15 respectively,  is shear wave
velocity equal to 3.2km/sec. s is soil type and equal to 1 for soil, and zero for rock, M is themagnitude of earthquake and r is the epicentral distance. The envelope function, E(t) presented inFig. 2.7, is calculated using eqs. 12 to 14.

E (t )   t 
0  t  TB :
 TB 

2(2.12)

TB  t  Tc : E (t )  1(2.13)

 ln 0.1
t  TC 
E (t )  exp
0  t  TB :
 TD  TC

J

1(2.14)

K

E(t)
0.1
OTB

B

TC C
Fig. 2.7 Envelope function

19

TD

D

To find out appropriate duration, all accelerations are disaggregated in terms of magnitudes anddistances as shown in Fig. 2.6. Disaggregated cells have separate magnitudes, distances and weights.
Separate significant durations for all cells using equations 2.9 to 11 were calculated, then, obtained
durations are multiplied by corresponding cell’s weight obtained from disaggregation and weighted
durations are found summing up all bins’ durations. We obtain duration for particular value of
response acceleration corresponds to specific period. However, we need a single value applicablefor all acceleration that fall in specified probability of exceedence in specified period of years. Thus,
using similar procedure, durations for all accelerations are calculated. These calculated durations
have combined effects of distance, magnitude and weight of deaggregation. For lower accelerations,contribution of lower magnitude earthquakes in hazard is significant but duration is short. For
distant earthquakes duration is long but its contribution to hazard is low. For frequent earthquakes,
smaller magnitude earthquake also contribute more but when probability decreases contribution ofhigher magnitude earthquake increases. In an average, the duration remains almost same for all
earthquakes which fall in same return period. Thus, the weighted durations corresponding to same
return period are in close margin. Then weighted average duration is calculated from allaccelerations. For spectra shown in Fig. 2.4, durations are presented in Table 2.1.
Table 2.1 Calculated durations

Durations

40% in 50 yrs

10% in 50 yrs

5% in 50 yrs

TD

39.0

50.0

53.0

TB

5.00

5.50

6.00

TC

18.0

26.0

28.0

2-4.3 Design earthquakes

The design earthquakes are simulated for calculated durations (Table 1). The total duration is
first divided into small interval dividing by number N (equation 7). Using incremental time, Fouriertransform pair Ck and xm are evaluated through equations 2.16 to 2.19 as proposed by Osaki 34).
T
(2.15)
t  DN
1 N 1
C k   xm exp  i 2km
, k=0, 1, 2, … , N-1(2.16)NN m 0

 

N 1





x m   Ck exp i 2km
k 0N, m=0, 1, 2, … , N-1

Ck  Fk cos k  i sin k 
Rd 

S ds
S dt

(2.17)(2.18)(2.19)

where Fk is Fourier amplitude, is phase angle, Rd, is ratio of simulated (Sds) to target spectra20

(Sdt). Envelope plot (Fig. 2.7) was divided into small increments and using equations (2.12 – 2.14)
value of envelope function E(t) was calculated. Cumulative value of E(t) was calculated at eachinterval and these all values are divided by final sum which give cumulative probability density
function from zero to one.
Considering total duration as three hundred sixty degree, phase angles for every time steps were
determined randomly using probability density function. Phase angles can be obtained fromprevious earthquake records. However, there are no recorded earthquake acceleration histories forthe region. Thus, random phase angles estimated from envelope function were used.
80
60

Acceleration (gal)

40
20
0
-20
-40
-60
-80
0

5

10

15
20
Duration (secs.)

25

30

35

Fig. 2. 8 Simulated acceleration histories for 40% probability of exceedence in 50 years

400
300

Acceleration (gal)

200
100
0
-100
-200
-300
-400
0

5

10

15

20
25
30
Duration (secs.)

35

40

45

Fig. 2.9 Simulated acceleration histories for 10% probability of exceedence in 50 years

At first, Fourier amplitude Fk is assumed unity. From, Fast Fourier Transform (FFT),
accelerations at each interval was calculated. Accelerations were obtained from Inverse Fourier
Transform. To make the simulated ground motion similar to natural earthquakes, the acceleration

21

obtained from inverse Fourier transform were multiplied by envelope function. Using the calculated
accelerations, response spectra was determined and compared with original spectra called target
spectra. Ratio from simulated spectra to target spectra at each interval was obtained. New Fourier
amplitude was then calculated multiplying old amplitude by obtained ratio. Again, FFT were
calculated and accelerations were determined. The process was repeated until the simulated spectra
and target spectra fit well.
750

Acceleration (gal)

500
250
0
-250
-500
-750
0

10

20
30
Duration (secs.)

40

50

Fig. 2.10 Simulated acceleration histories for 5% probability of exceedence in 50 years

1400
1 T98
2 T475
3 T975
4 S98
5 S475
6 S975Spectral acceleration (gal)

1200
1000
800
600
400
200
0
0

0.5

1

1.5
Period (secs.)

2

2.5

3

Fig. 2.11 Comparison of obtained and target spectra

The accelerations histories developed by this procedure for three values of the probabilities of
exceedence - 40%, 10% and 5% probabilities of exceedence in 50 years are plotted in Figs. 2.8 – 2-

22

10. From simulated acceleration histories, acceleration response spectra are calculated and plottedagainst target spectra (Fig. 2.11).
The spectra from simulated earthquake ground motions and originally calculated from attenuation law
are in good agreement. In real earthquakes, accelerations start from zero, increase gradually, attains peakvalues and decrease to zero finally. Simulated earthquakes also look similar to natural earthquakes.
Amplitudes and nature of simulated ground motions are totally depend on target spectra.

The earthquake ground motions are very essential for non linear dynamic analyses. However,for the regions like Kathamndu, there are no adequate records of historical earthquake
accelerograms which could be used for structural analysis and assessment. Simulation of theearthquakes ground motions compatible to response spectra estimated for specific region may be arational way out. The proposed method may be useful to estimate hazard where sufficient data are
not available. Three separate probabilistic earthquakes which satisfy the target spectra obtained
from probabilistic seismic hazard assessment were simulated. These earthquakes can be applied asseismic input for dynamic analyses of different structures.

2-5. Local Soil Effects
The effect of soil sediment overlying the bedrock is substantial in determination of free field
ground motion at the surface. It has been well recognized, in general, that soil deposits cansignificantly amplify the ground motion. Ground response analyses are carried out to modify theground motions obtained from the hazard analysis for the bedrock taking into consideration thelocal soil amplifications at a site.
The wide spread destruction caused by the large earthquakes in different parts of the world
evidently shows that the local soil amplification effect in most cases is the basic reason for thedisaster. For example, in the 2001 Gujarat-Bhuj earthquake in India, there were substantial damages
at places even at a distance of 250km from the epicenter 36).
The present section deals with an approach for estimating seismic design parameters like groundsurface acceleration time history, response spectrum, design response spectrum etc for the cultural
heritage site of Jhatopol, in the vicinity of the World Heritage Site of Patan Durbar square of
Kathmandu valley.

2-5.1 Soil Profile Data Acquisition and Interpolation

The initial step for site response analysis involves the collection and validation of thegeotechnical and geological information of the site. It includes the identification soil profile
information such as number of layers, depth of the water table and layer information such as
material name, thickness, unit weight, plasticity index, fines content etc and their damping value,
which influence the seismic responses. In the absence of the site specific soil sediment data withrequired explorations and tests, readily available data from boreholes in the vicinity and fromvarious literatures are used to arrive at the soil profile of the site of concern.
In this study, data of 27 deep boreholes with depth more than 30m are collected from private

23

agencies, government offices, and from literatures. These data basically consist of material of layers,
thickness, water table, elevation of boreholes etc. All these collected borehole log data areconnected/matched by drawing profiles by hole - to- hole cross-section method. Such techniquehelps to display logs of the boreholes along the desired direction passing through the site. Moreover,a subsurface geological database prepared by Piya 37) is also used to interpolate the soil profile atthe site of interest. Piya had collected borehole data from various organizations during field work ofKathmandu Valley nearly 192 deep boreholes with 45 up to bed rock level, 300 shallow bore holesof 5 to 30m depth. He had developed GIS layer model of the surface and the creation of borehole
logical cross-section by using a generalized subsurface geology model with X and Y coordinatesand depth values. For this work, he used ILWIS (Integrated land and water information system,1988) and Rockworks 99 to use borehole data in the generation of a subsurface geological database.
ILWIS is used for the generation hole to hole fence diagrams in same direction as done before. This
generalized geology was interpolated to a four-layer model and was used as the basis of the soilmodeling. The four layers were recent post lake deposits (alluvial), lake deposits, pre-lake deposits
and bedrock respectively. The first layer from the surface consisted mainly of sandy and silty
sediments, and the second layer consisted of clay sediments. The third layer consisted mainly ofgravel. The fourth layer was bedrock, which consisted mainly of limestone, sandstone, slates andphyllites.
Since the site specific geotechnical properties of soil strata are unknown, soil strata isinterpolated with the help of geotechnical information obtained from fence diagrams done on the
GIS model and plotted hole to hole cross section These two different outputs are cross checked andfinally established the soil column for our desired site.

2-5.2 Characterization of the Soil

For the proper modeling of seismic responses of the area it is necessary to identify all required
basic input data for SHAKE 2000 software. The basic input regarding soil profile like soil type,thickness, shear wave velocity or shear modulus, unit weight of material. After interpolating theborehole log profile with soil type and thickness at specified site, other character of soil is derived
as described in the following paragraphs.
(1) Estimation of Shear wave velocity

Out of 15 various empirical equations, investigated by Ohta and Goto 38), the one relation forshear wave velocity with the depth, soil type and geological age, is selected for use in the study.
The selected equation has a correlation coefficient of 0.86. The selected relationship is given by:(2.20)

24

The shear wave velocity for the bed rock is considered to be approximately 1520 m/s based on
the available different literatures.
(2) Density of Soil Strata
The study team on Earthquake Disaster Mitigation in the Kathmandu Valley 39), under Japan
International Cooperation Agency (JICA) measured shear wave velocities of five drilled boreholes
using P and S waves (PS) logging. The study team recognized the relation between N values andshear wave velocities from previous tests results in Japan and also recommended the same relations
for Kathmandu valley and gave the representative bulk density values of the different soil strata
with shear wave velocities shown in Table 2.2. The density of soil layer is derived from this tableaccording to the shear wave velocity.
Table 2.2 Shear wave velocities and density for different soil strata in Kathmandu valley (Source: 39)

Soil type
Clay to clay silt

Silt to fine sandMedium to course
sand
Sand and gravel

Shear wave velocity(m/s)
Vs <175
175<Vs<300
300<VsVs <200
200<Vs<350
350<VsVs <200
200<Vs<350
350<VsVs <200
350<VsDensity(KN/m3) kcf
15
0.093
16
0.099
17
0.105
16
0.099
17
0.105
18
0.112
17
0.105
18
19
19
20

0.112
0.118
0.118
0.124

In the case of dynamic shear modulus curves and damping curves, these curves are selectedfrom the list given in shake2000 according the type and properties of soil

2-5.3 One Dimensional Site Response Analysis

One dimensional wave propagation analysis is carried out to determine the ground response of
the soil sediment of the study area. For the purpose, the earthquake ground motion acceleration time
history at the bedrock, simulated for the site is taken as the input. The ground response analysis is25

carried out using the software package SHAKE 2000, considering the linear as well as equivalentlinear properties of the soil layers. The obtained soil amplification factor is used to determine thefree field ground motion parameters.
The locations of the 27 deep boreholes with their depth varying from 30 m to 475m, the data of
which were collected from various agencies and from literatures, are presented in Fig. 2.12.

Fig.2.12 Bore Hole Locations and Directions of Different Hole to Hole Cross-sections

The hole to hole borehole log columns profile are made in seven different directions as shownin Fig. 2.12, and the cross section profiles are shown in Figs. 2.13a – 2.13g The fence diagrams arealso computed from IWLIS software in combination of Rockworks 99 for same seven directions as
described. The borehole log profile cross-sections with fence diagrams of respective direction are
shown in Figs. 2.14a – 2.14 g. The soil profile is interpolated for the location of the specified site,
based on the above borehole log profile hole to hole sections and fence diagrams, and presented inTable 2.3.
Table 2.3 Soil Layer Interpolation Detail
Layer
No.

Layer TypeInterpolated from
Sections

1

Sandy Clay

1-1 and 2-2

2Fine to Coarse Sand

1-1 and 2-2

3Black Clay

1-1, 2-2, 3-3, 4-4 and 7-7

4

Sand and Gravel

2-2, 4-4 and 7-7

5Black Clay

2-2 and DMG8-B23

6

Bed Rock26

Remarks

Thickness of layer is taken as
average thickness of usedinterpolated sections

Fig.2.13 a Borehole-log columns along section 1-1

Fig.2.13 c Borehole-log columns along section 3-3

Fig. 2.13 b Borehole-log columns along section 2-2

Fig.2.13 d Borehole-log columns along section 4-4

Fig. 2.13e Borehole-log columns along section 5-5

Fig. 2.14a Fence Diagram along Section 1-1

27

Fig. 2.13f Borehole-log columns along section 6-6

Fig. 2.14b Fence Diagram along Section 2-2

Fig.2.13g Borehole-log columns along section 7-7

Fig. 2.14c Fence Diagram along Section 3-3

Fig. 2.14d Fence Diagram along Section 4-4

Fig. 2.14f Fence Diagram along Section 6-6

28

Fig. 2.14e Fence Diagram along Section 5-5

Fig. 2.14g Fence Diagram along Section 7-7

The interpolated soil profile with type and thickness of soil for the site is shown in Fig. 2.15.
After finding the soil profile for the site, the total depth of the soil sediment is divided into 96
sub-layers. The thickness is given to each sub-layer such that the characteristic site frequency(fundamental frequency) is greater than the maximum value of frequency content in the input rockmotion so that the layer can propagate the motion. Thickness of sub-layer:
H = Vs/(4*fmax)(2.21)

Where, fmax is the highest frequency that the layer can propagate, and
Vs is the shear wave velocity of the layer.
The shear wave velocity for each sub-layer is estimated using relations described in (1) above,and density is assigned to those sub-layers as described in (2). The properties of the soil sub layers
including the shear wave values and the densities, along with the simulated seismic ground motion
at the bedrock are used to carry out the ground response analysis. The shear modulus reduction
curves and damping curves used for different soil types are shown in Fig. 2.16. The water tablelevel in the analysis is taken as 3m from surface, which is the value found for the construction site
in the vicinity. The Linear as well as Equivalent linear site response analysis are carried out in
SHAKE 2000 using simulated earthquake motion for the bedrock of the same location taken as
input motion shown in Fig. 2.17. The Fourier amplitude spectrum of the simulated ground motion
acceleration time history at the bedrock is shown in Fig. 2.18. The ground motion acceleration time
histories, Fourier amplitude spectra, and response spectra for each site response analysis arecomputed at the surface of the site.

29

Fig. 2.15 Interpolated Borehole log at the Site

Fig. 2.16 The dynamic material properties and their relation to the shear strain

Fig. 2.17 Simulated Acceleration Time History at the Bed Rock (For 475 Years Return Period)
30

The time histories, Fourier spectra and spectral acceleration at the surface computed from bothlinear and equivalent linear site response analysis are shown in the Figs. 2.19 – 2.24.

Fig. 2.18 Fourier Amplitude Spectrum of Simulated
Earthquake

Fig. 2.19 Acceleration time history at surface (Linear
site response)

Fig. 2.20 Fourier amplitude spectrum (Linear site
response)

Fig. 2.21 Response Spectrum (Linear site response)

Fig. 2.22 Acceleration time history at surface obtained from Equivalent site response analysis

31

Fig. 2.23 Fourier amplitude spectrum (Equivalentlinear site response analysis)Fig. 2.24 Response Spectrum (Equivalent linear site
response Analysis)Fig. 2.25 Comparison of design response spectra(Newmark-Hall’s Method) 40) with NBC 41) design
spectrum (Soft soil)

Fig. 2.26 Comparison of design response spectra(Newmark-Hall’s Method) 40) with IS code 42)
design spectrum (Soft soil)-Very severe

The response spectra are smoothened by Newmark- Hall’s method 41) to obtain design response
spectra for both type of site response analysis, and are compared with Nepal Building Code design
spectrum 42) and IS code design spectrum 43) as shown in Fig.2.25 and Fig.2.26 respectively. The
Newmark-Hall design spectrum is obtained by using nonlinear software. The velocity time history
and displacement time history of surface motion required for the input ground motion for Nonlinear
are calculated from Seismosignal software.
The acceleration time history at surface as shown in the Fig. 2.19 obtained from linear site
response analysis gives peak ground acceleration 0.425g which is 1.6 times greater than the PGA at
bed rock. As seen in Fig 2.20, the Fourier Amplitude spectrum at surface, the majority of energy isconcentrated between the frequencies 0.5 Hz to 2.5 Hz. It shows that the linear effect of soil
subjects more seismic energy to the structures having natural time period ranging from 0.4 sec to 2
sec.
32

The acceleration time history at the surface as shown in Fig. 2.22 from equivalent linear
analysis gives peak ground acceleration 0.314g which is 1.18 times greater than the PGA at the bed
rock. As seen in Fig 2.23, the Fourier amplitude spectrum at surface, the majority of energy isconcentrated at frequency of about 1 Hz. Comparison of the Fourier amplitude spectrum with that at
bed rock shows that the soil conditions greatly influence the frequency content of the earthquake
motion. The results show that the board banded spectrum is converted into narrow banded. It showsthat the nonlinear effect of soil subjects more seismic energy to the structures having natural time
period of about 1 sec. The amplification value of this response is less than that of linear analysis
because comparatively dissipation of energy within the soil mass is more in equivalent linear
analysis.
The response spectrum presented in Fig 2.21 obtained from linear site response analysis showsthat peak spectral value is about 1.54 g at period of 0.38 sec. Comparison of the response spectrumwith the spectrum at the bed rock shows that the peak of the response spectrum at surface issignificantly deviated from that at the bed rock. This clearly shows that the input excitation to thestructures having those periods may be significantly influenced by the soil conditions. The response
spectrum given in the Fig. 2.24 obtained from equivalent linear analysis shows that the peak
spectral value is 1.28g at period 0.84 sec. The comparison of response spectrum with that of linear
analysis shows the spectral shapes become boarder banded and the spectral values are drasticallyreduced near the peaks when equivalent linear analysis is taken into account.
The site response analysis results show that the average site period is about 2 sec. So, the site
can be classified into soft soil site. Fig. 2.25 presents the comparison of Smooth response spectrum
obtained by Newmark-Hall’s method 41) at surface for both type of site response analysis withdesign response spectrum of NBC 42) for soft soil. The smooth response spectrum of linear siteanalysis shows that the maximum spectral accelerations for the period ranging from 0.13 sec to 0.62
sec are about 1.2 times greater than that are stipulated in code. And the smooth response spectrumof equivalent linear site analysis shows that the peak spectral accelerations for the period ranging
from 0.15sec to 0.99 sec are about 1.1 times less than that are stipulated in code. This indicates thatthe structure of period between those ranges have to be faced little bit smaller seismic forces thanstipulated in codes for the site response analysis. The comparison shows that the spectra are lower
at longer periods greater than 0.7 seconds in the case of linear site response analysis which seems
very conservative at longer periods.
Fig. 2.26 presents the comparison of Smooth response spectrum obtained by Newmark-Hall’s
method 41) at surface for both type of site response analysis with IS code design spectrum 43) for
soft soil. The smooth response spectrum of linear site analysis shows that the maximum spectral
accelerations for the period ranging from 0.13 sec to 0.62 sec is nearly equal with the value
stipulated in the code. And the smooth response spectrum of equivalent linear site analysis showsthat the peak spectral accelerations for the period ranging from 0.15sec to 0.99 sec are about 1.3
times less than that are stipulated in code. This indicates that the structure of period between those
ranges have to be faced little bit smaller seismic forces than stipulated in codes for the equivalentsite response analysis. This comparison shows the spectra for longer period are closer to each otherfor both site analyses. Fig. 2.19 presents the simulated acceleration time history at the surface forthe return period of 475 years, and the peak ground acceleration (PGA) is about 0.4 g. Fig.2.19 alsopresents the simulated acceleration time history at the surface for the return period of 475 years, and33

it is developed through ground response analysis with the simulated ground motion at the bedrock.
It is seen from Fig. 2.19 that the peak ground acceleration is about 0.425 g, which is slightly larger
than the PGA in Fig. 2.9.

Some of the major conclusions of the study are:
1. The maximum PGA amplification is about 1.6 times greater than PGA at bed rock for linear
ground response analysis and 1.18 for equivalent linear response analysis.
2. The soil conditions greatly influence frequency content of the earthquake motion. The broad

banded spectrum is converted into narrow banded.
3. The linear effect of soil subjects more seismic energy to the structures having natural time

period ranging from 0.4 sec to 2 sec and nonlinear effect of soil subjects more seismic energy
for those structures having natural time period of 1 sec.
4. When the soil has a linear behavior, the input excitation to the structures having 0.38 seconds

periods (with peak spectral value 1.54g) may be significantly influenced by the soil conditions.
On the other hand, when the soil goes to the non linear behavior, soil may influence more
excitation (with peak spectral value 1.28g) to the structures having period of 0.84 sec
5. The spectral shapes become broader banded and the spectral values are drastically reduced near

the peaks when equivalent linear analysis is taken into account.

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26) Kanno, T., Narita, A., Morikawa, N., Fujiwara, H., and Fukushima, Y.: A new attenuation relation for strong ground motion in
Japan based on recorded data, Bulletin of Seismological Society of America , 96 (3), pp. 879-897, 2006.
27) Zhao, J. X., Zhang, J., Asano, A., Ohno, Y., Oouchi, Takahashi, T., Ogawa, H., Irikura, K., Thino, H. K., Somerville, P. G.,
Fukushima, Y., and Fukushima, Y.: Attenuation relations of strong ground motions in Japan using site classification based upon
predominant period, Bulletion of Seismological Society of America , 96 (3), pp. 898-913, 2006.
28) Woo, W. : Kernel estimation methods for seismic hazard area source modeling, Bull. Seismol. Soc. Am. , 86 (2), pp.353-362,
1996.
29) Chen, Y., Liu, J., Chen, L., Chen, Q., and Chan, L.S.: Global seismic hazard assessment based on area source model andseismicity data, Natural Hazards, Kluwer Academic Publishers , 17, pp. 251-267, 1998.
30) Wells, D.L., and Copersmith, K.J.: New empirical relationships among magnitude, rupture length, rupture width, rupture area,and surface displacement, Bull. Seismol. Soc. Am. , 84 (4), pp. 974-1002, 1994
31) Lave, J., Yule, D., Sapkota, S., Basnet, K., Madan, C., Attal, M., and Pandey, R.: Evidence for a great medieval earthquake (1100
A.D.) in the central Himalayas, Nepal, Science , 307, 2005.
32) Mcguire, R.K.: Probabilistic hazard analysis and design earthquakes: Closing the loop, Bull. Seismol. Soc. Am., 85, (5), pp.12751284, 1995.
33) Chapman, M.C.: A probabilistic approach for ground motion selection for engineering design, Bull. Seismol. Soc. Am. 85, pp.
937-942, 1995.
34) Bazzurro, P., Cornell, C.A.: Deaggregation of seismic hazard, Bull. Seismol. Soc. Am., 89 (2), pp. 501-520, 1999.
35) Osaki , Y.: Introductory book for spectral analysis of earthquake motions”, Kajima Institute of Publishing Co. Ltd, 1994.
36) Kempton, J. J. and Stewart, P. J.: Prediction equations for significant duration of earthquake ground motions considering site andnear-source effects, Earthquake spectra, Vol. 22(4), pp. 985-1013, 2006.
37) Govinda Raju, L. Ramanna, G. V. Rao, C. Hanumantha, and Sitharam, T. G.: Site-specific ground response analysis, Current
Science, Vol. 87, No. 10, 2004.
38) Piya, B.K: Generation of a Geological Database for the Liquefaction Hazard Analysis For Kathmandu Valley, Thesis, 2004.
39) Ohta, Y. and Goto, N.: Estimation of s-wave velocity in terms of characteristic indices of soil, Butsuri-Tanko, Vol. 29, No. 4, pp.
34-41, 1976.
40) Nippon Koei & Oye: The study on Earthquake Disaster Mitigation in the Kathmandu Valley, Kingdom of Nepal, report, 2001.
41) Newmark, N. M., and Hall, W. J.: Procedures and criteria for earthquake resistant design, Building Practices for Disaster
Mitigation, Building Science Series 46, U. S. Department of Commerce, pp 209-236, and 1973.
42) NBC 105- 1994: Seismic Design of Buildings in Nepal, Nepal National Building Code, HMG of Nepal, Ministry of PhysicalPlanning and Works, DUDBC, Kathmandu, Nepal, 2004.
43)IS 1893 (Part 1) 2002: General Provisions and Buildings (Fifth Revision), Indian Standard Criteria for Earthquake Resistant
Design of Structures, Bureau of Indian Standards, New Delhi, India, 2002.

35

36

3. Structural Analysis of Traditional Brick Masonry Buildings
3-1. Present situation of Traditional Brick Masonry Buildings in Patan
Prem Nath Maskey

3-1.1 Structural Design and Construction
The study area of Jhatapol represents the prototype of settlements in Patan city which has
become a heritage site in terms of traditional buildings and historical structures. The area and its
neighborhood have their layout with a mixture of buildings of different periods, with very different
levels of maintenance, from the 15th century onward. Recently a significant number of original
buildings have been intervened with concrete framed buildings, usually with extension of floors
making the buildings with 5 or more than 5 storeys. This has aggravated the seismic vulnerability
situation with substantially greater height and small plan area.
The large number of private buildings in the core area of Patan city has traditional architecture
and constructed with indigenous technology. Most of the buildings are three or four stories highwith floor height between 1.8 to 2.4m. Generally these buildings have a simple rectangular planwith depth about 6 m and length varying from 3 to 10 meters. The foundation is usually shallow,
made out of stones or brick. The superstructure is constructed with locally available burnt clay
bricks and mud-mortar. The whole structure is supported by three walls, two outside walls and one
spine wall at the centre. At the upper storey the spine wall is sometimes replaced by a timber frame
system so as to create a larger continuous space. The floors and roof are supported by timber joists,over which wooden boards or planks with a thick layer of mud topping is applied. The roof isusually doubly pitched covered with traditional roofing tiles made of burnt clay.
The buildings are coalesced with each other forming a courtyard. At least one house in the
courtyard provides access to the street through a gateway on the ground floor. This is generally due
to lack of space or due to security reasons. A brief description of the most important structuralcomponents is described in the following paragraphs.
Foundations
The foundations of the traditional masonry houses, small temples, and monasteries are typicallyshallow and normally strip foundations constructed with brickwork at a depth of about 150 cm or
more below grade level for a three story structure. These are sometimes often stepped, and thebottom most step has a width of about 75 cm and more. The base is generally formed by a few
layers of large pebbles or broken stones. This is followed by the usual brickwork, which continues
into the upper structure. No damp proofing was used in traditional masonry structures.
Masonry walls

The structural system of the traditional brick masonry buildings is based on the unreinforced
brick masonry in mud mortar. Walls usually consist of three different vertical layers of masonry.
The outer face is made of a wythe of burnt brick, locally known as ma apa. For the main front ofimportant buildings or temples, a special wedge-shaped brick, daci apa is employed quite often to
create a veneer-like façade. The taper of these bricks results in a varying thickness of the mortar
37

joint from the front to the back. A hairline joint is created, which decreases the weathered area of
the joints. These hairline joints are filled with saldhup, a mixture of natural black resin and mustardoil (Fig. 3-1.1).
The inner face of the wall is made of one wythe of burnt or even unburnt brickwork (kaci apa).
Only rarely do those thick walls consist of continuous solid brickwork. More often they consist of acore of brick rubble infill set between an outer faces of brick (Fig.3-1.1). The bricks are
traditionally laid in mud mortar. Commonly, all bricks of the outer face are laid as runners, so that
there is no or only little bonding between the different leafs. Cross walls are often simply butt
jointed with no interlocking at all. Figs. 3-1.2a and 3-1.2b presents the walls made of ordinary clay
brick and walls made with the conical bricks, daci apa.

Fig. 3-1.1 Typical wall cross section

Fig. 3-1.2 (a) ordinary brickwork (b) original dachi aapa brickwork

Floor system
The floor of the traditional houses is constructed of timber floor. Such a floor is supported on
timber joists running from party wall to party wall with variable dimensions, but usually of section
50 x 100 mm and closely spaced at a spacing of 200 to 300 mm. Floors are supported by closely
spaced timber joists with a layer of terra cotta tiles or wooden planks. This subfloor is topped with a
10cm thick cover of fine clay. The joists rest on continuous wooden wall plates that are embeddedin the masonry. Wooden pegs are provided at the ends of the timber joists adjacent to the supports,
which are normally wall plates, to restrain the horizontal movement of the joists. The averageheight of the floors is about 2.20 m.
38

Roof system
Traditionally the buildings have the roof structure based on timber rafters, sometimes on timber
trusses, with the local roofing tile (jhingati) and with a thick mud insulating layer present The mostprominent feature of the traditional masonry buildings is the wide projecting roofs, which typically
protrude more than one meter from the façade; in the case of larger buildings and temples this canbe more than 2 meters. All roofs are pitched purlin roofs, with a slope of about 30 degrees. Ridge
beams are typically supported by kingposts. The eave purlins are supported by often magnificently
carved wooden brackets (tunalas). The brackets are set at an angle of approximately 45 degrees,and spaced at about 2m centers. These are supported either on a brick cornice or a wooden ledge, or,less often, on a slightly projecting beam. The rafters are connected above the ridge beam with half
splice joints. A layer of horizontal wooden planks or flat terra cotta tiles is placed on top of therafters. A thick layer of mud (5 – 20cm) is put on top of this substructure, in which the local roof
tiles (djingati) are pressed.
Windows size and frames
The traditional masonry buildings are characterized by windows, in general, of smaller squaresize, and located symmetrically in the walls. The windows are built with a wooden double frame,
and with wooden lintels extending in multi layers to the surrounding walls. The window opening
shape, size and layout in the traditional buildings in later periods are different and are generally
altered in style. The most prominent feature of the traditional buildings is the latticed window (SanJhya) peculiar to the Newar house, a richly decorated window that takes most of the façade at thethird storey level, and with seating framed within it. The short opening ratios for the windows in the
traditional houses allow a larger shear area near the openings, and stops decrement of the horizontal
in plane stiffness of the walls, which are crucial in the seismic resilience of the unreinforced
masonry buildings.
Timber framed structure of the ground floor (dalan)
The dalan is one of the prominent features of many traditional buildings in the locality. It is
normally a ground floor space with a timber frame made of twin columns, surmounted by a capitalon which sits a double beam (Fig. 3-1.3). The two adjacent timber frames are usually connected
only at the level of the beam. This space is most commonly found at the ground floor of the mainfaçade of buildings in which the front room is used as shop or workshop.

39

Fig. 3-1.3 dalan structure at ground floor of a courtyard

A similar timber construction is also common in upper storeys as an internal structure in placeof the spine wall. The columns usually have square cross section of about 100 x 100 mm to 150 x
150 mm, pinned to the ground or floor, and at a spacing of 100 to 150 cm apart. The capital and thebeam are also connected to the column by timber pins and the joists of the floor above sit directlyon the beam, connected to this in some cases by timber pegs. As is seen, the first floor joists directly
support the façade of the upper storeys. The dalan structure, somehow imparts a soft storey effect inseismic terms associating with the failure mechanism, as all connections are simply pinned; thissituation may increase the seismic vulnerability factor of the traditional masonry buildings.
Earthquake resistant measures
The traditional masonry buildings of Patan have the following earthquake resistant measures:
1. Configuration: Most of the buildings are rectangular. These simple and Symmetricconfigurations in plan make the building more stable. This causes no excessive torsion
because the centre of mass and center of rigidity coincides in the building.
2. Length to breadth ratio: In most of the buildings the length to breadth ratio is 2 or less.
3. Openings: Openings are relatively small and symmetrically located. The small openings
increase the length of the facade and substantially increase the stiffness of the building.
4. Double framing of opening: Buildings have two complete frame of timber around theopenings to strengthen it against lateral force.
5. Wall thickness: Wall thickness at the ground floor is normally 45 cm or more. Thickness
decreases with succeeding upper floors. As the horizontal thrust at the ground level develops
highest at the time of earthquake in the building, the greater thickness reduces the shear
failure at that time.
6. Floor height: In all cases the storey height is less than 2.5m
7. Number of stories: Most of the buildings are three stories.
8. Wooden bands: Wooden bands around the building at sill level, lintel level and at the floor
level can be found curved as “Naga”. These bands protect the walls from out of plane
failures as well as provide integrity between different structural elements by connecting
orthogonal walls. Also building act as monolithic, so that earthquake force is resisted by thebuilding as complete unit rather than by individual part.
9. Vertical post at corners: These vertical posts at corners act as vertical tensile reinforcement.
This protects the building from damage due to tensile cracks in the building. In some cases
they provide some redundancy in the system which is very useful to withstand earthquake
force.
10. Struts: Struts are long wooden planks which support the overhanging roof of the temple. It
transfers the load of the roof to the vertical load bearing wall.
11. Wooden corner stitch: In addition to wooden bands, corner stitch can be found whichconnects orthogonal walls and protects from separation at corners.
12. Wooden pegs: Proper connection of all wooden elements by wooden pegs can be seen in
traditional buildings, which helps for proper connection of roof and floor with wall as wellas the different elements of roof or floor.
13. Boxing of opening: Boxing of opening by wooden frames, either all around or along bothedges of the masonry wall provided strength around the opening.
14. Reducing load consecutively in upper floors: There are the reduction of the wall thickness
in upper floors due to lesser load carrying requirement and the use of light partition walls,
second and third floor central walls are often total timber frames. This reduces dead load ofupper floor and gives more shear strength to the spine.
4015. Plinth: Mostly on temples, foundation design for tall temples was changed into massive
multiple plinths. These improve response against wave amplification and avoid resonancewith ground.
Deficiencies increasing the vulnerability of the traditional masonry buildings
The deficiency elements for earthquake resistant measures in traditional masonry buildings are
as listed below:
1. Wall: Wall structure was always built in mud mortar with three vertical layers. Outer andinner face layers were not well connected with the middle core wall. Normally the middle
core was filled with rubbles and mud, which makes wall very poor to hold the heavy loadfrom the main structure. The quality of the bricks was always good on the exterior surface,
but normally for interior walls inferior bricks were used. In many places, fired bricks wereused only for the exterior while for the interior and middle fill, simple sun-dried bricks andrubbles were used.
2. Shape: Most of the buildings are simple and symmetric in plan. However, they can beslender and thus vulnerable to damage.
3. Pounding effect: In urban most of the buildings are joined together to form blocks, Henceduring severe earthquake, when all buildings shake according to their own natural period ofvibration, pounding action between adjoining houses can take place.
4. Material: Sun dried bricks used for walls in buildings are brittle in nature and cannot taketensile stresses incurred during earthquake, thus resulting in large cracks or collapsing ofwalls. Also the quality of mortar is poor.
5. Heavy roof and flooring: In many buildings roof is held relatively tightly to wall by use ofwedges and tie members. However, roof is heavy due to use of thick layer of mud and heavy
tiles that can create problems as bigger the reactive masses of the building, the bigger is theearthquake forces.
6. Workmanship and maintenance: The construction workmanship is entirely depends on
the skill and experience of the craftsmen. The climate with heavy monsoon rains places
several demands on materials. In some cases, no measures are taken until the building
finally falls down.

3-1.2 Method of Repair
The existing stock of traditional brick masonry buildings of Patan constructed in different
periods of history is in various states of condition. The aging of the materials, lack of regular
maintenance and repair, modification of the buildings as per the social requirements havesubstantially reduced their original strength and serviceability. It is well recognized that the brickmasonry buildings have a limited capacity to withstand the earthquake action even when these arenew. In order to prepare the traditional buildings to properly perfom their intended functions, andmore over to withstand safely the seismic action in future earthquakes, repair, restoration andstrengthening of these buildings become essential. The need to improve the ability of these existingbuildings to withstand seismic forces arises generally from the evidence of damages of masonrybuildings in past earthquakes.
The need as well as the degree of strengthening must be based on the structural assessment of
the buildings in reference with the possible seismic hazard in the locality. The establishment of
actual strength and capacity is encountered with considerable uncertainties related with material
properties and with the amount of strength deterioration due to age. However, the decisions are41

generally based on gross conservative assumptions about actual strength.
The method of repair or restoration and strengthening largely depend upon the structural system,
materials of construction, and technology to be adopted. Moreover, there may be a restriction on
use of new materials from the Department of Archaeology, if the traditional buildings are labeled ashistorical structures, and are located in the monumental zones. In most of the cases, the materials to
be used in the process of repairs, restoration and strengthening are confined to bricks, mud mortar,
timber and stones.
(1) Concept of Repair
The main purpose of repairs is to reinstate the original character of the building so that thebuilding will function as originally intended including all its services. However, repairs are notintended to improve the structural capacity, and hence may not meet the structural requirements toundertake the seismic action in future earthquakes. The repair works in the traditional brickmasonry buildings of Patan include the actions like,i. Patching up of defects such as cracks and fall of plaster;ii. Repairing doors, windows, replacement of glass panes;iii. Re-building non-structural walls etc;
iv. Re-plastering of walls as required;v. Rearranging and replacement of disturbed/broken roofing tiles(jhingati);vi. Relaying cracked flooring at ground level;vii. Relaying mud topping of the timber floor;viii. Replacement of planks/boards of the timber floor;
ix. Treatment or replacement of timber elements such as joists, rafters, wooden stairs and wall
plates etc.;
x. Treatment for efflorescence and dampness;
xi. Repainting/ relaying preservative on wooden surfaces;xii. Redecoration — whitewashing, painting, etc;xiii. Repairing services such as electric wiring, gas pipes, water pipes and plumbing services.
(2) Concept of Restoration
The main purpose of restoration is to carry out repairs to structural elements of the buildings,
and hence restoration is the reinstatement of the strength the building had before the damage
occurred. This type of action is generally is undertaken when there is evidence that the structural
damage can be attributed to exceptional phenomena that are not likely to happen again and that theoriginal strength provides an adequate level of safety. The restoration process includes the actions
like rebuilding portions of structural elements or addition of more material with an aim to bringback the original strength. The restoration process may involve inserting temporary supports,
underpinning, etc.
The restoration works in the traditional brick masonry buildings of Patan may include:
i. Removal of portions of cracked masonry walls and piers and rebuilding them in richer mortar.
Use of no shrinking mortar will be preferable.
ii. Addition of reinforcing mesh on both -faces of the cracked wall, holding it to the wall throughspikes or bolts and then covering it suitably. Several alternatives have been used.
iii. Injecting epoxy like material, which is strong in tension, into the cracks in walls, columns,
beams, etc.
(3) Strengthening Concept
The main purpose of strengthening of the traditional brick masonry buildings is to increase its
42capacity of withstand the seismic action in future earthquakes. The seismic performance of theexisting traditional brick masonry buildings is affected by their original structural inadequacies,
material degradation due to time, and alterations influencing the behavior of the structural system.
Seismic strengthening of these buildings is essential, as their evaluation reveal that the original
strength was not adequate to combat the seismic hazard expected in the area.
The traditional brick masonry buildings are located in the monumental zone and most of thesecarry heritage value, hence complete replacement of the buildings by new construction withearthquake resistant features adopting modern materials is not possible to retain the social harmony
and cultural heritage. This situation calls for an essential need for improvement over the original
seismic capacity of the buildings as a primary step towards disaster risk mitigation of the area.
The determination of the degree of strengthening depends upon the structural and seismic
assessment of the buildings. The process should not be limited to improving the strength ofstructural elements in isolation, but should consider the overall structural behavior of the structural
system of the buildings.
In reference with the existing traditional brick masonry buildings of Patan, the general principleof the seismic strengthening procedures is focused on:i. Increasing the lateral strength and stiffness in one or both directions, by increasing wall areasor the number of walls and columns.
ii. Providing proper connections between the structural elements: walls, floors, roofs,
foundations etc so that the whole structure acts as a unit. It should have a clear load pathcapable of transmitting the gravity as well as inertia force due to earthquake action.
iii. Removing the features, which are the sources of weakness or which produce stressconcentrations in some structural members. Mass and stiffness irregularity in plan and inelevation and large openings in the walls are the intrinsic reason for such defects.
iv. Providing the traditional detailing of connection of timber joists with the wall plates or wallswith timber pegs (shear lock); providing timber ties between the door and window frames atstrategic levels, upright post at corners and also adjacent to openings to give the framing
action.
v. Improving in-plane stiffness of the timber floors by providing extra layer of wooden planks orboards nailed perpendicular to the existing layer of planks or boards over joists.
vi. The methods of repair, restoration and seismic strengthening of unreinforced brick masonrybuildings are highlighted by 1), whereas the traditional methods of them applicable totraditional brick masonry buildings of Patan are elaborated in section 2).

