SEISMIC PERFORMANCE OF REINFORCED
CONCRETE WALL-SYSTEM WITH ELECTROWELDED MESH
Jenny Taira Higa∗
MEE08172

Supervisor: Shunsuke SUGANO∗∗
Taiki SAITO∗∗∗
ABSTRACTA new structural system consisting of reinforced concrete wall with electro-welded mesh is
being used for the buildings construction in Peru. These walls have small thickness. ThePeruvian standards for this wall –system were published in 2004 in order to restrict the use of
the electro-welded mesh as main reinforcement. However many buildings have been built
before that and electro-welded mesh was used as reinforcement for whole building.
In order to evaluate the behavior of this system, the test results of 7 isolated walls and1-story wall-system house were used. This test results have been compared with analyticalresults in order to find out an adequate way for the analysis of this wall-system. In theisolated walls analysis, the cracking strength and ultimate strength were calculated to apply a
tri-linear model to be used in the degrading tri-linear hysteresis model to compare it with thehysteretic curve of the isolated walls. The isolated wall analysis was applied in the analysis
of 1-story wall-system house to evaluate its behavior and compare it with test results. In
order to apply the proposed evaluation methods, a 2-story house wall system was analyzed toevaluate the seismic response by the displacement method using the degrading tri-linear
hysteresis model.
It is expected to use this analysis to evaluate the behavior of existing and newbuildings using the reinforced concrete wall-system with electro-welded-mesh.
Keywords: hysteresis model, strength, behavior, seismic performance.

1. INTRODUCTIONSince 2000, many buildings in Peru have been built with a new structural system
consisting of reinforced concrete with ductile steel bars at the ends and electro-welded meshin the middle part to support gravity and lateral loads. The minimum thickness for these walls
is 10 cm and reinforcement is arranged in one line. In October 2004, the addendum for thestandard of building design with these walls was published in order to standardize the criteria
for the analysis and design of these buildings. This standard restricts the use of electrowelded mesh as main reinforcement for the building construction due to its low ductility
compared with ductile steel (See Figure 1). However, many buildings were built before thepublication of the above standards; the electro-welded mesh has been used as main
reinforcement for whole building for the sake of reducing cost.
According to the standard, the electro-welded mesh is allowed as reinforcement inbuildings up to 3 stories. In case of higher-story buildings, electro-welded mesh is prohibitedfor the lower one third of the total high of the building of 4 stories or higher. The maximum
number of story is 7. In case of higher buildings the wall thickness should be greater than 15∗

Japan - Peru Center for Earthquake Engineering Research and Disaster Mitigation (CISMID), Peru.
Visiting Research Fellow, International Institute of Seismology and Earthquake Engineering,
Building Research Institute, Japan.
∗∗∗International Institute of Seismology and Earthquake Engineering, Building Research Institute,Japan.
∗∗12

Tensile stress (kg/cm )cm six stories lower from the top and below that story, to allow the confinement at the ends ofthe walls. The maximum relative displacement for each story divided by its height should notexceed 0.005.
The advantages of this system
are its rapid process ofconstruction since electro-welded
Ductile steel
mesh is pre-fabricated andconcrete is pre-mixed. Thesefactors reduce the cost, time andElectro-welded meshlabor in the construction. The
high walls density makes thestructure becomes rigid. The
main disadvantage is its low
ductility due to concrete andmesh are not ductile materials.
Displacement (mm)Figure 1. Tensile tests for ductile steel and electro-welded mesh

2. OBJECTIVES
The objectives of this thesis are to evaluate the behavior (load-displacement relationship) of
isolated walls obtained from the laboratory test using the “tri-linear model”. Also, to evaluate
the cyclic behavior (cyclic load-displacement relationship) of a one-story wall-system houseobtained from the laboratory test using the “degrading tri-linear hysteresis model”. In orderto achieve this objective, the analysis of 7 isolated walls and 1-story wall-system house tested
in laboratory were carried out to compare the hysteretic curve from test and analysis. This
analysis was applied to evaluate the seismic response of a 2-story wall-system by thedisplacement method.
The analysis is intended to be applied in order to evaluate the performance in new andexisting buildings. In case of new buildings, the use of the electro-welded mesh is restricted.
For existing buildings built before the standard publication, this evaluation can be used toknow whether the building requires retrofitting.

