Implementation of Database of Masonry Walls Test
– Review of Existing Test Data in Peru

Paper:

Implementation of Database of Masonry Walls Test
– Review of Existing Test Data in Peru
Lourdes Cardenas∗ , Reyna Roy∗∗ , Lucio Estacio∗ , and Carlos Zavala∗∗∗∗ Japan Peru Center for Earthquake Engineering Research and Disaster Mitigation

Montero Rosas Street 1476, Santa Beatriz, Lima 01, Peru
E-mail: lcardenasp@uni.edu.pe∗∗ Toyohashi University of Technology, Japan∗∗∗ National University of Engineering, Lima, Peru
[Received August 1, 2014; accepted November 5, 2014]

Confined masonry walls represent one of the mostwidely used construction systems for dwellings in Peru
and other Latin countries. This study describes theprocedure for implementing a database with a web interface of results collected from the experiments conducted over the years by the Japan Center for Earthquake Engineering and Disaster Mitigation. This paper attempts to contribute to the seismic design procedure of this type of structure, and parameters suchas stiffness ratios and the deformation (drift) for thecharacteristic stages of confined masonry walls under
different limit states or performance levels are proposed. Also, a semi-empirical equation for estimating
the shear capacity using the database is proposed.

performance while taking into account the needs generated by the criteria incorporated in the modern seismic
design standard in which different levels of performanceare recognized (limit stages), it is necessary to know the
deformation capacity of confined masonry walls to define
the limit stages. Therefore, the main objective of thiswork is to determine the levels of deformation of confined masonry walls for a given limit state and their corresponding designs. To these ends, the information provided by some experimental studies conducted over the
past 25 years in the laboratory of structures of CISMID,
which belongs to the National University of Engineering,are used.

Keywords: confined masonry walls, limit states, data
test, shear capacity

2. Background

1. Introduction
Masonry dwellings are commonly used around theworld, and Peru is no exception. In Peru, the construction
evolution started with adobe, quincha (cane with mud),
adobe with quincha and masonry walls using clay bricks.
Confined masonry buildings have been widely used in
Peru since the middle of the last century, especially because of good earthquake performance of confined masonry houses having one and two stories. For example,
San Juan de Dios Hospital stood up well in the 2007 Pisco
Earthquake. Other advantages are that the materials usedin the construction of confined masonry buildings are relatively inexpensive and their execution does not require
specialized inspections, although the buildings do need to
be well designed.
The main feature of this type of construction is thatthe structural system is formed by a reinforced concrete(RC) frame filled in with masonry walls (confined masonry walls). This type of construction is thought to resist
the actions of axial loads (gravity) and lateral loads (earthquakes), but it is the lateral loads that dominate their design (seismic resistant design).
To achieve proper designs that ensure good earthquake
Journal of Disaster Research Vol.9 No.6, 2014

As masonry walls have a low capacity to resist tension
due to their brittle behavior after cracking occurs, they
have important limitations in their ability to resist seismic actions. It is therefore necessary to strengthen them,and one such way is through reinforced concrete elements(columns and beams). These confine the masonry walls,
but they must comply with the requirements of the standards design and calculation of masonry structures [1].
Confinement is achieved to the extent that the column
and beam frames completely the masonry, providing thelateral deformation capacity and energy dissipation once
cracking of the masonry wall occurs. The design of confined masonry must follow some specifications.
• The masonry wall must be built in two phases. The

first phase is at half of the height (1.2 m, approximately) to avoid the excessive compression of themortar in the joints between the masonry units. The
second phase is continued building until the fullheight is reached; on both lateral edges of the wall
it is necessary to leave mesh conformed for clay
bricks units, after that is joined with concrete elements. Furthermore, it is recommended that the masonry units fill the space in completely or, if a perforated pattern is used, that the space reduction of theperforations be less than 30% of the total.

993

Cardenas, L. et al.

Table 1. Characteristics resistances of masonry.

Material
Adobe
Masonry Factory
Masonry Handmade

Adobe Standard:
Compression
NTE 080 (1999)
Strengthf  m (kgf/cm2 ) Masonry Standard:(pile test)
NTE 070 (1997)
8.6
8.0
188.9
65
54.9
35

Typical Wall

Composite Wall

Reinforced Wall

Two-Story Wall

Wall + Opening

Wall + Two Openings

Fig. 1. Construction process of confined masonry wall in Peru.

