bluuebunny/crossref_metadata_2025 huggingface dataset:
Seismic retrofit of buildings
Authors: Dritsos Stephanos E.
Published: January 2020

Some important aspects of the subject of the repair to and the strengthening of buildings, before and after an earthquake, are investigated in this paper. It has to be noted that, far more than that of recent constructions, many older buildings are susceptible to earthquake damage. It is certain that, from the techno-scientific side of problem alone, the subject is incomparably more difficult and complex than that of designing new structures. The structure of the building has to be dealt with as a whole and the process of redesign includes the following three stages: The assessment of the capacity of the existing structure during seismic activity, the process of decision making and the design of a solution for a pre-selected performance level. The method that will be selected for the intervention will have to be included in the plan of the strategy. This will depend on the required levels of strength, stiffness and deformation of the structure. Practical aspects for six main categories of methods of intervention are discussed in this paper. The six main categories are listed as follows: The addition of infilled walls, the addition of new external walls, the addition of bracing systems, the construction of wing walls, the strengthening of weak elements and the incorporation of energy absorbing systems. In particular, recent results from ongoing experimental research programs concerning the retrofitting of existing structures are presented. Finally, certain important aspects of practical application are pointed out that may often puzzle the engineer or may be solved in an erroneous way. These concern either the choice of the most suitable solution for the intervention or the application of technological methods of intervention.
Revised models for attenuation of Modified Mercalli intensity in New Zealand earthquakes
Authors: Dowrick D. J. , Rhoades D. A.
Published: January 2020

This paper presents simple two-dimensional models for attenuation of Modified Mercalli intensity in New Zealand earthquakes, which improve upon the models published by the present authors in 1999. First, the models now ensure that the attenuation functions in the two orthogonal directions converge to the same value at zero source distance. Secondly, an improved fit has been achieved through a modification of the algebraic form of the log distance term in the attenuation function. An additional improvement is the completion of the attenuation model for Deep events (hc ⩾ 70 km) in the subducting Pacific plate, which was not fully dealt with in our previous paper. Intensity saturation effects are demonstrated. A comparison is made between our New Zealand model and one for the intraplate region of South China where the attenuation rate is considerably lower.
Survey of the December 26th 2004 Indian Ocean tsunami in Sri Lanka
Authors: Goff James
Published: January 2020

An International Tsunami Survey Team (ITST) consisting of scientists from the U.S., New Zealand, and Sri Lanka evaluated the impacts of the December 26th 2004 transoceanic tsunami in Sri Lanka two weeks after the event. Tsunami runup, height, inundation distance, morphological changes, and sedimentary characteristics of deposits were recorded and analyzed along the southwest and east coasts of the country. Preliminary results show how local topography and bathymetry controlled the limits of inundation and associated damage to the infrastructure. At some sites, human alterations to the landscape increased damage caused by the tsunami.
Base-isolated building connected to adjacent building using viscous dampers
Authors: Matsagar Vasant A. , Jangid R.S.
Published: January 2020

Seismic response of multi-storied base-isolated building on various isolation systems connected using viscous dampers to an adjacent dissimilar base-isolated or fixed-base building is investigated. The multi-storied buildings are modeled as a shear type structures with lateral degree-of-freedom at each floor, which are connected at different floor levels by the viscous dampers. Performance of this novel combination is studied by deriving the governing equations of motion and solving it in the incremental form using Newmark's step by-step method of integration. The variation of top floor absolute acceleration and bearing displacement under different real earthquake ground motions is computed to study the behavior and effectiveness of the connected systems. It is concluded that connecting the two adjacent base-isolated buildings with the viscous dampers is helpful in controlling large bearing displacement in the base-isolated structures; thereby, eliminating isolator damages arising due to instability at large displacement or pounding with adjacent structures during the earthquakes. Parametric studies are also performed to identify optimal parameters such as damper damping and distribution pattern of viscous dampers to achieve the maximum response reduction in the damper-linked adjacent buildings. The connection of viscous dampers to adjacent structures are found to be most effective when: (i) the adjacent base-isolated and fixed-base buildings are connected, (ii) dissimilar isolation systems are used for the two adjacent buildings, (iii) the time periods of adjacent structures are well separated, and (iv) the superstructure flexibility is higher.
The RoGlider
Authors: Robinson W. H. , Gannon C.R. , Meyer J.
Published: January 2020

The research on a number of new approaches to seismic isolation continues with the development of a RoGlider capable of supporting both light and high vertical loads with an effective co-efficient of friction of ~ 11% together with an appropriate elastic restoring force. Preliminary tests on prototype RoGliders have been promising.
A RoBall with an elastic restoring force
Authors: Robinson W. H. , Gannon C.R.
Published: January 2020