3-1.3 Present Situation of Buildings
The old city of Patan is a dense urban area within the Kathmandu Valley. It is predominantly
inhabited by indigenous `Newar` people on housing clusters laid out around open courtyards.
Similar to other Newar settlements, it is common to observe regular cultural function like ritual in
the open space. The urban settlement in Patan is organized into various neighborhood units and islinked by a hierarchy of streets and open spaces, used for various rituals. The traditional
neighborhood units, in terms of spatial extent, are defined prominently by a series of houses joined
wall to wall along the street or by a built form enclosing an open area 3). As a typical characteristicof the traditional settlement, the sequence of open spaces are very much part of the life of thepeople for carrying out daily activities and rituals. The open space and the community structures
like sattals and patis may serve as the excellent emergency escape and shelters respectively in theevent of disasters such as earthquake, epidemy or fire. The inhabitants in Patan city, as in other old
43cities of the Kathmandu Valley, are exposed to the earthquake hazard.
It is evident from various characteristics of the existing traditional buildings that the inhabitants
had a fail deal of knowledge and practice of planning the space, and constructing the buildings tocombat with the earthquake hazards. Within the limits of the availability of the indigenous materials
and technology, the builders practiced to achieve the most possible earthquake resistant buildings.
The regular configuration with symmetrical plans, number of storeys limited to three, symmetricallocation of openings with minimum sizes is planning features appropriate for the earthquake
resistance characteristic of the structure. Several details of connections, such as the shear locks inthe joists, vertical upright posts, provision of timber ties at strategic levels of walls, provision of
double framing in the door and window openings are some of the examples of many design
methods and technology adopted, which considerably help in overcoming the intrinsic weaknessesof the unreinforced brick masonry.
The old city of Patan has been able to hold its urban fabric including the traditional brickmasonry buildings. However, there has been a recent trend of modernizing the buildings in the area
basically due to change in socio-economic condition, and the new requirements according to thechanging living styles.
The present situation of the buildings in the area can be described as the conglomeration of
three broad categories: (i) traditional brick masonry buildings in original form, and (ii) traditional
brick masonry buildings with modifications, and (iii) buildings with modern features like inclusionof concrete frames. The structural condition and seismic resilience of these types of buildings aredifferent. The salient features of these categories are briefly described as follows:(1) Traditional brick masonry buildings in original form
The structural configuration and the construction method have been retained as original with alittle or no change (Fig. 3-1.4 and 3-1.5). These are the traditional buildings constructed during the
Malla Period, or Shaha Period. However, many of these buildings at present are not in a good shapedue to various blemishes, basically due to deterioration of materials in age and lack of repair andmaintenance. Most of these buildings still exhibit the grandeur of the architecture and excellent
configuration appropriate for the structural response against the possible seismic action, but these
are in urgent need of restoration so that nor only the strength of the structural components arereinstated but also the building could perform with adequate strength in an integrated manner.
(2) Traditional brick masonry buildings with modifications
These are the traditional brick masonry houses modified considerably in terms of configurationand characterized by horizontal as well as vertical irregularity. Addition of extra stories with larger
openings and replacement of traditional roofs by corrugated galvanized iron sheets are the main
deviation from the original form (Fig. 3-1.5). Addition of balconies with a provision of concreteslab from the masonry wall without proper anchorage (Fig. 3-1.6) further increases the vulnerabilityof the building. Such type of modifications gravely affects the originally planned lateral load
resisting nature in terms of stiffness and strength. In some cases, the buildings may not be adequate
even for gravity loads. Evidently such buildings are not assessed for their structural adequacy andthe existing foundations are not checked for the addition of more floors.

44

Fig. 3-1.4 a)Traditional brick masonrybuilding in originalform, Jhatapol study area, Patan

Fig.3-1.4 b) Traditional brick masonry building in originalform( a mixture of traditional and 19th century imported
architecture) Dhaubaha, Patan

Fig. 3-1.5 Traditional brick masonry building withaddition of extra floors, Jhapapol study area, Patan

Fig.3-1.6 Traditional brick masonry building with additionof extra floors and balconies without proper anchorage at
Patan(3) Buildings with modern features
These are the buildings in the locality which must have been constructed as a substitute for the
repair or restoration of the traditional brick masonry buildings. The structural system in general ofsuch buildings is reinforced concrete frames. However, most of such buildings do not comply withthe code provisions related with concrete structures and the seismic resistant structures. Although
the provision of reinforced concrete slabs substantially impart the in- plane stiffness of the floors inthe buildings, and the concrete frames are better than masonry load bearing walls, the construction45

of such buildings without proper design and detailing may not yield the expected performance ofthe building. For the regular buildings with the provision of infill walls of adequate thickness, theprovision of concrete frames with inadequate frame sections may act as the framing of the walls,
and hence enhancing the brick masonry structural system; this way such buildings could be treatedstructurally as the wall systems framed by concrete frames. Deficiencies such as inadequate size ofthe concrete columns and the absence of load path (Fig. 3-1.7) substantially aggravate theperformance of the structures. The popular trend of providing masonry walls over the projectedbeams to increase the room space substantially increases the seismic vulnerability of the buildings(Fig. 3-1.8). This type of buildings are usually with more floors like 5 or more, with increased floor
height of about 2.4 to 3 m. Plan and elevation irregularity are common in these buildings, with
provision of larger openings for windows, and with projecting overhangs with walls. The external
walls are either brick exposed or covered with plaster and painted. The roof is constructed eitherwith corrugated galvanized iron sheet or reinforced cement concrete, which is either flat with aterrace or gently sloped.

Fig. 3.7 Reinforced concrete frame building with unclear
load path, Jhatapol study area.

Fig. 3.8 Reinforced concrete frame building with walls onoverhang beams, Jhatapol study

References
1)

International Association for Earthquake Engineering (IAEE): Repair, restoration and strengthening, Guidelines for Earthquake
Resistant Non-Engineered Construction, pp. 1-23, 1986.
2) Ranjitkar, R.K.,: Advice for Maintenance of Historic Houses in the Kathmandu Valley, Kathmandu Valley World Heritage Site,
Nepal, Heritage Homeowner’s Preservation Manual, UNESCO Kathmandu 2006
3) Bhandari, R. B. and Okada, N.: Formulating Time Tested Knowledge for Sustainable Disaster Risk Reduction; A Case Study ofKathmandu, Annuals of Disas. Prev. Res. Inst., Kyoto Univ., No. 52 B, 2009.

46

3-2. Structural Analysis of Traditional Brick Masonry Buildings (Case study)

3-2.1 Structural Survey of Traditional and Historical Buildings
Hari Ram Parajuli
The selected target area for the study is the Jhatapol, typical urban areas in Patan of the
Kathmandu Valley. The Jhatapol area includes a part of the boundaries of the World Heritage
Monument zone and its buffer zone. The research area with respect to the World Heritage
Monument Zone is presented in Fig. 3-2.1.

Fig. 3-2.1 The World Heritage Monument Zone and the research area47

For the purpose of the building survey for the seismic vulnerability assessment, the study areaof Jhatapol is divided into three clusters, namely Block A, B and C (Fig. 3-2.2). There arealtogether 218 numbers of buildings within the three blocks. Before undertaking the detailed
structural survey of the buildings, the buildings are indexed in the base map using a specificnomenclature, such as A1, A2, .., B1, B2,… and C1, C2,… , the first letter indicating the cluster
block and the numeric value indicating the building number (Fig. 3-2.2 and 3-2.3).

Fig. 3-2.2 Jhatapol study area with building stocks in 3 subzones: Block A, B and C

The main purpose of the structural survey of the buildings is to record the structural condition
and the construction history of the buildings. In this connection, for each of the buildings theinformation collected are on:(i) Building No. in the base map(ii) Uses(iii) Building type48

(iv) Construction pattern(v) Number of storeys(vi) Modifications(vii) Inclination of building(viii) Damages of foundation(ix) Structural condition of walls(x) Material deterioration in walls
All the above information are recorded in the building survey forms, a sample of which is given
in Appedix A. The results of the visual screening of the buildings are presented in Table 3-2.1.

Fig. 3-2.3 Jhatapol study area with building indexes

Analyzing the structural survey of the buildings the following points were observed.
1. From the utility aspect, the buildings are categorized into two groups-residential andcommercial. About half of the total buildings surveyed have been using for dual purpose,
49

2.
3.
4.

5.

residential as well as commercial. The owners in general, rent out the ground floor of thebuilding for shops or other purposes.
The buildings are constructed either in brick masonry or in reinforced concrete. About threequarter of the total buildings is made in brick masonry.
The number of storeys of the surveyed buildings varies from one to six storeys. Majority ofbuildings are of 3-5 storeys with large window openings.
All buildings are categorized into damaged and undamaged. A building is categorized asdamaged if it has cracks or inclinations at any locations such as near the openings (windows,
doors), walls and foundations. Out of 218 buildings, 100 buildings, which is about 45% of
the total buildings surveyed, are found in the class of damaged already because of sustained
vertical loads, environmental deterioration and aging. It clearly shows that there will besevere damages in the buildings if even a moderate magnitude earthquake hits the city.
A building is categorized modified if any kind of repair, maintenance works has been madeon the building. It also includes the addition of floors. A maximum number of modificationand damages are observed in the 4 storeyed and the 5th storeyed buildings. This is basically
due to the floor additions which have increased the vulnerability even in vertical loads.
Table 3-2.1 Construction type and structural condition of the existing buildings

No. ofstoreys
1
2
3
4
5
6
Total

No. ofbuilds
.
13
2
35
90
71
7
218

Building type
Brick
RCC
OthersMasonry
2
10
1
0
2
0
5
30
0
18
72
0
18
52
1
3
4
0
46
170
2

Damage
6
0
18
43
32
1
100

Res.
0
0
16
46
35
3
100

Uses
Res. &
Comm.
1
0
14
41
32
4
92

Others
12
2
5
3
4
0
26

Modifications
0
0
3
35
39
4
81

The classification of the surveyed buildings by number of storeys, type of the construction andutility is presented in Figs. 3-2.4 to -3-2.6. The status of the buildings in terms of modification anddamage state are shown in Figs. 3-2.7 and 3-2.8.

Fig. 3-2.4 Buildings by no. of storeys

Fig. 3-2.5 Buildings by construction
type

50

Fig. 3-2.6 Buildings by usage

Fig. 3-2.7 Buildings by modification stateFig. 3-2.8 Buildings by damage state

Visual inspection of the buildings from structural survey show that three quarter of the buildings
are made of traditional bricks have sustained stresses and cracks due ageing. Forty five percentages
buildings are already sustained some kinds of damages even in vertical and environmental attacks.
Then question arises what would happen if an earthquake hit the buildings.

51

3-2.2 Experimental verification for Element of Reinforced Technology
Prem Nath Maskey

In order to investigate the seismic capacity of the buildings with reinforced concrete frames inthe study area of Patan it is necessary to establish the material properties of the existing buildings.
Mainly the compressive strength of the hardened concrete has to be established for the structures.
Since any destructive testing is not possible to conduct, the testing of concrete by cutting the corefrom the existing structure is ruled out, and the test is confined to non-destructive tests only. The
determination of the compressive strength of the concrete by Schmidt (Rebound) Hammer test and
by Ultra-sonic Pulse Velocity are described.
(1) Non-Destructive Tests (NDT)The Non Destructive Testing (NDT) of concrete has a great technical and useful importanceespecially in the case of construction quality assessment. The main advantage of non-destructive
testing method is to avoid the concrete damage or the performance of building structuralcomponents. Additionally, their usage is simple and quick. Test results can be made available at thesite and the problem of core drilling is overcome. The Schmidt rebound hammer (SRH) and theultrasonic pulse velocity (UPV) tests, are two simple and useful non- destructive tests, which areuseful when a correlation can be developed between hammer/ultrasonic pulse velocity readings andthe strength of the same concrete. This non-destructive measurement method has proved to be ofreal importance in all constructions serving the purpose of testing and as an effective tool for
inspection of concrete quality in concrete structures(2) Schmidt Rebound Hammer Test
Schmidt Rebound Concrete Hammer test is carried out to assess the concrete and strengthcharacteristics. It is a non-destructive test in which concrete can be tested in situ condition. This
instrument enables engineers to control concrete quality and to detect weak spot. As the test can bedone in the site condition, the strength of concrete can be evaluated in different time interval. The
main advantage of this test is that it is easy to handle and it saves time. A typical Schmidt reboundHammer is shown in Fig. 3-2.9.

Fig. 3-2.9 Typical rebound hammer

52

The Schmidt rebound hammer is principally a surface hardness tester. It works on the principlethat the rebound of an elastic mass depends on the hardness of the surface against which the mass
impinges. There is little apparent theoretical relationship between the strength of concrete and therebound number of the hammer. However, within limits, empirical correlations have been
established between strength properties and the rebound number. The method of using the hammer
is described in reference with Fig. 3-2.10. With the hammer pushed hard against the concrete, thebody is allowed to move away from the concrete until the latch connects the hammer mass to theplunger. The plunger is then held perpendicular to the concrete surface and the body pushed
towards the concrete. This movement extends the spring holding the mass to the body. When the
maximum extension of the spring is reached, the latch releases and the mass is pulled towards thesurface by the spring. The mass hits the shoulder of the plunger rod and rebounds because the rod ispushed hard against the concrete. During rebound the slide indicator travels with the hammer massand stops at the maximum distance the mass reaches after rebounding. A button on the side of the
body is pushed to lock the plunger into the retracted position and the rebound number is read from ascale on the body.

Fig. 3-2.10 working of Schmidt Rebound Hammer Test

The hammer can be used in the horizontal, vertically overhead or vertically downward positions
as well as at any intermediate angle, provided the hammer is perpendicular to the surface under test.
The position of the mass relative to the vertical, however, affects the rebound number due to theaction of gravity on the mass in the hammer. Thus the rebound number of a floor would be expected
to be smaller than that of a soffit and inclined and vertical surfaces would yield intermediate results.
Although a high rebound number represents concrete with a higher compressive strength thanconcrete with a low rebound number.
To carry out the test firstly the site for the site is selected. The ceiling, columns and beams of aframed structured building are selected for the test. For testing of concrete slab, a grid of 1m x 1m
is marked where the tests have to be performed. The points for testing on beam are selected at a
distance of 1m. Three numbers of columns are selected with 3 points for tests on each of them.
The plaster or coating on the concrete surface is removed, and the cement slurry present in top layer
53also is removed.
The rebound values obtained for each testing point in the grid are tabulated and the mean value
is calculated for each row of the points and tabulated. These mean values are corrected using
correction factors for inclination of 900 downward. The corresponding average values of the cubestrengths for every row point are found with the help of correlation chart developed from the test
conducted on the cubes. In order to develop correlation chart, standard cube specimen are preparedand cured as per standard specification. The Schmidt rebound hammer test is carried out on eachcube and the compressive strength of these cubes is determined by testing on compressive testingmachine. Then a chart is developed using R – value and the corresponding compressive strength.
The correlation between Rebound number and uniaxial compressive strength is presented in Table
3-2.2.The correlation chart developed is shown in Fig. 3-2.11. The Rebound Value Correction forinclination (90° downward) is given in Table 3-2.3. The test results with rebound number andcompressive strength for slab, beam and columns respectively are presented in Table 3-2.4 –3-2.6
Table 3-2.2 Correlation between Rebound Number and Uniaxial Compressive Strength:
S.N

1

2

3

Specimen type

Weight (Kg)

Rebound No.

Avg.
Rebound No.

Failure load
(KN)

Compressive
Strength(Mpa)

1

2

3

4

5

2.460

26

30

24

24

20

24.8

210

21.0

2.440

26

24

18

36

28

26.4

235

23.5

2.500

26

28

26

22

28

26.0

160

16.0

2.646

42

40

50

52

36

44.0

288

28.8

2.566

28

36

34

28

34

32.0

282

28.2

2.575

32

28

38

42

38

35.6

268

26.8

2.563

30

30

32

32

40

32.8

258

25.8

2.568

21

21

20

22

22

21.2

208

20.8

2.582

23

23

39

49

50

36.8

260

26.0

Cylinder

3.710

20

24

20

30

22

23.2

80

10.2

(10 mm dia)

3.700

20

20

26

24

20

22.0

90

11.5

3.740

18

24

28

26

30

25.2

100

12.7

3.760

26

28

28

26

28

27.2

132

16.8

3.779

20

26

34

36

38

30.8

125

15.9

3.660

22

22

26

26

27

24.6

121

15.4

3.710

22

21

20

23

22

21.6

141

18.0

3.788

28

25

32

30

30

29.0

140

17.8

3.737

24

25

43

38

52

36.4

154

19.6

Prism

4.670

28

30

26

20

22

25.2

84

14.9

(75 x 75 mm)

4.270

31

24

33

20

20

25.6

74

13.2

4.342

25

25

26

30

30

27.2

95

16.9

4.370

39

34

32

27

26

31.6

97

17.2

4.403

32

33

34

42

28

33.8

151

26.8

4.606

32

38

32

36

32

34.0

141

25.1

Cube
(100 x 100
mm)

54

Table 3-3.3 Rebound Value Correction for inclination (90° downward)
Rebound Value
10
20
30
40
50
60

Correction in rebound value
+3.2
+3.4
+3.1
+2.7
+2.2
+1.7

Fig. 3-2.11 Correlation chart between rebound number and uniaxial compressive strength
Table 3-2.4: Rebound number and compressive strength of slab
S.N.

Position

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

Slab-1
Slab-2Slab-3Slab-4Slab-5Slab-6Slab-7Slab-8Slab-9Slab-10Slab-11Slab-12Slab-13
Slab-14
Slab-15
Slab-16
Slab-17
Slab-18
Slab-19
Slab-20

1
21
17
29
18
28
20
24
24
18
22
29
20
22
20
29
22
19
27
19
20

Rebound Number
2
3
4
20
16
27
22
26
21
29
26
22
19
24
20
18
23
22
25
20
24
20
22

25
20
30
24
32
18
24
26
18
22
22
20
24
23
18
22
24
22
22
24

24
18
29
18
30
24
25
24
24
24
22
24
26
24
24
20
24
22
29
28

5

Avg.
Rebound

Correction

28
19
33
26
26
24
26
28
24
22
20
24
22
19
22
22
22
20
24
28

23.60
18.00
29.60
21.60
28.40
21.40
25.60
25.60
21.20
21.80
23.40
21.60
22.40
21.80
23.00
22.20
21.80
23.00
22.80
24.40

3.508
3.360
3.688
3.448
3.652
3.442
3.568
3.568
3.436
3.454
3.502
3.448
3.472
3.454
3.490
3.466
3.454
3.490
3.484
3.532

55

Corrected
Value

Compressive
Strength (Mpa)

27.10821.36033.28825.04832.05224.84229.16829.16824.63625.25426.90225.04825.87225.25426.49025.66625.25426.49026.28427.932
Avg.=
S.D.=

22.00
19.25
24.94
21.01
24.35
20.92
22.98
22.98
20.82
21.11
21.90
21.01
21.41
21.11
21.70
21.31
21.11
21.70
21.60
22.39
21.78
1.28

Table 3-2.5: Rebound number and compressive strength of beam
Rebound Number

S.N.

Beam
Position

1

2

3

4

5

Avg.
ReboundCompressive
Strength (Mpa)1position-1

20

28

28

20

30

25.20

21.09

2

position-2

22

22

28

29

30

26.20

21.56

3

position-3

16

22

26

28

28

24.00

20.51

4

position-4

24

28

31

34

36

30.60

23.66

5

position-5

24

30

32

32

32

30.00

23.38

6

position-6

20

20

20

22

22

20.80

18.99

7

position-7

24

20

20

32

32

25.60

21.28

8

position-8

22

16

18

20

18

18.80

18.03

Avg.=

21.06

Table 3-2.6: Rebound number and compressive strength of column
S.N.

Position

1

Column-1
Bottom2

3

Rebound Number
1

2

3

4

5

39

40

40

44

42

Avg. ReboundCompressive
Strength (Mpa)

41.00

28.62

Middle

40

42

46

43

38

41.80

29.00

Top

44

40

44

42

44

42.80

29.48

Bottom

40

34

40

40

42

39.20

27.76

Middle

30

33

41

34

38

35.20

25.86

Top

44

42

40

48

42

43.20

29.67

42

41

39

38

42

40.40

28.34

Column-2

Column-3
BottomMiddle

41

39

43

40

40

40.60

28.43

Top

42

46

38

44

45

43.00

29.58

Avg.=

28.53

Strength at 95% confidence level = 21.78 – 1.64 x 1.28 = 19.68
Strength at 90% confidence level = 21.78 – 1.28 x 1.28 = 20.14
Strength at 95% confidence level = 21.78 – 0.84 x 1.28 = 20.71(3) Ultrasonic Pulse Velocity Test
This type of non-destructive test used to determine the longitudinal ultrasonic pulse velocity inconcrete structure through which the wave is propagated. There is no unique relationship between
the wave velocity and the strength of the concrete; however, under specified conditions these twoquantities are interrelated. The common factor is the density of concrete; a change in the density
results in a change in the pulse velocity. If the velocity of a pulse of longitudinal waves through a
medium can be determined, and if the density and Poisson’s ratio of the medium is known, then the
dynamic modulus of elasticity can be computed.
The equipment for the test consists essentially of an electrical pulse generator, a pair oftransducers, an amplifier and an electronic timing device for measuring the time interval between
the initiation of a pulse generated at the transmitting transducer and its arrival at the receiving
transducer (Fig. 3-2.12). Two forms of electronic timing apparatus and display are available, one ofwhich uses a cathode ray tube on which the received pulse is displayed in relation to a suitable timescale, the other uses an interval timer with a direct reading digital display.
56

Fig. 3-2.12 Ultrasonic pulse velocity test equipment

A pulse of longitudinal vibrations is produced by an electro-acoustical transducer, which is heldin contact with one surface of the concrete under test. When the pulse generated is transmitted into
the concrete from the transducer using a liquid coupling material such as grease or cellulose paste, it
undergoes multiple reflections at the boundaries of the different material phases within the concrete.
A complex system of stress waves develops, which include longitudinal, shear and surface waves,and propagates through the concrete. The first waves to reach the receiving transducer are thelongitudinal waves, which are converted into an electrical signal by a second transducer. Electronic
timing circuits enable the transit time T of the pulse to be measured.
Longitudinal pulse velocity (in km/s or m/s) is given by:VLT(3-2.1)

where
V is the longitudinal pulse velocity,
L is the path length,
T is the time taken by the pulse to traverse that length.
If the density () and Poisson’s ratio () are known, then the modulus of elasticity of concrete (E)can be calculated using the equations 3-2.2 (for one dimensional body), 3-2.3 (for two dimensionalbody) and 3-2.3 (for three dimensional body).
VP 
VP 

E

(3-2.2)

E 1  
57(3-2.3)

VP E 1   1   1  2 

(3-2.4)

Where, Vp = P – wave velocity
After obtaining the value of E from above equations, the characteristic strength (fck) and modulus ofrupture (fcr) can be calculated by using the IS456-2000 (equations 3-2.5-3-2.6).
Ec  5000 f ck

(3-2.5)fcr  0.7 f ck

(3-2.6)

where, Ec = modulus of elasticity of concrete
fck = characteristic strength of concrete
fcr = modulus of rupture of concrete
Although the ultrasonic pulse velocity test can be applied for many purposes, here the use isbasically aimed at determination of correlation of pulse velocity and strength as a measure ofconcrete quality, and also for determination of the modulus of elasticity and dynamic Poisson's ratioof the concrete.
The transducer for the test may be arranged in different ways. It is possible to makemeasurements of pulse velocity by placing the two transducers on either: opposite faces (directtransmission), adjacent faces (semi-direct transmission) (Fig. 3-2.13) or the same face (indirect orsurface transmission) (Fig. 3-2.14).

Fig. 3-2.13 Direct transmission and semi-direct transmission

Fig. 3-2.14 Indirect or surface transmission

58

For the ultrasonic pulse velocity test, 6 points in each of the members (beam and column) of theframed building are selected. These points are selected on different faces of the members, and at thebottom and top of column height, and at the left and right support of the beam. Table 3-2.7 and 32.8 presents the test results of the column and the beam respectively.
Table 3-2.7 Ultrasonic pulse velocity and compressive strength of column no. C4
Velocity of ultrasonic pulse
Correction factor
Final value of velocity
η
Equivalent value of compressive strengthof concrete
Mean value of compressive strength(N/mm2)

1
3.623
1.0
3.62
1.0
21.87

2
3.508
1.0
3.51
1.0
20.16

Location points
3
4
3.581
3. 882
1.0
1.0
3.58
3.88
1.0
1.0
21.25
25.91

5
3.421
1.0
3.42
1.0
18.76

6
3.711
1.0
3.71
1.0
23.27

21.87

Table 3-2.8 Ultrasonic pulse velocity and compressive strength of beam along grid B
Velocity of ultrasonic pulse
Correction factor
Final value of velocity
η
Equivalent value of compressive strengthof concrete
Mean value of compressive strength(N/mm2)

1
3.372
1.0
3.37
1.0
17.99

2
3.404
1.0
3.40
1.0
18.45

Location points
3
4
3.318
3.188
1.0
1.0
3.32
3.19
1.0
1.0
17.21
15.19
16.77

59

5
3.212
1.0
3.21
1.0
15.50

6
3.256
1.0
3.26
1.0
16.28

3-2.3 Experimental investigation and Analyses of Traditional Brick Masonry Buildings
Hari Ram Parajuli

In connection with the research on the disaster risk management of the cultural heritage site of
the historic city, the historical site of Jhatapol was selected as the focal area. The public structure of
Lalitapura Pati, the land mark of the area was chosen as a case study for determination of its seismic
vulnerability for the given seismic hazard, and, in its turn, to identify the building’s seismic risk.
The Lalitapura Pati (Fig 3-2.15.) is a two-storeyed masonry building, constructed about 300 years
ago and represents the traditional construction. The building has a length of 16.5 m and a width of
5.6 m. The structural system of the building is based on unreinforced brick masonry walls
constructed in mud mortar, with timber floor and sloped timber roof. The walls are made of
traditional brick work with thickness 60 cm at the ground floor and 50 cm at the upper floor. In the
ground floor, on the front side towards the main road, it has a series of timber colonnades instead ofwalls, and hence giving the traditional dalan appearance. Over these colonnades on the first floor
the building has an elaborate latticed window with traditional wood carvings. The building has been
repaired many times following the local damages mostly due to leakages and material deterioration.
Recently, its sloped roof originally with local roofing tiles (jhingati) has been replaced bycorrugated galvanized iron sheet, and the internal sides of the walls have been plastered withcement sand mortar. The current condition of the building appears as different from its original
construction by look, possibly due to changes in the usage in time of the building. In order to carryout the seismic vulnerability of the building, the material properties of the walls are required to beassessed. The non destructive tests carried out to obtain the properties are described hereunder. As
is obvious, any kind of destructive techniques in heritage structures are not allowed. The
investigation is carried out by elastic wave measurement.

Fig. 3-2.15 Lalitpura pati, the model building; south-front (left) and west-side view (right)(1) Material properties of historical masonry buildinga) Elastic wave tomography
Elastic waves produced by a sudden redistribution of stress in a material due to external forces
such as pressure, load, temperature etc., releases energy in the form of stress waves and propagates
through the surfaces and recorded by sensors. The back side wall of the house shown in Fig. 3-2.15
was selected for the elastic wave experiment with tomography. An area of 1.5 m X 1.5 m was taken
and 16 sensors were attached with wax at equal distances (Fig. 3-2.16). In case that the measured
point was found at joints, the sensors were moved to the nearest brick surface. Then three set of60

measurements - two on each surface, and the other on cross sections were taken. Sensor
arrangements at surfaces and at cross sections are shown in Fig. 3-2.16. Then impact on wall was
given by a steel hammer having a small spherical ball at its edge near one sensor and the stresswaves obtained at all sensors were recorded. Similarly, impact was given near to each sensor turnby turn and measurements at other sensors were recorded.

Fig. 3-2.16 Arrangement of sensors on two sides of the wall

Based on the first arrival time of P waves at various sensors, stress wave velocities in divided
cells were evaluated aided by tomography algorithm as given in Figs. 3-2.17 – 3-2.18. The left
figure is the distribution of P-wave, namely tomogram at outer surface (brick exposed surface Fig2) and the right one is for inner surface tomogram when the wall was hit by a 8 mm diameter
hammer. The figures show that P wave velocity varies from 500 to 1000 meter per sec. In the Fig.32.18, tomography has been shown in three dimension and cross section when impact was given to
the wall by 25 mm diameter hammer. It shows that interior of the wall is stronger than towards thesurface.

Fig. 3-2.17 Elastic wave tomography in 2D

Fig. 3-2.18 Elastic wave tomography in 3D61b) Measurement by Pocket AE
The Pocket AE is a handheld instrument for acoustic emission testing and performs advanced
wave-form based signal acquisition and processing. The elastic wave velocities estimated by the
tomography give a wide range of values. The Figs. 3-2.17-3-2.18 show that these range from 500 to1000 m/sec. For the finite element method (FEM) analysis, the specific values are required rather
than the range. Thus, using pocket AE, a series of measurements were taken at various locations ofdifferent walls (Fig. 3-2.19). Noting the first arrival time of elastic waves, time differences ofsuccessive peak amplitudes at the near and the far end sensor channels were calculated. Then,
velocity was calculated by thickness through which wave passes, divided by the time difference
between two sensors. Then from the primary wave velocity, with the measured unit weight(19KN/m3), and the assumed Poison’s ratio (0.2), the modulus of elasticity (E) and the shear wave
velocity (Vs) of the material are calculated, and shown in Table 3-2.9 using Kramer 1) relations.

Fig. 3-2.19 Instrumentation of two channel Pocket AE
Table 3-2.9 Obtained parameters
Types of walls

Vp (m/sec.)

G (N/mm2)

Vs (m/sec.)

E (N/mm2)

Single brick

2499

4537

1531

10889

11 cm wall

2576

4820

1677

11567

23 cm wall

1312

1250

803

3000

44 cm wall

670

326

410

782

Fig. 3-2.20 Plotting of P-wave velocity with wall thickness

The experiment results show that as the wall thickness increases its P wave velocity decreases.
The joints and voids inside the wall sharply decrease its strength, as a result P wave velocity is

62

found decreasing. If the P wave velocity from the equation shown in Fig. 3-2.20 is projected for
55cm wall, it becomes 547m/sec. which lies in the ranges shown in Fig. 3-2.17-3-2.18 and seems
reasonable. Though, interpolation and extrapolations would not be the case always, rather vary wall
to wall depending upon its own properties. However, the trend of curve in the Fig. 3-2.20 shows,elasticity decreases with the increase of joints and voids in thicker wall.
c) Micro tremor measurement
The second experiment was ambient vibration measurements of the building and ground.
Ambient vibrations of the historical model building at various locations and at three other locations
in nearby areas were measured by three seismometers. The instruments measuring microtremors on
ground and the buildings are shown in Figs. 3-2.21 and 3-2.22 respectively. The predominantfrequency of ground was estimated from H/V spectrum. Various natural frequencies of the building
were estimated from the Fourier spectrum, and damping of the masonry was estimated from therandom decrement and transfer function between ground floor, first and second floors 2). In order todetermine the damping from free vibration, the building was pushed off (Fig. 3-2.23). The push off
was followed by recording of the free vibration history, and the damping value was calculated. The
predominant frequency of the ground is found to be 2.1Hz, whereas the fundamental frequencies ofthe building are found as 4.3Hz, 4.7Hz, 6.8Hz and 7.7Hz along transverse and longitudinal
directions respectively. The damping of the building is 6.4%.

Fig. 3-2.21 Measurements on groundFig. 3-2.22 Measurements on building

Fig. 3-2.23 Push off on building

The numerical models used for dynamic analysis of structures are idealizations of real structures
to represent the response of real structures. The validity of the models can be verified by ambient
vibration experiments or forced vibration experiments. Both methods have their own merits anddemerits, however, for the heritage structures where any kind of destructive experiments are notallowed, non destructive experiments such as micro-tremor ambient vibration measurements is thesuitable. Since the amplitudes are very small, only linear response can be investigated.
Seismic resistant capacity evaluation requires materials properties such as modulus of elasticity,
Poisson’s ratio, strength of walls and elements such as bricks, mortar timber etc., in tension,
compression and shear as well as dynamic properties such as fundamental natural frequencies,
mode shapes and damping. Civil engineering structures such as buildings, bridges, electric towers
etc., are always vibrating due to ambient vibrations produced by wind, ocean waves, andatmospheric conditions. These ambient vibrations are measured by seismometers and their
responses are studied in frequency domain. Since, the amplitudes of ambient vibration are verysmall, they describe only linear behavior of the structures. Ambient vibration signal get amplified at63the natural frequency of ground and structures. Taking advantages of those characteristics of
response natural frequencies are obtained. Thus as a part of efforts, micro tremor measurement on ahistorical house located at Patan City has been carried out and the dynamic properties such as
natural periods, mode shapes and damping ratios are obtained and discussed.

Acceleration (gal)Acceleration (gal)Acceleration (gal)Fig. 3-2.24 Location of seismometers in World heritage site Patan Durbar Square area

Longitudinal Component

5
0
-5

0

200

400

0

200

400

0

200

400

5

600
800
Duration (secs.)
Transverse Component

1000

1200

600
800
Duration (secs.)
Vertical Component

1000

1200

600
Duration (secs.)

1000

1200

0
-5

2
0
-2

800

Fig. 3-2.25 Sample micro-tremor record at location 1
64

6

6

4

4

H/V ratio

H/V ratiod) H/V Spectrum
Micro tremor measurement has long been recognized for in- situ evaluation and micro-zonation,
which are widely used by engineers and planners. The most commonly used way to interpret therecords is horizontal to vertical ratio namely H/V spectrum. This technique was originallyintroduced by Nakamura 3) to analyze Rayleigh waves in micro-tremor records. Now, it has been
the method to estimate the site characteristics such as predominant frequency of site, amplificationand vulnerability assessment. However, in this study, only predominant frequency of the ground isevaluated. For this purpose, seismometers were placed at four locations of the city as shown in Fig.
3-2.24, and three components of micro-tremors were recorded for 12 minutes. Sample micro-tremor
records of site 1 are shown in Fig. 3-2.25.

2
0

0

5
Frequency (Hz.)

0

10

0

5
Frequency (Hz.)

10

0

5
Frequency (Hz.)

10

2

4

H/V ratio

H/V ratio

6

2
0

2

1.5
1
0.5

0

5
Frequency (Hz.)

0

10

6

6

4

4

H/V ratio

H/V ratio

Fig. 3-2.26 Sample micro-tremor record at location 1

2
0

0

5
Frequency (Hz.)

0

10

0

5
Frequency (Hz.)

10

0

5
Frequency (Hz.)

10

10
H/V ratio

H/V ratio

10

5

0

2

0

5
Frequency (Hz.)

5

0

10

Fig. 3-2.27 Sample micro-tremor record at location 2

65

6

4

4

H/V ratio

H/V ratio

6

2
0

0

5
Frequency (Hz.)

0

10

0

5
Frequency (Hz.)

10

0

5
Frequency (Hz.)

10

2
1.5

4

H/V ratio

H/V ratio

6

2
0

2

1
0.5

0

5
Frequency (Hz.)

0

10

6

4

4

2
0

H/V ratio

H/V ratio

605Frequency (Hz.)

2
0

10

6

6

4

4

H/V ratio

H/V ratio

Fig. 3-2.28 Sample micro-tremor record at location 3

2
0

0

5
Frequency (Hz.)

5
Frequency (Hz.)

10

0

5
Frequency (Hz.)

10

2
0

10

0

Fig. 3-2.29 Sample micro-tremor record at location 4

Considering the records are stationary, the whole record is cut into various segments having
number of data in each segment equivalent to 2N which is essential to do Fast Fourier Transform(FFT). Then Fourier spectrum of each segment was plotted which are shown in Figs. 3-2.26 to 32.29 and obtained natural frequencies at are summarized in Table 3-2.10. From the calculation
predominant frequency of the ground is found 2.07Hz.

66

Table 3-2.10 Frequencies from H/V spectrum
S.N

Location

Figs.

Frequency (Hz.)

1site 13-2.26(a)2.00

2site 13-2.26 (b)

2.15

3

site 13-2.26 (c)

2.49

4

site 13-2.27 (d)

1.95

5

site 23-2.27 (a)

2.39

6

site 23-2.27 (b)

1.71

7

site 23-2.27 (c)

1.93

8

site 23-2.27 (d)

1.95

9

site 33-2.28 (a)

2.20

10

site 33-2.28 (b)

1.83

11

site 33-2.28 (c)

2.03

12

site 33-2.28 (d)

2.10

13

site 43-2.29 (a)

1.95

14

site 43-2.29 (b)

2.37

15

site 43-2.29 (c)

1.88

16

site 43-2.29 (d)2.27

Average

2.07e) Natural frequency of building
The building has been partitioned into two parts along longitudinal direction. The front side has
big opening. Series of micro tremor ambient vibration measurements were taken at various
locations of the building in the ground, first and second floors respectively. The measurements wererecorded at seven different locations of the building as shown in the plan of the building in Fig. 32.30.