• For the vertical concrete elements (columns), theconstruction process must be uninterrupted, andcolumns must be vibrated so that honeycombs are
not generated. Then, the construction of the beam
may proceed.
The behavior of a confined masonry wall depends on
the quality of the masonry, dimensions, and number of reinforcement elements of confinement (RC frames). The
horizontal and vertical reinforcement of RC frame must
resist the tensile stresses produced by the bending moments due to loads acting in the plane of the wall, suchas bending and shear forces. Everything together makes
the confined wall perform well under seismic loading andstresses. Still, it is necessary to have a bigger concentration of stirrups in areas where the cracking may occur
in the masonry wall. To avoid these cracks, stirrups arelocated around the joints of the RC frame.

H Wall

3. Database Collection on Masonry Walls
Masonry takes on many forms around the world. In
Peru, the materials most commonly used are adobe, quincha and masonry bricks.

3.1. Results of Masonry Compression Tests
Some tests were conducted to obtain compression
strength values for adobe and masonry. The following values were obtained for the average compression strength.
Table 1 presents the mechanical properties of masonry,
both those from the database and those prescribed in thestandard.
3.2. Masonry Walls Collection
Nowadays, red clay brick is the material most commonly used to build masonry walls, and they have many
994

Fig. 2. Masonry configurations.

configurations and set ups. Fig. 2 shows the masonry arrangements and configurations tested in CISMID-UNI.
This collection provided 30 typical walls, two composite walls, two reinforced walls, eight two-story walls, twowalls + one opening, two walls + two openings, and three
H walls for a total of 49 walls [2–8].
It must be noted that 80% of the total of hysteresis
curves used in this study were digitalized from former
studies due to their digital data is not available. Thus,
some errors may be have been introduced, related toscales, distortion of plots, or determination of cracking
and yielding points.
Journal of Disaster Research Vol.9 No.6, 2014

Implementation of Database of Masonry Walls Test
– Review of Existing Test Data in Peru

Table 2. Characteristics of typical wall.
N◦ Author
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

P. Gibu, C. Serida
P. Gibu, C. Serida
P. Gibu, C. Serida
J. Delgadillo
J. Delgadillo
J. Delgadillo
J. Delgadillo
J. Delgadillo
J. Delgadillo
J. Delgadillo
Salinas, Lazares
Salinas, Lazares
M, Ramirez
M, Ramirez
M, Ramirez
M, Ramirez
M, Ramirez
M, Ramirez
Zavala, Kaminosono
Zavala, Kaminosono
Zavala, Kaminosono
Zavala, Kaminosono
Zavala, Kaminosono
Zavala, Kaminosono
O. Ramirez
O. Ramirez
O. Ramirez
O. Ramirez
O. Ramirez
O. Ramirez

Type of
Unit
MCST1
Factory
MCST2
Factory
MLCC1
FactoryMC1-1
FactoryMC1-2
Factory
MCR-1
Factory
MCH-1
Factory
MCH-2
Factory
EML-1
Factory
EML-2
Factory
M-ART
Handmade
M-IND
Factory
M-1-A
Factory
M-2-A
Factory
M-3-A
Factory
M-4-A
Factory
M-3-B
Factory
M-4-B
Factory
WALL A1-3
Handmade
WALL A1-4
Handmade
WALL A2-3
Handmade
WALL A2-4
Handmade
WALL C2-HM Handmade
WALL C2-FM Factory
MEL-1
Factory
MEL-2
Factory
MC1
Factory
MC2
Factory
MEC 1
Factory
MEC 2
FactoryID