We present recent research on the development of the seismic isolator, the RoBall, a rubber container holding a number of metal balls. This version of the RoBall, which in addition to friction includes an elastic restoring force and contains 7 metal balls, took a maximum vertical load of -0.5 MPa and had a force-displacement wavelength of - 450 mm.
Economic payback of improved detailing for concrete buildings with precast hollow-core floors
Authors: Dhakal R. P. , Khare R. K. , Mander J. B.
Published: January 2020

A seismic financial risk analysis of typical New Zealand reinforced concrete buildings constructed with topped precast concrete hollow-core units is performed on the basis of experimental research undertaken at the University of Canterbury over the last five years. An extensive study that examines seismic demands on a variety of multi-storey RC buildings is described and supplemented by the experimental results to determine the inter-storey drift capacities of the buildings. Results of a full-scale precast concrete super-assemblage constructed and tested in the laboratory in two stages are used. The first stage investigates existing construction and demonstrates major shortcomings in construction practice that would lead to very poor seismic performance. The second stage examines the performance of the details provided by Amendment No. 3 to the New Zealand Concrete Design Code NZS 3101:1995. This paper uses a probabilistic financial risk assessment framework to estimate the expected annual loss (EAL) from previously developed fragility curves of RC buildings with precast hollow core floors connected to the frames according to the pre-2004 standard and the two connection details recommended in the 2004 amendment. Risks posed by different levels of damage and by earthquakes of different frequencies are examined. The structural performance and financial implications of the three different connection details are compared. The study shows that the improved connection details recommended in the 2004 amendment give a significant economic payback in terms of drastically reduced financial risk, which is also representative of smaller maintenance cost and cheaper insurance premiums.
Controversial aspects in seismic assessment and retrofit of structures in modern times
Authors: Pampanin Stefano
Published: January 2020

Several alternative seismic retrofit and strengthening solutions have been studied in the past and adopted in practical applications ranging from conventional techniques, utilizing braces, jacketing or infills, to more recent approaches such as supplemental damping devices or advanced materials (e.g. Fibre Reinforced Polymers, FRP, or Shape Memory Alloys, SMA). A series of controversial issues are implicit in the complex decision-making process of seismic retrofit, where both rational and counter-intuitive solutions can satisfy some of the most critical aspects of multi-level performance-based seismic retrofit criteria. Interesting and fascinating suggestions and lessons can be obtained by reviewing the current trends in new design (i.e. innovative solutions for the future generation of buildings systems) as well as the architectural solutions used by the ancients. While walking this “bridge of knowledge” of our cultural heritage with the critical eyes of a curious and passionate observer, we can observe surprising commonality in engineering problems and their successful (and recently attempted) solutions. Understanding and implementing this heritage could lead to a uniquely stable platform for major breakthroughs in the development of “new solutions” in seismic design and retrofit.
Earthquakes that have initiated the development of earthquake engineering
Authors: Reitherman Robert
Published: January 2020

The recent 75th anniversary of the 1931 Hawke’s Bay Earthquake reminds us that a particular earthquake can have a great effect on the development of engineering methods to contend with this natural hazard. Factors other than the occurrence of a single earthquake are also present before and after such a historically important event, and there are examples of countries that began on the path toward modern earthquake engineering in the absence of any particular earthquake playing an important causal role. An earthquake that was large in seismological (e.g. magnitude) or engineering (e.g. destructiveness) measures may have had little effect on engineering tools developed to contend with the earthquake problem. The history of earthquake engineering is not merely a set of events rigidly tied to a chronology of major earthquakes. Nonetheless, some significant earthquakes have been step function events on the graph of long-term progress in earthquake engineering. Only earthquakes that bring together several prerequisites have had such historic effects, creating in a country a beachhead for earthquake engineering that persisted in the following decades. In this brief historical review, the following seminal earthquakes are discussed: 1906 Northern California, United States; 1908 Reggio-Messina, Italy; 1923 Kanto, Japan; 1931 Mach and 1935 Quetta, India-Pakistan; 1931 Hawke’s Bay, New Zealand.
From brittle to ductile
Authors: Megget Leslie M.
Published: January 2020

This paper traces the development of seismic structural design in New Zealand since the 1931 Hawke’s Bay Earthquake, with emphasis on reinforced concrete buildings. From the mainly rigid and brittle unreinforced masonry structures which behaved so poorly in the 1931 earthquake through the development of flexible ductile seismic design and base (seismic) isolation of the 60’s to 80’s to today where the structural engineer is expected to design and construct a building which will not only remain standing with little damage but will be operational a short time after the major earthquake. In some ways the structural design aims and objectives have turned full circle in the intervening 75 years. We have gone from brittle rigid structures through a period where flexibility was paramount to now where flexibility is limited and greater lateral stiffnesses are required, but with ductile elements in the structure. This paper traces the efforts of New Zealand’s pre-eminent structural engineers and scientists to make seismic design techniques world leading. In most facets they have been successful (in my view) but as I will say more than once, only time will tell!
Decision tools for earthquake risk management, including net present value and expected utility
Authors: Smith W.D. , Vignaux G.A.
Published: January 2020