3. ANALYSIS OF ISOLATED WALLS
In the analysis of isolated walls, 7 full scale isolated walls tested in the Laboratory ofStructure in CISMID in 2004 were used. The parameters were the kind of electro-weldedmesh and dowel to join wall and foundation.
.12

Q221

.12

Q221

Mesh
2.40

2.40

Mesh
O3/8"

O3/8"

.50.30

Dowel.30

8O5/8".80

Figure 2. Characteristics of isolated wall

2Table 1. Isolated wall reinforcement
Specimen
MQE188EP-01
MQE188EP-02
MQE188EP-03
MQE257EP-01
MQE257EP-02
MQE257EP-03
MFIEN3EP-01

Reinforcement
QE188
QE188
QE188
QE257
QE257
QE257
φ3/8”@25

Table 2. Characteristics of reinforcement

Dowel
QE84/188
QE84/188
φ3/8@25
QE84/257
QE84/257
φ3/8@25
φ3/8@25

Diameter(mm)
6.00
7.00
4.00
9.5

Mesh
QE-188
QE-257QE-84
φ3/8”

Spacing(mm)150
150150250Density(mm2/m)
188
257
84284

For each isolated wall, the skeleton curve was plotted from the hysteretic curve of the testedwall. These skeleton curves were used in the comparison with analytical results explained
below.
Laboratory of Structure - CISMID/FIC/UNI
MFIENEP01

Envelope - MFIEN3EP-01
50

6040403030

20

Force (ton)50

Load (ton)20
100-60-50-40-30-20-10 -10 0102030

405060100-30-20-10-1001020-20-20-30-30-40

1/200-40-50-50-60

Displacement (mm)Displacement (mm)Figure 3. Isolated wall behavior

MyQy

McQc

kfeαykseβθyδyFlexural model

Shear model

Figure 4. Tri-linear model•Flexural cracking strength:•ND
M c = 0.56 σ B Z e +6
Ultimate flexural strength:

For the tri-linear model, thecracking and ultimate strength
were calculated in flexure andshear. This was made to know
how the behavior of isolated
walls is. According to theresults, the isolated walls haveflexural behavior (See Figure4). The equations for thecalculation of tri-linear model
were shown below:(1)

M u = atσ y l w + 0.5awσ wy lw + 0.5 Nlw(2)•Stiffness reduction at flexural yielding:•a d 
α y =  − 0.0836 + 0.159 + 0.169η 0   , a/d < 2D D Shear cracking strength:

2Vc =•

Ultimate shear strength:τ scr t wlw

(3)

(4)

xw




0.23
 0.068 pte (18 + Fc )
Qwsu = + 0.85 pwhσ wh + 0.1σ 0 te ⋅ jM

+ 0.12

QD

3(5)

30

•

Stiffness reduction at ultimate shear strength:

βu =
δt

0.46 pwσ yFc

δftotaldisplacem ent

flexuraldisplacem ent(6)+ 0.14
δsIn order to obtain a better
approximation in the flexural
model, the displacements inshear were added to thedisplacements in flexure.

shear
displacem ent

Figure 5. Total displacement
Mesh QE188

Mesh QE188
70403050Force (ton)Strength (ton)60403020Flexure

10Shear
Test

20Analysis

10Test000

510015246Displacemente (mm)Mesh QE257

10121416Ductile steel

50504040Force (ton)Force (ton)

8Displacement (mm)3020Analysis

103020Analysis

10TestTest

0002468101214160

Displacement (mm)246810121416Displacement (mm)Figure 6. Flexural and shear tri-linear model and total displacement.
The equations used for the calculation of the cracking and ultimate strengths can be used todescribe the behavior for this kind of walls.

4. ANALYSIS OF 1-STORY WALL-SYSTEM HOUSE
In 2004, 1-story house was tested in the Laboratory of structures of CISMID, at the same timefor walls. The house walls have the same characteristics of the isolated walls. In thereinforcement was used mesh QE188. According to the behavior, the maximum load was 88
ton for a displacement of 11 mm.
The degrading tri-linear hysteresis model was used in the comparison with thebehavior from the test. This hysteresis model considers the (a) yielding stiffness, (b) stiffness
degradation, (c) slip stiffness and (d) strength degradation.

φ 
φ ' = 1 + 0.05 n y φmn φm m

M φ
My 
 k = y  yk y = −0.01
 φ  r  φ y  φm
 y (a)(b)0.05

 M m  φyk s =  φm − φ x  φm(c)40.1(d)Figure 7. Degrading tri-linear
hysteresis model

For the analysis, the house walls were replaced by shear spring devices with the properties ofwalls by using the hysteresis model based on degrading tri-linear model. The same calculation
for the analysis of isolated walls was made for the house walls. In the analysis was used
Stera3D computer program made by Dr. Saito.
According to the comparison, the behavior
Comparison in Skeleton
Test Analysis
calculated by using the hysteresis model forCurveflexure shows a good approximation compared
Cracking strength (ton) 30
27.4
with test results. For this reason, hysteresis
model for shear was not taken into account. The
Ultimate strength (ton) 73.8 73.2
values for cracking and ultimate strength has a
Elastic stiffness (ton/mm) 45.9 72.1
small variation compared with the test results. In
case of elastic stiffness, the variation is around 50%. This can occur due to shrinkage, smallfissures or cavities in the concrete walls. However, this variation is acceptable in the analysis
and it can be considered as good result.
Envelope - 1-story house