Brick Dimension(cm)
9.5 × 12 × 25
9.5 × 12 × 25
9.5 × 12 × 25
9.0 × 12 × 24
9.0 × 12 × 24
9.0 × 12 × 24
9.0 × 12 × 24
9.0 × 12 × 24
9.0 × 12 × 24
9.0 × 12 × 24
10.0 × 11.5 × 23
11.0 × 11.5 × 23
9.0 × 13 × 24
9.0 × 13 × 24
9.0 × 13 × 24
9.0 × 13 × 24
9.5 × 12 × 25
9.5 × 12 × 25
9.0 × 14 × 24
9.0 × 14 × 24
9.0 × 14 × 24
9.0 × 14 × 24
9.0 × 14 × 24
9.0 × 14 × 24
9.0 × 12 × 25
9.0 × 12 × 25
9.0 × 12 × 25
9.0 × 12 × 25
9.0 × 12 × 25
9.0 × 12 × 25f m
Beam/Slab Column(b × h)∗(kg/cm2 ) (b × h)∗
97.91
30 × 20
25 × 1597.91
30 × 20
25 × 1597.91 200 × 20
25 × 15251
30 × 20
25 × 15251
30 × 20
25 × 15251
30 × 20
25 × 15251
30 × 20
25 × 15251
30 × 20
25 × 15251 200 × 20
25 × 15251 200 × 20
25 × 15
33.2
30 × 20
25 × 15
22.1
30 × 20
25 × 15108
30 × 20
25 × 15108
30 × 20
25 × 15108
30 × 20
25 × 15108
30 × 20
25 × 1591
30 × 20
25 × 1591
30 × 20
25 × 15
59.26
30 × 2030 × 25
59.26
30 × 2030 × 25
59.26
30 × 2030 × 25
59.26
30 × 2030 × 25
59.26
30 × 20
25 × 15
70.24
30 × 20
25 × 15304
30 × 20
25 × 12304
30 × 20
25 × 12304
30 × 20
25 × 12304
30 × 20
25 × 12304
30 × 20
25 × 12304
30 × 20
25 × 12

Horiz.
Bars
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 1/2
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 1/2
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8

Vert.
Bars
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 1/2
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 1/2
4 φ 1/2
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 1/2
4 φ 1/2
4 φ 3/8
4 φ 1/2
4 φ 1/2
4 φ 1/2
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8
4 φ 3/8

∗ Units in centimeters.

On the other hand, some parameters are shown in Table 2, such as author, id, type of unit, brick, beam andcolumn dimension, and reinforcement amount (horizontal and vertical bars).

3.3. Media Store and Web Application
The database was collected from experiments conducted on structural walls in the structure laboratory of
CISMID over the past 25 years. The collected database ismeant to be disseminated, so a web application has beendeveloped using freeware in order to store new data as
experiments are conducted. This technology consists ofa web application that allows remote users with regularcomputer, independent of the operating systems used, toaccess this information for any academic purpose.
The database1, MySQL, uses PHP/JavaScript as programming languages, which are hosted on a Linux server
located at CISMID. It is important to note that as the freeware applications used are open-source, there are no an1. To get access to the database, just sign up on the following website:
http://www.cismid-uni.org/wallx/

Journal of Disaster Research Vol.9 No.6, 2014

Fig. 3. Media storage and web application flow.

nual licenses to be paid. This is desirable for academic
purposes (Fig. 3).

4. Characteristics of Database
4.1. Limit States on Confined Masonry Walls
Before the collected data is evaluated, the evolutionof structural damage (cracks) on confined masonry walls
will be studied. Damage is defined according to the fol995

Cardenas, L. et al.

Q

Q

a)

δ

Q

b)

δ

Q

Q

c)

δ

d)

Py

δ

Fig. 4. Process of limit states on confined masonry walls.

K2

Pm

K3
Pu

K1

Pc

lowing stages (Fig. 4).
a) Elastic Stage: This occurs when the wall has elastic
behavior with an initial stiffness (K0 ) until the first
cracks are found on confined masonry walls. Thisis called the cracking point (Pc ). When the small
displacements and strength are given by the cyclic
lateral loading test, the horizontal cracks appear incolumns.

K0
δFig. 5. Limit states and levels of stiffness degradation.
Elastic Stage

Post-Elastic Stage

Yielding Stage

Ultimate Stageb) Post-Elastic Stage: After the first cracks, there is incremental cracking until the initial diagonal cracks
appear. This is called the yielding point (Py ). Thenthe confined masonry wall shows a post–elastic stiffness slope (K1 ). This stiffness has a value lower than
the initial one.
c) Yielding Stage: During this stage, characterized bya large level of deformation with a slight strength
increment, exhibits a huge reduction in stiffness(K2 ) until the point of maximum resistance (Pm ) isreached, until the stiffness and resistance go down.
At the same time, the diagonal cracks increase incrementally.
d) Ultimate Stage: The stiffness decreases with a negative slope (K3 ), and there is a drastic reduction inresistance until the wall fails. In this research, thepoint of failure, called the ultimate point (Pu ), is considered reached when there is a 20% reduction instrength. In some walls, the envelope curve does notreach a level of strength reduction lower than 20%
of its resistance. In this case, the ultimate point wasconsidered to be the ultimate drift reached during the
test.
Figure 5 shows the proposed theoretical envelope
curve following the limits states and stiffness degradation
stages for confined masonry wall defined above.