The results of earthquake risk assessments should be presented in ways that will help facilitate risk management decisions. So the measures of risk that are chosen need to be those that will assist decision-makers. Annualised Loss may not be the best basis on which risk management decisions can be made. The Conditional Expected Value of the loss, defined for a suitable set of probability ranges, is a promising measure of the risk because it is similar to a scenario loss and can be readily comprehended by decision-makers. Utility Theory provides a further measure by taking account of individuals’ perceptions of the severity of losses. It can be combined with the concept of Net Present Value to give an overall measure of the risk in terms of the value judgements of the individual decision-maker. The reduction in risk that would result from proposed mitigation works can be readily assessed, so that the decision-maker who is faced with the costs of mitigation is in a position to assess the benefits.
The 1904 Ms6.8 Mw7.0-7.2 Cape Turnagain, New Zealand, earthquake
Authors: Downes G. L.
Published: January 2020

The 1904 August 09 NZT (August 08 UT) MS6.8 earthquake caused widespread structural and chimney damage from Napier to Wellington and was felt over a large part of New Zealand. Other than a brief paper in 1905, and determinations of its surface wave magnitude in the last 20 years, little has been done to better locate the earthquake or detail its effects.

Comprehensive data have now been obtained from searches of historical documents, including newspapers, private and government papers, as well as instrumental records. Interpretation of the intensity data shows that the earthquake was probably centred near Cape Turnagain at relatively shallow depth. The paucity of aftershocks suggests that the earthquake occurred either on the subduction interface, or in the lower seismicity band or upper mantle of the subducting Pacific Plate. The area encompassed by the higher intensity isoseismals suggests the earthquake had a magnitude greater than the calculated surface wave magnitude MS6.75 ± 0.14 — possibly as high as MW7.2. At this magnitude, the earthquake becomes a more significant event in New Zealand’s historical record, and certainly the largest earthquake suspected of rupturing the plate interface along the Hikurangi Margin.

A notable feature of the earthquake is the chimney and parapet damage caused in parts of Wellington Central Business District, approximately 170 km from the epicentre. Much of the city and inner suburbs experienced MM5-6, while MM6-7 occurred in several areas, mostly in those areas that are recognised as possibly susceptible to shaking enhancement, but also in several locations outside these areas.

The 1904 Cape Turnagain earthquake has several implications for seismic hazard dependent on whether it was intra-slab or on the plate interface. Of particular importance, are the questions whether the damage in Wellington is exceptional and could represent microzone, focussing or directivity effects; the goodness of fit of the intensity distribution to modelled isoseismals using published attenuation relations; the compatibility of the magnitude with the maximum magnitude/magnitude cut-offs used in this area in the New Zealand Probabilistic Seismic Hazard model; and finally, the possibility that the 1904 earthquake might characterise plate interface earthquakes in southern Hawke’s Bay.
The serviceability of normal-use, non-domestic buildings in earthquakes
Authors: Dowrick David
Published: January 2020

This paper reports on an empirical study of whether it is necessary to carry out design checks on the serviceability of normal-use non-domestic buildings in earthquakes in New Zealand. It is found that at the relevant hazard level, i.e. at a return period of 25 years, the highest intensity anywhere in New Zealand is Modified Mercalli VII (MM7). At that intensity, no loss of function (predictable by a serviceability design check) has been reported in any structures classified as Buildings Type III (brittle) or better, since the introduction of reinforced concrete construction. For normal-use non-domestic structures designed for the ultimate limit state earthquake loading, the author contends (with one interim proviso affecting 10 percent of the country) that serviceability can be deemed to be satisfactory for new buildings anywhere in the New Zealand.
Earthquake design of rectangular underground structures
Authors: Wood J.H.
Published: January 2020

Severe damage to six out of a total of 21 subway stations in the Kobe area during the 1995 Hyogoken-nanbu earthquake indicated a need for more attention to be given to the earthquake design of rectangular underground structures. This paper presents work undertaken to extend the present knowledge of the dynamic interaction of box-section structures with the surrounding soil, and a design method for predicting the earthquake loads on underground structures such as basement walls, tanks, subways, utility boxes, highway underpasses, and culverts.
Inelastic demand spectra for bi-linear seismic isolation systems based on nonlinear time history analyses and the response of lead-rubber bearing isolation systems subjected to near-source ground motions
Authors: Zhao John X. , Zhang Jian
Published: January 2020

