Experimental Study on Dynamic Behavior of Unreinforced Masonry Walls

Paper:

Experimental Study on Dynamic Behavior of
Unreinforced Masonry Walls
Taiki Saito∗ , Luis Moya∗∗ , Cesar Fajardo∗∗ , and Koichi Morita∗∗∗∗ Department of Architecture and Civil Engineering, Toyohashi University of Technology

1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Japan
E-mail: tsaito@ace.tut.ac.jp∗∗ Japan-Peru Center for Earthquake Engineering Research and Disaster Mitigation (CISMID),
Faculty of Civil Engineering, National University of Engineering (UNI)
Av. Tupac Amaru, 1150 Rimac, Lima 25, Peru∗∗∗ Building Research Institute1 Tatehara, Tsukuba, Ibaraki 305-0802, Japan[Received November 5, 2012; accepted January 8, 2013]

The dynamic behavior of an unreinforced masonrywall is investigated through a shaking table test of two
specimens. In order to represent a non-engineering
one-story house, the first specimen consists of a Cshaped structure with masonry walls connected onlyat their ends. The second specimen is built to represent an upper story, so the C wall is connected at the
top by a wooden diaphragm floor, and a weight is suspended onto it. The test results show each specimen
exhibits different behaviors. In the first specimen, an
out-of-plane failure mode governs. In the second specimen, a shear failure mode governs.

Fig. 1. URM house.

Keywords: masonry wall, shaking table test, out-ofplane failure

1. Introduction
The main reason behind the extensive earthquake damage in developing countries is the collapse of unreinforced
masonry (URM) houses. Because of large variations inmaterial properties and construction accuracy, as well as
the brittle characteristics of brick materials, it is very difficult to develop engineering models of masonry buildings.
A fundamental purpose of this study is to mitigate theseismic hazard of URM walls. This concern is relevant to Peru because residential buildings located in areas
with low economic resources are mostly non-engineering
houses. Fig. 1 illustrates a non-engineering house builtwith URM walls and without a floor diaphragm. Fig. 2
illustrates typical URM exterior walls of a masonry building, which could injure people around it when they collapse during an earthquake.
As for in-plane failure properties, a number of static
experiments have been done to capture failure mode. For
out-of-plane failure properties, since both inertia forcesfrom the floor and the wall panel must be produced, it isnecessary to carry out shaking table dynamic experiments
rather than static experiments. Very few such studies havebeen done.
Journal of Disaster Research Vol.8 No.2, 2013

Fig. 2. Building with URM wall.

The most extensive research on URM buildings wasdeveloped by ABK Joint Venture [1, 2]. It was developed based on structural systems with a flexible wood diaphragm. It is the primary source of guidelines developedby the Federal Emergency Management Agency [3–5].
The weakest shape of failure in URM walls is the outof-plane failure; in those tests it consisted of horizontal
cracks located at the bottom, top, and around the middle
wall.
An URM building model that included a floor diaphragm as well as in-plane and out-of-plane wall components was developed by Simsir et al. [6]. In that test,
the in-plane and out-of-plane walls were connected only305

Saito, T. et al.

Groudi r nd mec otio tion nSpecimen

Weightsuspended

Diaphragm
floor

Gr
ou
d ir n d mec otio tion nSpecimen

Support

Sh

ak

i ng

Y

X

Ta

bl e

Z

Sh

ak

in

gT

le
ab

Support

Sh

ak
in g

Y

X
Z

Ta

ble

Sh

T
in g
ak

le
ab

(a) Scheme of the test set up(a) Scheme of the test set up(b) Specimen of the shaking table(b) Specimen of the shaking table

Fig. 3. The first specimen (specimen without floor).

Fig. 4. The second specimen (specimen with floor).

by the flexible diaphragm, and an axial load was applied
to the out-of-plane walls. Instead of the mid-height horizontal crack observed in ABK research and others, a horizontal crack located at approximately 70% of the wallheight from the base was observed.
This paper summarizes a study that aimed to improveunderstanding of the interaction between in-plane andout-of-plane walls when they are connected by their ends
(i.e., when they have continuity at the corners). The wall
test was carried out in the Structural Engineering Laboratory at the Building Research Institute, Japan.

(a) Compression(b) Shear

Fig. 5. Test of masonry prism.