Fig. 3-2.30 Plan of the building and location of micro-tremor measurements

As in the H/V ratio calculation, twelve minutes long records are cut into six segments making
4096 data in each segment to make compatible for FFT excluding the possible noise caused byexternal factors such as pedestrians and vehicles etc. Fourier spectra of all the records obtained
along both longitudinal and transverse directions at various locations of the building were
calculated and plotted through Figs. 3-2.31 to 3-2.38 and summarized in Table 3-2.11 for. From thecalculation, most dominant natural frequencies are 4.30Hz and 6.52Hz along transverse direction
and 6.80Hz and 9.39Hz along longitudinal direction.
67

0

0

5
10
Frequency (Hz.) - along X
Amplitude

0.02
0.01
0

Amplitude

Amplitude

0.01

0

0.02
0.01
0

0

0.02
0.01
0

5
10
Frequency (Hz.) - along X

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0.02
0.01
0

5
10
Frequency (Hz.) - along X
Amplitude

Amplitude
Amplitude

0.02

0.02
0.01
0

Amplitude

0.02
0.01
0

0

5
10
Frequency (Hz.) - along X

0.01
0.005
0

3
2
1
0

0

5
10
Frequency (Hz.) - along X

3
2
1
0

-3

0

0

5
10
Frequency (Hz.) - along Y

x 10

0

5
10
Frequency (Hz.) - along Y
-3

x 10

Amplitude

5

0

-3

x 10

Amplitude

Amplitude-3

Amplitude

Amplitude

Fig. 3-2.31 Fourier spectrums

510Frequency (Hz.) - along X

5

0

x 10

0

5
10
Frequency (Hz.) - along Y

Fig. 3-2.32 Fourier spectrums

68Amplitude

Amplitude

0.02
0.01
0

0

0.01
0.005
0

5
10
Frequency (Hz.) - along X

00

Amplitude

5

-3

x 10

0

5
10
Frequency (Hz.) - along X
Amplitude

0.01
0.005
0

0

5
10
Frequency (Hz.) - along X

x 10

5

0

0

5
10
Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0.01
0.005
0

Fig. 3-2.33 Fourier spectrums

Amplitude

-3

5

5

0

5

0

0

5
10
Frequency (Hz.) - along X

x 10

0

5
10
Frequency (Hz.) - along X

x 10

0

0.02
0.01
0

0

5
10
Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y-3

Amplitude

0

0.02
0.01
0

-3

Amplitude

Amplitude

Amplitude

x 10

Amplitude

Amplitude

Amplitude-3

5
10
Frequency (Hz.) - along Y

5
10Frequency (Hz.) - along X

0.05
0Fig. 3-2.34 Fourier spectrums

69

Amplitude

0.005
0

0

Amplitude

0.01
0

0.01
0

5
10
Frequency (Hz.) - along X

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0.02
0.01
0

5
10
Frequency (Hz.) - along X

0.02

0

0.005

5
10
Frequency (Hz.) - along X

0.02

0

Amplitude

00.01

Amplitude

Amplitude

Amplitude

0.01

0.05

0

Fig. 3-2.35 Fourier spectrums-3

Amplitude

Amplitude

x 10
5

0

0

0.01
0.005

5
10
Frequency (Hz.) - along X

0

0

5
10
Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

Amplitude

5

0

5
10
Frequency (Hz.) - along X

0.02

Amplitude

Amplitude

Amplitude

-3

x 10

0.01
0

0

5
10
Frequency (Hz.) - along X

0.02
0.01
0

0.04
0.02
0

Fig. 3-2.36 Fourier spectrums

70

-3

Amplitude

Amplitude

x 10
5

0

0

5
10
Frequency (Hz.) - along X

0.02
0.01
0

0

5
10
Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

Amplitude

5

0

5
10
Frequency (Hz.) - along X

0.01

Amplitude

Amplitude

Amplitude

-3

x 10

0.005
0

0

5
10
Frequency (Hz.) - along X

0.02
0.01
0

0.04
0.02
0

0.01

Amplitude

Amplitude

Fig. 3-2.37 Fourier spectrums

0.005
0

0

5
10
Frequency (Hz.) - along X

0.02
0.01
0

0

5
10
Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

5
10Frequency (Hz.) - along Y

0

Amplitude

5

0

5
10
Frequency (Hz.) - along X

0.01

Amplitude

Amplitude

Amplitude

-3

x 10

0.005
0

0

5
10
Frequency (Hz.) - along X

0.02
0.01
0

0.02
0.01
0

Fig. 3-2.38 Fourier spectrums71Table 3-2.11 Natural frequencies identified from two horizontal components
X
S.N

Plot figureYmode 1mode 2mode 1mode 21

3-2.31

6.86

9.50

4.30

5.84

2

3-2.31

6.84

9.50

4.30

5.79

3

3-2.31

6.84

9.50

4.30

6.91

4

3-2.32

6.74

9.50

4.27

5.79

5

3-2.32

6.81

9.40

4.22

5.88

6

3-2.32

6.91

9.50

4.27

6.93

7

3-2.33

6.74

9.49

4.20

8.45

8

3-2.33

6.64

9.50

4.18

8.35

9

3-2.33

6.71

9.50

4.22

5.81

10

3-2.34

6.81

9.50

4.35

5.79

11

3-2.34

7.18

9.50

4.37

5.84

12

3-2.34

6.76

9.50

4.19

5.81

13

3-2.35

6.84

9.50

4.25

5.79

14

3-2.35

6.91

9.50

4.37

5.84

15

3-2.35

6.86

9.50

4.39

5.81

16

3-2.36

6.91

9.50

4.32

5.79

17

3-2.36

6.89

9.50

4.32

5.81

18

3-2.36

6.84

9.50

4.35

7.15

19

3-2.37

6.91

9.50

4.32

7.20

20

3-2.37

6.89

9.50

4.32

7.15

21

3-2.37

6.91

9.50

4.35

7.18

22

3-2.38

5.81

7.01

4.37

7.25

23

3-2.38

6.74

9.50

4.35

7.10

24

3-2.38

6.86

9.50

4.37

7.18

6.80

9.39

4.30

6.52

Averagef) Transfer function and damping
In order see amplification of seismic motions, ratio of Fourier spectrum between first floor to
ground floor, and second floor to ground floor was calculated and plotted in Fig. 3-2.39. It showsthat the response along transverse direction is more amplified than in longitudinal direction. It also
justifies the point that the building is vulnerable along transverse direction. From this ratio, thenatural frequencies in rocking modes are identified at 4.69 and 5.85 Hz along transverse direction
and 7.72Hz along longitudinal direction which is shown in Table 3-2.12. Other modes are notdetectable.

72

3

2

2
F3/F1

F2/F1

3

1
0

0

1
0

5
10
Frequency (Hz.) - along X

10

0

5
10
Frequency (Hz.) - along X

0

5
10Frequency (Hz.) - along Y

20

F3/F1

F2/F1

15
5

10
5

0

0

0

5
10
Frequency (Hz.) - along Y

8

8

6

6
F2/F1

F2/F1

Fig. 3-2.39 Ratio of Fourier spectrum between first and ground floor

4
2

2
3

4
5
6
Frequency (Hz.)

0

7

15

15

10

10
F3/F1

F3/F1

0

4

5
0

3

4
5
6
Frequency (Hz.)

7

3

4
5
6
Frequency (Hz.)

7

3

4
5
6
Frequency (Hz.)

7

50Fig. 3-2.40 Transfer function between the floors and ground responses

73

5

4

4

3

3

F3/F1

F2/F1

5

2
1
0

1
0

0

5
10
Frequency (Hz.) - along X

15

5
10
Frequency (Hz.) - along X

0

5
10Frequency (Hz.) - along Y

15
F3/F1

F2/F1

0

20

10
5
0

2

10
5

0

5
10
Frequency (Hz.) - along Y

0Acceleration (gal)Fig. 3.41 Ratio of Fourier spectrum between first and ground floor after pushed

1

2

2

0.5

1

1

0

0

0

-0.5

-1

-1

Acceleration (gal)

-1
31

32

-2
-2
33
129
130
131
277
Duration (secs) - Longitudinal direction

2

4

4

1

2

2

0

0

0

-1

-2

-2

-2
14

15

-4
-4
16
31
32
33
44
Duration (secs) - Transverse direction

278

279

45

46

Fig. 3-2.42 Acceleration records after the buildings pushed

74

Table 3-2.12 Natural frequencies in rocking modes
X

Y

S.N

model 1mode 2model 1mode 2

1

7.62

N/D

4.64

5.76

2

7.59

N/D

4.66

5.81

3

7.89

N/D

4.76

6.01

4

7.79

N/D

4.69

5.81

4.69

5.85

7.72

Table 3-2.13 Damping calculated from transfer function
S.N

f1

fm

f2

h

1

4.27

4.63

4.85

6.26

2

4.54

4.76

5.13

6.20

3

4.32

4.66

4.91

6.33

4

4.32

4.69

4.96

6.82

Average

6.40

In order to estimate damping, average value of transfer function obtained from the ratio between
floors and ground responses are plotted in separate Figs. 3-2.39-3-2.41. Then damping is estimatedby half power band width method 4) given by the equation taking the transfer function alongtransverse direction only and obtained results are shown in Table 3-2.13. Average damping value of
damping is estimated 6.4%.
h

f 2  f1
2 fm

(3-2.7)

Then, as an alternate method of estimation of damping, the building was pushed by 4-5 persons
in both longitudinal and transverse direction. The micro tremor was taken when the building was
pushed at each story. Then, ratio of Fourier spectrum between the floors and ground were plotted to
see whether there is changes from the transfer functions plotted (Figs. 3-2.39-3-2.41) without
pushing the building. No significant changes were noticed. Then, the time history records were cut
just (Fig. 3-2.42) after the building was pushed and damping is calculated by random decrement
method 4). From logarithmic decrement of wave, the damping ratios are obtained 3.6% and 5.2%
along longitudinal and transverse directions respectively.
h

1 x2
2 x1

(3-2.8)Micro-tremor ambient vibration measurements on a building and four different locations of
Lalitpur sub-metropolitan city, Kathmandu, Nepal were carried out. From the measurements atgrounds, H/V spectrum was plotted to estimate the predominant frequency of the ground and fromthe measurements at various locations of the building, natural frequencies of various excitation
modes were identified. Damping of the building was investigated from random decrements, transfer
function between ground and second story, and frequency domain decomposition. Mode shapes ofthe buildings were obtained from FDD methods. The results show that the building has dominantfrequencies along shorter direction than in longer direction and damping of building is around 5%.
This study is helpful to understand the dynamic behavior of building under normal loads as well as
extreme loads such as those caused by seismic events or high winds.
75

Table 3-2.14 Calculation of damping from logarithmic decrement
SN

Longitudinal direction

Transverse direction

t1

x1

t2

u2

h

t1

x1

t2

x2

1

31.81

-0.79331.86-0.661

2.90

14.62

1.869

14.65

1.515

3.34

2

31.86

-0.66131.91-0.417

7.34

14.65

1.515

14.67

0.99

6.77

3

31.91

-0.41731.94-0.346

2.97

14.73

1.481

14.76

0.999

6.27

4

31.94

-0.34631.99-0.278

3.48

14.76

0.999

14.78

0.74

4.78

5

129.881.197

129.93

1.122

1.03

14.66

-1.973

14.69-1.6792.57

6129.931.122

129.98

0.894

3.62

14.69

-1.67914.72-1.0297.80

7129.980.894

130.03

0.649

5.10

14.77

-1.27414.74-0.9065.43

8130.030.649

130.08

0.567

2.15

14.81

0.903

14.84

0.682

4.47

9

130.080.567

130.12

0.425

4.59

14.84

0.682

14.86

0.442

6.91

10

129.92-1.02

129.97-0.939

1.32

31.70

2.565

31.78

1.812

5.53

11

129.97-0.939130.02-0.672

5.33

31.78

1.812

31.86

1.306

5.21

12

130.02-0.672130.07-0.521

4.05

31.86

1.306

31.94

0.935

5.32

13

130.27-0.823130.32-0.669

3.30

31.94

0.935

32.02

0.649

5.81

14

130.32-0.669130.37-0.553

3.03

44.68

1.362

44.76

1.026

4.51

15

130.37-0.553130.42-0.377

6.10

44.92

2.264

45

1.796

3.69

16

277.371.08

277.42

0.851

3.79

45.00

1.796

45.08

1.25

5.77

17

277.420.851

277.47

0.736

2.31

44.95

2.100

45.03

1.521

5.14

18

277.470.736

277.52

0.649

2.00

45.03

1.521

45.11

1.071

5.59

19

277.820.47

277.85

0.382

3.30

45.16

1.221

45.19

1.057

2.30

20

277.850.382

277.87

0.312

3.22

45.19

1.057

45.21

0.674

7.16

3.55

Average

Averageh

5.22

Table 3-2.15 Summaries of results
S.N

Descriptions

Results1

Predominant frequency of ground

2.1Hz

2

Natural Frequency along transverse direction sway

4.3Hz

3

Natural Frequency along Longitudinal direction sway

6.80Hz4

Natural Frequency along transverse direction sway

4.69Hz5

Natural Frequency along Longitudinal direction rocking

7.72Hz6

Maximum damping

6.40%

The results show that the building has dominant frequencies along shorter direction than inlonger direction and damping of building is around 3.55% along longer direction and 5.2-6.4%
along shorter direction of the building. The key dynamic parameters are summarized in the Table 32.15. Since, the building has dominant frequency along shorter direction; damping estimate fromlonger direction may under estimate the actual value. Looking at all the analyses and Figs., thefrequencies along transverse direction are more clear and detectable than in longitudinal direction. It
is quite obvious that the building has big opening along transverse direction which makes stiffness
weaker than in perpendicular direction. Higher modes’ frequencies are not observing clearly in that
direction. If its various vibration frequencies are not detecting from micro-tremor measurements, it
is difficult to say exact vibration characteristics during strong motions. The damping estimate fromunclear vibration modes may make wide difference than its actual value. Thus, the damping shouldbe 5.2-6.4% for that kind of typical masonry buildings and other key parameters are given in the
Table 3-2.15. Since, the dominant frequencies are seen along transverse direction, the building
seems stronger along longitudinal direction. Large opening in the ground storey and big window at
the first storey weaken the wall stiffness significantly which leads the building vulnerable alongtransverse direction.
76

References
1)
2)
3)
4)

Kramer, S.L.: Geotechnical earthquake engineering, Prentice-Hall International series in Civil Engineering and Engineering
Mechanics, 1996
Parajuli, H. R., Kiyono, J., Maskey, P. N., Shiotani, T., Momoki, S., Toki, K., Masuda, K., Taniguchi, H., and Furukawa, A.:
Parametric Study on Old Brick Masonry Walls by Elastic Wave Measurement, 28th conference, Japan Society for Natural
Disaster Science, Kyoto, Japan, Sept. 2009
Nakamura Y.: Clear identification of fundamental idea of Nakamura’s technique and its applications, Proceeding of 12th
World Conference on Earthquake Engineering, 2000.
Chopra A. K.: Dynamics of Structures; Theory and Applications to Earthquake Engineering, Prientice Hall of India P. Ltd,New Delhi, 1996.

77

(2) Laboratory Tests on Material properties of Traditional Masonry Buildings
Brick masonry is heterogeneous construction in which bricks are laid one over another joinedby mortar. Mortar can be mud (clay), lime, cement-sand etc. mixed with water in various
proportions. In the Kathmandu Valley, modern masonry constructions are made by bricks withcement sand-mortar, but, in the past, most of the constructions had been made in mud mortar
bonded bricks made of local technology since the beginning of the Malla period (300 years ago).
There are hundreds of temples and residential buildings constructed with such traditional
technology, which still exist and have been in usage. Most of them have gained aged value and areincluded as historical structures in the World Heritage Sites of the Kathmandu Valley. Deteriorationof these structures due to aging and adverse environmental degradation is a prime concern.

Fig. 3-2.43 Compression loading

Fig. 3-2.44 Diagonal loading

Fig. 3-2.45 Combined loading

Table 3-2.16 Experiment plan
S.N

Description

Testing method

1

Compression
Type:
Bricks and mortar cubes, mud bonded wall
Samples: 90 bricks, 11 mortar cubes and 3 walls
Sizes:
Length=35cm, Width=35cm & Height=35cm for wall,
48 mm cube mortar and approximately 45mm cut brickcubes
Measure: Vertical load, vertical and lateral deformations.
Plot:
Compressive stress vs. strain
Calculate: Ultimate compression stress, strain, elastic modulus andPoisson’s ratio

2

Shear
Test:
Diagonal shearType:
Mud bonded wall
Samples: 4Size:
Length=60cm, Width=60cm & ,Thickness=35cm
Measure: Force and deformation
Plot:
Shear stress vs. strain
Calculate: Ultimate shear stress, shear strain and shear modulus

3

Combined horizontal and vertical loadingType:
Mud bonded wall
Samples: 5
Sizes:
Length=35cm, width=70cm and height=70cm
Measure: Vertical load and horizontal load
Plot:
Horizontal and vertical stress relationshipCalculate: Elastic modulus, equivalent cohesion and tangent angle

78

For step towards combating the existing low strength masonry structures is to find basic
material properties such as modulus of elasticity, strength in compression, tension and shear.
Strengthening of these structures requires rigorous analysis using more precise properties andstrengths. Advanced researches on reinforced and steel structures have already been done and someresearch may have been done on reinforced masonry or unreinforced masonry structures such as
those lime or cement mortar bonded brick masonry. Some investigations 1, 2) regarding thematerial of similar kind of bricks and brick walls in the laboratory Institute of Engineering (IOE).
But, they have only investigated on cement-sand mortar bonded masonry specimen focusing themodern constructions and there are no investigations on mud bonded masonry buildings have beenreported so far. Thus, an experiment was planned and done which has been summarized in Table 32.16. Brick units, mortar cubes and wallets were applied three kinds of loadings. They are diagonal
shear, vertical compression and combined vertical and lateral loads. The numbers of samples, sizes,
method of load application, reading of load and deformations etc. have been given in the Table 32.16.
Main purpose of this test was to take the core samples from the existing buildings and test in thelab. But, it was not possible because of various reasons such as difficulty of transportation, andstability of the core after taking out of wall, and owners do not want to drill in their walls. So, bricks
fabricated in Malla period were collected from the old buildings which were dismantled recently.
Sample brick wallets were constructed at IOE, Pulchowk Campus. Using IOE laboratory testing
facilities, three kinds of tests – compression, shear, combined shear and compression loading tests
were conducted (Figs. 3-2.43 –3-2.45).
a) Compression testing
The compressive strength of masonry is measured by the materials being used to build with. An
individual brick's compressive strength is a physical property that measures how compressed thematerial is, which determines how much strength a brick offers a structure. A brick's compressive
strength is based on its solidness or hollowness, its base material and the method is used to fire theraw materials into their final consistency. When bricks with a high compressive strength are used tobuild a structure, that structure will be very strong because of the quality of the materials.
Compression loads (Fig. 3-2.43) were applied on 3 walls and the compressive load versus
deformations has been deformations were recorded at various intervals of loadings. The results
initial stress and strain, modulus of elasticity (E), Poissons`s ratio ( ), shear modulus (G) and shear
wave velocities (VS) of the walls are given in the Table 3-2.17. Same symbols have been used in thefollowing sections also. All the properties have been calculated from initial tangent stress strain
ratios. Shear modulus and shear wave velocity is calculated and summarized in the Table 3-2.17.
Table 3-2.17 Experiment results from compression test

S.N.

Initial stress N/mm2

1
2
3
Average

0.10
0.10
0.10

Initial strain

E (N/mm2)n

G (N/mm2)0.000430.000370.00031

234
270
319
274

0.32
0.24
0.17
0.24

88
109
136
111

79

VS ( m/sec)
347
373
406
375

Fig. 3-2.46 Compressiive stress and strain relation

Compressive stress and strain obtained from the test is plotted in Fig. 3-2.46. At the beginning,
the ratios which is in fact modulus of elasticity, is higher and after small increment of loads it starts
cracking and the ratio drops. It is because of cracks at mortar joints. Again after few steps ofloadings bricks start taking loads and the relationship goes linear.
b) Shear test
Four sample walls were placed diagonally on the testing plat form as shown in table 3-2.16 andFig. 3-2.44. The load was applied at the top and increased gradually. Deformations of wall along
the bed of the joint were measured. The dimensions, shear height and obtained shear modulus havebeen given in the Table 3-2.17. Shear modulus is calculated from the ratio of shear stress and shear
deformation. The shear stress and stain relationships are plotted in the Fig. 3-2.47. As the loadincreases, the stress strain behavior gets nonlinear. Thus shear modulus is calculated from initial
three values which are very close before starting to decline. Taking Poisson`s ratio equal to 0.24
obtained from the compression test modulus of elasticity is calculated. The obtained results are
given in Table 3-2.18. Average value of shear modulus, elastic modulus and shear wave velocity arefound to be 250 N/mm2, 621 N/mm2 and 366m/sec. respectively. Similarly, average shear stressand stain at ultimate stage are found to be 0.126N/mm2 and 0.00608 respectively. Shear strength of
the wall is governed by the mortar/interface which comes from friction due the asperities between
the surface of mortar layer and the surface of the brick unit, and the bond between mortar and brickunits. Normal compression perpendicular to the interface further increases its shear strength because
the asperities cannot easily slide over one another. In the Fig. 3-2.47, shear stress and strain
relationship looks linear, however, it behaves non linearly. Only in the very small stress levels thewall as a whole behaves and the shear modulus looks linear. However, quickly after increasing theloads, the wall tries to shear at the joint. Then crack initiates at the weakest bed and starts to slip
forming likes two rigid bodies. Thus, the deformation is controlled by the mortar joint and the shear
modulus for joint and wall remains same as the deformation phenomenon totally governed by joint.
Table 3-2.18 Results from diagonal shear tests
Length
mm

Width
mm

Area
mm2

Height
mm

G
N/mm2



E
N/mm2


kg/m3

VS
m/sec

StressN/mm2

Strain

1

585

365

213525

585

225

0.24

557

17.68

353

0.154

0.00582

2

585

365

213525

585

280

0.24

695

17.68

394

0.128

0.00599

3

585

365

213525

255

352

0.24

874

17.68

442

0.128

0.00606

137

0.24

339

17.68

275

0.097

0.00646

250

0.24

621

17.68

366

0.126

0.00646

Test

4
Average585

365

213525485

80

Fig. 3-2.47 Shear stress strain relationc) Combined shear and compression
Five wallets were given vertical 1 ton load initially and then lateral load were applied at upperedge to the specimen (Fig.3-2.45). The deformations at each load increment were noted and load
displacement curve is plotted. From the plot modulus of elasticity was calculated from the initialtangent stiffness (k0) obtained from the initial load divided by initial deformation. The results are
given in Table 3-2.19. In the Table, 0 is horizontal displacement at initial force P0. For historicalmasonry structures, it is widely accepted to examine E and G for a wall as a whole, rather than forthe constituent materials, since brick masonry is not an elastic, homogeneous, or isotropic
material. Because the value of initial stiffness k0 represents the elastic stage of the wall, k0 can becalculated (eqn. 3-2.9) for walls with the fix-ends against rotation as given by Drysdale and Hamid
3).
k 0

Et
3
 h   1.2  h     lw   G E  lw 

(3-2.9)

Table 3-2.19 Results from combined lateral and vertical loadings
S.N.

P0
KN

0
mm

k0
KN/mm

E
N/mm2



1

6.03

0.07

86

955

0.25

2

6.03

0.08

75

836

3

6.03

0.14

43

477


kg/m3

G
N/mm2

VS
m/sec

382

444

0.25

17.68
17.68

334

415

0.25

17.68

191

314

4

6.03

0.12

50

557

0.25

17.68

223

339

5

6.03

0.20

30

334

0.25

17.68

134

263

57

632

0.25

17.68

253

355

Average81

Fig. 3-2.48 Horizontal deformation of wall on 1 ton vertical force

Horizontal loads were gradually increased on four walls with vertical loads 1.0, 1.2, 1.4 and 1.6
tons. The loads were kept constant and horizontal load was increased until the wall fails. The
obtained results are given in Table 3-2.20 and plotted in Fig. 3-2.49.
Table 3-2.20 Relationship between shear and normal stresses
Vertical force
KN

n
N/mm2


N/mm2

30.10

9.81

0.123

0.040

31.50

11.77

0.129

0.048

3

33.90

13.73

0.138

0.056

4

35.30

15.70

0.144

0.064

S.N

Horizontal force
KN

1
2

Fig.3-2.49 Relationship between normal and shear stress82

RemarkEquivalent Coulomb
parameters
C=0.0857
tan=0.9174

S.N
1
2
3

Type
Brick
MortarWall

Density
kg/m3
1768
1705
1768

Table 3-2.21 Summary
Compressive
Shear
G
Strength
Strength
2
N/mm
N/mm2
N/mm2
11.03
1740
1.58
1.82
0.15
318



0.11

E
N/mm2

VS
m/sec

3874

1037

0.25

794

402

In this section, we have investigated the mechanical properties of masonry from experiments by
various methods. Masonry is a composite material of brick units and mortar joints and interface
between mortar and unit. Together, they determine the properties of masonry. The interface is
known as the weak link in the system with minimal tensile bond strength, thus masonry has limited
tensile strength and usually negligible. Under uniaxial compression, state of stresses in the brick ina masonry prism is compression-tension-tension; whereas, softer mortar joint is under tri-axial
compression. Under tension, masonry is linear elastic material; tensile failure is characterized by
splitting along the interface. Masonry exhibits nonlinearity under biaxial loading. Cyclic loading
reduces compressive strength of masonry prism by 30%. Shear behavior of masonry depends uponnormal stress; under high normal stress, dilatancy is insignificant. Mohr-Coulomb model isappropriate for modeling shear behavior in joint.

References
1) Shah, U. S.: Performance of cement mortar in brick masonry, Master’s thesis, TU, IOE, Pulchowk Campus, Nepal, 2002.
2) Pun, R : Response of load bearing brick masonry: Experiment and numerical simulations, Master’s thesis, TU, IOE, Pulchowk
Campus, Nepal, 2005.
3) Drysdale, R., and Hamid, A. : Masonry structures: behavior and design, Canada Masonry Design Centre, 2005

83

(3) Structural analysis of historical masonry building
With a purpose to develop the strengthening technique of the heritage buildings, as a primarystep towards seismic disaster risk mitigation, the structural analysis of the historical masonrybuilding, Lalitpura pati (Fig.3-2.50) is carried out. The selected historical masonry building islocated in the Jhatapol area of the Patan city. Following the investigation of the material propertiesand determination of other structural parameters, as described in earlier sections, a numerical modelof the building is prepared for analysis. The structural analysis is carried out by using Finite
Element Method (FEM) for various possible earthquake ground motions as seismic input.
Masonry behaves distinct directional properties due to the interfaces between the constituent
elements. The large number of influencing factors such as interior voids, anisotropy of bricks,
dimension of bricks and joints, arrangement of bed and head joints and quality of workmanshipmake the numerical model of masonry wall very complex. Limited number of variables that areused in the numerical model cannot reflect the actual behavior of brick walls due to its variety ofproperties. Basically, two methods are used for analyzing masonry houses – one, distinct element
method (DEM) which considers the brick units as non-deformable solids and their movements areevaluated through equation of motions, and the other, finite element method (FEM), which
considers the masonry wall as a deformable element. The FEM analysis has a wide scope, startingwith a simple approach with consideration of masonry as a single phase material to a very
sophisticated approach with assumption of masonry as a two or multi-phase material. The
versatility of the FEM method has made it popular and has become a well accepted tool.

Fig. 3-2.50 Lalitpura pati, the historical brick masonry house at Jhatapol area

Fig. 3-2.51 Formulation of solid and joint elements

Since the brick masonry walls are composed of brick units and joints (Fig. 3-2.51), they behave
non linearly governing the entire deformation phenomenon by weak joints. The ordinary FEM
84which is based on continuum mechanics may not be applicable for such kind of problems. Thus, themodified FEM considering discontinuities has been used in the field of rock mechanics 1) andrecently, it has been used in brick and stone masonry 2,3,4) to simulate time dependent sliding andseparation along the mortar joints. This concept has also been applied to investigate theeffectiveness of wooden beams in dry stone masonry houses 5). Thus, similar idea of modeling thebrick units as solid elements and interfaces between them with zero thickness of joint elements is
employed here. However, there is large number of bricks in a house and modeling of each brickseparately is very complicated and practically impossible. Thus simplified numerical model isdeveloped making equivalent eight noded elastic solid elements for brick wall blocks and eight
noded joint elements 2) for interfaces between brick elements.
For FEM modeling, the parameters such as density, modulus of elasticity, Poisson ratio, spring
constants for joints along normal and shear directions are very much essential. The material
properties were taken from the experiments described in the previous sections. The stiffness
constants along shear and normal directions are calculated by considering the differences of moduleof elasticity between a single brick and wall. The wall is represented by series of two springs, one
by brick element and other by joint 4) as shown in Fig. 3-2.51. The concept of joint element is torepresent the non linear behavior of the adjacent elements. The model has elements with varying
thickness, therefore separate values of coefficients are required depending upon their depth.
However, in this study an average value of depth 25cm has been taken and calculated corresponding
values of normal and shear stiffness coefficients are 3.4GN/m3 and 1.4GN/m3 respectively. Unit
weight and modulus of elasticity for wooden elements are 4.47KN/m3 and 8.1xGN/m2 respectively.
Regarding the damping, very limited information is available in linear solid mechanics problem,and even very less information is available in non linear dynamic analysis. For problem underconsideration, the Raleigh coefficients α=0.0174 and β=0.172 are taken maintaining the damping
approximately 3% following Wakai and Ugai 6).
The model building (3-2.50) has been divided into two rooms longitudinally is modeled asshown in the Figs. 3-3.52-3-2.53. It is a double storeyed building; 16.5 m long and 5.6 m wide. The
wall is made of traditional brick and 60cm thick at the bottom and 50 cm at the top, a slight taperingfrom bottom to top. An average thickness 55cm is taken for an analysis. It was constructed threehundred years ago. It sustained damages in earthquakes and repaired many times. Recently, its
original roof has been replaced by corrugated galvanized iron sheet which rests over wooden planks
and battens and the interior wall has been plastered by cement sand mortar. The floor has been
recently replaced by concrete which rests over wooden boards supported by planks and beams. Now,
it is repaired hiding its original construction and has been using as public purpose. The building hasvery large opening in the front side. Wooden posts are supporting the wall of upper storey. In theupper storey, there is a big wooden window placed at mid span of the wall and is slightly projected
to outside showing a nice aesthetic view.

Fig. 3-2.52Simplified FEM model

Figure 3-2.53 Modified FEM model85

In the numerical model, vertical wooden posts have been put in the ground floor and an
equivalent wooden frame has been put to replace the big window of the upper storey. Separate
modelings of walls, floor, roof, and their component-bricks, windows, doors, posts are extremelycomplicated jobs. Small partition walls have not been considered in the model. Simplified model
considering load bearing walls have been constructed (Fig. 3-2.52). The wall is discretized into
small number of solid brick elements, vertical posts are modeled as wooden solid and the big
window of the upper storey is modeled as equivalent solid elements. Total elements are 2995, solids
are 1186 and joint elements are 1809. As a possible strengthening solution, two wooden frames
have been added inside the building (Fig. 3-2.51). The different colors shown in the models show
the different materials. In the first model (Fig. 3-2.52), there are joint elements between the
different materials whereas in the second (Fig. 3-2.53), model has been modified putting the rigid
joint between the posts and connecting elements, floor elements and window elements. The added
frame should be fixed into the wall and thus the connectivity between them is considered rigid.
These changes make significant changes in the numerical model though they look similar in theFigs. Wooden elements and bricks are inter-connected at floor and roof levels, they behave likesemi-rigid floor diaphragm. If theses element are considered separately the model becomes very
complicated and thus, floor mass is lumped at wall where the floor and roof rest. To differentiate
the material properties separate color can be observed in the model (Figs. 3-2.52- 3-2.53). Duringlateral loadings, floor acts rigidly and the corresponding solid elements at floor and roofs are
assigned rigid with same material properties. Joint elements are provided to connect the floors withwalls. Total loads of floors were calculated 1.5KN/m2.
At first, static analysis was run for vertical loads and self weights. And obtained stresses wereused in dynamic analysis as initial stresses. In the second step, dynamic analyses were run with an
input of Kobe1995 earthquake, El Centro 1940 earthquake, simulated for 98 years and 475 years
return period (Fig. 3-2.54). Equations of motions were evaluated at 0.01 interval of time byNewmark’s beta method satisfying the Mohr-Coulomb criterion for slide and separation 3). The
residual forces obtained from deducting actual force developed and permissible force calculated
from constitutive relationship produces non linear deformation at the joints which are evaluated by
Newton Raphson method.

Fig. 3-2.54 Input ground motions86

In full three dimensional analyses, there is possibility of obtaining tensile and compressive
forces right from the beginning. So, the building experiences tension at some areas, most likely near
openings and at other weak zones which goes on iteration and finds non linear deformations. If theresidual forces are big, iteration takes very long time and ultimately computation becomes very
lengthy. Since, there are no predefined criteria to define failure of masonry buildings; a ceilingvalue-30cm displacement has been set in the program. Normal length of brick is 23cm, and, if
deformation exceeds 30 cm, it completely dislocates by its original position. However, it isarbitrarily assumed value and one can take its own definition and value. The purpose of terminationof analysis is just to save the time only. The building experienced more than 30cm displacements in
El Centro 1940, Kobe 1995 and 475 years return period earthquakes in few seconds. The
deformations obtained by various time histories are shown in Figs. 3-2.55 – 3-2.60. The
deformations of elements are shown in different colors (values are in meters). The deformation
depends upon amplitude, frequency content and duration of earthquakes. The building sustains verylarge deformation quickly in Kobe 1995 earthquake since it has highest amplitude. It also gets large
deformation in El Centro 1940 earthquake simulated for 475 years return period after few seconds(Figs. 3-2.55-3-2.60). The difference between them is time only. In all cases the large deformations
can be seen in the gable wall and near the large openings which is quite expected. The deformations
are bigger along in Y (shorter) direction than in X (longer). It is usual because the wall stiffness isgreater along X than in Y.
Dislocation of vertical posts and initiation of deformations also can be seen in the simulated 98
years earthquake, however, the values are very small (Fig. 3-2.59). This shows that the building isable to resist the around 100 gal or less amplitude earthquakes, but, it cannot resist even greater than
150 gals acceleration since it has sustained large deformation in 50% reduced El Centro earthquakes(Fig. 3-2.58). However, duration and frequency content should also be considered while defining
complete failure. As reported in contemporary literatures, El Centro 1940 earthquake is the firstrecorded earthquake and 40% houses had been damaged. It is quite reasonable to say that this brickmasonry house sustain very large cracks and deformations and cannot survive. The building
sustains very large deformations under all given earthquakes and it is proved to be very weak andcannot take any kind of severe earthquake loadings.

Fig. 3-2.55 Deformations in 475 years RP earthquake

Fig. 3-2.56 Deformations in Kobe 1995 earthquake

Fig. 3-2.57 Deformations in El Centro 194087

Fig. 3-2.58 Deformations in 50% de-amplified El Centro
1940

Fig. 3-2.59 Deformations in 98 years RP

Fig. 3-2.60 Deformations on modified in El Centro 1940 earthquake

Being historical building, it has heritage value and should be protected against future earthquake.
There could be many possible methods of strengthening of buildings, however, archeologists andconservationists do not allow intrusion by all kind of materials such as concrete, steel, FRPs etc.
Thus, there are very few options remained; for example, addition of wooden beams and column
internally could be one of the possible options. Thus, looking at the weak zones, near the openings
and top of the shorter walls, strengthening measures are applied; joints between the posts and theconnecting elements are made fixed, the floor elements are connected with the wooden elements
placed around the openings, wooden beam and posts (Fig. 5-2.53). Then, the house is analyzed
again in the El Centro 1940 earthquake ground motion. During full cycles of analysis it gets
maximum displacement 3.4 cm (Fig. 3-2.60) along Y direction. It shows that simple method ofstrengthening can contribute significant strength and reduce the large deformation. Being old brickmasonry, the wall is already stressed and propagation of crack is obvious even in small
deformations. Though it might not be serviceable after earthquake, it may protect the lives. And
also, wood is easily available in local areas and easily acceptable by the heritage conservation
community, thus, becomes good strengthening alternative for those kinds of buildings.

References
1) Zienkiewicz, O.C., Best, B., Dullage, C. and Stagg, K.G.: Analysis of non linear problems in rock mechanics with particularreference to jointed rock systems, Proceedings of 2nd International conference, Society of Rock Mechanics, pp501-509,
Belgrade, (3), 1970.
2) Tzamtzis, A.D. and Nath, B.: Application of three-dimensional interface element to non -linear static and dynamic finite
element analysis of discontinuous systems, PD-Vol. 47-1, Engineering System Design and Analysis, (1), ASME, 1992.
3) Tzamtzis, A.D. and Asteris, P.G.: FE analysis of complex discontinues and jointed structural systems, Electronic Journal of
Structural Engineering, (1), 2004.
4) Senthivel, R., Lourenco, P.B. and Vasconcelos, G.: Analytical modeling of dry stone masonry wall under monotonic andreversed cyclic loading, Structural Analysis of Historical Constructions, New Delhi, 2006.
5) Parajuli, H., Kiyono, J. and Ono, Y.: Effectiveness of wooden bond beams in dry stone masonry houses, Journal of Applied
Mechanics, JSCE, Vol. 11, pp.615-623, 2008.
6) Wakai, A. and Ugai, K.: A simple constitutive model for the seismic analysis of slopes and its applications, Soil andFoundation, Japanese Geotechnical Society, Vol. 44, No. 4, 83-97, 2004.

88

89

3-2.4 Simulation of Building Collapse
Aiko Furukawa
Junji Kiyono
Hitoshi Taniguchi
Kenzo Toki
Masatoshi Tatsumi(1) Introduction
In this section, seismic damage to an existing historic masonry building in Jhatapo area issimulated using the refined version of the DEM. Results for three input ground motions withdifferent occurrence probabilities, two cases with different input ground motion directions arecompared.
(2)Analytical Methoda) Basic conceptThis study employs a refined version of the DEM1) to simulate a series of structural dynamic
behaviors from elastic to failure to collapse phenomena. A structure is modeled as an assembly of
rigid elements, and interaction between the elements is modeled with multiple springs and multiple
dashpots that are attached to the surfaces of the elements. The elements are rigid, but the method
allows the simulation of structural deformation by permitting penetration between elements.
Fig. 1 (a) shows a spring for computing the restoring force (restoring spring), which models theelasticity of elements. The restoring spring is set between continuous elements. Structural failure ismodeled as breakage of the restoring spring, at which time the restoring spring is replaced with acontact spring and a contact dashpot (Fig. 1 (b)). Fig. 1 (b) shows the spring and dashpot forcomputing the contact force (contact spring and dashpot) and modeling the contact, separation, andrecontact between elements. The dashpots are introduced to express energy dissipation due to thecontact. Structural collapse behavior is obtained using these springs and dashpots. The elements
shown in Figs. 1 (a) and (b) are rectangular parallelepipeds, but the method does not limit thegeometry of the elements.
The surface of an element is divided into small segments as shown in Fig. 1 (c). The segment in
the figure is rectangular, but the method does not limit the geometry of the segment. The black
points indicate the representative point of each segment, and the relative displacement or contact
displacement between elements is computed for these points. Such points are referred to as contact
points or master points in this study. One restoring spring and one combination of contact springand dashpot are attached to one segment (Fig. 1 (d)) at each of the representative points in Fig. 1 (c).
The spring constant for each segment is derived on the basis of the stress-strain relationship of thematerial and the segment area.
Forces acting on each element are obtained by summing the restoring force, contact force, andother external forces such as the gravitational force and inertial force of an earthquake. The
behavior of an element consists of the translational behavior of the center of gravity and therotational behavior around the center of gravity. The translational and rotational behaviors of eachelement are computed explicitly by solving Newton’s law of motion and Euler’s equation of motion.

89

(a) Restoring spring(b) Contact spring and dashpot(c) Segments and contact points(d) Multiple springs and multiple dashpots
Fig. 1 Basic concept of the analysis method

Element A
GA

Element A
GA

contact point(master point)A

contact point(slave point)A

contact point(slave point)

contact point(master point)

B

B

GB
Element B

GB
Element B(a) Continuous elements(b) Restoring spring between elements
Fig. 2 Modeling of the restoring spring between elementsb) Spring constant of each element
There are two types of springs, namely restoring and contact springs. It is assumed that the
spring constants of the restoring spring and those of the contact springs are the same. It isconsidered that each segment has its own spring.
Springs are set for both the normal and shear (tangential) directions of the surface. Let us denotethe area of the segment as dA and the relative (contact) displacement at the surface segment as un
and us. The subscripts n an s indicate the values in the normal and shear directions, respectively.
The spring constants per area in the normal and shear directions, kn and ks, are obtained as follows.

kn E(1  )
2

ks 

,

E
,
2(1   )(1)

where E is Young’s modulus,  is Poisson’s ratio, and  is the distance from the surface at which
the spring is connected to the center of gravity.
c) Modeling of elastic behavior
It is assumed that two elements, A and B, are continuous, and that a contact point of element A
is continuous with element B as shown in Fig. 2(a). The contact point of element A is the “masterpoint” and the contact point of element B is the “slave point.” The slave point does not have to be90

the center of the segment. The combinations of continuous elements for each segment are
determined in the initial stage of the computation.
Let GA and GB be the centers of gravity of elements A and B, respectively. Let  A be thedistance from GA to the surface of element A in contact. Let  B be the distance from GB to thesurface of element B in contact. Let EA and EB be Young’s moduli and A and B be Poisson’s ratiosof elements A and B.
It is assumed that both elements have their own spring constants in the normal and shear
directions based on their material properties as shown in Fig. 1(b). The spring constants per area foreach element are obtained from Eq. (1). Assuming that these springs are connected in series, thespring constants between elements per area, k n and k s , are shown in Fig. 2(b).

kn 

1
A

E A /(1  A2 )B

, ks 

E B /(1  B2 )

1
A
B

E A / 2(1   A ) E B / 2(1   B ).