In this study, we present an inelastic demand spectrum for the design of seismically-isolated structures using lead-rubber bearings or other types of isolators with bi-linear hysteresis loops and the inelastic spectrum can be used in the design of seismically-isolated structures in a very similar manner to capacity spectrum method. The inelastic demand spectrum is a very useful design tool for visual selection of optimal isolation parameters, and eliminates the use of equivalent linear-elastic substitute structures as the displacement demand is obtained from nonlinear time history analysis. The responses of seismically-isolated structures subjected to near-source ground motions with either large forward-directivity pulses or fault-fling pulses are presented. Our analyses suggest that seismic isolation can be used to protect structures subjected to recorded ground motions currently available to us, with acceptable levels of base shear coefficient and isolator displacement, except for one component of the TCU068 record from the 1999 Chichi, Taiwan, earthquake (which contained a large permanent displacement of nearly 10 m).
Experimental development, tradeoff analysis and design implementation of high force-to-volume damping technology
Authors: Rodgers Geoffrey W. , Chase J. Geoffrey , Mander John B. , Leach Nicholas C. , Denmead Caleb S.
Published: January 2020

Supplemental dampers are a means of repeatedly dissipating energy without damage to the underlying structure, increasing life-safety and helping provide better serviceability of structures following a major earthquake. High performance (small size) lead dampers are designed and tested to characterise their force-displacement behaviour and produce trade-off curves relating device geometry to force capacity, to parameterise the design space to enable further devices to be designed for structural applications. Peak forces of 120-350 kN were obtained for devices that were all able to fit within standard structural connections. Results show that prestressing the working material is critical to obtain optimal energy dissipation. Although previously characterised as extrusion dampers it is shown that classical extrusion modelling formulations do not strictly work well for this class of damper. Instead a coulomb type of stress-based model is proposed, with relationships presented that are independent of device scale. Empirical reduction factor equations are applied to the New Zealand Structural Design Actions to enable lead extrusion devices to be incorporated into structural design analyses. The overall results indicate that repeatable, optimal energy dissipation can be obtained in a compact device to minimise damage to critical buildings and infrastructure.
Seismic strengthening of columns by adding new concrete
Authors: Dritsos Stephanos E.
Published: January 2020

Placing reinforced concrete jackets or layers to strengthen or repair and strengthen concrete columns is a normal construction practice but there are many unresolved issues regarding the capacity of the strengthened elements. In the absence of any guidance, engineering judgement is often used. This paper sets out to assist the engineer when considering some of these unresolved issues. Revised values for factors of safety are proposed for design. A procedure to guarantee a sufficient connection between contact surfaces and to determine the performance of retrofitted columns is presented, considering the strengthened columns as “composite” elements. The parameters affecting the main mechanisms for the transfer of shear stress at the interface between new and old concrete are described and practical design considerations are given. An approximate procedure is presented, based on the design of monolithic elements, supplemented by the use of specific modification factors (monolithic factors), in order to evaluate the capacity of a strengthened element. Available experimental results are processed to derive appropriate values for monolithic behaviour factors and an extended analytical analysis is used to fill in gaps in the experimental work. Although this paper has particular relevance to seismic strengthening, its contents will have a wider application to strengthening in general. The object of this paper is to provide guidance so that the engineer is better equipped to deal with the practical design needs of today.
Proposed macro-model for the analysis of infilled frame structures
Authors: Crisafulli Francisco J. , Carr Athol J.
Published: January 2020

Reinforced concrete frames infilled with masonry panels constitute an important part of the high-risk structures in different regions of high seismicity. In some developing countries, they are still used as main structural system for low to medium rise buildings. Consequently, reliable methods to analyse infilled frames are required in order to reduce the loss of life and property associated with a possible structural failure.

The equivalent strut model, proposed in the 1960s, is a simple procedure to represent the effect of the masonry panel. Several improvements of the original model have been proposed, as a result of a better understanding of the behaviour of these structures and the development of computer software. This paper presents a new macro-model for the evaluation of the global response of the structure, which is based on a multi-strut formulation,. The model, implemented as 4-node panel element, accounts separately for the compressive and shear behaviour of masonry using a double truss mechanism and a shear spring in each direction. The principal premises in the development of the model are the rational consideration of the particular characteristics of masonry and the adequate representation of the hysteretic response. Furthermore, the model is able to represent different modes of failure in shear observed for masonry infills. The comparison of analytical results with experimental data showed that the proposed model, with a proper calibration, is able to represent adequately the in-plane response of infilled frames.
A blind prediction test of nonlinear analysis procedures for reinforced concrete shear walls
Authors: Kelly Trevor
Published: January 2020