2. Shaking Table Test
In January 2012, two specimens were constructed on
the shaking table of the Structural Engineering Laboratory
at the Building Research Institute. Figs. 3 and 4 illustrate
the idealized models, which represent a URM wall of asingle-story building and an upper level of a multistory
building, respectively. Each specimen consists of threemasonry walls: A, B, and C.
The wall B was 1440 mm high × 2850 mm wide ×
100 mm thick. The orthogonal walls (A and C) were306

Fig. 6. Connection between wall and diaphragm.

Journal of Disaster Research Vol.8 No.2, 2013

Experimental Study on Dynamic Behavior of Unreinforced Masonry Walls

A10

A11

A13

A12

A15 A16

A14

A17

A18

A19

Wall C

Wall B

Wall A

A23
A22

A21

(a) Accelerometers
P6

P1

P7

P5

P2

P3

P4

Wall C

Wall B

Wall A(b) Pi-gages
Fig. 7. Instrumentation for the wall test.
Table 1. Shake table runs and recorded peak values for the 1st specimen.

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

Type Frequency Amplitude
Peak Table
wave
(hz)
(mm)
Acceleration (g)sweep 0.8 - 20
0.5
0.01
sweep 0.8 - 20
0.5
0.43
sweep 0.8 - 20
0.5
0.40
random
5 - 200.5
0.02
random
5 - 2010.0
0.67
random 12 - 20
5.0
0.28
random 12 - 20
5.0
0.24
random 12 - 20
10.0
0.67
random 12 - 20
15.0
1.21
random 10 - 15
5.0
0.17
random 10 - 15
10.0
0.39
random 10 - 15
15.0
0.66
sweep 0.8 - 20
0.5
0.25
random
5 - 1510.0
0.70
random
5 - 1520.0
1.01
random
5 - 1020.0
0.45
random
5 - 1030.0
0.60
random
5 - 1040.0
0.73
random
5 - 1050.0
1.18
random
3-8
70.0
---

1440 mm high × 1450 mm wide × 100 mm thick. The
above dimensions give a slenderness ratio of 14.4.
Solid bricks and type O mortar (cement : sand ratio of
1 : 6) were used in the specimen. The average compression strength of the masonry prism with four bricks wasfound to be 6.09 MPa from the test, as shown in Fig. 5(a).
Diagonal compression tests according to the ASTM E519
were carried out on 430 mm × 410 mm specimens, as
shown in Fig. 5(b). The average shear strength of the masonry was found to be 1.28 MPa.

Journal of Disaster Research Vol.8 No.2, 2013

Displacements (mm)Top
Mid-height
0.13
0.09
2.74
1.75
2.31
1.83
0.21
0.15
3.34
2.92
1.21
0.77
1.33
0.76
2.75
1.7
4.93
2.56
1.58
0.62
3.16
1.41
7.46
2.78
3.12
1.03
4.91
2.01
8.39
4.12
7.68
2.93
9.39
3.38
12.94
5.17
11.49
6.18
-----

Accelerations (g)TopMid-height
0.05
0.03
2.15
1.56
2.02
1.37
0.11
0.08
3.10
2.18
0.88
0.45
1.06
0.47
2.31
0.88
5.01
1.41
1.18
0.23
1.96
0.55
3.33
0.97
1.47
0.33
2.69
1.17
5.00
1.50
2.45
0.91
3.24
1.22
4.89
1.69
5.73
2.59
-----

The specimen was constructed on a steel frame supportand hoisted up to set on the shaking table. The first specimen has no floor at the top. On the other hand, the second
specimen has a wooden diaphragm floor and steel weights
at the top. The diaphragm was connected to the masonrywall by sandwiching it between two plates as shown in
Fig. 6.
The ground motion was applied perpendicular to wall
B. Therefore, walls A and C would behave in-plane andwall B would behave out-of-plane. In the second speci-

307

Saito, T. et al.