4.2. Database on Confined Masonry Walls
In order to investigate the results of experiments on
confined masonry walls and their variation, results werecollected from experiments done on 30 typical masonrywalls subjected to axial loads (simulating the weight ofupper floors) and lateral loads (simulating seismic loads).
These specimens were subjected to reversal lateral loading (cyclic). The predominant behavior of these walls
was flexural-shear failure because the initial cracks appeared in the columns (flexural cracking). This corresponds to the elastic stage. Then, as lateral displacement
increased, stiffness degradation was observed during the996

Fig. 6. Cracking pattern of the limit states.

tests. Cracks expanded onto the wall, and this state corresponds to the post-elastic stage until the initial diagonal cracking appears (shear cracking). After that, the lateral displacement increase until the maximum shear capacity of the wall was reached during the yielding stage,in which the shear crack opened to form a full diagonal crack. Finally, as lateral displacement increased after
the maximum shear strength was reached, shear wall failure, with a drastic reduction in resistance, occurred. The
cracking pattern of the limit states is shown in the Fig. 6.
The wall database comes from theses and corresponding tests conducted in CISMID. For these walls, it is notedthat the stiffness ratio for the elastic stage present similarvalues in most of the specimens. However, there are several discrepancies, for example the maximum resistance.
It can be observed in Fig. 7, the maximum resistanceof walls MEC-1 and MEC-2 are significantly different
from the others because MCE-1 and MCE-2 are longer(360 cm) than the other specimens (240 cm).
In Fig. 7, the difference in the initial behaviors of walls
A2-3 and A2-4 can be observed. Both of them have thesame geometrical dimensions, but there is a difference beJournal of Disaster Research Vol.9 No.6, 2014

Implementation of Database of Masonry Walls Test
– Review of Existing Test Data in Peru

Fig. 8. Stiffness ratios.
Table 3. Ratios of stiffness parameters of masonry.
RatiosK0 (tonf/cm) K1 /K 0 K2 /K 0 K3 /K 0
Minimum
12.745 0.052 0.000 −0.322
Maximum
265.344 0.696 0.200
0.000
Average
94.757 0.314 0.051 −0.051
Stand. Dev.
49.789 0.149 0.040
0.068

Fig. 7. Envelopes of thirty typical masonry walls.

tween the reinforcement of columns. Also, the cracking
pattern on wall A2-3 starts with a sliding crack in themasonry bricks and the base foundation. This pattern isdifferent from the usual initial cracking pattern (flexural
cracking in columns).
The database also includes details such as geometrical properties, the horizontal and longitudinal reinforcement of columns and beams, mechanical properties ofthe materials, and vertical load and wall configurations.
After all envelopes of the thirty walls were investigatedand collected, an analysis of the parameters was carriedout. First, all stages were identified, and then the initial stiffness (K0 ), corresponding to the initial cracking oncolumns of confined masonry wall, was determined by Pc
which corresponds to the initial cracking on columns on
confined masonry walls. To determine the secondary stiffness (K1 ) was considered using a linear regression from Pc
over the envelope curve until Py with a correlation coefficient above 95%. For other parameters, such as (K2 ) and(K3 ), the slope corresponds to from Py to Pm and from Pm
to Pu , respectively. Stiffness ratios K1 /K0 , K2 /K0 , andK3 /K0 are shown in Fig. 8.
Some tendencies of the K2 /K0 and K3 /K0 ratios canbe observed while the K1 /K0 ratio presents a high dispersion. In the case of K2 /K0 ratio, values are greater than
Journal of Disaster Research Vol.9 No.6, 2014