A full scale slice of a 7 story reinforced concrete building was tested on the shake table at the UCSD Engelkirk Structural Research Centre in 2006. As part of the research project, a blind prediction contest was sponsored to assess the capability of currently available analysis procedures to predict the seismic response of cantilever reinforced concrete shear wall structures. This paper describes an entry based on a nonlinear finite element model, using macro elements to represent both the shear and the flexural modes of behaviour. A comparison of the predicted response with the test results showed that the analysis procedure produced reasonable predictions of deformations for the lowest and highest of the four earthquakes but under-estimated response for the two moderate earthquakes by approximately 30%. For all earthquakes, the analysis base moment was much lower than the test value. Modifications to the procedure to improve the correlation were identified and implemented but did not remedy the deficit in base moments. Detailed results of the test program revealed that the causes for this discrepancy were the contribution to overturning results of gravity columns and the flange wall, neither of which had been included in the model. When these were incorporated the average error between test and analysis results was less than 10% for all earthquakes, well within acceptable limits for a design office type of model. The correlation of tests and analysis also provided useful information on design aspects for shear walls, such as the influence of secondary components and dynamic magnification factors.
Adapting the structural design actions standard for the seismic design of new industrial plant
Authors: Lindup G. H.
Published: January 2020

In the late 1970’s it was recognised that the seismic provisions of the current NZS 4203:1976 did not readily apply to the types of structures normally used within the land based processing facilities of the “heavy industries” such as petrochemical and oil and gas processing plants impending under the “Think Big” regime.

Since the 1984 revision to NZS 4203, there have not been any publicly available New Zealand guidelines on how to interpret the earthquake provisions of the various versions of NZS 4203 (and now AS/NZS 1170) that would update the 1981 publication created by the Ministry of Works for the Ministry of Energy, “Seismic Design of Petrochemical Plants”.

There are overseas publications that have considered the differences in the typical structural systems necessary to support the equipment and distributive systems needed to process industrial feedstock. How they behave seismically has been reviewed and recommendations made on the methods to be used to determine the design seismic actions. Such standards as ASCE 7 and FEMA 450 incorporate these in a specific manner relating to the design of industrial plant.

With the advent of new oil and gas processing plants in Taranaki, this paper takes the opportunity to review AS/NZS 1170 and adapt these overseas guidelines for the seismic design of new industrial plant in New Zealand. The background for these guidelines will be presented with examples of typical industrial structural systems and their seismic actions. This is with the aim of re-establishing a basis of seismic design for industrial plant within the framework of the new standards AS/NZS 1170.0 and NZS 1170.5.
Performance of cylindrical liquid storage tanks in Silakhor, Iran earthquake of March 31, 2006
Authors: Eshghi Sassan , Razzaghi Mehran S.
Published: January 2020

Several on-ground cylindrical liquid storage tanks experienced strong ground motion during the “Silakhor” earthquake of March 31, 2006 in western Iran, and some of the tanks suffered minor to moderate damage. In this study two of the affected tanks that were located close to the station of recording the time history of the earthquake were investigated. Responses of these tanks to the earthquake were estimated using published methods and also non-linear time history analysis, for both rigid foundation and flexible foundation assumptions. Theoretical results were compared and were generally in good agreement with the observed performance of tanks during the earthquake. For the broad tank uplift displacements observed from the earthquake matched quite closely the predictions of numerical analysis and some of the published methods, although there was a significant variation in the predictions of various methods. It was also shown that axial stresses in tank shells uplifting under earthquake are very dependent on the rigidity of the foundation.
Base isolation of timber-framed buildings
Authors: Thurston Stuart J.
Published: January 2020

This paper investigates the practicality of using base-isolation devices to protect lightweight buildings, such as timber-framed houses, against earthquakes.

As the timber-framed buildings considered are designed to a lateral seismic force of 0.24W in Wellington (where W is building weight), it was considered that the appropriate isolation level should be significantly lower, say 0.1W, and lower still in Auckland where such buildings are designed for a lateral force of 0.12W. An analysis showed that houses which had a base-isolation yield set to yield at 0.1 W would have unacceptable deformations under the design wind load if the isolators were located beneath a timber floor, but may be satisfactory if located beneath a concrete slab. A large-scale test using isolators beneath pre-cast floor slabs showed the method used would work even if it was unduly expensive. However, an analysis indicated that there might be little protection for some building contents.

A literature survey of alternative base-isolation solutions showed a wide range of innovative, but often impractical, concepts have been proposed. However, one concept showed promise for timber-framed structures. This used two layers of synthetic sheet beneath a concrete floor slab to provide a slip layer. The sheet materials recommended reputably gave a dynamic friction coefficient of 0.07. BRANZ measured the friction coefficient using large samples of both these and other sheet materials. It was concluded that the measured friction was too high for use for the planned buildings, although it may have application for low-rise heavy-brittle construction.