(2)

The spring constant between elements connected by mortar is also obtained in a similar manner. For
example, in masonry structures, bricks are often connected with mortar. In this case, the spring
constant per area between elements (bricks) is obtained as
kn 

ks 

1
 A  tM / 2tM
 t /2
 B M 22
2
E A /(1   A ) E M /(1   M ) E B /(1   B ),1
 A  tM / 2 B  tM / 2tM
E A / 2(1   A ) E M / 2(1   M ) E B / 2(1   B ),(3)

where tM is the mortar thickness, EM is Young’s modulus, and M is Poisson’s ratio of the mortar.
The normal direction of forces is the direction perpendicular to the surface of the master point ofelement A.
Let  and τ be the normal and shear stresses acting at the contact point, and let un and us be therelative displacements between the adjacent master and slave points in the normal and shear
directions. The relation between traction (, τ) and relative displacement (un, us) is then written as  knun ,   ksus .

(4)

It is noted that the method cannot handle Poisson’s effect since it considers the contact between twoelements.
d) Modeling of failure phenomena
The elastic behavior of structures is demonstrated by the linear multiple restoring springs
between continuous elements until the restoring force of a spring reaches its elastic limit. The
elastic limits are modeled using the criteria of tension, shear, and compression failure. When aspring reaches one of these limits, it is judged that failure has occurred at that segment of the spring.
91

Shear stress 
Sheartan
failureccCompression failure

Tensile failureft
ft Normal stressfm
fm

Fig. 3 Modeling of failure phenomena

After the failure, the restoring spring is replaced with a contact spring and dashpot at this segment.
The method can trace the expansion of failure between elements. The three failure modes—namely,
tension, shear, and compression failure modes—are defined based on the Mohr-Coulomb cap model
as follows.
Tension failure mode
For the tension failure mode, the parameter considered is tensile strength ft. When the normal stressof spring  exceeds the tensile strength, the restoring spring is assumed to be broken by the tension
failure. The yield function has the following form (Fig. 3).
f1 ( )    f t .

(5)

The normal restoring stress cannot exceed this limit.
Shear failure mode
For the shear failure mode, the Coulomb friction envelope is used. The parameters considered arebond strength c and friction angle . The yield function has the following form (Fig. 3).
f 2 ( ) |  |  tan   c .

(6)

The shear restoring stress cannot exceed this limit.
Compression failure mode
For the compression mode, an ellipsoid cap model is used. The yield function has the following
form (Fig. 3).
f 3 ( )   2  C s 2  f m ,2(7)

where fm is the compressive strength and Cs is the material model parameter. Cs = 9 is adopted on thebasis of past research2). When the restoring stress exceeds this limit, both the normal and shear
restoring stresses are reduced in the same proportion to meet this limit.
In real structures, failure occurs not only at the mortar, but also inside bricks and at the interface
between brick and mortar. However, in this study, it is assumed that failure does not occur insidebricks but at the interface between bricks, and we do not discriminate failure at the mortar from failure
92

Element A
GA

contact point(slave point)

Element A

GA

AA
contact point(master point)

contact point(slave point)

GB

B

contact point(master point)
B

GB
Element B

Element B(a) Discontinuous elements in contact(b) Contact spring and dashpot between elements
Fig. 4 Modeling of the contact spring and dashpot between elements

at the interface between brick and mortar. The restoring spring between elements is linear until any
failure occurs. In tension, linear tensile reaction force acts until it reaches the tensile strength. Aftertensile failure, no tensile reaction force acts between these elements until they are in contact again. In
compression, the linear compressive reaction force acts until it reaches the compression strength, andthe compressive reaction force then obeys the Mohr-Coulomb cap model. During the unloading
process after the failure, the compressive strength decreases linearly with the initial stiffness, and it
becomes 0 when elements are separated. The shear reaction force is also linear until it reaches the shear
strength, and it then obeys the Mohr-Coulomb cap model. During the unloading process after the
failure, the shear strength decreases linearly with the initial stiffness and obeys the limit of Eq. (6).
Since the face of the elements is divided into many segments and each segment has its own spring,these springs gradually break during loading.
e) Modeling of contact and recontact between elements
If a segment of an element is in contact with another element with which the segment is notcontinuous via the restoring spring, the contact spring and dashpot generate contact force between
the elements. Contact between a segment and the surface of another element is detected at each time
step for all segments that are not continuous with other elements via a restoring spring.
Figure 4(a) illustrates the situation where a contact point of element A is in contact withdiscontinuous element B, and Fig. 4(b) shows the contact spring and dashpots between theseelements.
The spring constant and the contact forces in the normal and shear directions are calculated in
the same manner as for the restoring force. The differences from the case for the restoring force arethat the contact force is generated only while the compression force acts and that the shear force isbounded by the friction limit.

   tan  ,(8)where  is the friction angle.
The dashpot is introduced to express the energy dissipation of the contact. The damping
coefficient per area is calculated as follows.

c n  2hn m ave k n ,c s  2hs m ave k s ,

93

(9)

where hn and hs are the damping constants for the normal and shear directions. mave is the equivalentmass per area relevant to this contact. In this study, mave is calculated asm ave   A  A   B  B ,(10)where  A and  B are the mass densities of elements A and B.
The damping constants should be evaluated according to the properties of the elements, but thisstudy adopts critical damping (hn = hs = 1.0) by considering the fact that most structural components
tend not to bounce greatly and that their oscillation tends to quickly disappear when they collidewith each other.
f) Restoring and contact forces acting at each element
The restoring and contact forces are calculated at all segments for both elements A and B. The
restoring and contact forces acting at each point are obtained by considering the area of the masterpoint. Assuming dA is the area of the master point, the effective area can be half the segment areadA to avoid double counting of the contact force, since the contact points of both elements A and B
can be the master points. Therefore, assuming that dA/2 is the effective area of the master point, thespring constants and damping coefficients are

K n  k n dA / 2 ,K s  k s dA / 2 ,C n  c n dA / 2 ,C s  c s dA / 2 .

(11)

In consideration of this, the size of the segments should be small and the same for elements A and B.
Finally, the spring forces (en, es) and damping forces (dn, ds) in the normal and shear directions
are written ase n  K nu n ,es  K su s ,d n  C n u n / t ,d s  C s u s / t ,(12)

where un and us are the increments of relative displacement and t is the time interval. The
variables written in bold face are vectors.
g) Structural damping
In this study, structural damping that expresses energy dissipation in structural vibration isconsidered. This differs from energy dissipation of the contact expressed by damping constants cn
and cs.
Damping constant c is introduced as mass-proportional damping asc  m ,(13)

where  is a variable defining the damping constant.  can be calculated as  2hi  i ,(14)

where i is the angular frequency and hi is the corresponding damping constant.
Mass-proportional damping is adopted since the method solves the equation of motion for eachelement and mass-proportional damping is easily applicable. The dashpot attached between contact94elements is a stiffness-proportional damping. We plan to investigate an appropriate model of damping
in a future study.
h) Equations of motion
Equations of motion can be constructed using the restoring and contact forces and other external
forces. The motion of each element is obtained by solving the two equations of motion. One is theequation for the translational motion of the center of gravity, and the other is the equation for therotational motion around the center of gravity.
Translational motion of the center of gravity
The forces acting on an element are the sum of external forces, such as the gravitational force
and inertial force due to an earthquake, and the restoring and contact forces between elements. The
equation of motion for the translational motion ismx g (t )  cx g (t )  mg  mz(t )   F(t ) ,(15)

where xg(t) is the displacement vector of the center of gravity of an element at time t, m is the massof the element, c is the damping constant of the element, g is the gravitational acceleration vector,
z t is the ground acceleration vector at time t, and F(t) is the sum of the restoring and contact

force vectors at time t.
Rotational motion around the center of gravity
First, the angular velocity vector (t) is obtained by solving the following Euler equation of
motion.
 (t )  ω (t )  Iω (t )   R (t )r (t )  R (t ) F (t ) .
Iω

(16)

Here, I is the tensor of the moment of inertia, r(t) is the vector between the center of gravity and thepoint where force F(t) is applied. R(t) is the matrix representing the transformation from theabsolute coordinate system to the inertial frame of reference.
The vector from center of gravity xg(t) to arbitrary point xp(t) in an element, xgp(t), is obtainedby solving the following differential equation using the angular velocity vector.
x gp (t )  (R T (t )ω(t ))  x gp (t ) ,(17)

where (t) is the angular velocity vector in the inertial frame of reference obtained by solving Eq.
(16). The coordinates of point xp(t) are then obtained as follows.
x p (t )  x g (t )  x gp (t ) .
In this study, Eqs. (15)–(18) are solved explicitly using the central difference scheme.

95

(18)

Spring and dashpot

Mortar joint
Brick

Element(a) Masonry structure(b) Analytical modelFig. 5 Analytical modeling of masonry structuresi) Critical time interval
Since the equations of motion are solved explicitly, the solution is conditionally stable3). The
following inequality is used to determine the time interval for the computation.

E /(1   2 ) .
t  min  /






(19)

The term on the right hand side of Eq. (19) is obtained for all segments of all elements, and the timeinterval is determined. If the solution is unstable using this time step, a smaller value is used until
stability is attained.
j) Modeling of bricks and mortar
In this study, individual components of the masonry structure shown in Fig. 5 (a) (i.e., brick andmortar joints) are modeled in a simple manner as shown in Fig. 5 (b). The bricks are modeled withrigid elements and the mortar joint between elements is modeled with multiple springs and multiple
dashpots. The size of one element is the sum of the brick size and the thickness of mortar together.
The multiple springs and multiple dashpots interact with the surfaces of adjacent elements.
The modeling in this study is three-dimensional, and the elements are modeled with rigid
rectangular parallelepipeds and hexahedrons. Faces surrounding the elements are divided into
segments. The interval between contact points of neighboring segments is set to a quarter of theshortest edge length according to a past study1). The method was verified through a comparison withthe experimental results of monotonic loading and the analytical results of free vibration by the FEM1).
Verification by comparison with cyclic loading and shaking table tests is very important and comprises
one of our future plans. The dynamic failure patterns and scattering of elements, which will be shown
later, are numerical solutions based on the assumptions shown in the previous section. Moreover,
adobe brick is a very brittle material compared to other masonry elements such as burnt brick, stone,
and concrete block, and the adobe bricks themselves fracture during earthquakes. However, due to thelimitation of the analytical method, we do not model failure inside such bricks. Therefore, the solution
focuses on structures where mortar failure is dominant and brick failure is negligible. In this respect,
the method may not be appropriate for structures where failure inside the bricks occurs with highprobability. Modeling of failure of the brick itself is also one of our future plans.

96Fig. 6

Target area (Jhatapo area) and the location of the target building(a) Western wall
Fig.7(b) Eastern wall(c) Eastern room of the 2nd floor
Target historic masonry building(3)Analysis outlinea) Target historic masonry building
A building to be analyzed is a historic composite building whose location and pictures areshown in Figs. 6 and 7. It was built in the seventeenth century, but it has been damaged by many
earthquakes, and repaired many times.
The building is two-storied, and has the dimensions of 16.5m  5.6m. The height of the 1st and2nd floors is 2.4m and 2.1m, respectively. The maximum height is 6.5m. Each wall has openings,
and the western wall has the largest openings as shown in Fig.7(a). The walls are composed ofbricks, and the bricks are connected with each other by mortar. The size of bricks is not unified anddepends on when and where they were made. There are two separated rooms with the width of 23m as shown in Fig.7(c).
b) Analytical model
An analytical model is shown in Fig. 8(a) (b) (c). Members except bricks, such as columns,
beams and ring beams, are shown in Fig. 8(d). The axis of the coordinate is shown in Fig. 8(a). In
the western wall, there are eight wooden vertical columns in the 1st floor, and 6 wooden verticalcolumns and 2 wooden horizontal beams on the 2nd floor. Moreover, there are two ring beams on
the top of the 1st and 2nd floors. The depth of the walls is 55cm.

97

Z
Y
x
(a) View from the northwest(b)View from the northeast(c) View from the top(d)Columns and beams
Fig. 8 Analytical model

Table 1 Analytical parameter
Variable
Adobe Brick
Mortar3
3
Mass density (kg/m )1.8  10Young’s modulus (N/m2)
2.7  108
2.7  108
Poisson’s ratio
0.11
0.25
2
Tensile strength ft (N/m )0.0
Shear strength c (N/m2)
9.0  104
Friction angle 42.5
Compressive strength (N/m2)
1.58  106

Wood
7.0  102
6.3  1080.3
1.1  108
9.0  1060
4.5  107

Material properties, such as mass density, Young’s modulus and poisson’s ratio are listed inTable 1. The values used for bricks are not the actual values of a single brick, but averaged valuesof the wall including bricks and mortar. The properties are estimated through an experiment using
an bricks taken from an existing building. Since the material properties of wooden columns andbeams on the western wall were not measured, a general values for woods are used instead. The
roof is a tin roof and not modeled considering that its weight is very light and it does not affect thevibration behavior.
The building is modeled as an assembly of rigid elements of rectangular parallelepipeds. The
size of each brick is 10cm x 10cm x 20cm. The total number of elements is 63978. The rigid
elements are connected with each other by springs. The rigid element itself does not deform, but thebuilding as a whole shows deformation by overlapping of the rigid elements. When one of thetensile, shear and compression stresses acting at the spring exceeds the strength, the spring is cut
and the failure occurrence is expressed.
Table 1 also lists the tensile strength, bonding strength, friction angle and compressive strength.

98Mode number
Frequency
Mode

Table 2 Natural frequencies by microtremor observation
2nd mode
3rd mode
1st mode
4.3Hz
5.8Hz
6.8Hz
Translational mode in Y direction Torsional mode Translational mode in X direction(a) Time history(b)Fourier spectrum
Fig.9 Dispalacement response in X direction when the impact acceleration is input in X direction(a) Time history(b)Fourier spectrum
Fig.10 Dispalacement response in Y direction when the impact acceleration is input in Y directionc) Verification of analytical model
The microtremor observation was done for the target building and the natural frequencies wasobserved as shown in Table 2. The first natural frequency is 4.3Hz and it is a translational mode in
Y direction. The second natural frequency is 5.8Hz and it is a torsional mode. The third natural
frequency is 6.8Hz and it is a translational mode in x direction.
To obtain the natural frequencies of the analytical model, the impact acceleration of 100 gal is
input to the building in X and Y directions, separately, and the displacement response is computed
at one point at the 2nd floor. The displacement history in X direction when the impact acceleration
is input in X direction is shown in Fig.9(a). The Fourier spectrum is also shown in Fig.9(b). The
displacement history in Y direction when the impact acceleration is input in Y direction is shown in
Fig.10(a). The Fourier spectrum is also shown in Fig.10(b). From these figures, the Fourier spectra
for Y direction has its peak around 4.0Hz, so it corresponds to the translational mode in Y directionof the first mode. The Fourier spectra in the both X and Y directions has their peak around 5.0 Hz,
and it can be considered to be the torsional mode of the second mode. The Fourier spectrum for X
direction has its peak around 6.6Hz and it can be considered to be the translational mode in X
direction of the third mode. From this comparison between the analytical results and themicrotremor observation, the analytical model expresses the vibration characteristics almost
correctly, therefore the validity of the analytical model is confirmed.
99

ACC (gal)ACC (gal)

800
600
400
200
0
-200
-400
-600
-800
0

10

20

30

40

50

800
600
400
200
0
-200
-400
-600
-800
0

10

TIME (s)(a) 40% (Return period of 98 year)

20
30
TIME (s)4050(b) 10% (Return period of 475 year)

800
600
ACC (gal)

400
200
0
-200
-400
-600
-800
0

10

20
30
TIME (s)4050(c) 5% (Return period of 975 year)
Fig. 11 Input ground acceleration with respective occurrence probability in 50 years
Table 3 Cases with different directions and occurrence probabilities of input ground motion
Cases
Direction of input ground motion Occurrence probability of input ground motion
Case 1X
X
40%
Case 1YY
40%
Case 2X
X
10%
Case 2YY
10%
Case 3X
X
5%
Case 3YY
5%d) Input ground acceleration
Input ground accelerations are shown in Fig. 11. These are estimated from the Nepalese historic
seismic data and active fault data by seismic hazard analysis. Fig. 11(a) is an acceleration with theoccurrence probability of 40% in 50 years (return period is 98 year) and has the peak acceleration of
84gal. Fig. 11(b) is an acceleration with the occurrence probability of 10% in 50 years (return
period is 475 year) and has the peak acceleration of 420gal. Fig. 11(a) is an acceleration with theoccurrence probability of 5% in 50 years (return period is 975 year) and has the peak acceleration of
630gal.
e) Analytical cases
The analytical cases are shown in Table 3. There are 6 cases with 2 different directions and 3
different occurrence probabilities of input ground motion.
(4) Simulation results
The three input ground motions with differente occurrence probabilities are input to the model.
The seismic behavior for every 5 second is whosn in Figs. 12-17.
Based on damage investigation surveys, the typical failure patterns of adobe buildings havebeen discussed by many researchers4),5). Here, the outcome of the DEM is compared with the100

observed failure patterns to confirm the performance of the DEM.
Mohmoud et al. 4) reported that the out-of-plane failure of walls was the main failure mode of
the adobe houses. They describe that lack of proper connections between the perpendicular walls
resulted in the separation of walls from each other, failure of the walls, and subsequent collapse of
the roof. The DEM succeeded in demonstrating this failure mode. For example, in Fig.13, the outof-plane deformation of the shorter walls in the south side can be seen. Zahrai and Heidarzadeh5)
pointed out that the failure of adobe buildings normally started in a corner by separation of the walls
from the top. The DEM also demonstrates this behavior. For example, from Fig. 13, it is found thatthe separation between walls starts from the top.
a) Input ground acceleration with the occurrence probability of 40% in 50 years
The input ground motion with the occurrence probability of 40% in 50 years is input in X and Y
directions, separately. Seismic behavior for these directions are shown in Figs. 12 and 13.
When we look at the triangle part on the shorter wall, the difference due to the input groundmotion directions cannot be seen. And the northern wall completely fell down while the southernwall partially fell down. This is because the northern wall has larger openings at the second floor
and this made the northern wall vibrate more largely.

Y(East)Z
X(South)Fig.12

Seismic behavior of Case 1X (input ground motion : X direction, occurrence probability in 50 years : 40%)101

When the input ground motion is input in X direction (case1X), more damage occurred to thewider wall compared to the case when the input ground motion is input in Y direction (case1Y).
As for case1X, the northern part of the wall in the east side suffered severe damage. This isbecause the ground motion in X direction excites the vibration of the shorter wall in the out-ofplane direction. The wall in the north side has larger openings in the 2nd floor, and it is more likely
to vibrate compared to the wall in the south side. Therefore, the upper portion of the northern wall
separated from the other part and fell down, which caused failure of the eastern wall. The northernwall suffered from the failure due to the vibration in the out-of-plane direction, whereas thesouthern wall suffered from slight damage. From those observation, it can be said that the southernpart with smaller openings in the 2nd floor has more earthquake-resistance compared to the northernwall.
As for case1Y, the both eastern and western walls are wide with larger openings and easy tovibrate in the out-of-plane direction, but the western wall has less damage than the eastern wall.
This is because the columns in the western wall acted as the reinforcement and avoided the westernwall from failure.

Fig.13

Seismic behavior of Case 1Y(input ground motion : Y direction, occurrence probability in 50 years : 40%)102b) Input ground acceleration with the occurrence probability of 10% in 50 years
The input ground motion with the occurrence probability of 10% in 50 years is input in X and Y
directions, separately. Seismic behavior for these directions are shown in Figs.14 and 15.
When the ground motion is input in Y direction, the building completely collapsed. The easternwall firstly separated from the buildings and collapsed, then the shorter wall collapsed, and thewestern wall collapsed lastly. The reason why the western wall with the largest openings collapsed
lastly is the columns resist against the tensile failure. When the ground motion is input in X
direction, the both shorter walls get damaged in the second floor followed by the failure of the 1st
floor, and this causd the damage to the southern parts of the eastern and western walls.

Fig.14

Seismic behavior of Case 2X(input ground motion : X direction, occurrence probability in 50 years : 10%)103

Fig.15 Seismic behavior of Case 2Y(input ground motion : Y direction, occurrence probability in 50 years : 10%)c) Input ground acceleration with the occurrence probability of 5% in 50 years
Finally, the input ground motion with the occurrence probability of 5% in 50 years is input in X andY directions, separately. Seismic behavior for these directions are shown in Figs.16 and 17. Similar
to the case with the occurrence probability of 10%, the buildings collapsed when the ground motion
is input in Y direction, When the ground motion is input in X direction, the 2nd floor collapsed, but
the 1st floor did not collapsed.
(5) Conclusions
The seismic behavior of the existing masonry building is analyzed using the refined version of theDEM. The first three natural frequencies of the analytical model coincide with those obtained fromthe microtremor observations. When the ground motion with the occurrence probability of 10% and
5% in 50 years is input, severer damage occurred especially when the ground motion is input in Y
direction.

104

Fig.16 Seismic behavior of Case 3X(input ground motion : X direction, occurrence probability in 50 years : 5%)

105

Fig.17 Seismic behavior of Case 3Y(input ground motion : Y direction, occurrence probability in 50 years : 5%)

References
1) Furukawa, A., Kiyono, J., Toki, K.: Proposal of a numerical simulation method for elastic, failure and collapse behaviors ofstructures and its application to masonry walls, Journal of Disaster Research, Vol.6, No.1, Paper: Dr6-1-4524, 2011.
2) Lourenco, P.B.: Analysis of masonry structures with interface elements, theory and applications, Delft University of Technology,
Faculty of Civil Engineering, TU-DELFT report no.03-21-22-0-01, TNO-BOUW report no.94-NW-R0762, 1994.
3) Courant, R.L.:Variational Methods for the solution of problems of equilibrium and vibration. Bulletin of the American
Mathematical Society, 49:1-23, 1943.
4) Mahmoud, R.M., Farzad, N., Michael, M.: Performance of adobe residential buildings in the 2003 Bam, Iran, Earthquake,
Earthquake Spectra, Vol.21 No.S1, pp.S337-S344, 2005.
5) Zahrai, S.M., Heidarzadeh, M.:Destructive effects of the 2003 Bam earthquake on structures, Asian Journal of Civil Engineering(Building and Housing), Vol.8, No.3, pp.329-342, 2007.

106

3-3 Damage Potential of Buildings in Case Study Area
3-3.1 Characteristics of Traditional Brick Masonry Buildings
Hari Ram Parajuli

Out of the three block clusters of the Jhatapol area (Fig. 3-2.1) the focus for the disaster risk
management plan is on Block B. The buildings surveyed in Block B is indexed with nomenclature
B1, B2, B3 etc. as shown in Fig. 3-2. 2. Block B contains altogether 90 buildings comprising ofbrick masonry buildings and buildings made of reinforced concrete buildings. Block B contains a
total of 76 traditional brick masonry buildings with different characteristics. Details of each of thesebuildings as a result of the building survey are presented in Appendix B. The traditional brickmasonry buildings constitute about 85% of the total buildings in the area. The brick masonrybuildings in the study area have the following characteristics:
i. Almost all the buildings have a rectangular plan. Some buildings have foot prints based on
combination of more than one rectangle but of different size. However, the plinth area of suchbuildings being relatively small, the torsional effect due to non-coincidence of the center ofmass and center of rigidity is not substantial. Few buildings having more than 3 storeys,
modified with addition of one or two storeys, have irregular plan in the added upper storeys,causing horizontal torsional effect as well wise additional vertical bending effect.
ii. The length to breadth ratio in almost all the buildings is 2 or less. This indicates a positive
characteristic of the buildings in regard with stability.
iii. The openings for windows and doors in majority of the buildings are small in size and arelocated symmetrically, and the numbers of the openings are limited. These are positive
features towards sustaining the necessary horizontal stiffness of the walls. The large openings
for windows in buildings, especially in the buildings with extended storeys, and locatedwithout symmetry, reduces the wall stiffness and the horizontal shear area of walls needed towithstand the earthquake force.
iv. The buildings with original configuration, especially buildings with maximum number ofstoreys not more than 4 storeys, have retained the traditional double framing of the openings,
to strengthen the openings. This traditional detailing is missing in the buildings with added
floors, which in general, have large openings.
v. The thickness of the structural walls is 230 mm or more in all buildings. The thickness islarger of about 450 mm in the ground floor of the buildings with original configuration. The
upper floors have wall thickness limited to 230 mm, which is the minimum required for thelongitudinal stability of the walls of length or height up to about 2.5m.
vi. The floor to floor height of all the buildings are less than 2.5 m, crucial for limiting the storey
drift of buildings during the lateral action due to earthquake.
vii. The number of storeys ranges from 1 to 6 storeys. The storey-wise distribution of the brickmasonry buildings is presented in Table 3-3.1.

107

Table 3-3.1 Storey wise distribution of brick masonry buildings in Block B
Number ofbuildings% of total

Remarks

Single - storeyed
Two - storeyed
Three - storeyed
Four - storeyed

10
0
8
31

13.16
0.00
10.53
40.79

Five - storeyed

25

32.89

Six - storeyed
Total

2
76

2.63
100.00

Originally 1 storeyed
No 2 storeyed building exist
Originally 3 storeyed
8 originally 4 storeyed (25.8%); 23 originally 3 storeyed(74.2%)
6 originally 5 storeyed (24%); 12 originally 4 storeyed (48%);
7 originally 3 storeyed (28%);
Originally 4 storeyed

The 4-storeyed buildings are maximum in number constituting 40.79%, of the brick masonrybuilding stock in the area. About 74.2% (23 numbers) of these 4-storeyed buildings evidently used
to be originally 3-storeyed, and only 8 numbers of these had been constructed originally as 4storeyed buildings. Only 32 buildings, constituting about 42% of the building stock have retained
the original number of stories. These are 10 numbers of single storyed, 8 numbers of 3-storeyed, 8
numbers of 4 storeyed and 6 numbers of 5 storeyed buildings. Rest buildings are with additional
one or two storeys as is clear from Table 3-3.1.
i. Usage wise, about two-third of the buildings is being used for only residential purpose, whereas
the remaining one-third is used for residential and commercial purposes.
ii. Most of the brick masonry buildings are observed with blemishes like inclination, cracks inwalls and deterioration of materials due to aging. About one-third of the buildings do not show
any sign of such damages. The basic reason for the two-third of the buildings having defects anddamages is the lack of maintenance and repair.
As is known, the brick masonry buildings have a limited capacity against the earthquake actions.
Recognizing the brittle properties of the brick masonry, the optimum seismic resistance of thebuildings is achieved best by proper planning, connection details, and workmanship. Extensive useof timber as the structural or non-structural elements in the traditional brick masonry buildings in
mud mortar is crucial in development of the load path and necessary redundancy. It has been wellrecognized that such buildings with low rise and limited unsupported length of structural walls may
exhibit adequate resistance to earthquakes. The configuration with horizontal and vertical regularity
in terms of mass and stiffness is the most important feature of such buildings, and any deviationfrom these result into a substantial increase in seismic vulnerability. Of the brick masonry building
stock in the study area of Jhatapol, in general, the buildings with number of storeys up to 3 haverelatively the best structural characteristics in terms of the original configuration, connection details
and load path. However, the current status of these buildings with a lot of defects without repair andrestoration makes them more vulnerable to seismicity. On the other hand, the buildings with morethan 3 storeys, modified in later stage, including addition of extra storeys to the originally 3storeyed buildings, are more seismically vulnerable by virtue of larger height, disturbed structural
integrity of members, mass and stiffness irregularity, larger openings and lack of clear load path.
The seismic and structural characteristics of the buildings, if confined to their original configuration
with 3-storeys, and repaired and restored to the original condition by eradicating the defects due toaging and environmental degradation, would have been the best.
1083-3.2 Classification of Building Type for Traditional Brick MasonryPrem Nath Maskey

The traditional brick masonry buildings of the Kathmandu Valley originated and developed in
the of Malla (Medieval) Period during 1200 – 1769 A.D., This period is marked with theculmination of the art and architecture in Nepal. The masonry building built in this period has, ingeneral, the structural system based on wall system with a spine wall at the middle of the plan,symmetrical configuration, with small opening ratio and pitched roof covered with local roof tiles(djhingti). The original brick masonry building is presented in Fig. 3-3.1.

Fig. 3-3.1 Elevation of typical traditional brick masonry building. Source: Drawing: N. Gutschow. Newari towns and buildings.

Fig. 3-3.2 Cross section of typical traditional brick masonry building. Source: Drawing: N. Gutschow. Newari towns
109

The cross section of the typical traditional brick masonry building (Fig. 3-3.2) clearly gives a
picture of the structural system, integrity of the structural elements and the load path in suchbuildings. This style of the buildings was retained with a little change, basically enlarging in
proportion, in the later Shah period (1769 – 1846) with a blending of Mughal architecture. The
substantial influence of other countries in the brick masonry buildings is observed during the laterstage of Rana period (1846 – 1951), marked with imported technology and materials. Based onthese developments the brick masonry buildings are classified, in general, by the name of Mallastyle, Shah style and Rana style. The basic transformation of the style from the Malla period to later
periods is shown in Fig. 3-3.3.

Fig. 3-3.3 Transformation of style of traditional brick masonry building from Malla to Rana period. Source: Drawing:
W. Korn. The TraditionalArchitectural of the Kathmandu Valley.

At present, the building stock of the old settlement of Patan, represented by the Jhatapol area isthe conglomeration of all these three types of buildings, with or without modifications. The
structural system and the general features of traditional brick masonry buildings of some buildings
have changed since their construction; these are the buildings which have been raised withadditional floors or reconstructed in a later stage. However, the pattern of the settlement,characterized by the integrated location of the buildings, and having the common open spaces,
remain unaltered.
The buildings distributed in the area of Jhatapol today, have different levels of seismic
vulnerability by virtue of their difference in configuration, size, irregularity, opening size and age ofthe building. For the purpose of detailed structural analysis of the buildings, the brick masonrybuildings have been classified into 6 types based on their configuration, size, area of openings, mostimportantly on number of storeys. Each category of the buildings is designated by a building index
number, and represents a set of buildings, which fall into the category or closer to the category. The
classification of the brick masonry buildings based on their structural characteristics to obtain theseismic vulnerability is shown in Table 3-3.2.
Table 3-3.2 Classification of traditional masonry buildings
Class

MB1

MB2

MB3

MB4

MB5

MB6

Number of storeys

3

3

4

4

5

5

Building Representing
Class

A75

C25

A48

C26

B47

B4-B5

A15

A12

A3

A1

A4

A21

A34

A30

A6

A2

A5

A25

A37

A40

A7

A18

A13

A54

110

Buildings Falling under
the classes

A47

A45

A9

A19

F53

A56

A69

A46

A16

A20

A22

A58

A73

A57

A24

A29

A23

A62

A77

B17

A27

A38

A26

A76

B18

B32

A31

A39

A36

A84

B42

B52

A32

A41

A50

B12

B88

B65

A33

A44

A51

B24

C9

B85

A35

A55

A64

B29

B89

A42

A61

A66

B41

C0

A43

A71

A74

B50

C6

A60

A72

A79

B54

C7

A70

A83

A80

B69

C10

A78

A85

A81

B77

C22

B1

B4

A82

C1

C32

B2

B5

B3

C5

C55

B6

B8

B15

C30

C59

B7

B9

B19

C58

C60

B14

B10

B20

B16

B11

B26

B33

B13

B28

B38

B25

B30

B47

B27

B31

B57

B49

B39

B66

B68

B40

B67

B79

B43

B75

B80

B45

B78

B86

B48

B81

B87

B76

B82

C56

C2

B84

C3

C13

C29

C17
C23
C24
C26
C35
C57
C61

In the above classification the single storey buildings are not included because the vulnerability
analysis for them is not necessary. The building classes of MB1 and MB2 are having the same
number of storeys, indicating that the classification in not based only upon the number of storeys,
but also on other parameters, like, size, configuration, openings in the walls and age etc. Similarly
the classes of MB3 and MB4 both have 4 storeys, the classes of MB5 and MB6 both are 5 storeyedbuildings for the same reasoning.
111

References
1) Gutschow, N., Kolver, B. and Shresthacharya, I.: Newar Towns and Buildings: an Illustrated Dictionary Newari - English. VGH
Wissenschaftsverlag Sankt Augustin, Germany. 1987.
2) Korn, W.: Traditional Architectural of the Kathmandu Valley. Ratna Pustak Bhandar, Kathmandu. 1979.

.

112

3-3.4 Characteristics of RC Buildings
Prem Nath Maskey

Out of the three block clusters of the Jhatapol area (fig. 10) the focus for the disaster risk
management plan is on Block B. The buildings surveyed in Block B is indexed with nomenclature
B1, B2,… as shown in figure 11. Block B contains altogether 90 buildings comprising of brickmasonry buildings and buildings made of reinforced concrete buildings. Block B contains a total of
14 buildings constructed in reinforced concrete frame as the structural system. These buildings havedifferent structural characteristics. Details of each of these buildings as a result of the building
survey are presented in Appendix C. The traditional brick masonry buildings constitute about 15%of the total buildings in the area. The brick masonry buildings in the study area have the following
characteristics:
i. Almost all the buildings have a rectangular plan, or a plan with combination of more than
one rectangle. In general, the buildings have irregular plans, presumably the reason forchoosing the framed structure in concrete. These buildings are prone to torsional effects
when subjected to horizontal or lateral loads, for example, due to earthquakes.
ii. The length to breadth ratio in almost all the buildings is 2 or less. This indicates a positive
characteristic of the buildings in regard with stability.
iii. The buildings have large area of openings, as is envisaged in framed structures. The
openings for windows and doors are located rather based on the location of columns, andhence not necessarily followed the rule of symmetry. The provision of brick masonry infill
walls, especially the external infills of marginal thickness, coupled with the large window
openings leads to the weak storey stiffness, indicating the vulnerability feature of thebuildings. Many of the buildings have isolated lintels above the openings rather thanproviding a continuous lintel band, losing the opportunity to tie the masonry walls with thestructural frame at the strategic levels.
iv. The buildings, which have not undertaken the vertical expansion, have retained the original
configuration. But the buildings with recent addition of extra floors have possess large
projections for extra covered space or balcony, resulting into the state of mass and stiffness
irregularity. Worse is when walls are constructed supported on projected slab or beam toenclose the space. This is the most undesirable practice in case of low rise buildings
constructed in concrete frames.
v.
The thickness of the partition walls (infill wall) is limited to not more than 230 mm. The
thickness is reduced to 115 mm, particularly in the upper floors, with a notion that these are
non structural elements. The provision of such thin walls of brick masonry without
reinforcement and anchorage with the supporting structural frame makes the building more
vulnerable due to reduction of storey stiffness as well as the reduced out-of-plane capacityof the wall.
vi. The floor to floor height of all the buildings are less than 2.5 m, crucial for limiting thestorey drift of buildings during the lateral action due to earthquake.
vii. One of the best features of the buildings constructed with reinforced concrete frame
113

viii.

ix.

structural system is the solid concrete slab at each floor level, imparting very high in-plane
stiffness. However, more important is the concrete column size, its flexural and shear
capacity to resist the inertia force due to earthquake. In most of the buildings the size of thecolumn is limited to 230 mm square. The concrete frame with such size of column will not
be able to perform as intended. It will be like the concrete frames are made to tie the brickmasonry walls vertically and horizontally, undermining the role of the principal structural
system. Providing maximum reinforcements in beams and slabs, and providing minimum
reinforcements ( in most cases limited to 4 numbers of 16 mm dia.) have been the usual
practice, as a result the columns are weaker and the building hence may not be able to resist
the horizontal loads effectively.
Most of the buildings have no engineering design, and constructed following the rules of thethumb, and relying on the traditional masons, who are highly skilled in traditional brickmasonry buildings, but not in reinforced concrete construction. As a consequence, thebuildings, on one hand do not comply with the prevailing codes of practice on concrete
construction, and on the other, the technology of construction is applied not with the needed
details of construction.
The number of storeys ranges from 1 to 5 storeys. The storey-wise distribution of thereinforced concrete buildings is presented in Table 10.
Table 3-3.3 Storey wise distribution of reinforced concrete buildings in Block B
Number ofbuildings% of total

Single - storeyed
Two - storeyed
Three - storeyed
Four - storeyed

2
0
1
3

14.29
0.00
7.14
21.43

Five - storeyed

8

57.14

Total

14

100.00Remarks
Originally 1 storeyed
No 2 storeyed building exist
Originally 3 storeyed
2 originally 4 storeyed (66.7%); 1 originally 3 storeyed(33.3%)
4 originally 5 storeyed (50%); 1 originally 4 storeyed(12.5%); 1 originally 3 storeyed (12.5%); 2 originally 2
storeyed (25%)

The 5-storeyed buildings are maximum in number constituting 57.14%, of the reinforced
concrete building stock in the area. About 50% (4 numbers) of these 5-storeyed buildings evidently
used to be originally 5-storeyed, that is, without any extension; about one fourth (2 numbers) of the
5-storeyed buildings was originally constructed as 2-storeyed, and 1number (12.5%) used to beoriginally 3-storeyed and another (12.5%) 4-storeyed structures. Only 9 buildings, constituting
about 65% of the building stock have retained the original number of stories. These are 2 numbersof single storyed, 1 number of 3-storeyed, 2 numbers of 4 storeyed and 4 numbers of 5 storeyedbuildings. Rest buildings are with additional one or two storeys as is clear from Table 10.
i. Usage wise, about 71% of the buildings is being used for only residential purpose, and about
15% of the building stock is used for residential and commercial purposes, whereas theremaining 14% is used for other usage like monument or store.
ii. Most of the buildings (about 93%) are observed without any kind of damage, where as one
building (about 7%) is observed with a lot of defects and damages like inclination, joint
114

damage and lack of mortar.
As is well recognized, the structural performance of framed concrete buildings is better than thatof brick masonry buildings, and hence the framed buildings generally have a better resisting
capacity against the earthquake actions. However, as the reinforced concrete construction is asophisticated technology, it should be designed and constructed according to the accepted standards
and codes of practice. Numerous factors influencing the concrete strength may not be known tocommon local masons, the development of required ductility in the structure by proper rebar details
may be even far from their experience. The buildings constructed with RC cannot be efficiently
built in non-engineering approach. Further, irrespective of better strength of the RC framed
structure, the configuration with horizontal and vertical regularity in terms of mass and stiffness isstill the most important feature of the buildings, and any deviation from these result into asubstantial increase in seismic vulnerability. The concrete framed buildings without extension offloors, in general, possess relatively the best structural characteristics in terms of the original
configuration, connection details and load path. On the other hand, the buildings with 5 storeys,
modified in later stage, including addition of extra storeys to the originally 2 to 4 -storeyedbuildings, are more seismically vulnerable by virtue of larger height, disturbed structural integrityof members, mass and stiffness irregularity, larger openings and lack of clear load path.