Wall A

Wall B

Wall C

Wall B

Wall C

Wall B

Wall C

Wall B

Wall C

Wall B

Wall C

After Test 05

Fig. 8. The first natural frequency of the 1st specimen.

men, a constant axial load of approximately 18kN was applied by means of steel weights suspended over the floor
diaphragm
Fourteen accelerometers, seven pi-gauges, and a dataacquisition system were used to record the dynamic characteristics of the walls in the specimens.
Figure 7(a) shows the positions of the accelerometers.
The A10, A15, and A23 accelerometers recorded vibrations in the up-down direction, and all the others recorded
vibrations in the direction perpendicular to the wall where
they were located. Assuming that the wall “B” would faildue to out-of-plane behavior, it was decided that the pigauges would be arranged as illustrated in Fig. 7(b).
Most of the accelerometers were placed on wall B because previous researchers showed the out-of-plane modeof failure to be the weakest. Three additional accelerometers were placed over the floor diaphragm for the second specimen. One accelerometer located at the middleof the diaphragm recorded acceleration in the same direction as the shaking table, and the other two accelerometers, which were located at the ends, recorded up anddown acceleration.

Wall A

Wall A

Wall A

Wall A

3. Test Procedure and Results

After test 09

After test 13

After test 19

After test 20

Fig. 9. Crack patterns developed in the 1st specimen.

3.1. First Specimen
A total of twenty unidirectional signals were appliedat the base of the first specimen. For each test, the typeof signal, the amplitude of the table shake, the peak tableacceleration, the maximum measured displacement, andacceleration at the top and mid-height of Wall B are given
in Table 1. The displacements shown are relative to thebase; the accelerations are absolute values.
Two types of signals were applied over the tests: thefrequency sweep test and frequency random test. The
frequency sweep test was useful to monitor the shift in
the natural frequency of Wall B. As a result of the damage caused in the specimen during the tests, the natural
frequency of the specimen decreased continuously. As
shown in Fig. 8, which is the record of the accelerometer
placed at the middle top of Wall B, the natural frequency
decreased from an initial value of 19.34 Hz to 6.29 Hz by
the end of the 19th dynamic test run.
Although most cracks were observed over the out-of308

plane wall component, the crack patterns before the failure were different from those in previous investigations.
As shown in Fig. 9, the first cracks were observed after
the 5th test, and they were located at the middle top ofWall B and also at the tops of the corners. After the 9th
test, the initial cracks became wider, and a diagonal crack
appeared over Wall B. Such a diagonal crack had not been
seen in previous research. Another diagonal crack appeared in the same wall after the 19th test.
Besides, the cracks located at the upper corners became
larger, and they reached the half-height of the wall. Finally, when the connections between in-plane and out-ofplane walls were partially lost, a horizontal crack formedat the middle of the wall; this wall corresponds to the collapse of the specimen (see Fig. 10).

Journal of Disaster Research Vol.8 No.2, 2013

Experimental Study on Dynamic Behavior of Unreinforced Masonry Walls

Table 2. Shake table runs and recorded peak values for the 2nd specimen.
Teest
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
2
20
2
21
2
22

Displacemeents (mm)Typee
Frequenncy Amplitude
Peak Table
Acceleration (g)
wavee
(hz))
(mm)
(
Top
M
Mid-heightsweepp
0.8 - 20
2
0.5
0.15
0.91
0.48
0.15
1.37
0.21
sweep
p
0.8 - 20
2
0.5
0.02
0.14
0.10
randomm
5 - 20
0
0.5
0.01
0.11
0.13
randomm
10 - 15
1
0.5
0.04
0.27
0.10
randomm
10 - 15
1
2.0
0.23
1.31
0.42
randomm
10 - 15
1
10.0
0.52
1.92
1.17
randomm
10 - 15
1
15.0
0.90
2.06
1.45
randomm
10 - 15
1
15.0
0.78
3.38
1.36
randomm
12 - 15
1
20.0
0.19
13.87
0.13
0.2*
Kobe earth
hquake--1.13
2.66
1.44
randomm
12 - 15
1
20.0
0.17
0.97
0.29
sweep
p
0.8 - 20
2
0.5
1.35
5.27
2.38
randomm
5 - 15
5
30.0
1.44
4.25
2.99
randomm
5 - 15
5
30.0
1.82
4.20
5.45
randomm
5 - 15
5
30.0
0.20
1.18
0.86
sweep
p
0.8 - 20
2
0.5
1.52
4.70
6.25
randomm
5 - 15
5
30.0
1.97
5.32
9.04
randomm
5 - 15
5
40.0
2.11
4.87
6.34
randomm
5 - 15
5
40.0
2.05
5.24
8.18
randomm
5 - 15540.0------randomm
5 - 100
50.0----0.5*
Kobe earth
hquake-----Fig. 10. Shape of failure of the 1st specimen.