Alternative base-isolation concepts are presented which will be useful to others interested in this topic.
Modelling ground motion in the Hutt Valley, New Zealand
Authors: Ma Shu Qin , Savage Martha , Yu Jiashun
Published: January 2020

The Hutt Valley is an alluvial basin that hosts the city of Lower Hutt, in the North Island, New Zealand. The basin is bounded by the Wellington Fault on its northwest side, and exhibits ground motion amplification factors up to about 15, measured by several seismic experiments using weak motion and portable seismic arrays during 1990-1991. Synthetic seismograms computed by using local 1D stratigraphic models under each station reproduce qualitatively the amplitudes and durations of the corresponding observed seismograms at most of the soft site stations of the arrays. Amplification factors estimated from spectral ratios of the synthetic seismograms are up to about 9. The authors present comparisons of amplification between synthetics and observations, allowing a “calibration” of the model so that it could be used to determine more realistic ground amplifications for earthquake scenarios.
Revised isoseismal maps for the 1956 Bay of Plenty and 1987 Edgecumbe, New Zealand, earthquakes
Authors: Dowrick David J.
Published: January 2020

The Modified Mercalli intensities of the 1956 Mw 6.3 Bay of Plenty and 1987 Mw 6.5 Edgecumbe earthquakes have recently been reviewed and about one-third of them were found to be erroneous. The resulting revisions to their isoseismal maps are substantial, and both new maps now show the strong influence of the high attenuation in the Taupo Volcanic Zone (TVZ). An analysis of the causes of the errors in the intensities is given. The new maps will help improve the modelling of attenuation in the TVZ, and will contribute to improvements in assessments of seismic hazard and risk in that region. An important implication is that the mean damage ratios estimated from studies of damage costs in the Edgecumbe earthquake by Dowrick and Rhoades are likely to be erroneously low, and need to be reviewed.
Seismic hazard of the Canterbury region, New Zealand
Authors: Stirling Mark , Gerstenberger Matthew , Litchfield Nicola , McVerry Graeme , Smith Warwick , Pettinga Jarg , Barnes Philip
Published: January 2020

We present a new probabilistic seismic hazard model for the Canterbury region, the model superseding the earlier model of Stirling et al. (1999, 2001). The updated model incorporates new onshore and offshore fault data, new seismicity data, new methods for the earthquake source parameterisation of both datasets, and new methods for estimation of the expected levels of Modified Mercalli Intensity (MMI) across the region. While the overall regional pattern of estimated hazard has not changed since the earlier seismic hazard model, there have been slight reductions in hazard in some areas (western Canterbury Plains and eastern Southern Alps), coupled with significant increases in hazard in one area (immediately northeast of Kaikoura). The changes to estimated acceleration for the new versus older model serve to show the extent that major changes to a multidisciplinary source model may impact the final estimates of hazard, while the new MMI estimates show the added impact of a new methodology for calculating MMI hazard.
The challenges of reconstruction after the October 2005 Kashmir earthquake
Authors: Mumtaz Hamid , Mughal S. Habib , Stephenson Maggie , Bothara Jitendra K.
Published: January 2020

The 8th October 2005 Kashmir Earthquake was one the largest earthquakes in Northern Pakistan in its recorded history. It caused an unprecedented level of damage and destruction in Pakistan Administered Kashmir (PAK) and the North Western Frontier Province (NWFP). It damaged or collapsed more than 0.6 million buildings - leaving 3.5 million people shelter less as winter approached. A large part of the earthquake-affected area is difficult to access and highly snow-prone, with rugged terrain and scattered settlements. It posed unique challenges and efforts on a massive-scale for reconstruction. For residential buildings, the Pakistan government adopted a house-owner driven approach. The reconstruction policy stated that the government and other agencies would provide equal technical assistance and subsidy to each family, without differentiating between who lost what. To increase capacity in earthquake-resistant construction, large-scale training of artisans, technicians, engineers, and community mobilisers has been conducted. Campaigns to “build back better” have raised awareness in the communities. Local Housing Reconstruction Centres have been established for training, advice, and dissemination of earthquake-resistant technology. This decentralised approach has helped in achieving reconstruction smoothly. This paper will present the authors’ first-hand experience in the reconstruction effort, and the opportunities and unique challenges faced.
Dynamic testing of precast, post-tensioned rocking wall systems with alternative dissipating solutions
Authors: Marriott D. , Pampanin S. , Bull D. , Palermo A.
Published: January 2020

During the past two decades, the focus has been on the need to provide communities with structures that undergo minimal damage after an earthquake event while still being cost competitive. This has led to the development of high performance seismic resisting systems, and advances in design methodologies, in order respect this demand efficiently.