115

3-3.5 Development of Seismic Risk Evaluation method
Prem Nath Maskey(1) Classification of Reinforced Concrete Buildings
The reinforced concrete buildings of the area are relatively new, because these have been
constructed substantially later. However, these buildings distributed in the area of Jhatapol today,
have different levels of seismic vulnerability by virtue of their difference in configuration, size,
irregularity, opening size and age of the building. For the purpose of detailed structural analysis of
the buildings, the RC buildings have been classified into 6 types based on their configuration, size,area of openings, most importantly on number of storeys. The six classes of the buildings aredesignated by CB1to CB6, each one of which represents a set of buildings, which fall into thecategory or closer to the category. The plans of the reinforced concrete buildings representing theclassification are shown in Figs. 3-3.4 – 3-3.9. The classification of the reinforced concretebuildings based on their structural characteristics to obtain the seismic vulnerability is shown in
Table 3-3.4.
In the above classification the single storey buildings are not included because the vulnerability
analysis for them is not necessary. The building classes of MB1 and MB2 are having the same
number of storeys, indicating that the classification in not based only upon the number of storeys,
but also on other parameters, like, size, configuration, openings in the walls and age etc. Similarly
the classes of MB3 and MB4 both have 4 storeys, the classes of MB5 and MB6 both are 5 storeyedbuildings for the same reasoning

A-7

Fig. 3-3.4 Plan and isometric view of the building of class CB1

A-30

Fig. 3-3.5 Plan and isometric view of the building of class CB2
116

B-22

Fig. 3-3.6 Plan and isometric view of the building of class B3

C-56

Fig. 3-3.7 Plan and isometric view of the building of class CB4

B-63

Fig. 3-3.8 Plan and isometric view of the building of class CB5

117

C-22

Fig. 3-3.9 Plan and isometric view of the building of class CB6
Table 3-3.4 Classification of reinforced concrete buildings
Class

CB1

CB2

CB3

CB4

CB5

CB6

Number of storeys

3

3

4

4

5

5

Building Representing
Class

A7

A30

B22

C56

B63

C22

B23

A16

A28

B21

A52

C31

A59

A49

B55

A53

C33

B22

A63

B63

A65

C8

B36

B64

A67

C15

B44

B73

A68

C16

C11

A80

C18

C14

B46

C34

C56

B90

Buildings falling in the
class

C12

B72
C19
C20
C21
C22
C58

(2) Fragility Analysis of RC Buildings
With an objective to estimate the seismic vulnerability of the buildings in the area, aprobabilistic risk analysis is carried out resulting into fragility curves. The probability of failure
against different seismic intensity parameter, usually represented by peak ground acceleration(PGA) is obtained from the fragility curves. The simulated earthquake ground motion acceleration
time history at the free field of Jhatapol area and named Lalitapura time history (Fig. 3-3.10) is usedas the seismic input for the analysis f of buildings. The time history has a peak value of 0.437g. The
time history data, for simplicity are rescaled to PGAs of 0.45g.

118

The modal analysis is carried out to obtain the vibration properties of the structures tounderstand the structural behaviour. The non–linear static procedure (Pushover Analysis) is applied
to determine the capacity of the structure for the fragility analysis. The results of the pushover
analysis is demonstrated as resistance of the structure in terms of defined collapse mechanism as
formation of hinges to the top displacement, that is used as the capacity of the building structure.
The time history dynamic analysis is used to determine the response of the structures, required forthe fragility analysis. To obtain fragility curve, a failure mode for the frame is assumed, and theprobability of exceedance of that particular mode is determined. Building fragility curves, which
express the probability of a building reaching or exceeding certain damage state for a given groundmotion parameter. For seismic loading, the fragility simply looks at the probability that the seismic
demand placed on the structure (D) is greater than the capacity of the structure (C). Capacity of thebuilding is defined as the top displacement at the stage formation of at least one frame mechanism.
This probability statement is conditioned on a chosen intensity measure (IM) which represents thelevel of seismic loading. The generic representation of this conditional probability is given as byequation 3-3.1.

Fig. 3-3.10 Earthquake time histrorry Lalitpura

Fragility  P D  C / IM   P C  D  0 . 0 / IM 

(3-3.1)The structural reliability is calculated using first order second moment (FOSM) method. In thismethod random variables are characterized by their first and second moments. In evaluation of thefirst and second moments of the failure function, say mean and standard deviation the first order
Taylor’s approximation is used. In order to calculate the reliability, the limit state equation isdefined using equation 3-3.2.
M  Sc  Sd

(3-3.2)119

In which C is capacity, D is response of building. M is margin of safety.
S
Pf  P  d  1 Sc
(3-3.3)The probability of failure is determined by:  ln  S d   Sc  
Pf   22  d  c 

(3-3.4)

Table 3-3.5 Response of the building PGA 0.45g

Building A7 (CB1)Storey level
GroundFirst
SecondThird

Height (m)
0
2.84
5.68
8.52

GroundFirst
Second
Third

0
2.74
5.48
8.22

Displacement (mm)069.7
140.13176.09Drift ratio (%)
0
2.454
2.480
1.266

Base shear (KN)

864.05

Building A30 (CB2)
0
21.83
42.38
53.72

0
0.797
0.750
0.414

435.17

0
1.810
2.113
1.478
0.677

1373.32

0
2.258
2.311
1.477
0.551

1480.27

0
1.371
1.889
1.676
1.209
0.579

2814.91

0
1.757
2.006
1.622
0.965
0.464

1505.15

Building B22 (CB3)
GroundFirst
SecondThird
Fourth

0
2.6
5.2
7.8
10.4

0
47.06
101.99140.41158.01

Building C56 (CB4)
GroundFirst
SecondThird
Fourth

0
2.4
4.8
7.2
9.6

0
54.2
109.66145.11158.34

Building B63 (CB5)GroundFirst
SecondThird
Fourth
Fifth

0
2.7
5.4
8.1
10.8
13.5

0
37.01
88
133.24165.87
181.5

Building C22
GroundFirst
SecondThird
Fourth
Fifth

0
2.44
4.73
7.17
9.61
12.61

0
42.88
88.82
128.4
151.95165.88120

The RC buildings are modeled and analyzed using finite element (FEM). The fragility curves
for particular damage state are derived for the selected buildings from the capacity and response
analysis of corresponding buildings. For the response analysis the seismic input in the form ofground motion time history is applied for the individual model, and the structural response in theform of displacement at each storey level is obtained. The storey displacements, storey drifts, baseshear are shown in Fig. 3-3.5. These fragility curves for 6 classes of buildings are presented in Fig.
3-3.11 to 3-3.16.

Fig. 3-3.11 Fragility curves for building A7 (CB1)Fig. 3-3.12 Fragility curves for building A30 (CB2)121

Fig. 3-3.13 Fragility curves for building B22 (CB3)Fig. 3-3.14 Fragility curves for building C56 (CB4)Fig. 3-3.15 Fragility curves for building B63 (CB5)122

Fig. 3-3.16 Fragility curves for building C22 (CB6)

Non linear static (pushover) analysis is carried out to determine the capacity of each building.
Various iterations are performed to find the minimum top displacement at which at least one frame
forms base column hinges. Only all columns of the ground floor are assigned hinges. The hinge
property is taken default FEMA 356 hinges for concrete column. The top displacement at that stage
is defined as capacity of the building. The peak ground acceleration for a return period of 475 years
expected at the surface of the Jhatapol area is 0.45g. Correspondingly the probabilities of failure ofeach of the 6 building classes are obtained from the fragility curves. The probabilities of failure of
the buildings are presented in Table 3-3.6.
Table 3-3.6 Probability of Failure of the buildings for PGA =0.45g
Building Class
CB1
CB2
CB3
CB4
CB5
CB6

Damage stateheavily damaged
partially damaged
heavily damaged
heavily damaged
heavily damaged
heavily damaged

Max. I.S.D. (%)
2.48
0.797
2.113
2.31
1.89
2.01

Bldg drift (%)
2.07
0.65
1.52
1.65
1.23
1.32

Probability of Failure (%)
66
20
79
77
77
78

(3) Fragility Analysis of the traditional brick masonry buildings
As in the case of RC buildings, the seismic risk analysis in a probabilistic format is carriedout to estimate the probability of failure for different values of peak ground acceleration. Specificto the properties of brick masonry buildings, a failure mechanism, different from that of RC
buildings is assumed. At the outset, modal analysis of the brick masonry buildings is carried out
to obtain the vibration properties. From linear time history analysis, parameters like the baseshear and the displacement at different storey level are determined for the rescaled PGA value of
0.45g in the ground motion acceleration time history.

123

Fig. 3-3.17 FEM models of brick masonry building

The simulated ground motion acceleration time history with a PGA of 0.45g is used as theseismic input as in the case of RC buildings. The shear capacity of the brick masonry building isfound out by manual calculation to develop fragility curve. The finite element modeling formasonry building is not that simple compared to that of RC buildings. The masonry buildings
consist of walls of 45-60cm thickness reduced in upper floors, and with wooden usually doubly
framed, door and windows. The floor is made of timber joists with planks or boards overlaid with
mud or clay materials, and hence flexible floors. There is no actual data showing or proving exact
percentage of fixity of flexibility of these floors which poses difficulties in modeling. In thisanalysis, wooden purlins are modeled as beam members and end moments are released then it act
like hinge member. Six models considered for the building are shown in the Fig.3-3.17. The
buildings are A48, A04, B47, C75, B15 and C26 respectively. The prefixes A, B and C stand forthree blocks of the study area. Though survey has been done in three areas, only B block’s result
has been shown in this study. The response of the brick masonry buildings are the stresses in thewalls due to earthquake ground motion, where as the failure mechanism is assumed to the shear
failure in the wall, which is the usual reason for the serious damage , if not complete collapse.
The calculation for the development of the fragility curves of the masonry buildings is presented
in Table 3-3.7. The fragility curves for the six types of the masonry buildings classes arepresented in Figs. 3-3.18 to 3-3.23.
Table 3-3.7 Development of Fragility Curve for Brick Masonry Building
PGA(g)

Shear capacity
N/mm2, (Sc)

Sear demand
N/mm2, (Sd)log normal distribution,ln(Sd/Sc)/0.64

Probability of
failure0

0.3-0.00006

0

0

0.05

0.3

0.0867-1.939576

0.02621562

0.1

0.3

0.17346-0.855993

0.19600086

0.15

0.3

0.26022-0.222274

0.41205049

0.2

0.3

0.34698

0.2273198

0.58991246

0.25

0.3

0.43374

0.5760356

0.71770445

0.3

0.3

0.52050.8609491

0.80536696

0.35

0.3

0.60726

1.1018353

0.86473335

124

0.4

0.3

0.694021.3104973

0.90498618

0.45

0.3

0.78078

1.4945484

0.93248382

0.5

0.3

0.867541.6591862

0.95146086

0.55

0.3

0.95431.8081181

0.96470594

0.6

0.3

1.04106

1.9440816

0.97405719

0.65

0.3

1.12782

2.0691553

0.98073424

0.7

0.3

1.21458

2.1849549

0.98555392

0.75

0.3

1.30134

2.2927614

0.98906913

0.8

0.3

1.38812.3936074

0.9916582

0.85

0.3

1.474862.4883373

0.9935829

0.9

0.3

1.561622.5776509

0.99502628

0.95

0.3

1.64838

2.662134

0.99611765

1

0.3

1.735142.7422827

0.99694931

Fig. 3-3.18 Fragility curve for MB1

Fig. 3-3.19 Fragility curve for MB2

125

Fig. 3-3.20 Fragility curve for MB3

Fig. 3-3.21 Fragility curve for MB4

Fig. 3-3.22 Fragility curve for MB5

126

Fig. 3-3.23 Fragility curve for MB6

The probability of failure of the brick masonry buildings obtained for the value of peakground acceleration 0.45g determined from the fragility curves is presented in Table 3-3.8.
Table 3-3.8 Probability of Failure of the buildings for PGA =0.45g
Building
Class

Damage state

MB1

Heavy damage

MB2

Heavy damage

MB3

Heavy damage

MB4

Heavy damage

MB5

Heavy damage

MB6

No damage

Location

Crushing state

Top right corner of door at groundfloor 1st floor
Around the door opening at groundfloor
Top right corner of door at groundfloor and wall opening at 1st and 2nd
floor
Around the door opening at groundfloor
Around the small window opening at
ground floor

Crushing of masonry panel
at bottom far end

88

No

93

Crushing of masonry panel
at bottom far end

77

Crushing failure

81

Crushing of masonry panel
at bottom far end
Crushing of masonry panel
at bottom far end

Probability
failure (%)

of

85
55

(4) Vulnerability in the line of EMS-98
The vulnerability of the buildings, brick masonry buildings as well as the RC buildings are alsostudied for their seismic vulnerability in the line of the world accepted European Macroseismic
Scale - EMS-98 1). In this method vulnerability index values are given based on the vulnerability
classes for different building typologies as shown in Table 3-3.9. As the vulnerability (in the EMS98) depends also on other factors such as: quality of workmanship, state of preservation, regularity,
ductility, position, strengthening, and earthquake resistant design level; the methodology suggests
the following definition of the vulnerability index (equation 3-3.5):
V I =VI* + ΔVR + ΔVm(3-3.5)

Where, VI* is a Typological Vulnerability Index, ΔVR is a Regional Vulnerability Factor, andΔVm is a Behavior Modifier Factor. The scoring for the vulnerability factors for masonry buildings
is done as per Table 3-3.10.

127

Table 3-3.9 Attribution of vulnerability classes and vulnerability Index values for different building typologies 1)

Table 3-3.10 Scores for the vulnerability factors for Masonry Buildings 1)

The vulnerability indices, thus obtained, for all buildings of the site are shown in Table 3-3.11.
3-3.11Table Vulnerability Index of the buildings
Building Type
Code
No.

B1
B2

RCC

Brick
MasonryStateofpreven
tion

No.
of
floor
s

Structural systemPlanirregul
arity

Verti
cal
irreg
ularitySuperimpose
dfloorsRoof

Bldg
positionFoundati
on

TOTAL
Vm

√

0.04

0.02

0.04

0

0

0.04

0.04

0.04

0

0.22

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

128

B3

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B4

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B5

0.04

0.02

0.04

0

0

0.04

0.04

0.06

0

0.24

B6

0.04

0.02

0.04

0

0

0

0.04

0.06

0

0.2

B7

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B8

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

0

0

0.04

0.04

‐0.04

0

0.06

B9

√

‐0.04

0.02

0.04

B10

√

‐0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.06

B11

√

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

B12

√

‐0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.06

B13

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B14

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B15

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

B16

0.04

0.02

0.04

0.04

0.02

0.04

0.04

‐0.04

0

0.2

B17

0.04

0.02

0.04

0

0

0

0.04

0.04

0

0.18

B18

0.04

0.02

0.04

0

0

0

0.04

0.06

0

0.2

B19

0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.1

‐0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.02

0.04

0

0

0.04

0

0

0

0

0.04

0.12

B22

0.04

0

0

0

0

0

0

0

0.04

0.08

B23

0.04

0

0

0

0

0

0

0

0.04

0.08

B20
B21

√
√

B24

√

0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.1

B25

√

‐0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.02

B26

√

0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.1

B27

√

0.04

0.02

0.04

0.04

0

0

0.04

0.04

0

0.22

B28

√

‐0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.1

B29

√

‐0.04

0.06

0.04

0

0

0.04

0.04

‐0.04

0

0.1

B30A

√

‐0.04

‐0.02

0.04

0

0

0

0.04

0

0

0.02

B30

√

0.04

0.02

0.04

0.04

0.03

0.04

0.04

‐0.04

0

0.21

B31

√

0.04

0.02

0.04

0

0

0.04

0.04

0.04

0

0.22

B32

√

0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.14

B33

√

B34

‐0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.02

‐0.04

‐0.02

0.04

0

0

0

0.04

‐0.04

0

‐0.02

B35

√

0.04

‐0.04

0

0

0

0

0

0

0.04

0.04

B36

√

0.04

0

0

0.04

0

0

0

0

0.04

0.12

B37

√

‐0.04

0.02

0.04

0

0

0.04

0.04

0.06

0

0.16

B38

√

‐0.04

0.02

0.04

0

0.02

0

0.04

‐0.04

0

0.04

B39

√

0.04

0.02

0.04

0

0

0

0.04

0.04

0

0.18

B40

√

0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.14

B41

√

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

B42

√

‐0.04

0.02

0.04

0

0

0

0.04

0.04

0

0.1

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

0.04

0

0

0.04

0

0

0

0

0.04

0.12

0.04

0.06

0.04

0.04

0

0.04

0.04

‐0.04

0

0.22

0.04

0

0

0

0

0

0

0

0.04

0.08

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

B43
B44

√

B45
B46
B47

√
√

129

B48

0.04

0.02

0.04

0.04

0.02

0.04

0.04

‐0.04

0

0.2

B49

√

0.04

0.02

0.04

0.04

0

0

0.04

0.04

0

0.22

B50

√

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B51

0.04

‐0.02

0.04

0

0

0

0.04

0.06

0

0.16

B52

‐0.04

‐0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.02

‐0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.06

0.04

0.02

0.04

0.04

0

0.04

0.04

0.04

0

0.26

B53

√

B54
B55

0.04

0

0

0.04

0

0

0

0

0.04

0.12

B56

‐0.04

‐0.02

0.04

0

0

0

0.04

‐0.04

0

‐0.02

B57

0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.14

B58

0.04

‐0.02

0.04

0

0

0

0.04

0.06

0

0.16

B59

0.04

‐0.02

0.04

0

0

0

0.04

‐0.04

0

0.06

B60

‐0.04

‐0.02

0.04

0

0

0

0.04

‐0.04

0

‐0.02

B61

0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.1

B62

0.04

‐0.02

0.04

0

0

0

0.04

‐0.04

0

0.06

B63

0.04

0

0

0.04

0

0

0

0

0.04

0.12

B64

0.04

0

0

0.04

0

0

0

0

0.04

0.12

B65

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B66

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B67

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B68

0.04

0.02

0.04

0

0

0

0.04

‐0.04

0

0.1

B69

0.04

0.02

0.04

0

0.02

0.04

0.04

‐0.04

0

0.16

B70

0

0

0.04

0

0.02

0

0.04

‐0.04

0

0.06

B71

0.04

‐0.02

0.04

0

0

0

0.04

0.06

0

0.16

B72

0.04

0

0

0

0.04

0

0

0

0.04

0.12

0.04

0

0

0.04

0

0

0

0

0.04

0.12

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

‐0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.1

B77

‐0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.1

B78

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B79

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

B73

√

B75
B76

√

B80

√

‐0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.1

B81

√

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.14

‐0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.06

0.04

0.02

0.04

0.04

0

0.04

0.04

‐0.04

0

0.18

B82
B83

√

B84
B85

√

‐0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.06

B86

√

‐0.04

0.02

0.04

0

0

0.04

0.04

‐0.04

0

0.06

B87

0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.14

B88

0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.14

B89

0.04

0.02

0.04

0.04

0

0

0.04

‐0.04

0

0.14

B90

0.04

0

0

0

0.04

0

0

0

0.04

0.12

0.04

‐0.04

0

0

0

0

0

0

0.04

0.04

B91

√

The damage indices for each of the buildings are obtained by combining all the scores obtained from130

Vulnerability Index, Probability of failure from Fragility analysis, Vulnerability Class and Visual
Inspection. Using the expert opinion, the weightage for each of the method in the calculation of
Damage Index is as follows;
Vulnerability Index
10%
Probability of failure
60%
Vulnerability Class
10%
Visual Inspection
20%
The damage indices of the buildings are presented in Table 3-3.12 and in the Fig. 3-3.24.
Table 3-3.12 Damage Index of the buildings
Building Type
Code
No.

RCC

B1

Brick
Masonry
√

TOTAL
Vm

NormalizedVm

Originalfor RCC

Probabilityof failure(%)

Vulnerability
class

Visualinspection

Total

Max/
Min

0.22

0.37

77

0.644

0.20

0.60

0.75

B2

0.18

0.30

77

0.644

0.50

0.66

0.34

B3

0.14

0.23

85

0.644

0.20

0.64

B4

0.14

0.23

81

0.644

0.05

0.58

B5

0.24

0.40

81

0.644

0.20

0.63

B6

0.2

0.33

77

0.644

0.50

0.66

B7

0.14

0.23

77

0.644

0.50

0.65

B8

0.14

0.23

81

0.644

0.50

0.67

B9

√

0.06

0.10

81

0.644

0.00

0.56

B10

√

0.06

0.10

81

0.644

0.00

0.56

B11

√

0.18

0.30

81

0.644

0.20

0.62

B12

√

0.06

0.10

55

0.644

0.00

0.40

B13

0.14

0.23

81

0.644

0.50

0.67

B14

0.14

0.23

77

0.644

0.20

0.59

B15

0.18

0.30

85

0.644

0.50

0.70

B16

0.2

0.33

77

0.644

0.20

0.60

B17

0.18

0.30

93

0.644

0.50

0.75

B18

0.2

0.33

88

0.644

0.50

0.73

0.1

0.17

85

0.644

0.05

0.60

0.02

0.03

85

0.644

0.00

0.58

0.12

0.20

77

50

0.74

0.00

0.39

B22

0.08

0.13

79

50

0.74

0.00

0.39

B23

0.08

0.13

65

50

0.74

0.00

0.39

B19
B20
B21

√
√

B24

√

0.1

0.17

55

0.644

0.50

0.51

B25

√

0.02

0.03

81

0.644

0.00

0.55

B26

√

0.1

0.17

85

0.644

0.50

0.69

B27

√

0.22

0.37

81

0.644

0.50

0.69

B28

√

0.1

0.17

85

0.644

0.00

0.59

B29

√

0.1

0.17

55

0.644

0.00

0.41

B30A

√

0.02

0.03

55

0.644

0.00

0.40

B30

√

0.21

0.35

85

0.644

0.50

0.71

131

B31

√

0.22

0.37

85

0.644

0.05

0.62

B32

√

0.14

0.23

93

0.644

0.20

0.69

B33

√

0.02

0.03

77

0.644

0.00

0.53

B34

‐0.02

‐0.03

55

0.74

0.00

0.40

B35

√

0.04

0.07

55

50

0.74

0.00

0.38

B36

√

0.12

0.20

77

50

0.74

0.00

0.39

B37

√

0.16

0.27

55

0.644

0.00

0.42

B38

√

0.04

0.07

77

0.644

0.00

0.53

B39

√

0.18

0.30

85

0.644

0.50

0.70

B40

√

0.14

0.23

85

0.644

0.20

0.64

B41

√

0.18

0.30

55

0.644

0.20

0.46

B42

√

B43
B44

√

B45
B46

√
√

B47
B48

0.1

0.17

88

0.644

0.00

0.61

0.18

0.30

85

0.644

0.20

0.64

0.12

0.20

77

50

0.74

0.00

0.39

0.22

0.37

50

85

0.644

0.00

0.61

0.08

0.13

77

50

0.74

0.00

0.39

0.18

0.30

77

0.644

0.50

0.66

0.2

0.33

85

0.644

0.50

0.71

B49

√

0.22

0.37

81

0.644

0.20

0.63

B50

√

0.14

0.23

55

0.644

0.50

0.52

B51

0.16

0.27

55

0.644

0.50

0.52

B52

0.02

0.03

93

0.644

0.00

0.63

0.06

0.10

55

0.644

0.00

0.40

B54

0.26

0.43

55

0.644

0.50

0.54

B55

0.12

0.20

50

0.74

0.00

0.39

B56

‐0.02

‐0.03

55

0.644

0.00

0.39

B57

0.14

0.23

77

0.644

0.20

0.59

B58

0.16

0.27

55

0.644

0.20

0.46

B59

0.06

0.10

55

0.644

0.20

0.44

B60

‐0.02

‐0.03

55

0.644

0.00

0.39

B61

0.1

0.17

55

0.644

0.20

0.45

B62

0.06

0.10

55

0.644

0.20

0.44

B63

0.12

0.20

77

50

0.74

0.00

0.39

B64

0.12

0.20

77

50

0.74

0.20

0.43

B65

0.14

0.23

93

0.644

0.50

0.75

B66

0.14

0.23

77

0.644

0.50

0.65

B67

0.14

0.23

77

0.644

0.50

0.65

B68

0.1

0.17

81

0.644

0.20

0.61

B69

0.16

0.27

55

0.644

0.50

0.52

B70

0.06

0.10

55

B71

0.16

0.27

55

0.644

0.20

0.46

0.12

0.20

77

50

0.74

0.00

0.39

0.12

0.20

77

50

0.74

0.00

0.39

0.18

0.30

77

0.644

0.50

0.66

0.1

0.17

85

0.644

0.00

0.59

0.1

0.17

55

0.644

0.00

0.41

B53

√

B72
B73

√

B75
B76
B77

√

77

132

0.34

B78
B79

0.14

0.23

77

0.644

0.20

0.59

0.14

0.23

81

0.644

0.50

0.67

B80

√

0.1

0.17

81

0.644

0.00

0.57

B81

√

0.14

0.23

77

0.644

0.50

0.65

0.14

0.23

77

0.644

0.50

0.65

0.06

0.10

85

0.644

0.00

0.58

0.18

0.30

77

0.644

0.05

0.57

B82
B83

√

B84
B85

√

0.06

0.10

93

0.644

0.00

0.63

B86

√

0.06

0.10

81

0.644

0.00

0.56

B87

0.14

0.23

81

0.644

0.50

0.67

B88

0.14

0.23

88

0.644

0.50

0.72

B89

0.14

0.23

93

0.644

0.20

0.69

B90

0.12

0.20

77

50

0.74

0.00

0.39

0.04

0.07

77

50

0.74

0.00

0.38

B91

√

Fig. 3-3.24 Damage indices

The damage indices obtained for the B block are shown in the Fig. 3-3.24 with different
level of values. The dark black color shows higher damage potential and the light color shows
lower damage potential. It is seen from the figure that the buildings: B15, B17, B18, B30,
B39, B48, B65 and B88 are having the maximum damage index in the range of 0.71 – 0.75,
calling for the need of strengthening of the buildings. The high value of the damage index is133attributed to the high score for visual screening condition and the probability of failure as
output of the detailed structural analysis for the possible seismic hazard at the site. The
minimum damage index is in the range of 0.34 – 0.40, indicating basically the need forrestoration, that is, reinstatement of the strength of the structural members at par with their
original state, and necessary repairs.

Reference
1)

Grunthal, G.: European Macroseismic Scale 1998; EMS-98, Cahiers du Centre de European de Geodynamique et deSeismologie 15. Luxembourg: European Seimological Commission, Sub commission on Engineering Seismology, Working
Group Macroseismic Scales, 1998134

3-3.6 Application of Risk Evaluation Methods to Case Study Area
Aiko Furukawa
Junji Kiyono
Hitoshi Taniguchi
Kenzo Toki
Masatoshi Tatsumi(1) Jhatapo area
Our target area is Jhatapo area shown in Fig. 1. In Fig. 1, the buildings are classified by numberof stories and building types. There are many historic masonry building in the target area as shownin Fig.2, and most of them are unreinforced masonry buildings which have the high possibility to
get severe damage during earthquakes.

Fig.1 Target area (Jhatapo area)(a) residence and stores(b) residence
Fig.2 Typical masonry buildings in the target area135

(2) Complete enumeration
A complete enumeration was done for the buildings in the target area. There are 13 buildings
with one story, but they are neglected since they are monuments of vacant buildings for
nonresidential use.
When the buildings are classified with the number of stories, the ratio of 3, 4, 5 and 6 story
buildings are 3, 37, 56 and 4%, respectively as shown in Fig. 3. The buildings with 4 and 5 stories
occupies 93% of the buildings. The number of buildings with 3 and 6 stories are scant, and there areno buildings with two stories.
When the buildings are classified with the building type, 86% of the buildings are unreinforced
masonry buildings, and the other buildings are confined masonry buildings with reinforced concrete(RCC) as shown in Fig.4.
Most of the buildings experienced repair and an addition of stories to the original buildings. Allof the buildings with 5 and 6 stories experienced the addition of stories. The number of added
stories for 4 and 5-story buildings are shown in Fig. 5. From the figure, the most of the buildings
were originally 3 story buildings before the addition.
The buildings are classified into 7 types by the number of stories and building types as shown in
Fig. 6 and Table 1. They are masonry buildings of 3, 4, 5 and 6 stories, and confined masonrybuildings with reinforced concrete (RCC) of 4, 5 and 6 stories. We made 7 analytical models
according to this classification, and estimates the seismic risk in this section.

Fig. 3

Classification by the number of stories

Fig. 4 Classification by building type(a) 4-story masonry buildings(b) 5-story masonry buildings
Fig. 5 Number of additional stories

136

Fig.6 Classification of buildings
Table 1 Classification of buildings
building type
number of buildings
ratio (%)

masonry3F masonry4F masonry5F masonry6F
2
26
36
1
2.63%
34.21%
47.37%
1.32%

RCC4F
2
2.63%

RCC5F
7
9.21%

RCC6F
2
2.63%

Fig.7 Continuous buildings(3) Seismic risk evaluationa) Analytical modelingAll buildings are continuous and shear the party walls with the adjacent buildings as shown in
Fig.7. Moreover, according to the previous study by D’Ayala1), they assume the damage to façade
for the continuous buildings. Therefore, we considered that the failure to the façade is the dominantfailure mode and numerically estimated the damage to façade.
We made 7 analytical models according to the classification. The analytical models for a 4-story
masonry building, and a 4-story confined masonry building with reinforced concrete is shown in
Fig.8. The size of each brick is 10cm x 10cm x 20cm. The façade and side wall of 1m are modeled.
The back of the side wall is supported by the fixed elements which cannot be seen in Fig. 8.
For masonry buildings, each story is 2.0m high, and the width is 4.2m. Each floor is composed oftimber beams, The stories higher than 3rd floor is considered to be added, and the depth of the wallis 60cm for 1st-3rd floors, and 40cm for floors higher than 3rd floor based on the interviews to the
local people.
For confined masonry buildings, each story is 3.0m high, the width is 4.1m, and the section of
RC frame is 30cm x 30cm. The depth of the wall is 20cm for 1st-3rd floors, and 10cm for floors
higher than 3rd floor.
137

(a) 4-story masonry building(b) 4-story confined masonry building
Fig. 8 Analytical models
Table 2 Material properties and failure criteria
Variable
Adobe Brick
MortarWood
3
3
Mass density (kg/m )7.0  102
1.8  102
88Young’s modulus (N/m )2.7  10
6.3  108
2.7  10
Poisson’s ratio
0.11
0.25
0.3
2
Tensile strength ft (N/m )0.0
1.1  108
Shear strength c (N/m2)
9.0  104 9.0  106
Friction angle 42.5
0
Compressive strength (N/m2)
1.58  106 4.5  107

RC
2.3  103
2.5  1010
0.2
1.91  106
2.2  10632
2.4  107

The parameters used are shown in Table 2. The time interval is 4.0×10-5sec for the masonrybuildings, and 1.0×10-5sec for the confined masonry buildings.
The ground motion is input in the out-of-plane direction of the buildings.
b) Damage index
To evaluate structural damage, damage index proposed by Okada and Takai is used. Theirdefinition of each damage index is shown in Table 3 and Fig. 92). Coburn summarized theprogression of damage to the masonry structural system and damage grade as shown in Fig. 93), andthen Okada and Takai scored damage index which takes between 0 (No damage) and 1 (Total
Collapse) for each damage grade according to the definition by the European Macroseismic Scale
1998 (EMS98)4).
c) Damage index function and fragility curveThis study developed a damage index function for each classified building and a fragility curves
for all buildings except one-story buildings.
Damage index function is the relationship between the seismic intensity and damage index. The
fragility curve is the relationship between the seismic intensity and the probability which exceeds acertain damage index.

138

Damage Damage
Grade Index
D0

D1

0.0
0.1
0.2

D2

0.3
0.4

D3

0.5
0.6

D4

0.7

0.8

D5

0.9
1.0

Fig.9 Damage pattern and its relevant damage index 2),3)
Table 3 Damage index and classification of damage to masonry buildings (EMS98)4)
DamageGrade

Damage Index

DamageDescription

D0

0.0

No damage

No damage

D1

0.0～0.2

Negligible tosight damage

Hair-line cracks in very few walls. Fall of small pieces ofplaster only. Fall of loose stones from upper parts ofbuildings in very few cases.

D2

0.2 ～ 0.4

Moderate
damageCracks in many walls. Fall of fairly large pieces of plaster.
Partial collapse of chimneys.

D3

0.4 ～ 0.6

Substantial toheavy damage

Large and extensive cracks in most walls. Roof tiles detach.
Chimneys fracture at the roof line; failure of individual nonstructural elements (partitions, gable walls).

D4

0.6 ～ 0.8D5

0.8 ～ 1.0

Very heavy
damageDestruction

Serious failure of walls, partial structural failure of roofs andfloorsTotal of near total collapse

Damage State

139

(4) Resultsa) Estimated damage index
Three input ground motions with different occurrence probabilities are input to 7 models. The
results are shown in Figs. 10-16.
Since the ground motion is input in the out-of-plane direction of the façade, the façade of themasonry buildings vibrated in the out-of-plane direction and failed. This made the side walls fall
down and there are many fallen bricks around the buildings.

(a)40%
Fig. 10(b)10%(c) 5%
Seismic behavior of 3-story masonry building

Fig. 11(b)10%(c) 5%
Seismic behavior of 4-story masonry building

Fig. 12(b)10%(c) 5%
Seismic behavior of 5-story masonry building(a)40%(a)40%

140

(a)40%Fig. 13(a)40%
Fig. 14(b)10%(c) 5%
Seismic behavior of 6-story masonry building(b)10%(c) 5%
Seismic behavior of 4-story confined masonry building(a)40%(b)10%(c) 5%
Fig. 15 Seismic behavior of 5-story confined masonry building

By comparing the damage obtained by the DEM with the damage pattern in Fig.9, the damage
index is visually evaluated. The damage index for 7 classified models are summarized in Table 4.
Based on the simulation, the damage index for three input ground motions are mapped in Fig.
17. The shaded buildings are 1-story buildings. From Fig. 17(a), the maximum damage index is 0.2
for the ground motion with occurrence probability of 40% in 50 years. The buildings in the target
area are considered to have the strength to survive this scale of earthquake.

141

(a)40%Fig. 16(b)10%(c) 5%
Seismic behavior of 6-story confined masonry building

Table 4
Damage index

Damage index
Occurrence probability in 50 year
40%
10%
5%
Masonry 3F
0.2
0.8
0.8
Masonry 4F
0.2
0.8
0.9
Masonry 5F
0.2
0.8
0.9
Masonry 6F
0.2
1.0
1.0
Confined masonry (RCC) 4F
0.0
0.0
0.3
Confined masonry (RCC) 5F
0.0
0.1
0.3
Confined masonry (RCC) 6F
0.0
0.2
0.4

(a)Occurrence probability of 40% in 50 years

142

(b)Occurrence probability of 10% in 50 years(c)Occurrence probability of 5% in 50 years
Fig. 17 Estimated damage index for target area143

Fig. 18 Damage index function

Fig.19 Fragility curveb) Damage index function
From Table 4, the damage index function is estimated. The definition of damage index functionin this study is the relationship between PGA (peak ground acceleration) and the damage index.
Fig.18 is an estimated damage index function for 7 classified buildings. The buildings withlarger damage index have less strength against earthquakes. Line-up of buildings in order ofincreasing strength becomes masonry 6F < masonry 5F < masonry 4F < masonry 3F << confined
masonry 6F < confined masonry 5F < confined masonry 4F. The most weak building is the 6-story
masonry buildings. Confined masonry buildings have much strength than the masonry buildings.
From this, the effectiveness of reinforcement using reinforcement concrete is clear.
c) Fragility curve
The fragility curve for all buildings except one-story buildings are also computed. The definition offragility curve in this study is the relationship between PGA and the probability which exceeds eachdamage index. The probability is obtained by dividing the number of buildings whose damage
index exceeds a certain value by the number of total buildings assumed.
144

Fig.19 indicates fragility curves for DI>0.4 and DI>0.8.
About 85% of the buildings suffered damage (DI>0.4) at 420gal, and about 88.2% of thebuildings suffered damage (DI>0.4) at 630gal. About 48.7% of the buildings suffered damage(DI>0.8) at 420gal, and about 85.5% of the buildings suffered damage (DI>0.8) at 630gal.
d) Reinforcement using ring beams
The effectiveness of reinforcement using timber ring beams is examined. By using decorated
timber beams, the reinforcement is possible without reducing their historical values. The timber ring
beams are placed on top of each floor to unite bricks in the horizontal direction.
Figs.20 and 21 compare the damage to the buildings with and without ring beams for 5 and 6story masonry buildings when ground motion with the occurrence probability of 10% is input. The
ring beams successfully avoided the building from collapse and the effectiveness is shown.
However, for the ground motion with the occurrence probability of 5%, the ring beam could not
avoid collapse. Therefore, this type of reinforcement is not effective for severe earthquake, andconfined masonry is more stronger than the masonry with ring beams.

(a) with ring beams(b) without ring beams
Fig.20 Effect of introducing ring beams to 5-story masonry building(ground motion with occurrence probability of 10% in 50 years)(a) with ring beams(b) without ring beams
Fig.21 Effect of introducing ring beams to 6-story masonry building(ground motion with occurrence probability of 10% in 50 years)
145

(5) Conclusions
The seismic risk of buildings in the Jhatapo area is evaluated by using the refined version of theDEM. The complete enumeration was done and the buildings are classified into 7 types withdifferent building types and the number of stories. Only the façade is modeled for the analysis
assuming that the vibration in the out-of-plane direction is dominant. The input ground motion withdifferent occurrence probabilities are input in the out-of-plane direction of the models, and thestructural damage is evaluated by using the damage index. It is found that the masonry buildings get
severe damage but the confined masonry buildings using the reinforced concrete get less damage.
As the number of stories increases, the structural damage becomes severer. The damage index
function and the fragility curve for the Jhatapo area is estimated and the seismic risk for eachbuilding is shown on the map. The effectiveness of reinforcement using ring beams is also
confirmed.
References
1) D'Ayala, D.: Correlation of fragility curves for vernacular building types: Houses in Lalitpur, Nepal and in Istanbul, Turkey. In:
Proceedings of the 13th World Conference of Earthquake Engineering, Vancouver Canada, 2004.
2) Okada S, Takai N.: The basic framework for casualty modeling of victims of earthquake, (1) Classification of structural types anddamage patterns of buildings, and damage index function, Reports of the Tono Research Institute of Earthquake Science, No. 2,
pp.12-23 (in Japanese with English abstract), 1999.
3) Coburn, A.W.: Seismic vulnerability and risk reduction strategies for housing in eastern Turkey. Ph. D. Thesis, The Martin Centre
for Architectural and Urban Studies, University of Cambridge, United Kingdom, 1987.
4) Grünthal, G. (ed.): European Macroseismic Scale 1998 (EMS-98), http://www.gfz-potsdam.de/portal/gfz/Struktur/Departments/Department+2/sec26/resources/documents/PDF/EMS-98_Original_englisch_pdf, 1998.