100100808060604040

Force (ton)Load (ton)Comparison of Hysteretic Curve
1-story house200-30-20-100102030-20

200-30-20-10-200102030-40-40-60

Analysis
Test-60

Test
Analysis-80-80-100-100

Displacement (mm)Displacement (mm)Figure 8. Comparison between test and analytical results5. SEISMIC PERFORMANCE OF 2-STORY WALL-SYSTEM HOUSE
In order to evaluate the seismic response of a 2-story house,
the displacement method using the degrading tri-linear
hysteresis model was used. For the model, the 1-story house
was extended to 2 stories.
The capacity spectrum was calculated from theshear force-displacement relationship by using the equation
to calculate the spectral acceleration and spectral
Figure 9. Analytical model displacement. The demand spectrums was calculated fromthe response spectrums of Peruvian seismic code, Japanesebuilding standard and the earthquake occurred in Peru in October 1966. This earthquake had
the maximum acceleration registered in Peru. The maximum acceleration was around 270 gal.
Capacity vs. Demand (5% damping)

Behavior of 2-story house
3000

8060

2500

Capacity spectrum

Sa (cm/sec2)

Force (ton)40

200-30-20-100

102030-202000

1966 earthquake
Peruvian seismic code

1500

Japanese building standard

1000

Performance point

-40

500

-60

00-80

24681012Sd (cm)Displacement (mm)Figure 10. 2-story house behavior and performance point

514161820

The demand spectrums were calculated for 5% damping, this means for elastic range. Despite
this, in all cases the displacement in the performance point is very small. The structure
remains in the elastic range in the capacity spectrum, therefore the structure should not suffer
damage. The total strength of the walls is 2.3 times larger than the weight of the structure;
therefore the structure becomes very rigid and the spectral acceleration in the capacity
spectrum is high compared with demand spectrum.

6. CONCLUSIONS••••The load-displacement relationship of isolated walls obtained from the laboratory test waswell predicted by the tri-linear model for flexural and shear displacements.
The behavior of isolated walls is by flexure. In order to improve the analytical results, theshear displacements were added to flexural displacements. The difference between
analytical and test results for strength varies between 2% and 8%.
The cyclic load-displacement relationship of a one-story wall-system house obtained fromthe laboratory test was well predicted by the degrading tri-linear hysteresis model. The
ultimate strength calculated in the analysis is very close to the maximum load in the tests.
This variation can be reduced taking into account a modeling for shear in the analysis.
Despite this, the modeling for flexure can be used to predict the behavior for a structurewith good results.
The seismic response of the 2-story wall-system house was evaluated based on
displacement method using the degrading tri-linear hysteresis model. This method isproposed for the evaluation of the performance in buildings that use this structural system.
The hysteresis models proposed in this study can be applied to existing buildings andbuildings in new construction using the reinforced concrete wall-system with electrowelded mesh to evaluate their seismic behavior.

ACKNOWLEGDMENT
I want to express my sincere thanks and gratitude to Dr. Carlos Zavala for their valuableadvice, guidance and support during my individual study.

REFERENCES
ATC, 1996, Seismic Evaluation and Retrofit of Concrete Buildings, ATC-40 Report, Volume2, Applied Technology Council, Redwood City, California.
Colegio de Ingenieros del Perú, 2004, Normas para el Diseño de Edificios con Muros deDuctilidad Limitada.
Ministerio de Vivienda y Construcción, 2003, Norma Técnica E.030, Diseño Sismorresistente.
National Institute for Land and Infrastructure Management and Building Research Institute,2007, Manual on Technological Standard Related to Structure of Buildings.
Park, R., Paulay, T., 1973, Reinforced Concrete Structures, Department of Civil Engineering,
University of Canterbury, Christchuch, New Zealand.
Saito, T., 2009, STERA_3D Technical Manual Ver.2.2
http://iisee.kenken.go.jp/net/saito/stera3d/index.html
San Bartolomé, A., Muñoz, A., Madueño, G., Cavero, R., 2003, Control de la Falla por
Deslizamiento en las Placas de Concreto Reforzadas con Mallas Electrosoldadas –Proyecto SENCICO-PUCP, Pontificia Universidad Católica del Perú (PUCP).
Zavala, C., 2004, Ensayo de muros y vivienda de un piso de concreto reforzado con malla
electrosoldada UNICON/FORSA/PRODAC, National University of Engineering, JapanPeru Center for Earthquake Engineering Research and Disaster Mitigation (CISMID).

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