This paper presents the experimental response of four pre-cast, post-tensioned rocking wall systems tested on the shake-table at the University of Canterbury. The wall systems were designed as a retrofit solution for an existing frame building, but are equally applicable for use in new design. Design of the wall followed a performance-based retrofit strategy in which structural limit states appropriate to both the post-tensioned wall and the existing building were considered.

Dissipation for each of the four post-tensioned walls was provided via externally mounted devices, located in parallel to post-tensioned tendons for re-centring. This allowed the dissipation devices to be easily replaced or inspected following a major earthquake. Each wall was installed with viscous fluid dampers, tension-compression yielding steel dampers, a combination of both or no devices at all – thus relying on contact damping alone. The effectiveness of both velocity and displacement dependant dissipation are investigated for protection against far-field and velocity-pulse ground motion characteristics.

The experimental results validate the behaviour of ‘Advanced Flag-Shape’ rocking, dissipating solutions which have been recently proposed and numerically tested. Maximum displacements and material strains were well controlled and within acceptable bounds, and residual deformations were minimal due to the re-centring contribution from the post tensioned tendons. Damage was confined to inelastic yielding (or fluid damping) of the external dampers.
The Pisco (Peru) earthquake of 15 August 2007
Authors: Hopkins David , Bell Darrin , Benites Rafael , Burr James , Hamilton Craig , Kotze Rudolph
Published: January 2020

The Mw 8.0 Pisco earthquake struck at 6.40pm local time with an epicentre offshore about 150 km south of Lima. At least 519 people were killed, and over 1,300 injured. Over 38,000 homes were destroyed and more than 100,000 were made homeless. 14 hospitals were destroyed and many other facilities damaged. The city of Pisco was worst affected with serious damage to the majority of adobe buildings. Other cities and towns nearby suffered similar damage to a lesser extent, depending on the distance from the epicentre. The capital Lima was not seriously affected, although there was some minor damage to buildings.

Strong ground motions were felt for over two minutes. In this subduction earthquake a tsunami was generated and affected tens of kilometres of coast.

The New Zealand Society for Earthquake Engineering Society (NZSEE) sent a 6-person reconnaissance team to Peru. The team spent three days in Lima meeting with key authorities and four days in the field observing some of the earthquake-affected area. This report describes the team’s observations and comments on the implications for earthquake engineering practice.

Highlights of the event in the eyes of the team were:

The long duration of the event – over 2 minutes of strong shaking

The unique geotechnical context – no rainfall and sandy soils

Significant liquefaction damage to roads and buildings

Poor performance of adobe construction

Generally good performance of reinforced concrete brick infill – but there were major collapses.

Good performance of some unreinforced masonry buildings

Widespread use of shear walls in major buildings in Lima

Engineered structures generally performed well

Damage to parts of Pan American Highway due to liquefaction

Minimal damage to a major steel mill, designed to international standards

Collapse and/or overload of telecom systems for up to four hours following the event, isolating Pisco and Ica

Water and waste water systems and storage were seriously affected in Pisco, and significantly in Ica

Port St Martin, serving Pisco, was seriously damaged but functional

Coordination of overseas / international aid needs careful consideration as part of response planning.

Management of response resources is critical.

There were significant tsunami effects which were variable in height up to 10 metres.

Relatively minor damage to architectural finishes and building services can render hospitals non-functional.

Survival of industrial facilities was important in reducing social impact by saving jobs.

The best of Peruvian earthquake engineering is international standard.

The development of earthquake-resistant standards in schools over the last three decades has paid dividends with modern designs performing well.
Pseudo-static analysis of piles in liquefiable soils
Authors: Bowen Hayden J. , Cubrinovski Misko
Published: January 2020

In this paper, pseudo-static analysis of piles in liquefying soils is applied to a case study of a bridge foundation. The response of piles is separately evaluated for the cyclic phase during the intense shaking and development of liquefaction, and for the subsequent lateral spreading phase. With regard to the considerable uncertainties involved in predicting liquefaction and lateral spreading phenomena the effects of key parameters influencing the pile response are examined through parametric analyses. Particular attention is given to the variation in stiffness and residual strength of the liquefied soil, the magnitude of lateral ground displacement and the magnitude of inertial loads from the superstructure. The results shed light on the relative importance of key parameters for different combination of loads and ground conditions, and allow comparative evaluation between loads on the pile exerted by the crust layer and the liquefied layer.
Effective stress analysis of piles in liquefiable soil
Authors: Bowen Hayden J. , Cubrinovski Misko
Published: January 2020

When evaluating the seismic performance of pile foundations in liquefiable soils, it is critically important to estimate the effects of cyclic ground displacements on the pile response. Advanced analyses based on the effective stress principle account for these effects in great detail by simulating the process of pore pressure build-up and associated stress-strain behaviour of soils. For this reason, the effective stress method has been established as a principal tool for the analysis and assessment of seismic performance of important engineering structures.