146

4. Analysis of Heritage Values, Vulnerabilities and Resources
for Emergency Response
4-1 Reading Heritage Values of the Historic City of Patan in Kathmandu Valley
Sudarshan Raj Tiwari

4-1.1 Reading Urban Cultural Heritage of Patan
Patan Durbar Square Monument Zone (PMZ) is one of the seven monument zones of the
Kathmandu Valley World Heritage Site (KVWHS). The KVWHS was inscribed in 1979 and its
outstanding universal value (OUV) was assessed under criteria (iii), (iv) and (vi), clause 77,
Operational Guidelines for the Implementation of the World Heritage Convention. These criteria
note the attributes of KVWHS as outstanding architectural and technological ensemble ofsignificance to human history (iv), an exceptional testimony to a living cultural tradition (iii) and atangible artistic work of outstanding universal significance (vi). Since this is an urban cultural
heritage, the reading ofvalues of this heritage is not
limited to its monuments
Kumbheshvar
but
extendedtotheensembleofbuilding
components,
buildings,
Lalitapura Pati
streets and other networks,
crossings and urban spaces
Nagbahal
Swothaand the city. Also as it isnoted as a living heritage,
this study seeks to readlivingness value along withheritage values in theelements, networks andPatan Durbar
spaces. To meet theobjectiveofdisaster
mitigation
planning
particularly in rescue stage,a further reading ofresource/ecological values
in these aspects for access,
space
and
supplies
prospects is attempted. As
per UNESCO’s operational
Fig. 1 Patan Monuments Zone of KV World Heritage Siteguidelines, heritage values
147are read in terms of the indicators of historicity, architecture and artistry, authenticity and integrity,
technology and ecology. Further values are in the characteristics that make and expound it as therecognized stage of development of human and Nepalese history, which in the case of PMZ islargely related to the later Malla period.
Ecological values associated with sensitive human interaction with environment, particularly the
relation of settlement with the ground water and local aquifer as exhibited by the water works about
Kumbheshvar, are worthy of note and have been taken as important resource values.
The key objective of this study for disaster risk mitigation of the said property is to manage
vulnerabilities so as to preserve and continue the values, their authenticity and integrity mainly overearthquake and fire hazard events alongside the mitigation of disaster from the perspective of thehuman life and society and building structure.
Although it is usual to classify the cultural heritage in generic terms into tangibles (monuments,
spaces, windows, musical instruments, handicrafts etc.) and intangibles (language, music, songsetc.), for urban cultural heritage in general and KVWHS in particular as the listing criteria
specifically recognizes its exceptional testimony to a living culture, it would be important to seek its
living linkages to people, their social organization (family, extended family, clan, neighborhood andcitizenry) and cultural practices. Since tangible heritage assume a dominant position from theperspective of disaster mitigation, the consideration of intangible heritage are made within the studyof values and vulnerabilities through the measure of their ‘livingness’. The measure of values forthe urban heritage has been considered in terms of value indicators (such as history, architecture,artistry, representation of a period, social symbolism, ecology) as weighed by the status of theheritage (studied in terms of authenticity, completeness, integrity and associated elements).
Likewise measure of vulnerabilities are based on probability and propensity to damage and loss inthe event of the hazard factored as the effect of the damage or collapse of the structure of theheritage building as well as effect of collapse of neighboring or associated objects and spaces andpossibilities of recovery such as knowledge and skill availability for reconstruction etc. The
classification uses a combination of social and typological differentiation criteria (e.g. temple, pati,
residential building, baha, etc) and gives values to them depending upon their significance to thevalue indicators as well as the social units. The heritage of water (such as expressed in hiti, wells
and ponds and their user social groups) and planning (such as streets, underpasses to courts andnani and open spaces of courtyards and crossings) has been considered as a being additionally andspecifically significant as having resource value from disaster mitigation planning. Heritage ofwater is treated under a separate heading 4-1.3 below. The following description of the values of thecity, built elements, networks and spaces making and constituting the urban heritage are specificallyrelated to the study area of this research e.g. Jhatapol, Konti and Ikhache quarter at the northwestern edge of Patan and generally to historic town of Patan and the Kathmandu Valley World
Heritage Site.
(1) History, legends and symbolic values of the city of Patan
It is traditional in Nepal to attribute a fair share of symbolic values to the cultural heritage andthese are particularly derived from association with legends of happenings of the past.
Known as ‘Yala’ to the Newar, it is believed that the city of Patan was founded by King Birdeva
in 6th century and named Lalitpur in memory of a farmer named Lalita, whose leprous state was148cured by the magical spring of Kumbheshvar. According to a popular legend, the king laid out thecity of Lalitpur around the spring in the auspicious pattern of a yantra with nine jewels in the center,eight protective deities on the periphery (Astamatrika) and twenty four neighborhoods as instructedby Lord Kumbheshvar 1). The Lalitapur Pati and the upright stones of Jhatapol (which literallymeans ‘wet land’ in Newar language) keep memory of the myth alive. The origin of the town ofPatan is shrouded in such and other legends and tales. Buddhist legends relate that the town was
initially given a formal plan based on Dharma-Chakra, the Buddhist ‘wheel of righteousness’, by
the Mauryan Emperor Ashok. The main arterial streets of Patan link the two pairs of Stupa (eastwest and north-south) and intersect at the Durbar Square echoing the Dharma-Chakra layout. The
Patan Durbar Monuments Zone of Kathmandu Valley World Heritage Site is not only the hub of
Dharma-Chakra of this legend, it also houses the nine jewels that form the center of Lalitpur
according to the Lalitapur legend - of these ‘mani’ jewels, Mani-hiti, Mani-Keshavanarayana andMani-Mandap find place in the heritage list. The people of Patan find great value in establishinghistoricity through such legends. Many more of such legends, told and retold woven with nuances,to highlight events that suit each of the variety of faiths that share the urban space and the preferredpaths of cultural development they love to retell, all add value to the spirit of the place. Legend of
Matsendranath (Karunamaya), the founding of Ta-baha and the associated annual and twelve earlychariot festivities or the legend of King Sarvananda and the founding of Guita Bahi make the place
alive for the people. Even as many of such episodes may present a skewed sense of historical time
when viewed against the ‘established history’, mythologies remain defining realities of indigenous
cultural history. Hiranyaverna Mahabihar, Guita Bahi, Oku Bahal and the Mahaboudda temple havethus acquired greater historical, cultural and religious values among the heritage associated with
Buddhist development of Patan.
Despite of difficulties of tying established history and mythological histories, one would rightly
assert that ‘Patan area was almost certainly settled in the Kirata period’. It was already a collectionof vibrant settlements and activities several centuries before the earliest cultural marker ofGajalaxmi was left for posterity by the Lichchhavis at Chyasal-hiti. Popular folk memory in Patan isthat the Kirata and the Lichchhavi fought their final war at Chyasal! Likewise Patuko Don andPatuko Dyochhe in Patan Durbar Square show legendary link to Kirata days. In the area under study,legends claim as early a link for the site of Pimbahal and its Stupa.
The recurrence of important role of farmers in the myths of Patan, whether related to its
establishment or its progress in history, can be attributed to its agricultural origins. Irrigation water
works such as reservoirs, canals and distribution outlets and their urban services counterparts ofponds and pit water conduits have formed important component of tangible cultural heritage ofKathmandu Valley towns and Patan in particular. The development of urban water supply system
by as early as fifth century AD is unique to Kathmandu Valley. In the Patan Durbar Square
Monuments Zone, the landmarks of Mani-hiti (inscription from 6th century AD), the Bhandarkhal
pond, the Kumbheshvar-hiti, the wells and ponds of Kumbheshvar and Nagbaha-hiti tell the historyof this development of urban water supply and irrigation services. The values of the water systemdevelopment may be read in terms of historical, technological, aesthetic, as well as anthropologicalsignificance. These are elaborated separately under 4-1.3 and its subheading (3) below.

149

(2) Built Heritage Elements:
The traditional architecture of the ensemble of the multi-tiered temples, chaitya, palaces, baha,bahi, sattal and pati, the magnificent application art and craft of brickwork and woodwork in them,the design, proportioning and the human scale of the buildings and the resulting mesmerism of theurban landscape transcend the local living cultural value into the outstanding universal value ofaesthetic, technological and ethnographic significance. An extensive inventory of the built heritageof Kathmandu Valley has been published in Kathmandu Valley – The Preservation of PhysicalEnvironment and Cultural Heritage – A Protective Inventory. It has categorized them into different
classes (from class one to four) using indicators of historical-cultural antiquity, authenticity, artistic
quality and architecture and uniqueness within the ensemble 2). Similarly the list of built heritage
listed in the Kathmandu Valley World Heritage Site is available in publications of Department ofArcheology. The following details are given only for some specific elements of concern to thecurrent study and the study area.
a) Temples:
The public square in front of the Patan palace, the Patan Durbar Square is designated as one of
the seven monument zones of KVWHS. The temples and palace courts of Patan Durbar Square,largely built in the sixteenth and seventeenth century AD, represent excellence of Malla periodarchitecture. This square has a number of temples of national/town level significance such as theCharnarayan temple, the Krishna Mandir, the Bhimsen temple and the Viswanath temple. The
oldest temple structure in Patan Durbar Square, the temple of Charnarayan was built in year 1566
AD. Kumbheshvar temple complex was designated into the PMZ because of high historical,
symbolic, architectural and artistic value. As it is a major center of religious and ritual activities andpilgrimage, it holds great significance as a living heritage. The temple of Kumbheshvar is one of the
only two five tiered temple of Nepal and the artistry of woodworks in its struts are remarkable andpossibly some of them are original (from fourteenth century?). The antiquity of Kumbheshvar
temple complex is reinforced by the fact that the temple precinct has the oldest medieval record ofreconstruction for a tiered temple (1392AD) following the vandalism of the original temple by
Sultan Samasuddin in 1349. Apart from the Kumbheshvar temple, the complex also has the templeof Bagalamukhi, temple of Vishnu, a temple with a well (which offers it an ecological value) and anumber of smaller temples and images. A number of important deep pit conduits (hiti), a large
ceremonial water tank and a garden space are other elements of import in the complex.
The Stupa and pond of Pimbaha, a little to the south of the study area is an ancient monument
ensemble that was reconstructed in 1360 AD after it was also similarly vandalized at the hands ofSamasuddin. Besides the pond on its north is situated the temple of Chandeswori built in 1663. Alsoin the Sulima square, a small but beautiful tiered temple of Siva Ratneshvor is located. All thesebuildings of religious usage have legendary and ecological association with the study area. The
pond and the open spaces appear to play significant recharge role to the ground water resources of
the Jhatapol study area through traditional system passing through Nhykachuka and Nagabahal. The
palace square and the open spaces, like Nagabahal, could also play significant role as secondary
spaces in disaster mitigation planning.
In every Janaipurne day (which fell on 13th August in 2011), the people of the whole valley
come in pilgrimage to the festival of Siva that is celebrated in the water tank of Kumbhesvar. Every
150

Saturday and Thursday, the shrine of Bagalamukhi in the Kumbheshvar temple complex comes
alive with many devout visitors that come to offer worship, some with lighting of a one-hundredthousand wick lights (lakhbatti). The temples and spaces of the Durbar Square also come alive withmany festivals of national/town level such as the Chariot Festival of Machchhendranath, theprocession of Krishna, the Mataya festival etc. It also becomes a center of pilgrimage for the wholevalley during Krishna Astami days every year (21st August in 2011). Kartik Nach, a classical dance
drama, is performed in the space in front of Charnarayan temple with much cultural fervor in the
lunar month of Kartik also.
b) Baha-Bahi:
There are no Buddist monasteries in the pilot study area. To the west on the other side of thestreet bordering the study site at Ikhachen Tole is located the Ikhachen Baha which has a totallyreconstructed shrine of the Kwapadyo, the chaitya and the dharmadhatu mandala. Only the
courtyard space lives while all the other three wings have been converted into slender five or six
storey tall concrete housing blocks. Only the chaitya and the image of the Kwapadyo remain as
heritage elements in Duntu Bahi also at Ikhachen Tole. The use of foreign materials and technology
in reconstruction of the Kwapadyo shrine and the front wings have led to a significant loss of its
heritage value. Next door, Pintu Bahi, an ancient foundation, has its original Bahi structure althoughin state of great disrepair. It has significant historical and architectural typological value. Its square
court has a chaitya and a mandala as heritage resource. The chaitya, mandala and other images inthe enclosure of Yochaken Baha are another set of heritage resources. Konti Cidhangu Bahi at
Yokhachen Tole survives as an enclosed space with a chaitya at Konti Tole to the north of Konti
Bahi. Konti Bahi is a well preserved bahi building and the courtyard has a Lichchhavi chaitya. A
large chaitya situated in an open space to the east of Kumbheshvar complex is what remains ofKonti Baha. To the south of the study area, the very important monastery of the Golden temple(Hiranyavarna Mahavihara) and Nagabahal is located. Hirnayaverna Mahavihara has significant
historical, symbolic, artistic and socio-religious values. It’s three-roofed Kwapadyo shrine as wellas the shrine housing the Lichchhavi chaitya in the center of the courtyard are unique and exhibit
marvelous artistry and craftsmanship. Being a monastery with a very large following, Hiranyavarna
Mahavihara is unique in that it is a monastery for both Bajracharya and Sakya sanga. It is a very
active living monastery.
c) Sattal:
Sattal is a two storied public rest house of history usually located in neighborhood squares
formed at key crossing or on pathways. The sattal at the Jhatapol tole is of neighborhood levelsignificance as indicated by its use in tandem with the Dabu, which is one of the 24 neighborhood
Dabu of Patan 3). Making the entrance building to the Kumbheshvar complex is a large sattal withthe excellent woodworks in the columns of the dalan space in ground floor and a long single
Gajhya stretching all across the length of the building in first floor. It is used during large groupworship and other community and guthi ritual functions.

151d) Pati:
The pati (B51) located at the entry to courtyard 13 is in traditional form and is used by the siguthi of the Maharjans living in the courtyard. The large number of small religious images installedin the row of niches in the walls carries the ancestral memory of the associated families. The newly
constructed two storied community structure is a replacement of a pati used for singing Dafabhajan – religious songs. It only retains a symbolic value to the Maharjan community. The upper
storey is used by the si-guthi. The pati at Jhatapol crossing, although simple, retains its originalform and is used as neighborhood activity logistics storage space. There are a number of pati of
average architectural significance in and about the Kumbheshvar complex. area.
e) Chiba and Others:
Apart from the miniature chaitya in each of the baha and bahi noted under b) above, there are
four Chiba in the study area. The chiba in Courtyard 1 is very well preserved and has excellent
artistic quality. It carries an inscription and is over two hundred years old. Another Chiba in the
nearby courtyard 3 is also of similar artistic and antique values. It has a inscribed stele attached to aside wall. Both the Chiba have formed part of the Mataya festival circuit of Patan since history. The
Chiba in the courtyard 13 sited on a recently restored plinth structure in brick and stone has anabove average artistic and antique significance. Although its association is with the immediate
Maharjan community, like with all Buddhist religious entities in Patan, it is included in the town
level circumambulatory procession of the Mataya. The Chiba in Chhenko courtyard 11 displays
good aesthetic qualities but its restoration has not been done as sensitively as courtyard 13 andcaused loss of its antique value. It is also visited during the Mataya festival 3). A temple of Krishna
located in courtyard 19 is a small temple in Rana architectural tradition and has a family levelassociation with the Amatya of the court. The small Narayan shrine and the Math located incourtyard 14 is of relevance to Talache house of the Amatya family. The artistic quality of images
in both the courtyards of 14 and 19 are average.
f) Residential Buildings:
Residential buildings both as a street side and courtyard design make a significant component of
the ensemble of urban heritage of Kathmandu Valley. It is also the type where the ‘loss’ of heritage
has been extensive as the house accommodates the needs of living of the present generation as itchanged to met the needs of the previous generations. In the study area, there is no residentialbuilding that totally and truly represents the architectural, aesthetic and technological achievementof the Malla period. Thus architectural value has been read as an aggregated state considering
originality, integrity of structure, integrity of façade, elements of the component units such as roof,
strut, wall, window, door and dalan, artistic embellishments and socio-religious expressions(sculptures and paintings on the exterior). The measure of heritage value of the residential buildingsin the study area has been presented in detail under 4-2 below. The aggregated values show highheritage significance of B13, B14, B15, B16, B46, B48, B50, B81, B82 (see GIS plan, 4-2 Fig.9).
g) Inscriptions:
Tradition of leaving an inscription as a record of public activity has a long history in Nepal. The
earliest inscriptions in Kathmandu valley date to the Lichchhavi society and start in profusion from152

the middle of the fifth century and they are on stone stele. These have great heritage value as arecord as well as a historic object that gives a sense of time/history and relates the donor-builder
and the users in the past and the present. The heritage value of social and cultural linkage that the
inscriptions establish between the people in the past and the people at present through clan
association and ancestral identity building is immense and present society is waking up to it. In the
study area, we find several inscriptions in stone that establish local family, clan and neighborhood
centered socio-cultural identity while providing significant historical records of acts, ritual activities
and social institutions (such as Guthi – a traditional trust) specific to heritage elements, space andpeople. The location of these have been identified in the plan, Fig 2)

Fig.2 The location of Inscriptions(3) Streets
Although, Patan's urban cultural heritage is dominated by the architectural monuments
discussed above, value should be given to the urban spaces of the streets and the squares thatprovide the sites for the buildings and link them through varied festivities the monuments and theircultural occupants to the town and its residents. Festivals, the way they are held and managed by thecommunity, tell a lot about open space management, apart from living out the seasonal play of gods
to enliven, purify, renew and refresh, the spiritual and the mundane structure of the town.

153a) Main Street:
The street bounding the study area to the east is part of the Mahapal-Konti high street of the
Malla period organization of the city patterned as a ‘nine-square mandala plan’ with two parallel
streets running north-south and two running east-west. For this reason, some city level processional
festivals (like Ganesh and Bhimsen jatra) take place along the stretch of street between Jhatapol
and Konti. The location of two important Chibaha in the area in courtyard 3 and 7 brings the
Mataya festival circuit onto this street. Mataya circuit also links to the Chibaha in courtyard 11 and13 and puts ritual life to the side streets on south and west the site.
b) Alleyways and Underpass:
These narrow lanes passing under residential building are valued as important urban planning
tradition, offering both cultural and resource value and creating vulnerability all at once. The
underpass of B28 and B9, which respectively lead to courtyard 11 and 3 are specifically of culturalnote in the study area.
(4) Squares
Cultural practices that take place in spaces in and around the monuments, at crossings and its
environment and link the heritage elements through pathways to the society are of specific value as
they bring ‘livingness’ or contemporary life into traditions. Living heritages, thus, are unique
combinations of tangible and intangible heritages that bring the present time and the present
generation into play. Identity value and belongingness generated by the various traditional rituals
and festivals that take place along the main street and bring the whole towns’ population of Patan incultural processions is significant. Such festivals bringing people in pradakshina or going aroundtown travel through the north-south high street along Jhatapol pati in the study area and ritual
festive interactions take place at the crossings as the two of the twenty four historical dabali of
Patan, the ones at Jhatapol and Konti crossings fall in the study area. Likewise, the Mataya festival(in which a ceremonial circumambulatory procession is performed to each and every Stupa, Chaitya,
the Buddhist monasteries of Baha and Bahi and the miniature Chibaha shrines that dot Patan) brings
the Buddhist population of Patan to the study area to go round the Chibaha, Chaitya, Baha and Bahi
located in the study area. The public square at the entry to Kumbheshvar complex becomes a sceneof many a festive gatherings at specific days of lunar calendar. The large courtyards (numbered 13
and 14) are public at clan level and offer resource value as a primary rescue space.
(5) Society
Conservation, maintenance and operation of heritage monuments and associated socio-culturalactivities, services and festivals, the institution of Guthi and its agriculture land-based financing,neighborhood and clan based organization and seasonal initiation actions, are themselves cultural
heritages. The society organized as family, extended family and clan units and integrated in thecommunity scale at clan, neighborhood and city/nation level is expressed in the streets and squares
and associated cultural activities there in. Maharjan form the major jaat group in the study area.

1544-1.2 Reading Traditional Urban Water Systems
Buildings and structures of godly androyal/imperial importance and their ruins andremains dominate the built heritage passed on
to posterity by most ancient civilizations;
utilitarian structures are in general rare. Amongsuch rarities may be listed the Great Bath of
Moenjodaro, the Roman Aqueduct and the pit
water conduits of Kathmandu Valley. But, withthe glitter and charm of multiple-roofed
temples, Mahachaitya and palaces ofKathmandu valley drawing the viewer’s eye
skywards, these ancient and unique pit conduits
Fig.3 A Restored Hiti in Nagbahal.
of as great architecture, artistry and technology
are often missed and go unsung. Yet the heritage value of these monumental utilities should beperceived as even more since these were constructed for the use of the common man. The ancienturban water supply system consisting of ponds, canals, wells and artistic pit conduits is an urban
utility heritage that has few equals in the world and still retains its utility value. For a building
culture, which makes such a profuse use of wood in structural as well as architectural roles andwhose monuments have been lost more often to fires than to earthquakes in history, such heritages
have significant resource value from the perspective of fire-fighting.
Traditional Water Supply System of Kathmandu Valley has aroused contemporary interest
primarily for its heritage value based on the artistry, craft and architecture of the stone conduit
placed in deep terraced pits in fair numbers at road intersections and public places of the traditional
settlements. These terraced sunken pit courts with conduits, locally called Hiti or Dhungedhara, area class of monuments from Lichchhavi era, undoubtedly dated from as early as fifth century andpossibly evolving out of the practices and traditions of the Kirata era half a millennium earlier, areas much a part and parcel of heritage of its unique historic urbanism and urban development as are
the temples, Chaityas, palaces and residential neighborhoods popularly perceived to form theKathmandu Valley World Heritage Site as listed in UNESCO. A recent inventory study recorded
400 Hiti in the valley, including 47 sites where the pits have been lost by filling in recent years.
Their rapid loss in the wake of recent urban development and the specter of water shortage andfailing modern water supply systems have precipitated concern not just from heritage perspective
but also from the urban services context. Since quite a section of the residents of the urban core
have come to depend, for their daily needs, on water dispensed by these heritage utility outlets,
added public concern has centered on the potable quality of water as well as on protection andpreservation of the sources from pollution. Since such issues have propelled the available studies of
traditional water supply system, the investigations have looked beyond the artistry and craft on to
the architecture and engineering of sources, canals, reservoirs, outlet pits and their drainage. For
some particular Dhungedhara which have been harnessed for collection and distribution of water
through addition of modern storage and piping system at the tail of the traditional system, even thesystem ‘regulators and filters’ used in them have been opened and studied.
155

(1) History and Historicity:
The Hiti water structures are part of an elaborate urban water supply system that consisted ofponds (pokhari, pukhu), the terraced and sunken pit courts with conduits (pranali, Dhungedhara,Hiti), brick lined dug wells (tu, inar) and drinking spouts (jaladroni, jadhu) generously distributedin the settlements. The water to these system outlets were brought through canals (tilamaka,
Rajkulo, dehdha) that reached out along a ridge from the urban reservoirs to its sources in thefoothills of the valley, often with large intermediate storage ponds (udaka).
Of course, as an service utility of a living urban culture, much of the elements and the systemhave undergone continuous development over the centuries and if it was not for the Lichchhavi
practice of leaving inscription in the stone conduit and the use of very durable stone, which has
survived more than fifteen hundred years of use without needing a replacement, the antiquity of Hiti
system would have been difficult to substantiate.
With an inscribed stone that describes its construction for public use and dating it to 550 CE, thesunken water supply pit system of Satyanarayan at Handigaun, Kathmandu, is the oldest Hiti extant
in the Valley and comes from the Lichchhavi period. It was certainly not the first of its kind to bebuilt and the Hiti and other associated elements making the utility structure were already in use forsome time by then. We find inscriptions mentioning the networks and outlets for water supply andirrigation. For example, water canal (paniyamarga) is mentioned in an inscription of King
Basantadeva located at Thankot and dated to 507 AD. The jadhu - a stone bowl with spigot for
dispensing drinking water to passers by and devotee pilgrims to the religious complex, now locatedin Khapinchhe to the north-east of Patan Durbar, carries an inscription dated 530 AD. The
Satyanarayan inscription records construction of water supply system as well as the objective water
quality eg. testy, cool and clear water. An inscribed stone, located in Manihiti of Patan Durbar
dated 571 AD mentions the pious deed of Bharavi, the same donor who had constructed theHandigaun conduit.
Water supply to Kirat ridge-top settlements was based on reservoir ponds located at a higher
section of the settlement much like the ponds of the Malla period such as Rani Pokhari ofKathmandu, Siddhi Pokhari of Bhaktapur, etc. 4). In their early days, these reservoir ponds more
mostly either rain-fed or spring sourced with a few others fed by canals bringing water from natural
sources away from the settlements. The canals, called Tilamaka in Lichchhavi inscriptions, werealso used to carry water to the distribution
outlets in the sunken pit courts. The
preferential use of the Kirat term Tilamaka
instead of their Sanskrit equivalents such as
paniya marga or pranali-jaladroni in
Lichchhavi inscriptions would strongly
support the inference that the system ofcanal and the canal fed conduit predates thearrival of the Lichchhavi in the Valley asmuch as the reservoir pond itself. The Newarterm Hiti itself is derived from the Kirat
Fig.4 The Chaitya behind Manihiti of Patan possibly sitting
terminology of Tilamaka 4).
over the Hiti’s filter and regulator bed
156

Management Trusts set up by the state for distribution of drinking water in public gatherings
and festivities (paniya gosthika) and for maintenance of water systems (pranali gosthika) are notedin the 605 AD inscription at Lele, the area where we find the intake of Patan’s traditional watersupply and irrigation system. Another inscription of Sivadev (rule ca. 590-605 AD) located at
Chapagaun, where we find the extant path of the canal, speaks of extensive fishery, possibly using
ponds. A successful aquaculture is noted by Amshuverma in his 605 AD inscription at Bungamati,
the site where the temple of Machhendranath is located.
Later Lichchhavi inscriptions provide evidence that this water work was extended andmaintained several times. An in-situ stone slab inscription, with a image of fish in relief decorating
the top of the stele, situated at the crossing of Mamadugalli lane and Mahapal-Konti street west of
Patan Durbar, addressed to the people of that area (the then areas of Thambu, Gangul andMulabatika) speaks of the restoration of a Tilamaka canal of earlier construction by the then ruler
Jishnugupta in 624 AD. This canal appears later referred to in the Malla period as Lunkhusi,
meaning a golden river as the canal water carried gold dust washed down from the roofs of many
temples lining the main street there then.
Another stone slab inscription dated 726 AD, located in the pit courtyard of a water conduit near
the temple of Minnath, close to Lagankhel, to the south of Patan Durbar, renews the instructions foradministration and sharing of water from a Tilamaka canal into seven parts and among four
localities. Thus we can see the large water-works associated with the festival of Matsendranath,both for irrigation and drinking water, were installed at various times in the middle Lichchhavi
period. It had survived well up till recent times as Rajkulo and has gone into disuse and destruction
only in last three decades.
(2) Elements of the urban water supply system:
It can be observed that the main canal of the extant Rajkulo had intakes at Lele Khola and Naldu
Khola. The canal splits into several branches at Nakhipote leading to various reservoir ponds andshallow aquifers, which in turn charge and supply water to ponds, Hiti and wells generously
distributed in the town of Patan with an astute consideration of the topography, geology, shallow
aquifers and ground water table. During the Lichchhavi period itself, water as a urban utility appear
to have undergone significant development and refinement in system, architecture and decor. And it
is a tribute to their technological genius that the three natural elements of pond, river and springwere adapted into reservoir, canal and conduit and combined into the Hiti system.
a) Ponds:
The main reservoir ponds of Patan were located at Lagankhel and its ritual linkage with theNagas associated with the festival of Rato Machchhendranath led them to be named Sapta-patalpokhari. Remains of the system survive in parts at Lagenkhel area. Closer to the study area, we findthe Pimbaha pond, La pukhu and Kamal pokhari forming intermediate reservoirs and recharge
ponds of the larger system.

157b) Well:Wells are generously distributed in the living
neighborhoods of Patan and served as service
outlets in homogeneous social neighborhood.
These were fed by ground recharged by ponds,
shallow aquifers or natural water carrying veinsand layers. Natural black cotton soil layers appear
used to guide charge to required areas. Several
wells are found in the study area. Wells havebeen noted in the courtyards 3, 11, 13 and 16 andthe well of courtyard 13 displays an above
average heritage value also.
c) Hiti:
The Hiti system used (i) canals to port waterfrom the sources to local reservoirs and then on to
conduits, (ii) regulating and filter mechanism,(iii) conduits with a small freefall for ease of useand ‘ritual purity’ in dispensing water and (iv) a
deep channel to drain the pit. It displays historical,
technological, architectural and artistic andcultural-anthropological values of as muchsignificance as ecological and resource value.
These are noted as distinct subheads below.

Fig.5 Manuscript drawing showing filter andregulating bed of Hiti system (Becher-Ritterspach,1994).

(3) Water in Cultural Practices of Patan
A festive heritage of unique cultural and social significance for Kathmandu Valley in generaland Patan in particular, is the Chariot festival of Machhendranath, a Jatra celebrated by both
Buddhists and Hindus alike with great pomp and joy. This festival is as much a celebration of the
god Avalokiteswora (for Buddhists) and Birinchinarayan (for Hindus) symbolized in the image of
Machhendranath as of a large urban water supply cum irrigation system that has, since its creation,
proved to be a lifeline for Patan town and its farming hinterland.

158

According to legends, an extensive festivalof Sri Bungma Lokeswora, now popular as Rato
Matsendranath, was initiated and popularized in
the Lichchhavi period by King Narendradev
following a failure of monsoon that had caused
a long dry spell and famine then (Locke, 1975).
The faithful were told that the reason for the dry
spell was Guru Gorakhanath, who had
imprisoned the Naga, the agents of rain. As aritual solution Sri Lokeswora was to be brought
to the valley. They were guided in this quest byserpent king Karkotak. As Sri Lokeswora
arrived at Bungamati, Guru Gorakhnath got up
to pay his respect to the new arrival andreleased the Naga, who instantly made rain andsaved the valley. We can see that an extreme
draught that adversely affected the agricultural
output had invited a state intervention as aprelude to the festival. Although the legend is in
divine weave, in reality, it was an extension andreconstruction of a large irrigation canal system
for Patan.

Fig.6 The Alignment of Rajkulo of Patan based on
Extant Canal Sections and Ruins (Joshi,1993)

There is little doubt that this festival is a annual socio-cultural rendering of periodic inspections,repair and operational activities necessary to sustain the water system, its intake, canal, town
reservoir pond, distribution system and outlets and drainage. Indeed for the proper ritual conduct of
the festival, water must be available at Lagankhel and Pulchowk ponds and the stone water conduitof Sundhara running and well. Even the town reservoir had to be overflowing!
The Janaipurnima festivals held at the site of Kumveswor temple in north Patan happens in a water
pond that is fed by a spring source and a local aquifer. It is a celebration of Sivite Hindus and thefaithful believe that the waters of the pond come from Gosainkund, a high Himalayan pond in
Langtang ranges, which had relieved Lord Siva from the burning sensation of poison that he took in
a Hindu creation myth.
From Malla period records available at ponds, Hiti and some wells, it can be concluded that theconstruction, extension, renovation and maintenance of the traditional system continued with great
fervor not only at the royal level but also with community and neighborhood as well as family levelparticipation during medieval times in Patan. As a matter of fact, the involvement of the lattergroups in the development and extension of the traditional system of water supply in Patan appears
to have been much larger than that of the state. The Newar society considered establishing water
dispensing elements such as Jadhu, Hiti and well as pious acts of great value.

159

Fig. 7 Showing Linkage of Canal, Ponds, Aquifers and Hiti (Joshi, 1993)

It has been established that the Rajkulo feeds into at least eighteen out of the 39 traditional
ponds (Pokhari, Pukhu) known to have existed in Patan (Joshi, 1993), quite a few of these branches
and ponds were constructed in the Malla period. These ponds supplied water directly or indirectly to
51 extant Hiti including four which are dry (UN-HABITAT, 2008) and 220 dug wells. Most ofthese wells and Hiti are located within the urban core. The two ponds of great ritual significance(and therefore, functional relevance) in the Rato Machhendranath festival of Patan are theLagankhel Pokhari (Saptapatal Pokhari of legends linked with ritual bath of Machhendranath,
Bunganhavam) of Lagankhel and La Pokhari (water for wetting of cane used for tying timber
members of the Chariot and starting of the Chariot festival) of Pulchowk. Both the ponds are fed by
the Rajkulo by bifurcating it at Tikhel, the major portion of water going to the set of ponds at
Lagankhel, which served as the general reservoir for Patan. A smaller branch Rajkulo taken from
Tikhel goes north-west to feed La Pokhari. The overflow from these main reservoirs is again
channeled to a series of ponds within the settlement. The overflow from La Pokhari goes toKamalpokhari (Palesvanpukhu) and sequential overflow charge Podepukhu, Pimbaha Pokhari andpossibly to Nhyakachuka and Nagbahal. Similarly the chain of ponds fed by overflow from
Lagankhel are Pyapukhu, Bhandarkhal Pokhari, Extensive underground channels (in brick,160

terracotta or even wood) ran from these ponds to supply water to several nearby Hiti and torecharge ground water. The ponds and canals also charged the natural shallow aquifers as available
in different localities of the town- this novel approach was particularly important to recharge groundwater so that the dug wells were always replenished with water. Many Hiti are directly supplied
from canals taken out of shallow aquifers. Three major shallow aquifers of Patan located at
Nayokhyo to the southeast, Naricha east of Lagankhel and Khwyebahi south of Pimbaha arecharged in this manner.
Northernmost Hiti of Patan yield more water as topography slopes from southwest to northeastof the town and where ‘thick layers of black cotton soil at the outskirts of Patan protect the flow
path from seeping into the Bagmati River, while creating potential aquifers in the north (Joshi,
1993). In such areas, where local aquifers get sufficient recharge naturally, such as at Ikhachhe,
Kumbheswor, Chyasal and Guita, no pond overflow or canal linkage is provided. (See Figure 5
which details the branching of Rajkulo about Patan and linkage to ponds, aquifers and Hiti.)
Waste water from some Hiti is also at times collected into a pond and used for irrigation or
ritual purposes, for example, water draining out of Sougal Hiti is collected in Khapichen Pokhari,
Bya Hiti recharges Chyasah Pokhari, Subaha Hiti and Guita Hiti waste water is collected at
Balkumari Pokhari.
Lagankhel Pokhari, Guita pokhari, Lapukhu and Pyapukhu may be the oldest among the ponds.
Of the 39 historical ponds substantiated in popular memory, 16 are relatively in good condition
from shape and size considerations, 9 are encroached and the remaining 14 have been lost as public
utility (UN-HABITAT, 2008). Only one of them, Jawalakhel Pokhari, may be accepted as in a wellmaintained condition. It also has its own spring source of water.
(4) The Technology of Hiti
Although the application of the principle of gravity flow to transport water from the reservoir tothe pit may not seem like ground-breaking technology, using the same principle to drain out of the
deep pit and developing a design and construction technology that would work for more than athousand year is. Brick arched drainage channels constructed at such depths demand deep trenching
and/or tunneling techniques. The construction of a chain of conduit pits with successive conduits at
a level lower than the previous ones demands the use of filters in between to assure the purity ofwater all along the chain. Indeed, a complex maze of brick-lined, tile-covered circulating
contraption with sand beds in sections was constructed immediately behind the conduits. Thissystem is capable of settling silt, filtering and, even more amazingly, controlling and regulating theflow of water as it comes out of the spout.
What seems to be an architectural feature of progressively reducing terraces leading down to thepit courtyard actually covers the filtration and regulating structure of the conduit system. Anothermarvel is the waterproofing technology applied to the sides and bottom of the conduit pit. Not only
the conduit pits but also the sides and bottom of the reservoir ponds were made waterproof by the161application of an almost foot-thick layer of a particular type of lake silt deposit of gray/black soil
(Gathucha).
The small size of the drain-off channel and its use as a supply channel to pit conduits located atlower levels defy the possibility of maintenance and repair action and it is a wonder how these weremaintained or kept running and operational for so long at all. Whereas indigenous cultural practices
linked to the maintenance of the supply canal and well system are very distinct and articulated in
the sithi festival, among others, no such practices are known about the hiti drainage and filter-bed
maintenance. Local people mention the use of an unbelievable means of maintenance such as thedrains being unclogged and cleared by snakes as they go into the system in pursuit of their prey,toads! Local people recall that it was traditional in the Alko-hiti community to let fish and snakes
into the waters of the drainage pit. According to them, the residents of the neighbourhood wererequired to let any snake found in their land loose into the same pit. It seems the custom of raisingfish in the shallow waters of the drainage pit helped in the removal of moss, which served as foodfor the fish. Likewise, the toads fed on the fish and snakes would enter the drainage channel andslide through it as they fed on the toads, keeping the system maintenance free, as it were. Could thisbe a case of a self-maintaining aqua-technology assisted by animals such as fish, toads and evensnakes?” (from Tiwari, 2009)(5) Defunct Status of the Traditional Water system in Patan
The traditional water supply system of Patan is almost totally defunct and only some of theelements such as Hiti, wells and ponds are still functional purely because some sections of the
traditional system was based on natural shallow aquifers charged by rain and surface drainage. The
Rajkulo was last maintained and made working for irrigation purposes about fifty years ago. By
1993, the Rajkulo was working from the intake to only down to Chapagaun about four kilometersfrom Patan. Since then, the scale and pace of urbanization of the area along the road that almost
follows the canal alignment up to Tikabhairav has all but obliterated the mud lined canal. Thus the
Rajkulo has not supplied any water to the traditional urban water distribution system of Patan for
more than three decades already and it is only a matter of historical interest for the present.
Proposals to rehabilitate the Rajkulo in order to supplement the water supply to Patan also throughthe traditional outlets have been made but have not been accepted presumably for practical reasons.
No more fed by the canal waters, most of ponds making the Lagankhel Pokhari reservoir systemstarted on the drying process since the 1950’s and have since been encroached, filled up and built
up or downsized. Offices, schools and market functions occupy the buildings built over the originalland of the ponds. In a smaller scale, Laganpukhu, Nhupukhu and Lagankhel Pokhari (3 three
sections) remain as rain fed ponds. The La Pokhari has become a small tank and much of
Kamalpokhari has been converted into garden and Patan Municipal Office building built over the
rest of its land. Pyapukhu exists in a much reduced size encroached by a school building. With its
sides and bottom sealed, it has turned into a tank! Only 16 of the 39 traditional ponds of Patan
survive in respectful shape, size and condition. The replenishment of water in these ponds is largely
through collection of rain and residual surface drainage, although some are charged also by existing
natural spring sources.
162

Naricha aquifer remains well charged by rain and surface drainage of Lagankhel as it the area isstill open with unsealed surfaces allowing absorption of rain water into it. Wisdom of the urban
culture of yore to create open grassland (khyo) around the ponds and aquifers has been lost on thepresent day managers of the town and more and more of these open spaces are being put to otheruses that seal the ground. Such unplanned building up around other aquifers of Patan has started
causing them to dry. In 2009, even the almost perennial Kumveswor Hiti dried because of suchreasons. In some aquifers, indiscriminate digging new shallow wells have also led to its water table
falling low enough to cause drying of its Hiti and traditional wells, which tend to be shallow.
As the ponds which collected the rainwater and surface water from its khyo and as both thepond space and the khyo are lost ‘because of ignorance, change in habits and economy and greed ofpeople’, the aquifers fail to recharge sufficiently. Consequently, while some of the Hiti and wells
have a reduced discharge some others have completely dried up.
Since the Hiti gets its supply from ponds and aquifers through the medium of existing porous
seam, shallow brick or terracotta or wood canals or trough drains, variety of unplanned and reckless
public and private construction interventions along this line of passage have has destructive impact
on the Hiti. Many Hiti have failed due to their supply lines being cut or destroyed by large publicconstructions such as laying of sewer and drain pipes. The new drainage system also diverted
precious water that recharged aquifers into storm drains. Poor and careless introduction of thesenewer services have also led to impairment of water quality of some of the Hiti. Second negativeintervention into the system is the construction of foundation for large buildings in private sites due
to which the underground supply lines passing through such sites have been knowingly or
unknowingly destroyed.
In still other cases, the failure of drainage channel of the pit court has been the cause leading to
the collapse of the system. As we reported above, for quite a Hiti these drainage canals tend to be
too deep and inaccessible for repairs. The clogging of these drains due to disposal of plastics orother materials with slow biodegradability has led to ponding in the pit, collapse of the structure andits filling up.
Hiti occupies a vantage location in the urban heritage of Kathmandu, not only as a historical,
technological and artistic entity of great social and economic value but also spatially as it sits amid
the other built heritage with significant use of timber. The threat of fire and earthquake hazard to theother built urban heritage of Kathmandu Valley has been often highlighted. Further studies areneeded to seek to answer how the traditional water supply system may be used to reduce
vulnerability of the heritage buildings from fire hazards and for fire fighting in the event of fire. In
addition, the conservation of the Hiti as a urban cultural heritage by itself, particularly in the context
of the greater public concern directed at its utility role and loss of historicity, authenticity andartistry that has been a common consequence of the utilitarian actions undertaken at such instances,is an added objective. It is also likely that the traditional supply system is less vulnerable toearthquake and these systems could be expected to remain operational when large section of themodern urban water supply system may actually be dysfunctional due to damage from the quake.
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4-1.3 History and Traditional Knowledge of Disasters
Himalaya is one of the most seismically active zones in the world and makes Kathmandu valley
highly prone to earthquakes. Geological investigations indicate that Kathmandu valley was a lakethat dried about 12000 years ago. Thick deposits of soft clay that have so formed the valley floor
magnify tremors many times over and make the buildings built on it highly vulnerable toearthquakes. The great earthquake of 1934, which occurred in the Bikram calendar year 1990 andaffected 55000 houses destroying over 12000 completely in Kathmandu valley, was such a disasterthat Nabbesaal (meaning year 90 in Nepali) has become a standard word to denote massively
disastrous earthquakes. Nepal has been hit by such great earthquakes many times in history andexperts read a return periodicity of 70 to 100 years for Nabbesaal like earthquakes. Such aperiodicity of large earthquakes is not 'frequent' enough to be conducive to empirical learning anddevelopment of building technology as earthquake mitigation measures as the memory of theviolent shakings get diluted to ineffectuality for experiments at structural risk reductions over fouror five generations. Indeed, we find little record of structural damage or craftsmen's comments inaccounts of earthquake in traditional historical treatises such as vamsabali and thyasaphu. Table 1(following page) shows a list of earthquakes recorded in history and the scale of disaster noted. It
also reveals a fifty year periodicity of moderate earthquakes.
However, earthquake resistant features in traditional buildings of Kathmandu valley havedeveloped indigenously with little benefit from Vaastusashtra. These and other learnings onearthquake mitigation of Kathmandu valley relate more to experiences accruing from medium andsmall earthquakes that had shorter recurrence cycle. Since architectural design as well as
construction (or for that matter any other trade or profession) was 'jaat' based and knowledge andexperiences passed on orally or as practical skills from one generation to another, a continuity ofinnovations seems to have taken place leading to a significant accumulation of design, detail andpractice of construction systems that offered a great strength to buildings caught in earth shakes.
(Tiwari, 1998)
Nepali traditional architecture uses brick as a key building material and brick masonry laid in
mud mortar is common practice. The vulnerability of such materials and methods to earthquakes
and the strength and resistance offered by the use of timber in the structure must have been quickly
understood by the traditional builders as the building materials natural to Kathmandu valley faced
this other 'nature'.
Over time and with experience, further development of construction system and technology,
such as the application of simple planning approaches of symmetrical or square plan configurations,use of dalan, strengthening elements such as use of double framing of doors and windows, detailingsuch as use of wedges to connect and hold together brick wall and joists, joists and wall plates orcolumn and beams, rafters and eaves or struts, use of tie runners as string course, took place. These
measures individually and together as a system infused a great amount of technical resilienceagainst earthquakes. Such measures are found used in most building types, whether low rise or high.
The use of literally thousands of wedges in the construction of traditional building enabled them to164absorb great amount of energy out of the earthquakes by moving within the limits of tolerance ofthe structural materials and methods and attain safety against failure. Safety gains were enriched by
the timber ties and cornices that helped divide brickworks into smaller masses and offer tensile
strength.
Apart from the mitigating response of the design, detailing and construction technology of the
traditional buildings, traditional knowledge and capacity for mitigation of earthquakes appear tohave been developed also through a conscious spatial structure of open spaces and courts in town
(dalan in buildings, chuka, layebhu and lachchhi, layechi) and through preservation of the
agricultural economic base of the society achieved by building bounded towns in agriculturally
fallow tar land and consciously delimiting expansion of towns unto agricultural land through ritualand faith based socio-cultural deterrents.
Remarkable community based mutual support system had been developed through theapplication and development of the Guthi system (a community managed system of perpetual trust
institutions set up with publicly owned land resources) and mutually supporting and interdependent
jaat (caste) based division of society. The urban space itself was divided into neighborhoods with
distinct jaat specificity and Guthi specific to neighborhoods and supporting community activities
specific to particular jaat became common practice in the Malla period.
Kathmandu Valley's urban cultural heritage of building and urban spaces, water supply system,
festivals and street spaces, conservation practice and its institution of Guthi deserve to beresearched specifically to further inform the mitigation measures and ways of their incorporating
into the modern building, town planning and social institutions.
With the advent of modernism and modern administrative, technological and development
processes have overwhelmed the traditional knowledge of earthquakes and disaster management
and have all but wiped out the traditional knowledge system. The massive introduction of newer
building technologies without serious adaptation for earthquake resistance in terms of science,technology and skill in building, the loss of the spatial structure brought about by the accelerated
urbanization and new urban form and the loss of community organization of Guthi and social
structure that facilitated mutual support have all come together to make contemporary Kathmandu
valley greatly vulnerable to earthquake induced disasters socially, physically, spatially andinstitutionally.