0.000 and less than 0.200 while in the case of K2 /K0 ratio,
values are greater than −0.322 and less than 0.000.
Table 3 lists some statistical parameters, such as theminimum and maximum values, averages, and standard
deviations. Values of the initial stiffness indicate high dispersion because specimens have different geometrical andmechanical properties, etc.
Table 3 shows variation and a larger difference on K0
due to the minimum value (12.745 tonf/cm) from wall A23. This is because the sliding crack appears during the firststeps of the test. The maximum value (265.344 tonf/cm),
corresponding to wall MEC-2, has the highest slope because it has different geometrical dimensions than do others. On the other hand, wall A2-3 and A2-4 have thesame geometrical dimensions and mechanical properties.
In Fig. 7, differences on the positive side (pulling) can beobserved, but on the negative side (pushing), the elastic
stage is similar. For other parameters, note that the minimum value of K2 /K0 in Table 3 is zero when the pointof maximum resistance is the same as the yielding point.
For K3 /K0 , the maximum value is zero because the ultimate point is taken as the maximum point. As a resultof this research, it is recommended that the average values of K0 , K1 /K0 , K2 /K0 , and K3 /K0 , which correspondto 94.757 tonf/cm, 0.314, 0.051 and −0.051, respectively,
be taken.
The drift at important points when the loading is pushing and pulling during the cyclic lateral test on a confined
masonry wall, such as the cracking point (δc /h), yielding point (δy /h), maximum resistance point (δm /h), andultimate point (δu /h), are plotted in Fig. 9.
In the same way Table 3, Table 4 shows some statistical parameters, such as minimum and maximum values,997

Cardenas, L. et al.

5. Multi-Linear Regression and Shear Capacity Estimation
Using the experimental database from masonry walls,
a multi-linear regression was performed to get a semiempirical equation in order to estimate the shear capacityof masonry walls, as shown in Fig. 10.
Based on the multi-linear regression analysis, the following semi-empirical equation has been determined.
Pt σy
τu
σ0
h
= 0.050 − 0.026 + 0.010  + 0.008 
f m
L
fm
fm
where:

τu :fm :Fig. 9. Drift ratios.
Table 4. Ratios of the drifts of typical masonry walls.
RatiosMinimum
Maximum
AverageStand. Dev.

δc /h0.00010.004
0.00070.001

δy /h
0.0001
0.009
0.002
0.002

δm /h
0.001
0.015
0.007
0.003

δu /h
0.004
0.016
0.011
0.003

average, and standard deviation. Drift values indicate ahigh dispersion because specimens have different geometrical and mechanical properties. This condition occurs
mainly at the maximum resistance and ultimate stage.
In Fig. 9 and Table 4, the tendency for δc /h to show anaverage of 0.007 can be observed. Specimen 21 (wall A23) has a high value for the reason mentioned before. Also,
the drift δy /h, corresponding to the yielding point, has a
low accuracy or tendency. This variability comes from themethod used to obtain this point. Based on the results ofthis research, it is recommended that strain gauges be usedat the reinforcement points in columns to get the yielding
point accurately. Unfortunately, strain gauge data has notbeen collected for all walls.
For δm /h and δu /h, two criteria used to decide the ultimate point of the specimen were adopted. First, when
the state of stability of the specimen was compromised
and the capacity of the wall did not decrease by 20%, we
considered the last point over the envelope point as theultimate stage. A second criterion was adopted when theultimate point decreased more than 20% on the envelope
curve; in this case, we considered 20% of the capacity as
the ultimate stage.
According to the Peruvian Standard for masonry NTE
0.70 [1], the maximum drift allowed in repairing a walldamaged due to severe earthquake is 1/200 (0.005). Fig. 9shows that some walls reach their maximum drift (δm /h)under the drift limit. Walls 11 (M-ART) and 12 (M-IND)
shows the weakest behavior because they were made ofhollow bricks called “pandereta.”