In this paper, effective stress analysis is applied to a case study of a bridge pier founded on piles in liquefiable soil. The study examines the likely effects of liquefaction, cyclic ground displacements and soil-structure interaction on the bridge foundation during a strong earthquake. A fully coupled effective stress method of analysis is used to compute the dynamic response of the soil-pile-bridge system. In the analysis, an elastoplastic deformation law based on a state concept interpretation is used for modelling nonlinear behaviour of sand. The seismic performance of the pile foundation is discussed using computed time histories and maximum values of ground and pile displacements, excess pore water pressure and pile bending moments. The advantages of the effective stress analysis are discussed through comparisons with a more conventional pseudo-static analysis of piles.
The Mw 6.6 Gisborne earthquake of 2007
Authors: François-Holden Caroline , Bannister Stephen , Beavan John , Cousins Jim , Field Bryan , McCaffrey Rob , McVerry Graeme , Reyners Martin , Ristau John , Samsonov Sergey , Wallace Laura
Published: January 2020

Gisborne city experienced recorded peak ground accelerations exceeding 0.25g for the third time since 1966 in the magnitude Mw 6.6 earthquake at 075516 UT (8:55 pm local time) on 20 December 2007. The earthquake was at a hypocentral distance of 64 km from Gisborne at a depth of 40 km, well within the mantle of the subducted slab of the Pacific plate as it dips beneath the North Island of New Zealand. At this location the plate interface is about 10-15 km deep. The main event was followed by sparse aftershocks consistent with a rupture of the subducted plate, with the largest aftershock of magnitude 4.6 occurring on December 22nd. The GeoNet website received 3,257 felt reports, with a strongest intensity of MM8 (heavily damaging) assigned to the main shock. The 122 strong motion records of this event show a clear regional directional variation in the wave propagation, as well as a distinct 2 Hz peak widely observed throughout the country. At a local scale, three sites in the Gisborne region recorded accelerations around 0.2g. Recordings in Gisborne city also revealed a predominant displacement direction, parallel to the main street where most of the damage occurred. Source studies from moment tensor solution, aftershock relocations, GPS and strong motion data showed that the earthquake occurred within the subducted plate on a 45 degree eastward dipping fault plane. The mainshock rupture area is about 10 km2 reaching a maximum slip of 2.6 m. The computed high stress drop value of 17 MPa is as expected for an intraslab event and consistent with observations of very energetic seismic waves as well as heavy structural damage. GPS data recorded by continuous GPS instruments have also shown that slow slip occurred for about three weeks after the main shock. The slow slip was triggered on the subduction interface, rather than on the same fault plane as the aftershocks. This is the first clear-cut case worldwide of triggered slow slip, although three non-triggered slow-slip events have occurred in the same region since 2002.
A Multi-Function Disaster Decision Support System Based on Multi-Source Dynamic Data
Authors: Wang Wen-Ching
Published: January 2020

Disasters are unpredictable. However, occurrences follow a specific time sequence. Disaster management encompasses routine disaster reduction, pre-disaster preparation, mid-disaster response, post-disaster recovery, time management and allocating routine tasks over an extended period, and emergency response during highly stressful periods. Various response organizations rely on effective “integrated disaster management” to react to situations at different periods in time. In addition to making personnel and organization adjustments at different times, integration also requires systems for effective and fast communication and for providing first-hand supporting information to responders for data, manpower, organization, and resource integration. Based on design science theory, disaster decision support systems integrate internal and external data through (1) confirming problems and motivations, (2) defining solution objectives, (3) designing and developing a solution, (4) presenting the solution, (5) evaluating the solution, and (6) communicating protocols, and then consolidating the data into graphical or visual platforms and systems. These systems not only contain disaster prevention information, provide pre-disaster emergency response warnings, allocate supporting resources for mid-disaster response, evaluate the scale of disasters, and formulate response plans, but also simulate various disaster situations and scenarios during disaster-free periods for training and education purposes.
Does Reminding of Behavioural Biases Increase Returns from Financial Trading? A Field Experiment
Authors: Paola Maria De , Gioia Francesca , Piluso Fabio
Published: January 2020

Nudge policies are interventions that aim to guide the individual to behave according to the policy’s objectives without changing the option set or economic incentives. We ran a field experiment to investigate whether nudge policies, consisting in behavioural insight messaging, help to improve performance in financial trading. Our experiment involved students enrolled in a financial trading course in an Italian University who were invited to trade on Borsa Italiana’s virtual platform. Students were randomly assigned to a control group and a treatment group. Treated students received a message reminding them of the existence of behavioural biases in financial trading. We find that treated students significantly improve the performance of their portfolio. Several behaviours may explain the increase in performance. We find evidence pointing to a reduction in the home and status quo biases for risk averse nudged participants.