165

Table 1: Historical Earthquakes of Nepal

Year (A.D.)
Dec 24, 1223

DeathsMany people diedJune 7, 1255

One third of the population ofKathmandu valley was affected. Many
deaths including that of reigning kingAbhaya Malla after eight days oftremor1260

1408

Many people died, famine after
earthquake
Many people died including thereigning king Ari Malla in Deupatan
after one day of tremor
Many people died

1681

Many people diedJune 4, 1808
1810

Several people and animal perished
Some people died, mostly in Bhaktapur

1823
1833

No record of deaths
Estimated magnitude 7.7, 414 people
died in the vicinity of Kathmandu
valley1834
1837

No good record available
No good record available

1917 (1918?)
January, 1934

No deaths recorded
Estimated magnitude 8.3 (epicenter,
Eastern Nepal). Maximum Intensity X.
8519 people died of which 4296 died in
Kathmandu valley alone

1966
1980

24 people died
Magnitude 6.5 (epicenter far western
Nepal). 103 people died
Magnitude 6.5 (epicenter SE Nepal).
721 people died
Epicenter near Jajarkot

September 14, 1344

1988
1993

Damages
A lot of damages to residentialbuildings and temples
A lot of damages to residentialbuildings and temples, people left theirhouses and lived outside for a period ofa fortnight to a month after earthquake,while aftershocks were felt for thefollowing four months.
A lot of damages to residentialbuildings and temples.
A lot of damages to residentialbuildings and temples
A lot of damage to temples, residentialbuildings, fissures developed in the
ground. Machhendra Nath temple in
Patan collapsed.
A lot of damages to residentialbuildings
Houses collapsed
A lot of damage to buildings andtemples
Some damage to houses
4040 houses destroyed in Kathmandu,
Bhaktapur and Patan and Banepa.
18,000 buildings damaged in the wholecountry
Many buildings collapsed
No damage recorded in Nepal but
greatly affected Patna and other parts ofBihar, India
No record on damage
Over 200,000 buildings and temples
damaged, nearly 81 thousandcompletely destroyed in the country.
55,000 buildings affected in
Kathmandu (12, 397 completely
destroyed)
1300 houses collapsed
12, 817 buildings completely destroyed,
2,500 houses collapsed
66,382 buildings collapsed or seriously
damaged
40% of the buildings were estimated tobe affected(Based on Marahatta, 2011 sourced out of UNDP/UNCHS 1993, Pandey and Molnar, 1988, Bilham et al 1995, Pant,
2002)

166

References:
1) Gellner, David N., Monuments of Lalitpur (Patan) in Michel Hutt, 1995, Nepal, Shambhala, Boston.
2) HMGN, DHBPP, 1975. Kathmandu Valley – The Preservation of Physical Environment and Cultural Heritage – A Protective
Inventory.
3) Gutschow, Niels 1982. Stradtrum und Ritual der newarischen Stadte im Kathmandu-Tal, Kohlhammer, Stuttgart pp 168.
4) Tiwari, Sudarshan Raj 2009. The Temples of the Nepal Valley, Himal Books, Kathmandu.
Gellner in Hutt, 1994)The following books and reports have been used in the preparation of this report:
Tiwari, S.R. 1998 Traditional Architecture of Kathmandu valley – responsiveness to earthquake through empiricism', available atwww.kailashkut.com/publications.
Tiwari, S. R., Transforming Cultural Heritage into Sustainable Future: A Case Study of Patan, Nepal, in Urban Crisis, Culture andthe Sustainability of Cities, 2007, eds. M. Nadarajah and Ann tomoko Yamamoto, United Nations University Press, Tokyo.
Marahatta, Punyasagar 2011, Draft Chapters of PhD Disssertation, Institute of Engineering, unpublished.
Jigyashu, Rohit 2002, Reducing Disaster Vulnerability through Local Knowledge and Capacity – the Case of Earthquake Prone
Rural Communities in India and Nepal, PhD dissertation, NTNU, Trondheim.
UN-HABITAT, 2008. Water Movements in Patan with Reference to Traditional Stone Spouts, Water for Asian Cities Program
Nepal, Kathmandu.
Becker-Ritterspach R.O.A. (1994) Water Conduits in the Kathmandu valley, Munshiram Manoharlal Publishers Pvt. Ltd. New
Delhi.
Joshi, P.R. (1993). Feasibility Study of Rajkulo: Rehabilitation of Patan’s Traditional Water Supply Network, Final Report, Patan
Conservation and Development Program, UDLE/GTZ.
Theophile, E. & Joshi, P.R. (1992), Historical Hiti and Pokhari: Traditional Solutions to Water Scarcity in Patan, Patan
Conservation and Development Program, UDLE/GTZ.
Tiwari, S.R. (2009). The Temples of the Nepal Valley, Himal Association, Lalitpur.
Regmi, D.R. (1983). Inscriptions of Ancient Nepal, Vol I, Abhinav Publications, New Delhi.
MSc Urban Planning, Urban Planning Studio III, 2009 (Students Works)

167

168

4-2 Assessment of Heritage Values in Case Study Area
Sudarshan Raj Tiwari
Rohit Jigyasu
Naoko Itaya

4-2.1 Purpose of HeritageValue Assessment
The purpose of assessment of heritage values of the historic city of Patan is to identify andprioritize the protection of attributes with most important heritage values for disaster mitigation,
response and recovery, especially those attributes that can serve as important resources for disastermitigation and response.

4-2.2 The Target Area
The target area is a Jhatapo neighborhood in the historic city of Patan. This area includes core
and the buffer zone of World Heritage Monument Zone of Patan, which consists of Durbar (palace)
Square (Fig.1, 2).
The total population of the target area of Jhatapo is 507, which includes 68 children below ageof 12 and 49 elderly people above 65 year. Only one person in the area is handicapped.
This area is inhabited by Newars; an ethnic group in Kathmandu Valley. Many of them belong
to Maharjan caste. Most of them work in service sector that includes handicrafts, shops, hotels andother retail business. Also majority of them own their house from forefathers and have lived there
since birth. Also most of them do not own any agricultural land.

Fig.1 Patan WHsite Coa Zone and Buffer Zone

Fig.2 Jatapo, Research Area169

4-2.3 Overall Methodology
Overall methodology can be divided into four main stages:First Stage: Preliminary Site Documentation and Community Diagnosis
The first stage involved collection of background material from various secondary sources on
Patan’s history, settlement pattern and cultural heritage. After selection of target area, a base map
was prepared through field verification (from outside) and each building and open area was given aunique reference number. Next, specially designed inventory sheet was filled to gather data on eachbuilding and household related to architectural typology, ownership, usage, height, construction
system, age and additions, structural and material condition on the basis of visual observations.
Inventory forms to record other heritage components like temples, chaityas were also prepared.
Key informant interviews and a workshop with local residents of Jhatapol were also conductedwith some residents to know their perceptions about heritage values of the area, memory of pastdisasters especially 1934 earthquake and current perceptions of risks in the area. Views of the local
community demonstrated strong attachment of people to that area. It also showed low level ofdisaster preparedness.
All this data was subsequently analyzed and various thematic maps of target area were prepared.
Second Stage: Rapid Vulnerability Analysis
For all the heritage buildings/components identified during stage one, vulnerability analysis
with respect to earthquake, fire and flooding was conducted through visual observations. The data
for each building was recorded in data sheet and illustrated through photographs and three
dimensional drawing.
Third Stage: Detailed Documentation and analysis of integrity and transformations.
Detailed documentation of the target areas in terms of interior walls and primary/secondary
access points was undertaken to analyze the level of integrity and transformations in each structure.
Afterwards another round of survey was undertaken to visually record the integrity of thestructures through analysis of transformations. In some cases, the structure appeared as one
traditional house from outside but had been divided internally. In other instances, although two or
more houses from outside were infact one structure, which could be confirmed by their uniform
façade inside. However in both cases, transformations were linked to vertical division of ownershipof single traditional house among one or more families. There were rare instances, where a
traditional house was sliced to cut a new structure while retaining partial traditional structure.
On the basis of this analysis, original reference numbers were regrouped to arrive at anomenclature specific to each traditional house that retained its architectural and/or structural
integrity to a great extent.

170

Fourth Stage: Identification and analysis of Values
Various indicators were developed to analyze values for each attributes (heritage building andcomponent) as identified during detailed inventory. Based on visual analysis, numerical weightage
was assigned to each indicator from 4 (highest value) to 1 (lowest value). Comparison was drawn
separately among traditional houses and chaityas for which scores from various indicators were
aggregated for each building/component.
Other components like patis, trees, temples, wells, routes, courtyards were only assessed on thebasis of qualitative indicators.
Those heritage attributes which have special value as resources for emergency response such aswell and pati were identified separately.
A spreadsheet of all heritage attributes with their weighage scores for indicators was prepared toundertake comprehensive analysis for identifying attributes with highest values using Geographical
Information System (GIS). The results were presented in various maps showing traditionalbuildings in various value scales, as well as other heritage components containing various values(individual and composite)

4-2.4 Attributes for Assessing Values:
Various attributes of the target area are being assessed for their values. These attributes aremainly physical but have intangible aspects embedded in them. These exist at area, building andcomponent levels.
Area level Attributes (Fig.3) :- Open Spaces- Streets (Main streets, Alleways and Underpasses)- Squares

Open Space

Main Street
Fig.3 Area level Attributes

171

UnderpassBuilding level Attributes (Fig.4):- Traditional Houses- Patis- Temples

Traditional Houses

Pati
Fig.4 Building level Attributes

TemplesComponent level Attributes (Fig.5):-

Chaityas/Shrine/Pillar/Tulsi Math
Wells
Hitis (not seen in target area)
Inscriptions
Sculptures/ Bells
Trees (not seen in target area)

ChaityaInscription

Shrine/ Tulsi Math

Sculpture
Pillar
Fig.5 Component level Attributes

172

Well

Bell

4-2.5 Indicators for Assessment of Heritage Values of Attributes
The values embodied in cultural heritage are identified in order to assess significance, prioritize
resources, and inform conservation decision-making. Heritage values of the historic city of Patan
have already been elaborated in section 4.1. Based on this, following values have been identified for
detailed analysis of various attributes of the target area.
(1) Historic Value
Buildings and heritage components which are the product of human activities accommodate awide spectrum of significance in our history. Principally their historic values result from their sheer
life-span that reflect the corresponding times of construction in diverse periods as well as frommultitudinous distinctions and qualities added to them in the passage of time. Time specifictraditions and historic styles displayed in those buildings record and convey myriad fragments of
the individual and collective memory of the aspirations of a society and a people.
For historic city of Patan, historic value for all built components was assigned on the basis offollowing indicators that would determine their weightage on the basis of the following period oforiginal/first construction that might have subsequently been added/altered over time.
Criteria for Original Period of Construction

Score (Weightage)

More than 100 years

4 (highest)

Pre 1934 Earthquake

3

1934 to 1950 (until Rana Period)

2

Post 1950

1 (lowest)

For heritage components such as Chaityas (which are not buildings), historic value would also be
determined on the basis of originality of material on the basis of following criteria:Criteria for Original Material

Score (Weightage)

Original Material3(highest)

Added new material

2

Totally new material

1(2) Aesthetic Values
Aesthetic refers to the visual qualities of heritage. The many interpretations of beauty, of
sublime, of ruins, and of the quality of formal relationships considered more broadly have long beenamong the most important criteria for labeling things and places as heritage. Aesthetic values ofbuilt heritage can be classified further as architectural and artistic values

173

(3) Architectural Value
Architectural value can be seen as part of aesthetic value that is embodied in the design andevolution of a building. It is embodied in its spatial planning, integrity of structure and façade as
well as juxtaposition of individual elements that contribute towards its overall architecturalcharacter.
For historic city of Patan, architectural value for all built components was assigned on the basisof following indicators that would determine their weightage on the basis of following indicators: Originality of traditional height Integrity of structure Integrity of façade
 Traditional architectural elements
 Traditional artistic elements

Originality of Traditional Height

Structure and Façade of traditional Houses

Fig. 6 Architectural Value of Traditional House in Patan

Criteria for Originality of Traditional Height

Score (Weightage)

Traditional height; 3 floors plus attic

3 (highest)

Added floor to the traditional height: Total 4 to 5 floors

2Higher than 6 floors

1Single floor

1 (lowest)

174

Integrity of structure and façade is based on the transformation processes in traditional houses
affecting their vulnerability. These include:-

Vertical subdivision by adding thin partition walls inside but keeping traditional configurationand structural system. In this case, the house retains its integrity from outside.
Vertical subdivision by slicing the building and adding RCC framed structure while rest stays as
load bearing. In this case the structure has lost its integrity to a great extent.
Only skin façade is altered on either side facing the road or backyard or courtyard. In this casethe buildings may appear contemporary from outside but retain overall structural integrity. This
sometimes is confirmed by traditional façade seen from courtyard side.
Criteria for Integrity of Structure

Score (Weightage)

Overall Traditional Construction System (load bearing brickmasonry). This would include minor additions and partitions.

3 (highest)

Hybrid (traditional construction with major addition of modern
RCC frame walls, floors)

2

Concrete frame with brick infill (contemporary structure)1

Two facades (entrance and secondary) are investigated for their integrity and traditionalarchitectural and artistic elements.
Criteria for Integrity of Façade

Score (Weightage)

Original façade is symmetrical with traditional patterns andproportions between various elements

3 (highest)

Divided and/or partly changed original facade2

Totally new façade

1

Traditional Architectural Elements in Façade
Roof

Yes/No (1/0)

Sloping

□

Eaves

□

Wall in traditional brick/wood
Window□
Large Malla Style Window□

Traditional
Lattice□

Window

175with

(4) Artistic Value
Artistic value of built heritage (buildings) can be understood in terms of the works of art
through painting or carving, which can be evaluated on their own merit although they may be partof the architecture.
Traditional Artistic Elements in Facades of Traditional Houses

Yes/No (1/0)

Carving in Wood / Brick□

Painting on Wood / Brick□

Sculptures (including those inserted in the walls of houses)□

Painting on Brick

Sculptures (inserted in the walls of houses)
Fig.7 Artistic Value

For heritage components (not buildings) such as Chaityas, artistic value can be understood interms of following artistic elements of special values. These can be evaluated either on the basis ofweightage or as simple checklist determining their presence/absence . Various indicators include
1.
2.
3.
4.
5.

Degree/Quality of Carving (High-3/Medium-2/low-1)
Degree/Quality of Painting (High-3/Medium-2/low-1)
Presence /Absence of Sculpture (1/0)
Presence/Absence of Inscription (1/0)
Presence/Absence of Metal Canopy (1/0)

Some of the subcomponents like inscriptions can be evaluated in themselves for their historic or
artistic values determined by another set of indicators.

176(5) Socio-religious values of living heritage (livingness value)
As pointed out in section 4.1, one of the essential characteristics of urban cultural heritage in
Kathmandu valley is its living nature i.e. it is not just about the past but also the present
relationships that demonstrate continuity over time. This living nature is contiguous with the socioreligious values.
The concept of social value follows closely the notion of ‘social capital’, a widely used concept
in the social science and development fields. The social values of heritage enable and facilitatesocial connections, networks, and other relations in a broad sense, one not necessarily related tocentral historical values of the heritage. The social values of a heritage site might include the use ofa site for social gatherings such as celebrations and markets – activities that do not necessarily
capitalize directly on the historical values of the site but, rather, on the public space, shared-spacequalities. The kinds of social groups strengthened and enabled by these kinds values could include
everything from families to neighbourhood groups to ethnic groups to special interest groups.
Social values also include the ‘place attachment’ aspects of heritage value. Place attachment refers
to the social cohesion, community identity, or other feelings of affiliation that social groups derivefrom the specific heritage.
Heritage sites are sometimes associated with religious or other sacred meaning, which in case ofKathmandu value are deeply related to the social values and together contribute to the living
heritage. These attributes would include
1.
2.
3.
4.
5.

Temples
Chaityas
Sculptures
Stones in the paving used for worship
Religious Paintings on door etc.

Criteria for determining socio-religious values of various
attributes as living heritage

Yes/No (1/0)

City/National Level Association□

Clan Level□

Neigbourhood Level□

177

City/National Level Association : Janaipurnima Festival at Kumveswor, Matsyendranath Jatra

Clan Level Association:

Neigbourhood Level Association:

Family Level Association:
Fig.8 Socio-religious values of living heritage (livingness value)178

(6) Ecological Values
The ecological values are related to those attributes of natural environment that contributetowards sustainability. In the context of Patan these are represented by trees and water sources.
Attributes of natural environment

Yes/No (1/0)

Trees

□

Water Sources/catchment areas□(7) Resource Value for Disaster Mitigation and Response
Attributes with heritage values that have potential for disaster mitigation and emergency
response such as Patis, wells etc. are especially identified for protection. This will be elaborated in
section 4-3(8) Assessing HeritageValues of Traditional Open Spaces and Routes
Open spaces are very important element of urban heritage of Patan. In fact, traditional open spaces
and routes have retained the morphology of the city while built elements have been exposed tocontinuous transformations. Heritage Values of traditional open spaces and routes can be assessedon the basis of
1. Values of built heritage components in and around open space (historic architectural andartistic values)
2. Livingness Value demonstrating continuing relationship of open space at family,
neighbourhood, clan or national/city levels.
3. Resource value for disaster mitigation and emergency response due to accessibility throughtraditional underpasses, presence of traditional water systems and public buildings such as
Patis and Sattas that can be used for shelter and storage.

The relationship between attributes, indicators and values can be summarized as following:Attribute of the Site

Values to be assessed

Indicators for each values toe.g. traditional

for each attribute e.g.

be evaluated on the basis ofbuilding, Chaitya,

historic, architectural,varioustemple etc.

artistic etc.

attributes

179

characteristicsof4-2.6 Assessment of Heritage Values of Attributes
Geographical Information System (GIS) is used to prepare drawings of the area showing
comparative heritage values of traditional houses (historical, architectural and artistic, resource
value). These are aggregated to make comparison of composite values and represented in a drawingof the target area.
Comparative values (separate for each type of value and aggregate) are also assessed for
Chaityas and other attributes and represented on area drawings
A composite value index map is prepared for all the attributes through GIS to identify the mostimportant area from the perspective of heritage values.
It is very important to mention here that the results of the GIS analysis would be based on theweightage assigned to each value. In our case, we have assigned equal weightage to historic andaesthetic (architectural and artistic) values. However, if we were to give more weightage to either ofthese, the results might change significantly. Besides, results would also significantly alter if wewere to give weightage to the livingness value. In such situations, the attribute may not be so old or
aesthetically beautiful but would have higher value due to its continuous association with thecommunity at city or national level.

Fig.9 Assessment of Heritage Values of Buildings using GIS

180

Fig.10 Assessment of Heritage Values of Components using GIS

Fig.11 Assessment of Heritage Values of Open Space using GIS

181

B82

B16 B15 B14 B13

B81

B15

B50
Fig.12 High Value Buildings

B16

B48

B46

Chaitya and Inscliption (Open Sspace 3)
Chaitya and Inscliption (Open Sspace 7)
Fig.13 High Value Heritage Components

Well and Chaitya

Patis
Fig.14 High Value Open Space (Open Sspace 13)182

4-2.7 Indicators for Prioritization of Attributes for Disaster Mitigation.
The prioritization of each attribute for disaster mitigation is based on three factors:-

Aggregate heritage value
Resource Value for disaster mitigation and response
Physical vulnerability (especially to earthquake) : This will be elaborated in section 3-3

Based on this prioritization, the most critical area for detailed intervention/proposals for disastermitigation would be proposed.

Aggregate Heritage ValueHigh Value Buildings and Heritage Components

Resource Valuefor disaster mitigation and response

Fig.15 Indicators for Prioritization of Attributes for Disaster Mitigation

183

184

4-3 Assessment of Resources for Disaster Mitigation and Response
4-3.1. Survey for evacuation planning
Masahiro Yoshida
Takeyuki Okubo(1) Research of courtyard and courtyard entrance as evacuation routea) Layout
Nepalese traditional urban structure in Patan, which was built by native Nepalese as Newari
during Licchavis and Malla period, has the following features.
iii

A courtyard is enclosed by old houses (Pic. 1).
Each courtyard is linked with narrow courtyard entrances (Pic. 2)

Pic. 1 Courtyard

Pic.2 Courtyard Entrance

Fig. 1. Model of Unique structure

Therefore, in light of evacuation from earthquake disaster, Nepalese traditional urban structureis one of the elements of difficulties for people in the houses to evacuate to outside after theearthquake shock (Fig. 1).
Accordingly, the decision making of relative priorities for each element to be restored andreinforced within limited time and budget might be important.
In this research, at first, we conducted residents’ workshop with Disaster Imagination Game
method for understanding these risk from the residents view point, and calculated the quantitative
importance of each route as evacuation route for residents (the possible number of people passing
through each courtyard entrance was calculated).
b) Residents workshop on risk of courtyard entrance blockage with DIG
According to the results of DIG, residents indicated that the southern courtyard entrance should
be kept safe for surviving earthquake disaster (fig.2). However, the results included a problem that
not the all residents in Jhatapo participated in DIG workshop. In response to this challenge, thepossible number of people was calculated to find which courtyard and courtyard entrance wasrelatively important than the others.
Evacuation routes were selected by the residents in consideration of location of water supply,
location of open space, house of the vulnerable, location of community’s meeting place.

185

Fig.2. Disaster Imagination Game (DIG) in Jhatapoc) Risk analysis of courtyard entrances
Evacuation routes in each neighborhood, which consist of courtyard entrances and courtyards,
as well as buildings facing roads need to be restored and reinforced. Among these, reinforcement ofcourtyard entrances is the most inexpensive and feasible option. Access paths to be reinforced need
to be prioritized for effective safety improvement with limited resources. This section describes themethod to identify the access paths with number of evacuees (fig.3).
(a) Investigating the number of residents in the each building facing to the access paths.
(b) Dividing the number of residents in each building by the number of exits to calculate theaverage number of evacuees using each exit (In many cases, a building has exits both to road sideand to courtyard side).
(c) Calculating the number of evacuees in each access path.

Fig. 3. Method of Calculationd) Application to Jhatapo as a case study
The result of application to Jhatapo is shown in (fig.4). It also shows the risk of courtyard
entrances in five levels. The number of people going through courtyard is shown in fig.5.

186

Fig.4. Trial calculation of numbers of evacuees through the courtyard entrances

Fig.5. Trial calculation of numbers of evacuees through the courtyards(2) Challenges and Countermeasures for Disaster Mitigation
The workshop was conducted three times in all. Fifteen people, who abide in not only Jhatapol
but also core and buffer zone of WHS, were gathered to hear residents’ opinions in the firstworkshop. Their opinions could be considered as significant viewpoints for the further planning.
The second workshop is called DIG (Disaster Imagination game). It was a kind of workshop
method to extract challenges and countermeasures for disaster mitigation with a large scale map oftarget area. On Aug 13th 2011, this second workshop was participated by 7 people, who abide in
Jhatapo and the surroundings. Seven people divided into 2 groups in DIG; group 1 with 3 people
living in east side of Jhatapo, and group 2 with 4 people in west side and the surroundings. On Aug
20th 2011, last workshop as evacuation training was held. It was conducted to discuss more on
challenges and countermeasures for disaster mitigation, and make sure of the result of DIG. The
same 5 people (2 absentees) took part in evacuation training. The flow of DIG and evacuation
training were shown in (fig.6) and (fig.7).

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1
2
3
4
5
6
7
8
9
10

Taking a walking in target area
Writing a map
Pre-questionnaire
Self-introduction
Learning the past earthquake
Putting basic information on the map
Discussing fires
Discussing evacuation
Discussing the vulnerable
Post-questionnaire

1
2
3
4
5
6

Firefighting training
Checking a flared house
Checking a narrow road
Checking a disused entrance
Simulating vulnerable people
Going to selected evacuationarea
7 QuestionnaireFig.7.

Flowofevacuation

Fig. 6. Flow of DIG(3) Analysis of resultsa) Analysis of Fires Section
Although there is no traditional water supply called Hiti in
Jhatapo which is often seen in Kathmandu Valley, people living in
Jhatapo can use water supply equipment even in case of fire disaster,connected with pipeline from Konti Hiti (pic.3) in neighbor district
which Kumbeshole Club manages. They can help each other districts
such as Jhatapo not having one’s own water supply. However, toPic.3. Water supply fromform relationship between communities, they need a sustainableneighbor’s community
opportunity to discuss on disaster.
b) Analysis of Evacuation Section
In evacuation section, choice of route was discussed with theirunique urban structure taken into consideration. Group 1 said “wehave to discuss the wall which would prevent from evacuating”.
Group 2 said “Nepalese government should purchase the courtyards
including the wall as public domain and remove it”. The wall as
barriers for evacuation (pic.4) was seen as a problem by both groups.
Pic.4.

Wall

preventing

from evacuationc) Analysis of Rescue Section
In rescue section, system about their community was discussed toconvey information about support of vulnerable people quickly. They have two communities. One
is called Jhatapo Club and they have a chance to talk about to organize their festival andmaintaining their residential road every month. The other is called LUZA consisting of only
women and they save funds in case of emergency. They said “we would like to think about disasterprevention after this workshop now, because we did not create an occasion to discuss disastercountermeasure”.

d) Analysis of evacuation training
In the evacuation training, the program was conducted as shown (fig.6). In the first section,
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participants experienced the first-aid firefighting without giving any
information. However, it was seen that they tried to extinguish fire bythemselves (pic.5). After that, they can get Japanese method to
extinguish fire. This fact is found that conducting the workshop aboutfire disaster is effective in Nepal. In the sixth section, participants
discussed about evacuation space after going to official evacuationarea, shown in fig.8. Hearing agenda and its result are shown in Pic.5. Firefighting training
table.9.

Fig.8. Route used in the evacuation training
Table.9. Hearing agenda and its result

AgendaEffectiveness of
selected
evacuation area
recognition
degree ofselected
evacuation area

Question
Do you know whereselected evacuation area by
government is?
Do you think you can go toselected evacuation area at
the time of earthquakes?

AnswerNobody knows the place of selectedevacuation area.
First, Residents cannot go becauseof narrow road. Tourists cannot go
due to recognition degree of selectedevacuation area. Vulnerable people
cannot go because of the length tothe selected evacuation area.

According to the above result, current evacuation area could not be considered as sufficientevacuation space because of many tourists, the length of route and the urban structure (narrowroad). Therefore, this area needs complimentary evacuation area, which can compensate forshortcomings.

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4-3.2 Survey for Firefighting
Haruki Nagashima
Takeyuki Okubo(1) Current condition of the public firefighting capacity
The investigation was conducted with interview to the officer in Lalitpur Fire Station on
September 16, 2010. The purpose of the investigation was assessment of current condition of the
public firefighting capacity. The research items were mainly about human resources, equipment,
and water facilities for firefighting. The measurement of actual size of the fire engine wasconducted, because the specification of size was not kept in the fire station.
According to the results of the investigation, Lalitpur Fire Station is in charge of fire disastermanagement in the world heritage core zone of Patan, with 11 officers and only one old fire engine.
Several public fire hydrants are present, but they were installed more than 80 years ago during theRana period, and therefore they are unusable now. Water for firefighting is only stored in the tankof the fire engine. The tank’s capacity is 2,400 liters, which would run out after only 10 minutes offirefighting.
The investigation revealed the current condition that the public firefighting capacity is so
insufficient, and sustainable firefighting activities would be even difficult in normal situation.
Chart. 1 Actual size and capacity of the fire engine

Chassis/body
Chassis made: Magirus Deutz
Body model: 170 D 11

Chassis type: L1 Pruf-Nr.~~~S-48

year (model): 1975 AD.

Width×Length×Height: 2.25 m×6.25 m×2.85 m
Wheelbase: 3.20 m

Engine model: LO2303

year (donated): 1975 AD.
Tire: 0.94 m

Wheel: 0.58 m

Engine power: 200 HP

Total weight: 60 t

Watersupply
Pump made: Magirus
Water tank contents:

Pump type: low / high pressure (Max 100 mWs.)
2.400 lWater releasing capacity:
Spraying hosereels:
Suction hosereels:

50m at full throttle / all water is released in 10 minutes at 1 hose

8×35 m / 7" Ø (jointable) / top : 1.8" Ø×1 / 1.6 Ø×2
8×35 m / 7" Ø (jointable)

Cabin/superstructure
Number of seats in crew-cabin: 9 (7 members ride in usual)
Driver’s cabin: 2 (driver and helper)

Number of breathing apparatus/ fastening units: nothing

Number of equipment lockers/roller shutter doors: 2×3 + 1 at rear
Roof
Equipment:

ladder rack, ladder (small one : 0.3×3.6 m / large one : 0.3×6 m)

Accessories
Equipment:

rip pipe (60 m) / 9 helmets

190

(2) Assessing the effectiveness of Hiti: traditional water resource in Kathmandu Valley
The measuring investigation was conducted with simple measurement of discharge from Hitis in
the world heritage core zone of Patan on September 14 2010. The purpose of the investigation wasassessing the effectiveness of Hiti as a water resource for firefighting. 3 Hitis in the target area:
Konti Hiti, Nagabaha Hiti, Manga Hiti were surveyed.
a) Effective amount as a water resource for firefighting
The water releasing capacity of fire engine in Lalitpur Fire Station is 4 liters per second.
Therefore, Hitis which have discharge more than 4 liters per second can be considered as water
resource for firefightingb) Method of the simple measurement
The time to fill up 1 liter measuring container with discharge from each tap of all Hitis wasmeasured. Amount of discharge per second of each tap of Hitis was calculated, and total amount ofdischarge per second of each Hitis was calculated.
c) Results of the investigation
The results of measurement are shown in Chart. 2. According to the result of simple
measurement, only Konti Hiti had discharge more than 4 liters per second, and the result shows
Konti Hiti could function as a water resource for firefighting.
Chart. 2 Results of simple measurement
a1

a2

a3

A

a4

Filling timeAmount of discharge(sec. / lit.)(lit. / sec.)

a1

2.10

0.48

a2

1.35

0.74

Konti Hiti

a3

1.50

0.67

(A)

a4

11.90

0.08

a5

1.35

0.74

a6

0.70

1.42

Hiti

a5
a6

c1
b1
b2

B

b3

c2
c3

C

Tap

Total
Nagbaha Hiti
(B)

4.13
b1

0.95

1.05

b2

1.00

1.00

b3

2.95

0.34

Total
Mangah Hiti
(C)
Total

Fig. 1 Location of Hitis in the target area

191

2.39
c1

1.00

1.00

c2

0.85

1.18

c3

1.10

0.91

3.09

(3) Assessing the inaccessibility of the fire engine
The measuring investigation was conducted with measurement of the actual length that width,height, and the presence of obstacles on each street in the world heritage core zone of Patan. The
purpose of the investigation was assessing the inaccessibility of the fire engine on each street in thetarget area.
a) Method of the measurement and the assessment
The actual length such as width and height on each street in the world heritage core zone ofPatan were measured. The presence of obstacles was also surveyed. The actual size of the fireengine of Lalitpur Fire Station is 2.25m wide and 2.85m tall. Therefore, the fire engine cannot passthrough either street narrower than 2.5m or underpasses lower than 3m, and the points on eachstreet that the obstacles there are. Thus, such streets can be considered as inaccessible routes for thefire engine.
b) Results of the investigation
The results of assessment are shown in Fig. 2 as the map of inaccessible points for the fireengine. According to the result of assessment, the world heritage core zone of Patan has several
narrow streets and the obstacles which the fire engine cannot pass through.

2

2

1

1

3
: Inaccessible points for the fire engine● : Spots

within 2.5m width▲ : Spots within 3m height3

× : Obstacles

Fig. 2 Inaccessible points for the fire engine

192

(4) Assessing difficult areas for firefightinga) Concept of difficult areas for firefighting
The difficult areas for firefighting are identified from two perspectives: lack of water resources
and inaccessibility of the fire engine.
The concept model of difficult areas for firefighting is shown in Fig.3.
b) Method of assessment
Each of hoses equipped in the fire engine is 35m long. The fire engine with 8 hoses andmaximum hose length is 280m with all of them connected. Where the streets meander, themaximum reach from a firefighting water resource such as Hiti is 200m, approximately 1/√2 of
280m. Therefore, it can be assumed that water could be provided anywhere within a 200m radiusfrom a water resource. In other words, water supply would be insufficient in the areas further than
200m from any water resources.
Konti Hiti can be considered as effective water resource for firefighting at a situation of fire
spreading, because the capacity of tank on the fire engine is 2,400 liters, which would run out after
only 10 minutes of firefighting.
c) Results of the risk identification
The results of the assessment are shown in Fig.4 - Fig.6 as the map of difficult areas for
firefighting. Fig.4 indicated difficult areas for firefighting at normal situation. Fig.5 indicateddifficult areas for firefighting at a situation of fire spreading. At the situation, water supply would
be insufficient in the areas further than 200m from Konti Hiti. By utilizing all Hitis in the target
area as water resources, sustainable firefighting activities would be possible. Fig.6 indicateddifficult areas for firefighting at a situation in earthquake. At the situation, it is highly expected thatthe difficult areas for firefighting would be extended and isolated with all access routes blocked bycollapsed buildings.

Limit of reaching water supply for firefighting
Difficult area for firefighting activities

Water resource√21
Effective area of firefighting activities

1

Fig.3 Concept of difficult areas for firefighting

193

Effective range of water supply

Effective range with

Konti Hiti: fulfill theusing water in fire engin

Konti Hiti

standard of the effective
amount of water

200m
Nagbaha Hiti

200m

Manga Hiti

Potential range of water supply
utilizing other Hiti

Fig.4 Difficult areas for firefighting at normal times

Fig.5 Difficult areas for firefighting at a situationof fire spreading: Inaccessible points for the fire engine● : Spots within 2.5m width▲ : Spots within 3m height× : Obstacles■ : Disposition of fire engine: Roads connecting to WH Core Zone

Fig.6 Difficult areas for firefighting at a situation in post earthquake fire194

4-3.3. Survey for Community activities
Hiroki Akehara
Takeyuki Okubo
Masahiro Yoshida
Haruki Nagashima(1) Research of Community around the Hitia) Purpose of Research
In order to mitigate the damage of disaster, there is a limitation only to rely on "the help by apublic institution" in case of serious situation, and "to help oneself" and "to help each other" isrequired. The people's relationship in a local community is one of the major factors to determine thestrength to mitigate the disaster.
61 traditional water supplies called “Hiti” are located in Patan area, and these water are used
more than city water for daily life from ancient times. The values of the water system development
may be read in historical, technological, aesthetic, as well as anthropological significance and value.
In the world heritage core zone, there are 3 major Hitis: Manga Hiti, Konti Hiti, and Nagbaha Hiti.
They tell the history of this development of urban water supply and irrigation services. Construction,
extension, renovation and maintenance of the traditional Hiti system continued with community andneighborhood as well as family level participation from ancient times in Patan. Most of theresidents' life has deep relationship with Hiti, and they are one of the centers of the residents'
cooperative activities.
This research was conducted to investigate the activities of the each community around the Hiti.
b) Selection of 4 Hitis as research targets
Manga Hiti is located in the Patan Durbar Square Monuments Zone, Konti Hiti faces
Kumbheshvar temple, and Nagbaha Hiti is located near to the area including Golden Temple. Thus
they have historical and cultural value. On the other hand, they have applied by local residents intheir daily life from ancient time. Therefore, they
Alok Hiti
include the role as a collaboration space among
local community. In terms of potential for
emergency water supply, if rehabilitated, Konti
Konti Hiti
Hiti should be the best but for the given site,
Nagbaha Hiti offers advantage of gravity feed.
Nagbahal Hiti
Nagbaha Hiti however has a very low discharge
and is already dry even after a recent
rehabilitation. In that context, Manga Hiti which
has a greater discharge but needs pumping andpiping arrangements to feed to site may also be a
Manga Hiti
credible option. Only Alok Hiti is located outsideof core zone, but it provides most amount of wateraround Jhatapo area and also many amounts ofconsumption.1) There is community around Alok
Hiti and the community members maintain it
every day by themselves, and such activities arealso conducted by the community. Although80m
outside the world heritage core zone (Fig. 1), it
was selected as a research target.
Fig. 1 World Heritage site and the Target Hiti
195

(2) Challenges and Countermeasures for Disaster Mitigationa) Interview Research
The interview research was conducted to understand the community activities around each Hiti.
The name of the community around each Hiti, the name of the chairperson, and the date ofresearch are shown in Chart. 1.
Chart. 1 Objects and dates of interview research

Name of community
Kubheswar Community(Konti Hiti)
Mangal Tol Sudha Shangh(Manga Hiti)
Young Stars Club
(Nagbahal Hiti)
Alok Hiti Preventing andWater Supply Consume
Community(Alok Hiti)

Candidate
Aloj Kumar Khadgis

The researched date
2011/08/21

Human Shrestha

2011/08/21

Ghanbahadull Shakya

2011/08/10

Naresh Shakya

2011/08/16b) Outline of community around the Hiti
The summary of research outcomes are shown in Chart. 2.
Some communities raise funds from city office and international association. According tohearing investigation, after they apply to government for funds, governments decide which
community should get funds by considering current condition of the community.
Chart. 2 Outline of community around the Hiti

Name of Hiti Number of affiliation
Konti Hiti
11 persons.
(Community members
are chosen by election
from the 300 persons,
except a chairperson andanother one)
Manga hiti

112 persons(15 persons are chosen
by vote)NagbahalHiti

34 persons(3 of Chairman collect abudget and pay for 2 ofcleaning persons for Hiti)
210 persons(Three sections withseven persons takecharge )Alok Hiti

Public support (Budget)
20%:City
office(200000Rs)
20%:Community
60%:LGCDP(Local Government
Community
Development Project)
None

American Embassy paid
the support money tobuild the Hiti
The water tank was
donated by themunicipality.