998

h:
L:
Pt :
σy :

σ0 :

Shear stress of the masonry wall (kgf/cm2 )Compressive strength of masonry prism(kgf/cm2 )Height of the wall (cm)Length of the wall (cm)
Lateral reinforcement ratio (%)
Yielding strength of tensile reinforcement(kgf/cm2 )Average axial stress of wall (kgf/cm2 )The equation shows parameters used for multi-linear
regressions for those behavior curves on pulling and pushing during the cyclic lateral test on confined masonrywalls. The parameters used are explained as follows andshown in Table 5.
h/L:Pt σy / fm :σ0 / fm :Geometrical ratio of the wall. Dependingon the geometry, there will be some influence on the strength of the wall.
Resistance ratio of reinforcing steel over
the resistance ( f  m) of a pile of bricks. The
strength of the wall depends on the amountof steel reinforcement bars.
Ratio of load bearing capacity of the wall
because the axial load on the wall has influence its resistance.

Table 5 shows relevant values of Pt σy / f  m and σ0 / f  m ,such as those for wall 11 (M-ART) and 12 (M-IND), withhigher values than those for the other walls. This is because of the lower compressive strength of masonry prism( f  m), 33.2 kgf/cm2 for wall 11 and 22.1 kgf/cm2 forwall 12.
Some statistical parameters are shown below:
Multiple correlation coefficient:Standard deviation:
Variance:
Determination coefficient:

0.976
0.074
0.005
0.952

Those parameters correspond to the multi-linear regression analysis shown in Fig. 10. The analysis it was conducted in order to estimate the shear capacity of masonrywalls, for this purpose the semi-empirical equation wasdeveloped in terms of the ratio of masonry shear stressover the compressive strength of masonry prism (τu / fm ).
Journal of Disaster Research Vol.9 No.6, 2014

Implementation of Database of Masonry Walls Test
– Review of Existing Test Data in Peru

Fig. 10. Multi-linear regression of 30 typical masonry walls.

Fig. 11. Experimental values vs. calculated values for
30 typical masonry walls.

Table 5. Parameters for multi-linear regression.
Wall
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

h/L
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.96
0.96
1.00
1.00
1.00
1.00
1.00
1.00
0.94
0.94
0.94
0.94
1.09
1.09
1.33
1.33
1.00
1.00
0.67
0.67

Pull
Pt σy / f  m σ0 / f  m
4.72
0.04
4.72
0.04
4.72
0.04
1.84
0.02
1.84
0.02
3.27
0.02
1.84
0.02
1.84
0.02
1.84
0.02
1.84
0.02
24.77
0.12
37.22
0.19
3.95
0.04
3.95
0.04
3.95
0.04
3.95
0.04
5.08
0.05
5.08
0.05
11.13
0.04
11.13
0.04
6.26
0.04
11.13
0.04
12.96
0.05
10.93
0.04
2.03
0.02
2.03
0.02
1.52
0.02
1.52
0.02
1.01
0.02
1.01
0.02

h/L
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.96
0.96
1.00
1.00
1.00
1.00
1.00
1.00
0.94
0.94
0.94
0.94
1.09
1.09
1.33
1.33
1.00
1.00
0.67
0.67

Push
Pt σy / f  m σ0 / f  m
4.72
0.04
4.72
0.04
4.72
0.04
1.84
0.02
1.84
0.02
3.27
0.02
1.84
0.02
1.84
0.02
1.84
0.02
1.84
0.02
24.77
0.12
37.22
0.19
3.95
0.04
3.95
0.04
3.95
0.04
3.95
0.04
5.08
0.05
5.08
0.05
11.13
0.04
11.13
0.04
6.26
0.04
11.13
0.04
12.96
0.05
10.93
0.04
2.03
0.02
2.03
0.02
1.52
0.02
1.52
0.02
1.01
0.02
1.01
0.02

The masonry shear stress (τu ) was calculated using the
proposed equation, by multiplying corresponding compressive strength of masonry prism ( fm ). The experimental results were compared with the calculated results; bothresults are plotted in Fig. 11. The difference between
Journal of Disaster Research Vol.9 No.6, 2014

Fig. 10 and Fig. 11 can be observed because the compressive strength of masonry prism of the data wall has ahigh dispersion, with an average of 163.69 kgf/cm2 and astandard deviation 103.02 kgf/cm2 .
In order to safely estimate the shear stress of masonrywalls, values estimated using the proposed equation will
be equal to or greater than the resulting experimental values. Therefore, results are safely estimated when marks
in Fig. 11 are above the line. 57% of the results from a
total of 60 behavior curves (30 pushing and 30 pulling)from 30 specimens are safely estimated.