196

The purpose of activity
Religion and life areunited.
The water environment is
improved forpreservation of historicaland traditional customs.
Requests from residents,
such as environmental
preservation, healthimprovement, removing
pollution, and water
maintenance are solved.
To improve the water
quality of Hiti, newsystem introduced bytheir activities.
Activities are conducted
to keep the water
environment forresidents.

c) Introduction of water supply system with Hiti
The community around Alok Hiti has one of the advanced water supply system to get water on
daily basis. They established the building with water strage tank (Pic. 1). The system supplies waterfrom water taps (Pic. 2) of Hiti to each pipe for the houses (Pic. 3) by using electronic moter (Pic. 4).

Pic. 1 Building with water strage tankPic. 2 water taps of Alok Hiti

Pic. 3 Pipe for the houses

Pic. 4 Electronic moter

197

4-4. Current Status and Issues concerning disaster management of cultural
heritage in Nepal
Rohit Jigyasu
Naoko Itaya

4-4.1 Current Status and Issues confronting Cultural Heritage protection and management in
Nepal and Kathmandu valley in particular(1) Legal provisions for the classification of monuments
The legal provisions for the conservation, protection and management of cultural property arebased on the Ancient Monument Preservation Act (AMPA) 1956, its subsequent amendments (thefifth amendment in 1996) and the Ancient Monument Preservation Rules 1988. As per this act,
Article 3(a) sub-article (i) states that 'From the viewpoint of ownership, the ancient monuments
shall be classified In two categories as public ancient monuments and private ancient monuments".
Sub-article (ii) states "From the view point of Importance, the ancient monuments shall be classified
in three categories as of international importance, of national importance and of local importance".
The monuments would need to be categorized as 'Classification 1', 'Classification II' and'Classification III' respectively according to their antiquity, significance, nature, art and architectureetc. Specific criteria was developed for each classification. Refer appendix for details of thesecriteria for classification. However all these provisions have not been implemented yet.
Monuments / Monument Zones of international importance protected by the Department ofArchaeology:
The AMPA gives the Department of Archaeology the legal provisions to declare a monument or
area to be a Protected Monument Zone (PMZ). The Department of Archaeology is subsequently
responsible for the protection of the site, including the prescription of building bylaws, approving
requests for building permits and for any other construction activities within the zone. The
Department of Archaeology is given the authority to stop inappropriate and/or illegal building
activities and to request for the demolition of unauthorized constructions.
The seven Monument Zones of the Kathmandu Valley World Heritage property have been
declared PMZs and the boundaries have been gazetted under the provisions of the AMPA. The
Department of Archaeology is therefore responsible for the preservation of the areas comprising theproperty inscribed on the World Heritage List.

(2) Protection of urban cultural heritage besides monuments
The Local Self-Governance Act (LSGA) 1999 is the principle act for the decentralization of
powers to the District Development Committees (DDC), the Municipalities and the Village

198

Development Committees (VDC). The Local Self Governance Act gives the elected local
government bodies the function and duty – to varying degree - to record, maintain and preserve thetangible and intangible heritage within their area of jurisdiction.
Under the LSGA, the municipalities are given the mandatory function and duty to prepare an
inventory of the culturally significant places and maintain and protect them. In respect to thephysical development, the municipalities must prepare a land-use map and must approve design
permits. The wards of the municipalities are given the functions, duties and powers to help preservemonuments and important sites within their ward. These functions and duties however need to becoordinated with the Department of Archaeology.

(3) Lalitpur Sub-Metropolitan City:
The municipal services in Lalitpur started with the establishment of Chhevdel Adda (Cleaning
Office) in 1918, which was later incorporated in Municipality in 1996. On 1 February 1996, the city
was declared a Sub-Metropolitan, one of only two in the country.
Lalitpur Sub-Metropolitan City (LSMC) is the sole agency for providing municipal services andcarrying out urban development works in the city of Lalitpur. The Local Self Governance Act of2055 (1999), through decentralization, has empowered the local bodies such as municipalities and
VDCs to formulate and implement their own development plans and programs. As per the LSGA
1999, LSMC as the local government is a municipal service provider and engaged in public welfare,service and infrastructure development activities. As per the provision of LSGA 1999, themunicipalities as the local government have to perform mandatory and optional municipal functions.
The municipal organization is constituted by a city council at the apex of its structural hierarchy.
Municipal council constitute members that include mayor and deputy mayor, ward chairman, ward
member of each ward committee, and prominent people of the society of different backgrounds.
Municipal board is constituted by mayor, deputy mayor and various committees and subcommittees. This also includes ward committee comprising one chairman and four ward members(including one female member) who are nominated through local election. The board convenes
regularly to discuss and make important decisions on the day to day activities of the municipality.
Within the organization structure, there are various divisions and sections to carry out the day to
day municipal functions. There are main three divisions in LSMC, Administrative, Urban
Development and Public Construction. International relation, community development, publichealth, sanitation and environment are the sections. In addition to this there are several sections andsub-sections within the divisions as well. Recently, a unit called GIS and E-Governance has also
been added which is a new concept in the municipal organization in Nepal.
[Source: City Profile, Lalitpur Sub-Metropolitan City, 2005]

199

[Source: City Profile, Lalitpur Sub-Metropolitan City, 2005]

4-4.2 Current Status and issues concerning the impact of existing Urban policies and planningon Core and Buffer zones of the Patan World Heritage Site
National Building Code (of Nepal) has direct bearing on urban policies and planning that impact
core and buffer zones of Patan World Heritage Site.
The National Building Code, which was initially prepared in 1994, has recently come into effectand the municipalities have started enforcing the code. The code emphasises seismic stability, yetclearly makes provisions for load bearing masonry
As part of the comprehensive site management plan, special byelaws have been prepared forPatan Durbar Square Monument Zone and an integral part of the Municipal Building Bylaws that
respect the heritage values. The responsibility for the enforcement of these bylaws lies with theheritage section of Lalitpur Sub-Metropolitan City.
The buffer zone encompasses already existing zones within the Municipal Zoning Plan,
comprising of the “Conservation Sub-Zone” and the “Mixed Old Settlement Sub-Zone” whichcorresponds to the whole historic city of Lalitpur. The municipal bylaws for the “Conservation SubZone” and the “Mixed Old Settlement Sub-Zone” are to be enforced for the area within the buffer
zone.
However, these byelaws have still not been implemented by the responsible agency Lalitpur
municipality.

200

Land use regulations and development are a function of both the city and natioanl government.
The Town Development Act (TDA) mainly deals with the reconstruction, extension anddevelopment of towns. In the Kathmandu Valley, the Kathmandu Valley Town Development
Committee (KVTDC) is responsible for implementing the Act.
The Guthi Corporation Act (GCA) was established in 1964, nationalizing all Guthis to acentrally organized unit, the Guthi Sansthan. The Guthi Sansthan is still the legal owner of manymonuments and historic buildings within the PMZs.

4-4.3 The existing role of Central Government, army, municipality, owners and residents fordisaster risk management of urban cultural heritage(1) Central Government Level
The Ministry of Home Affairs through its department of Narcotics, Drug Control and Disaster
Management, is the national agency responsible for disaster management in Nepal. Formulation ofnational policies and their implementation, preparedness and disaster mitigation, immediate rescue
and relief works, data collection and dissemination, collection and distribution of funds andresources are the vital functions of the Ministry. Its network to cope with natural disasters is
integrated by 75 Chief District Officers, one in each of the administrative districts, who act as thecrisis manager in the event of natural disasters.
The main function of the department is to actively and efficiently co-ordinate and carry out
emergency preparedness and disaster management activities with concerned agencies.

(2) Army and Police
The Royal Nepal Army and Nepal Police play important roles in rescue operations. Police
officials collect first-hand information of a disaster and inform concerned officials. In the event of acatastrophic disaster, Nepal Police establish command posts to facilitate rescue operations.
Moreover, Nepal Police Personnel collect most of the disaster data and information.

(3) Municipality
On the occasion of Earthquake Safety Day on January 16, 2003, LSMC announced its plan toimplement NBC in all of its building permit process. LSMC became the first municipality inNepal
to implement NBC and it was done before the implementation was made mandatory.
The decision was historic in the sense that it not only awakened the government to enforce NBC
but also encouraged other municipalities on the necessity of building code implementation. It also
proved that implementation of NBC can be done by determination irrespective of legal constraints.

201

(4) Earthquake Safety Section
Initially application of NBC was carried out by the Technical Cell formed under theEngineering Sub-Committee to look after regular building permit process. The cell was composedof a group of Municipal engineers, engineers from DUDBC, NSET, NESF and NEA and wasfunctional for six months. The applications for building permit were first verified for conformity
with building by-laws. Then, they were checked by the Technical Cell for conformity with NBC.
However, it was soon realized that a separate section was needed in order to increase the efficiency
and performance. On November 27, 2003, Earthquake Safety Section was established. It worked inconsultation with the Earthquake Safety Committee (ESC), which was comprised of engineers from
DUDBC, academics and other professionals to help LSMC in technical matters related to NBC.
The organization chart for initial arrangement and the current arrangement for checking
compliance with NBC are shown schematically in the following figure

Following boxes explain the role/divisions among the Building Permit and Earthquake Safety
Sections and House Owners
Building Permit Section:










To check/verify architectural drawings/designs as per building by-laws and register the
file.
Notice to neighbors and field verification of plot/access roads and other legal documents;
Submit Field Verification Report;
Recommend for building permit to the Executive Officer/Mayor;
To check and verify at Tie Beam level as per by-laws;
To check and verify buildings for Completion Certificate as per by-laws
To monitor construction fields regularly;
To inform city dwellers about the permit and planning processes; andTo formulate new systems/mechanisms for effective enforcement of building by-laws

202

Earthquake Safety Section
 To check/verify structural drawings/designs as per NBC and to recommend ‘No
Objection’ for further process of Building Permit.
 To give suggestions to house owners and masons regarding earthquake safe technology inbuilding constructions; To monitor construction fields regularly
 To conduct training/orientation programs to designers, technicians, contractors and houseowners; To carry out awareness programs on earthquake safety to general public;
 To coordinate between ward level disaster management committees with Municipal Level
Committee
 To work closely together with supporting organizations like DUDBC and UN agencies forearthquake risk reduction and preparedness; and To formulate new program proposals for effective implementation of NBC.

House Owners








To prepare and submit structural design and drawings as per NBC;To follow the suggestions/comments given by the Earthquake Safety Section in design aswell as in the construction.
To apply earthquake safe techniques in construction field as per approved design;
To use the quality construction materials in the field;
To give special attention to quality of construction works and make it mandatory to use
vibrator, mixtures, compactor etc.
To carry out construction under the supervision of skilled technicians, andTo employ trained masons in the construction

General guidelines on building permit and earthquake safety published by LSMC is the guiding
document which has all the necessary guidelines and forms necessary for the building permit
process. The document is informative and comprehensive as it not only outlines the necessary
process but also provides information about relevant building codes, roles and responsibilities ofdifferent sections in the Municipality, designers and house owners.

(5) Challenges
 One of the main challenge is that the process of seeking building permit is very complicate
with the reason that many house owners tend to take illegal shortcuts.
 There is no proper system of ground verification that construction at each step is according
to approved drawings.
 There is lack of knowledge among masons and contractors on earthquake resistant building
construction technologies.
 Residents tend to add stories over existing traditional structures thereby increasing theirvulnerability to earthquakes.
 There is negligence and unwillingness of house owners to apply earthquake resistant
203








technologies due to perceived additional costs in construction.
Because of unfair competition between local masons and contractors, they work at low costs
by not following National Building Codes.
MOST IMPORTANTLY, THESE BUILDING BYELAWS DO NOT TAKE INTOCONSIDERATION THE HERITAGE VALUES FOR NEW CONSTRUCTIONS AS
WELL AS ASSESSMENT, REPAIR AND STRENGTHEINING OF TRADITIONAL
HOUSES.
IN PATAN MUNICIPALITY, THERE IS VIRTUALLY NO COORDINATIONBETWEEN HERITAGE SECTION AND THE EARTHQUAKE SAFETY AND
BUILDING PERMIT SECTIONS.
ALTHOUGH COMPREHENSIVE MANAGEMENT PLAN FOR WORLD HERITAGE
MONUMENT ZONES OF KATHMANDU VALLEY ADVOCATES RISKMANAGEMENT, THE PLAN HAS NOT BEEN PREPARED YET.

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5. Disaster Risk Management Proposals
5.1 Structural Reinforcement of Traditional Buildings and Open Spaces
Hari Ram Parajuli
Prem Nath Maskey
Junji Kiyono
As a result of the seismic vulnerability assessment the damage index of each and every building, brickmasonry as well as RC building, is determined and plotted in the base map as shown in Fig. 5-1.1. The valueof the buildings, as determined for the buildings is presented in Fig. 5-1.2.

Fig. 5-1.1 Damage Index of the buildings

Fig. 5-1.2 Value of the buildings

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The location of the open spaces and the underpasses, crucial for evacuation planning in case of earthquake
Disaster is shown in Fig. 5-1.3.

High Value Chaitya located Courtyard 7

Surrounding Buildings are high value and vulnerable

When Disaster occurred over 30 residents rush to this Underpass for evacuation
Fig. 5-1.3 Case study place for Disaster Risk Management206

5-1.1 Strengthening of buildings
In reference with Fig. 5-1.1 and 5-.2, it is evident that the buildings B82, B81, B16 and B15. Around theopen space 7, B16, B15, B14 and B13 by the side of the main road to Kumbheshwor Complex, and B50, B48
and B46 around the open space 20 have high values. The damage indexes of the buildings are the result of
the vulnerability assessment including the structural analysis using the seismic input obtained from theseismic hazard analysis of the study area, and represent the future damage scenario of the study area in caseof earthquakes. The values of the buildings are determined based on the location, social and heritage
importance. These vulnerable buildings with high value need to be strengthened to mitigate the possible
severe damages and loss during the disaster. The possible technique to be applied for strengthening of suchbuildings is suggested in reference with a building, B47. The typical plan and elevations of building B47 areshown in Fig. 5-1.4.

Fig. 5-1.4 Plan, Front elevation, back elevation, left side elevation and right side elevation of B47

For illustration, the vulnerability assessment of the building (B47) is carried out by modeling the building
using finite element method (FEM) for the structural analysis. The stress contours in the buildings as theresult of the analysis are shown in Fig. 5-1.5. The stresses in the wall panels at critical locations are found to
exceed the permissible values of stress in brick masonry.

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Building B47

Stress contours in 3D SAP modelStress pattern in front panel

Fig. 5-1.5 Photo, stress contours and stress pattern in panel of Building B47

Timber beams

Concrete band system with hooks andconcrete column

Timber posts

(a)

(b)

(c)

(d)

Fig. 5-1.6 Two simple techniques of strengthening the building B47 (a) plan showing the vertical timber upright posts(b) elevation showing the timber framing, (c) plan showing concrete columns and beams anchored with theexisting walls, (d) elevation showing the concrete bands at the strategic levels.

208

The maximum stress values are about 0.55 MPa, which are greater than the permissible value of 0.3 MPafor brick masonry, showing the need for strengthening of the building. The strengthening of the building canbe achieved by various methods depending upon factors, like importance of structure, cost, integrity to otherstructures etc. Out of many, two simple and possible methods are proposed. The first method consists ofproviding vertical timber upright posts as additional members to the wall along with the brick masonry at aregular spacing, and the posts are connected with the horizontal timber beams at floor level as shown in Fig.
5-1.6 (a) and (b). This method is in the line of the traditional technology with indigenous materials, easily
accepted by the local inhabitants. The second method consists of providing horizontal concrete bands at
strategic levels in each storey. Such concrete bands are inserted by cutting the wall partially and then the wall
is tied with the band by providing hooks. The horizontal concrete band is framed with the additional concrete
columns provided at the corner points as shown in Fig. 5-1.6 (c) and (d).

2095-1.2 Strengthening of open space and underpass
The open spaces and the underpasses, typical elements of the local community of the Kathmandu Valley,
are important in terms of disaster management. The open spaces are excellent places for shelter for people incase of damages of the houses, and underpasses are the only available thorough ways for exit from thetraditional courtyards. In this regard, the strengthening of the open spaces and the old, narrow but long underpass becomes equally important. Two suitable techniques for strengthening of the open spaces andunderpasses are suggested herein.
In case of earthquake hazard, the open spaces and underpasss are most important, because the people
have a general tendency to run away to the nearest open space in courtyard, and pass through the underpasses
from the courtyard to a larger open space or more safe places. Hence the strengthening of buildings to protect
courtyard like A and strengthening of the underpasses as B1 and B2 (Fig. 5-1.7and 5-1.8), which are the only
ways out from the inner parts is very important. The buildings which are exposed to the courtyard must be
framed with addition of RC columns to strengthen them as shown in Fig. 5-1.9. The under pass could beprotected by providing concrete shell throughout as a rigid structure as shown in figure Fig. 5-1.9 (b). As asecond option the timber frame could be provided as shown in figure 5-1.9 (c).
The principles of the strengthening techniques for the buildings, open spaces and the underpasses areproposed in general as the possible method of application, and also and in the line of tradition. Details of thetechniques and the quantitative values are not given here, limiting this section as a part of the proposal.
Different techniques with use of new materials and technology are also possible; however, they should matchthe existing structures and traditional methods as far as possible.

B2

B1

Fig. 5-1.7 Building stock plan with underpass passage B1 and B2

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Passage B1

Fig. 5-1.8 Isometric view of the building stock with open space A and passage B1(a) Photo showing underpass B1(b) Concrete shell in under passunder pass

Fig. 5-1.9 Strengthening techniques for under pass211(c) Timber frame in5-2 Utilization of Cultural Heritage for Evacuation and Rescue
Takeyuki Okubo
Rohit Jigyasu
Naoko Itaya
Masahiro Yoshida5-2.1 Summary
Many people would be affected in an event of earthquake in Kathmandu Valley. According to the recordof the Nepal Bihar Earthquake in 1934, people ran into open spaces in panic. However, as large part of theold open spaces has been filled up with new buildings and walls surrounding private lands because of theincreasing population, accessing them is not as easy as it used to be. A system for evacuation and rescue
activities should beprepared as a large earthquake is anticipated in the near future.
Accordingly, designation of monasteries (Bahas and Bahis) and temples in the daily milieu as primaryrefuge areas, improvement of the safety of the access paths to these places, and utilization of cultural heritage
components shared by the local communities (Patis, Sattels, wells, hitis etc.) for rescue activities, arerecommended.
This article takes up evacuation plan from Jhatapo neighborhood as a case target area of investigation.

5-2.2 Preparedness for Evacuation(1) Grounds of temples with functions as primaryrefugesDuring the Hanshin Awaji Great Earthquake inJanuary 1995, some people evacuated to the small parks(as large as 0.25 hectares used mainly by children andelderly people) whose service radius are approximately
250 meters. During the East Japan Great Earthquake inMarch 2011, shrines and temples in neighborhoods
functioned as refuges. During emergent time after adisaster, safety of a city would be enhanced withpreparation of primary refuge areas, where people could
be immediately sheltered, as well as municipally
designated city level refuge areas (Fig.1).
The surroundings of the target area include several
open spaces associated with temples that are closely
related to local people’s religious lives such as
Kumbeshwar Complex and the open spaces around theGolden Temple as well as courtyards of Bahals andBahils. These places may well have potentials for being
utilized as primary refuge areas in times of disasters.

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Fig.1 Municipally Designated City level
Refuge Areas(2) Traditional urban structure that hinders the accessibility to primary refuge areas
Typically, Nepalese traditional urban structure has the following features.
 Each courtyard is surrounded by several houses.
 Courtyards are connected to one another through underpassages below houses.
When an earthquake occurs and these underpasses collapse, residents in buildings not facing theroads would not be able to evacuate. In this way the traditional urban structure of Nepal makes
emergency evacuation difficult.

5-2.3 Preparation of evacuation plan “from Houses to Pattis and Sattels” (1st step)(1) Disussion with local residents on available evacuation routes through Disaster ImaginationGame (DIG)
In order to evacuate to primary refuge areas with relative ease during emergency, preparation ofan evacuation plan and enforcement of daily drills are important. Local communities should
actively participate in the preparation of an evacuation plan so that it is suitable to ground realities.
In order to have some clues for preparing an appropriate evacuation plan, a Disaster ImaginationGame (DIG) was conducted in Jhatapo neighborhood in September 2010. The local residents who
participated in the DIG stated their opinions as follows.
 Access paths for daily usage
・ Motorcycles go through the northern access path leading to large courtyard.
・ Pedestrians use the southern access path which is closer to the center of the area.
 What the residents think they should do in time of disaster・ The residents would wish to reach to the well as soon as possible so that they could
immediately start fire fighting.
・ The residents would want to immediately take refuge in the closest open spaces,
anticipating the collapse of the buildings.
・ Disabled, elderly and infantswould take more time for evacuation and need help fromothers.
 Evacuation routes selected by the residents
・ Through the DIG, the residents selected the most appropriate routes out of various potential
routes (Red arrow lines in Fig.2).

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Fig.2 Disaster Imagination Game (DIG) in Jhatapo

DIG would be one of effective methods to prepare an evacuation plan with the participation of
local communities .
(2) Calculation of the number of evacuees passing through the courtyards and access paths
Evacuation routes to the refuge areas in each neighborhood, which consist of access paths andcourtyards, as well as buildings facing roads need to be reinforced. Among these, reinforcement ofaccess paths is the least expensive and most feasible option. Access paths to be reinforced need to
be prioritized to effectively improve safety with limited resources. This section describes themethod to identify access paths where more number of evacuees are expected (Fig.3).
(a)Investigating the number of residents in the buildings
facing the access paths.

(b)

Dividing the number of residents in each building by the
number of exits to calculate the average number of
evacuees using an exit (In many cases, a building has exits
on the road side and courtyard side).

(c)

Calculating the number of evacuees who would use eachaccess path, anticipating that the residents would evacuate
to the refuge areas through the nearest courtyards.
Fig.3

The number of expected evacuees who would use each of the access paths was calculated
through a trial exercise (Fig.4). In this case, there are two important access paths indicated as red
arrow lines in Fig.4, and these well correspond with routes of residents’ selection in Fig.2.

214

The number of expected evacuees who would use each of the courtyard also was calculated
through a trial exercise. There are two important courtyards indicated as red circles in Fig.4.

Fig.4 Trial calculation of numbers of evacuees through the access paths(3) Selection of prioritized courtyard and access path to bereinforced for seismic safety
In the last phase of first step, we need to discuss the priority of courtyard and access path
reinforced for seismic safety. For this purpose, maps based on research outcomes from “culturalvalue”, “structural vulnerability” and evacuation plan” are overlayed for reference.

5-2.4 Preparedness of “Pattis and Sattels” for Rescue Activities (2nd step)(1) Establishing storage areas for rescue and salvage equipments in Patis and Sattels
During the Hanshin Awaji Great Earthquake, the sufferers had helped one another and worked
on rescuing their neighbors from the underneath of debris until the public rescue teams arrived. Inorder for local residents to do rescue activities, there need to be rescue instruments such as shovels,
bars, jacks and ropes. Moreover special equipments may be needed to salvage damaged/trapped
cultural heritage components. It is effective to house the rescue and salvage instruments required intimes of emergency at appropriate storage areas. On the street corners of Patan are Patis and Sattels;
thecultural heritage components shared by the local communities. It is suggested that they could be
utilized as storage areas. Wells and hitis are also valuable for supporting rescue activities with backup activities such as water supply.
(2) Enhancing functions of Guthi(s)Nepal has mutual aid organizations called Guthis. Although it is said that they have been
weakening, they can be revitalized for the purpose of evacuation and rescue, and can be utilized for
improving disaster preparedness of local communities.
Vulnerable people living in the city, such as infants, aged people and disabled. would need help
from others for evacuation, information about their residences is required to be shared in advance.
Moreover, wells and hitis should be better maintained for providing drinking water during
emergency. Collective support functions of Guthis should be utilized for achieving these.

215

(3) Utilization of Cultural Heritage in the Daily Milieu for Supporting Evacuation and Rescue
The measures to be taken by residents, local communities and the municipality for utilizing
cultural heritage components within the daily milieu to improve safety of the residents of thehistoric city are proposed as follows.
It is desirable to delegate cultural heritage components new roles to keep the historic city
sustainable, and to revitalize the traditional functions of Guthis for improving disaster preparednessof local communities.

Municipality

Community
basedorganizations

Residents

Evacuation Preparedness
Rescue Preparedness
Designation of primary refuges (Baha, Establishment of storage areas for
Bahi, temple and other open spaces in rescue and salvage (at Patis andeach neighborhood)
Sattels)
Maintenance of evacuation routes Deployment of rescue instruments(securing the safety of the routes to the
refuges by reinforcing access paths,
courtyards and buildings)
Support for preparation of an evacuation and rescue plan
Preparation of an evacuation and rescue plan、Practice of evacuation and rescue
drillsEnhancement of the collective support functions of Guthis
Checking the residences of vulnerable Maintenance of the back up facilities
people such as infants, elderly people for
emergency
supplyofand disabled.
water(wells/hitis)
Participation in evacuation drills
Participation in rescue and salvage
Preparation of survival kits (wears, drills
foods, household medicines, radios, Preparation of rescue kits (workgloves, ointments, cloths and etc.)
batteries and etc.）216

5-2.5 Preparation of evacuation plan “from Paties and Sattels to Squares” (3rd step)(1) Recent condition of Evacuation Sites
As the city levelevacuation sites designated by the municipality of Patan are at considerable
distance from the target area, ,other large and safe areas are required for effective evacuation,
especially for the elderly people and/or visitors who do not know the location of citylevelevacuation sites. (Fig.5)

Target Area (Jhatapo)

Fig. 5 Map of Existing Selected Evacuation Sites
217

(2) Strategy for Preparation of alternative evacuation sitea) Recomended complementary evacuation site: the Durbar SquareIn the case of Hanshin Awaji Great Earthquake, most people took shelter in parks which werelocated at less than 500 meters distance from their houses. But in the case of historical city of Patan,
there are not enough designated evacuation spaces for local residents.
Moreover, many tourists visit Patan, and most of them are unfamiliar with the local city layout
and therefore do not know the location of designated evacuation sites. On the other side, most ofthem know the location of the Durbar Square; a famous heritage site. The Square is easy to reacheven for tourists as well as for local residents.
The Durbar Square has both large open space and water resources as Hiti for immediate life
support during emergency. Therefore it has high potential as a complementary evacuation space.
(Fig.6)
For this reason, safety of the roads leading to the Square also needs to be ensured.

Fig. 6. Location of DS as the complementary evacuation site218b) Selection and repairment of evacuation routes to the Durbar Square
The risk of road blockage depends on the width of road. Therefore, recommended evacuationroutes are to be chosen based on their widths.
According to the records of the Hanshin Awaji Great Earthquake, most of the roads which were
narrower than 4 meters were completely blocked. The structure of buildings in Nepal is different
from Japanese one, but width of almost all the roads around Durbar Square is narrower than 4
meters.
For keeping the relative safety, the widest road might be chosen as the main evacuation routes.
And reinforcement of buildings which face to the road are required not only for keeping safety ofevacuation route but also for keeping the value of traditional street scape, as much as possible.

Fig. 7. Recomended evacuation routes from Paties and Sattels to the Durbar Square

219c) Repair and reinforcement of the monuments in the Durbar Square
The Durbar Square is as large as 2.8 hectares. However, if all the residents within a 500 meters
radius from the Durbar Square are to take refuge, there would be shortage of space forapproximately 10,000 people. Refuge space for at least another 200 people would be lost if thesemonuments collapse.
Maintenance of the monuments in the Durbar Square is required not only for preservation of
their heritage values but also for keeping safety of emergency space in case of disaster. And if the
back=yards are opened as parks, the open space will drastically increase and most of people will beable to stay not only for sightseeing but also for evacuation.

Fig. 8. The historic monuments in Durbar Square220

5-3. Improvement of Firefighting Capacity by Utilizing Cultural Properties
Takeyuki Okubo
Rohit Jigyasu
Naoko Itaya
Haruki Nagashima
5-3.1 Summary
Although fires would very likely break out in theevent of an earthquake, firefighting activities by publicagencies would be difficult in the case of Patan. Lalitpur
Fire Station, which is in charge of fire disastermanagement in the world heritage core zone of Patan,
only owns one old fire engine. Several public fire
hydrants are present, but they were installed more than
80 years ago during the Rana period, and therefore are
not reliable now. The public firefighting capacity isgrossly insufficient in current condition.
Thus, several measures to improve the firefighting
capacity of local residents, communities and themunicipality proposed.
This section focuses on the world heritage core andbuffer zones as target of investigation and proposal(fig.1).
5-3.2 Challenges for Firefighting in World Heritage
core and buffer area of Patan

Fig.1 The world heritage core zone of Patanand Hitis(1) Current condition of the public firefighting
capacity
Lalitpur Fire Station is located is located 1.0 km to
the west-northwest from the Patan Durbar Square, andapproximately 15 minutes away from the target area by
foot. The station has 11 officers and has only one fireengine. In average, 44 fires occured from July 2009 to
Pic.1 The burnt temple in Kumbeshwar
June 2010 within the Fire Station’s jurisdiction. Even
Complex, 2009
when the fire engine tries to reach the scene of a fire, itcannot go through crowded narrow streets. Because ofsuch condition, a fire burnt down an important temple (Pic.1) in Kumbeshwar Complex in 2009.
Moreover, water for firefighting is only stored in the tank of the fire engine. The tank’s capacity
is 2,400 litres, which would run out after only 10 minutes of firefighting. The public firefighting
capacity is insufficient that sustainable firefighting activities would be even difficult in case of
normal fire situations.

221

(2) Assessing the effectiveness of Hiti: traditional
water network in Kathmandu Valley
Traditional water resources called Hiti(s) are closely
connected to the lifestyle in Kathmandu Valley, andhave been maintained by local communities since
generations. The amount of water discharge was onceabandunt, but has been gradually decreasing because ofurbanization-induced exhaustion of underground waterand plugging of the conduit pipes due to insufficientmaintenance.
There are 3 Hitis in the target area: Kenti Hiti,
Nagabaha Hiti and Manga Hiti. By utilizing them asbackup for water resources, sustainable firefighting
activities would be possible.
The water releasing capacity of the fire engine in
Lalitpur Fire Station is 4 litters per second. Therefore,
hitis that discharge more than 4 litters per second can beconsidered as effective water resources for firefighting.
According to the result of simple measurement, only
Konti Hiti could be utilized as a water resource for fireengine (Chart.1 ).

Chart.1 Amounts of discharge of Hitis

Name of Hiti

Amount ofwater flow
(lit/sec.)(A) Konti Hiti

4.13(B) Nagbaha Hiti

2.39(C) Mangah Hiti

3.09

Pic.2 Fire engine of Lalitpur fire brigade
office(3) Narrow streets that make firefighting difficult
The world heritage core and buffer zones of Patan
has dense built fabric of traditional houses, and narrow
streets through which a fire engine cannot go through.
The fire engine that Lalitpur Fire Station owns
(2.25m wide and 2.85m tall) cannot pass through either
streets narrower than 2.5 meters or underpasses lower
than 3 meters (Pic.2). Thus, the heritage zones locatedbetween such barriers cannot be reached by the fireengine. Moreover, many obstacles on the streets are
regularly disturbing the traffic. It is expected that thestreets would be blocked and difficult areas for
firefighting would expand even more.
(4) Identification of difficult areas for firefighting
Firefighting difficult areas are identified from two
perspectives: lack of water resources and inaccessibilityof the fire engine.
Each of the hoses equipped in the fire engine is 35
meters long. The fire engine is equipped with 8 hoses,
and the maximum hose length is 280 meters with all of

222

Fig.2 Difficult areas for firefighting

them connected. Where the streets meander, themaximum reach from a firefighting water resource such
as Hiti is 200 meters, approximately 1/√2 of 280 meters.
Therefore, it can be assumed that water could be
provided anywhere within a 200 meters radius from awater resource. In other words, water supply would beinsufficient in the areas further than 200 meters from
Konti Hiti.
In the figure, the areas where the fire engine is hard
to reach and where water supply would be insufficient
are indicated (Fig.2).
It can be observed that difficult areas for firefighting
include neighboring districts of Jhatapur Area with theGolden Temple, and are located around the designatedworld heritage.

5-3.3 Challenges for Eliminating Difficult Areas for
Firefighting
The challenges are to secure water supply for
firefighting and to secure accessibility for the fire engine.

Fig.3 Effective or potential range of Water
supply with Hiti

(1) Security of water supply for firefighting
Currently, an effective amount of water discharge isconfirmed only in Konti Hiti. However, the other Hitis
also used to have sufficient water discharges, and it isdesired to restore them. In addition, a water resource
becomes effective only when channels for intake are
secured. Recharge areas/pits for water intake need to beinstalled(Fig.3).
(2) Securing accessibility for the fire engine
It is highly expected that the identified difficult areas for
firefighting would be isolated with all the access routes
blocked by collapsed buildings after earthquake. Thus,
the buildings along the streets within the areas need tobe reinforced as far as possible.
On the other hand, introduction of a compact fire engine
in the fire station is recommended (Pic.4). This would
solve the problem of inaccessibility through narrowroutes. These narrow routes should be restored evenafter the introduction of a small fire engine (narrower
than 1.5 meters, lower than 2 meters) (Fig.4).

223

Pic.4 Compact Fire Engine

Pic.5 Repair of the Curbs of the Buildings

In order to expand the widths of such places without
losing the value of the traditional townscape, repair of
the curbs of the buildings (Pic.5) and transfers ofmonuments owned by individuals (Pic.6) arerecommended.

Pic.6 Transfers of Monuments owned by
Individuals

Fig.4 Difficult areas for firefighting (Left), After the introduction of a Compact Fire Engine (Right)
Right shows the place that prefer to be reinforced

224

5-3.4 Improvement of Disaster Risk Mitigation with Residents, Communities and theMunicipality
Local residents, local communities and the municipality are recommended take the following
measures to eliminate the firefighting difficult areas.
The key is to delegate to Hitis, the traditional water network, new roles to sustain the historic
city, and to maintain the traditional urban structure.
Security of water supply for
firefighting(Recovery of Hitis)
Installment of water supply channels.
Installment of water intake channels.

Security of street widths(Not destroying the traditional urban
structures)
Introduction of a small fire engine.
Municipality
Reinforcement for preventing thebuildings from falling down.
Management of water usage.
Shifting of obstructive vehicles such
Community based Preparation of environment to utilize as motorcycles.
organizations
the Hitis.
Formulation of parking spaces andrules.
Daily maintenance such as cleaning.
Maintenance of the facades of the
Residents
residences including repair of the
curbs.

225

226

Acknowledgment
Seismic Hazard Assessment and Structural Analysis of Traditional Brick Masonry Buildings Part;
We would like to express our sincere gratitude to Dr. Bhakta Bahadur Ale, Professor, Director,
Center of Applied Research and Development, (CARD), Institute of Engineering (IOE), Tribhuvan
University (TU) for valuable cooperation in the research work.
We would like to express our gratitude to Dr. Tomoki Shiotani, Associate Professor,
Department of Urban Management, Kyoto University, Dr. Hisashi Umemura, Associate Professor,
Department of Architecture, Nagoya Institute of Technology for their valuable contribution in Nondestructive testings of heritage structures of Patan
We also deeply appreciate the valuable assistance of Mr. Sujan Tripathi, Mr. Jhapat Bahadur
Thapa, Mr. Govinda Raj Bhatta and Mr. Rakesh Dumaru, former IOE graduate students in in thetests at the site and in the laboratory, in survey of buildings and in analysis of the buildings.

Analysis of Heritage Values, Vulnerabilities and Resources for Emergency Response Part;
We would like to express our special gratitude to Mr. Kai Weise; the Architect of Planners’
Alliance for the Himalayan & Allied Regions (PAHAR Nepal) and UNESCO Consultant for his
immense help in implementing the field work especially with regards to documentation of the casestudy and interviews with key stakeholders. He was ably assisted by Mr. Manindra Shrestha andstudents from Khwopa Engineering College. The team also helped us in organizing workshop in thetarget area in 2010.
We also express our thanks to Dr. Rohit Ranjitkar, the Director of Kathmandu Valley
Preservation Trust (KVPT). He supported us by introducing us to the area and the house owners. He
enlightened us with his rich knowledge of the area.
Last but not the least, we wish to thank the residents of Jhatapo area. We went to their area
several times for conducting our research and every time they greeted us with warm smile. It is only
because of their kind cooperation that we could successfully accomplish our research. We sincerely
hope they can continue preserving their rich heritage as part of their life.

227

Authors List
Seismic Hazard Assessment/ Structural Analysis of Traditional Brick Masonry Buildings:
Prem Nath Maskey
Professor,
Department of Civil Engineering, Institute of Engineering,
Tribhuvan University, Nepal
1-1, 1-2, 2, 3-1, 3-2.2, 3-3.2, 3-3.4, 3-3.5, 5-1
Hari Ram Parajuli
Post Doctoral Fellow,
Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ristumeikan University, Japan
1-1, 2, 3-2.1, 3-2.3, 3-3.1, 5-1
Junji Kiyono
Professor,
Department of Urban Management,
Kyoto University, Japan
1-1, 2, 3-2.4, 3-3.6, 5-1
Simulation of Building Collapse/ Application of Risk Evaluation methods:

Aiko Furukawa
Associate Professor,
Department of Urban Management,
Kyoto University, Japan
3-2.4, 3-3.6
Kenzo Toki
Director, Professor,
Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University, Japan
3-2.4, 3-3.6
Hitoshi Taniguchi
Professor,
Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University, Japan
3-2.4, 3-3.6
Masatoshi Tatsumi
Master Course Student,
Department of Urban Management,
Kyoto University, Japan
3-2.4, 3-3.6
228

Heritage Values of the Historic City/Assessment of Heritage Values:
Sudarshan Raj Tiwari
Professor,
Department of Architecture, Institute of Engineering
Tribhuvan University, Nepal
4-1, 4-2
Rohit Jigyasu
Professor, President of ICORP,
Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University, Japan
4-2, 4-4, 5-2, 5-3
Naoko Itaya
Associate Professor,
Research Center for Disaster Mitigation of Urban Cultural Heritage,
Ritsumeikan University, Japan
4-2, 4-4, 5-2, 5-3
Assessment of Resources for Disaster Mitigation and Response:
Takeyuki Okubo
Professor,
Department of Civil Engineering, College of Science and Engineering,
Ritsumeikan University, Japan
4-3, 5-2, 5-3
Masahiro Yoshida
Master Course Student,
Department of Civil Engineering, College of Science and Engineering,
Ritsumeikan University, Japan
4-3.1, 4-3.3, 5-2
Haruki Nagashima
Master Course Student,
Department of Civil Engineering,
College of Science and Engineering,
Ritsumeikan University, Japan
4-3.2, 4-3.3, 5-3
Hiroki AkeharaStudent,
Department of Civil Engineering,
College of Science and Engineering,
Ritsumeikan University, Japan
4-3.3

229

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