6. Conclusion
Data from 25 years of experiments conducted in CISMID have been collected and the results of experiments
have been analyzed. In processing the data, some parameters have been determined, such as stiffness ratios anddrift ratios, for characteristic stages of confined masonrywalls.
Comparisons of the test results from 30 envelopes haverevealed that there are some differences among them,
mainly in terms of maximum resistance (MEC-1 andMEC-2) and initial stiffness (Wall A2-3).
From the thirty envelopes curves, after data of walls
were collected and investigated, the parameters were analyzed. First, all stages were identified, and then the initial stiffness (K0 ) was determined by the Pc , which corresponds to the initial cracking of the columns of a confined
masonry wall. To determine the secondary stiffness (K1 ),from Pc with a slope variation of less than 5% until Py wasconsidered. For other parameters, such as (K2 ) and (K3 ),the slopes corresponded to from Py to Pm and from Pm to
Pu , respectively.
One equation to estimate the shear resistance of masonry walls was proposed after a multi-linear regression
analysis was done on the database.
A total of 60 behavior-curve results (30 pushing and
30 pulling) were analyzed from 30 masonry wall tests,
999

Cardenas, L. et al.

some of them digitalized from former studies. This number is quite limited in terms of its use to produce accurate
ratios or equations. Further studies are needed to obtain
results that are more accurate and to be able to identify the
behaviors of confined masonry walls according to theircharacteristics.
Acknowledgements
The authors would like to express their gratitude to the Japan
Science and Technology Agency (JST) and the Japan International cooperation Agency (JICA) for supporting the Japan-Peru
SATREPS Project during this research project. We would like togive special thanks to Dr. Fumio Yamazaki, Principal Investigatorof the SATREPS project. The authors would also like to express
their gratitude to Professor Shunsuke Sugano for his guidance during this investigation.

Name:
Lourdes Cardenas

Affiliation:
Associate Researcher, Laboratory of Structures
CISMID – National University of Engineering,Lima, Peru

Address:
Montero Rosas Street 1476 Santa Beatriz–Lima 01, Peru

Brief Career:
2006 Undergraduate Course, Faculty of Civil Engineering, Ricardo Palma
University, Lima, Peru
2009 Master Course, National Graduate Institute for Policy
Studies/International Institute of Seismology and Earthquake Engineering,Japan
ATM Fellow 2010 - Study Leave - IABSE

Selected Publications:

References:[1] Ministry of Housing and Construction – N.T.E. 070 – MasonryStandard.
[2] P. Gibu Yague and C. Serida Morida, “Confined Masonry Walls
Subject to Lateral Load,” 1993.
[3] J. Delgadillo Huaranga, “Experimental and Analytical Study of the
Behavior of Confined Masonry Walls subjected to Static Loads,”
1994.
[4] A. Gamarra Estrella, “Experimental Study of Confined Masonry
Structures of Two Levels Subjected to Cyclic Lateral Loads,” 1995.
[5] R. Salinas and F. lazares, “The Tubular Masonry and its Use on
Buildings in Seismic Zones,” 2007.
[6] M. Ramirez, “Bricks and its Influence on the Behavior on Confined
Masonry Wall Earthquake-Resistant,” 2001.
[7] CISMID – FIC–UNI, Project, “Construction Monitoring and Improvement Techniques for Masonry Housing,” 2001.
[8] O. Ramirez, “Experimental Theoretical Behavior No Lineal Of
Confined Masonry Walls,” 1993.

1000• L. Cardenas and C. Zavala, “Structural Vulnerability Assessment ofComercio Hotel,” URP, 2006.
• L. Cardenas and T. Mukai, “Evaluation of Structural Performance for
Confined Masonry Walls Retrofitted with Wire Mesh and with Disposable
Fiber Mats,” IISEE master program, 2009.
• C. Zavala, L. Cardenas, J. Taira, and F. Rios, Report of Basic Data on
Non-Engineered Buildings Developed by The Japan Peru Center for
Earthquake Engineering Research and Disaster Mitigation of the National
University of Engineering - CISMID-UNI, in collaboration with GRIPSTokyo, Japan, March, 2010.

Academic Societies & Scientific Organizations:• Peru Engineering Association (CIP)

Journal of Disaster Research Vol.9 No.6, 2014