3.2. Second Specimen
A total of 23 unidirectional signals were applied at thebase. Table 2 shows the type of signal, the amplitudeof the table shake, the peak table acceleration, the maximum measured displacement, and acceleration at the top
and mid-height for the second specimen. However, whilethe values of displacement and acceleration at the top arefrom the wooden diaphragm, the values at mid-height arefrom Wall B.
There is no information on the maximum values of displacement or acceleration for tests 21 and 22 because theaccelerometers had been removed prior. Three types ofsignals were applied over the tests: a frequency sweep
test, a frequency random test, and a Kobe earthquake test.
As mentioned above, a frequency sweep test was used to
Journal of Disaster Research Vol.8 No.2, 2013

Acccelerations (g)To
op
Mid-heigh
ht
0.33
0.23
0.33
0.24
0.04
0.03
0.02
0.02
0.10
0.07
0.59
0.49
0.94
1.13
0.98
2.89
0.90
2.25
0.20
0.20
1.16
2.72
0.33
0.49
1.14
4.19
1.09
4.32
0.96
3.65
0.22
0.43
1.08
3.96
1.17
4.75
0.89
4.73
1.10
4.96
-----------

Fig. 11. The first natural frequency of the 2nd specimen.

ascertain the shift in the natural frequency of the specimen.
The change in the natural frequency can be used as a
trace of the damage caused in the specimen. Fig. 11 illustrates how the natural frequency of the accelerations
recorded over the diaphragm decreased. However, thenatural frequency recorded at the mid-height of Wall B
did not decrease significantly.
This time, most of the cracks developed in the in-planewalls. It seems that the axial load produced by the weightsuspended at the top improved the flexural strength ofWall B.
Furthermore, the floor diaphragm and the roof provided
a type of confinement. As shown in Fig. 12, at the beginning, the crack patterns that developed over the in-plane
wall components were totally different. After the 15th309

Saito, T. et al.

20

20

After Test 12
20

20

After test 15
20

20

After test 16
20

20

Wall C

Wall B

Wall A

20

Wall C

Wall B

Wall A

20

Wall C

Wall B

Wall A

20

Wall C

Wall B

Wall A

20

20

Fig. 13. Shape of failure of the 2nd specimen.

After test 18
20

20

4. Conclusions

20

After test 20
20

Wall A

Wall C

Wall B

Wall A

20

Wall B

After test 21

Wall C

Fig. 12. Crack patterns developed in the 2nd specimen.

test, a bed-joint sliding on a horizontal plane located at
the top developed in Wall A. Meanwhile, a sliding on astair-stepped diagonal crack developed in Wall C. Due tothe difference in behavior between the in-plane wall components, torsional movements developed in the specimen.
After the 18th test, diagonal cracks, which began in the inplane walls and ended up on wall B, developed because of
the torsional behavior. Finally, the shape of failure can beseen in Fig. 13.
310

The interaction between the in-plane and out-of-planecomponents of a URM wall when they are connected bytheir ends (corners) has been studied. To do this, two
specimens were tested on a shaking table.
The shape of failure of the first specimen, which simulated a single-story building, was found to be out-ofplane. However, at the beginning, the crack patterns weredifferent than those in the previous research due to the influence of the in-plane walls.
On the other hand, the damage in the second specimen
was observed on the in-plane walls. It is presumed thatthe floor diaphragm and the axial load produced by theweight suspended at the top enhanced the stability of theout-of-plane wall component.
As happened in the second specimen, the possibility ofdifferent modes of behavior in the in-plane wall components of a building produced torsional movements. Besides, the URM walls have several shear behavior modes,
such as wall-pier rocking, bed-joint sliding, spandrel-joint
sliding, and rocking/toe crushing, among others.
Almost all the cracks observed were located in the mortar. The brick units did not break. Therefore, analytical models based on simulations of rigid body dynamics
could give us a good estimate of the dynamic behavior of
URM buildings.
Journal of Disaster Research Vol.8 No.2, 2013

Experimental Study on Dynamic Behavior of Unreinforced Masonry Walls

Acknowledgements
This study was supported by the SATREPS project “Enhancementof Earthquake and Tsunami Mitigation Technology in Peru.”

Name:
Luis Angel Moya Huallpa

Affiliation:
Research Assistant, Japan-Peru Center for Earthquake Engineering Research and Disaster Mitigation (CISMID)

References:[1] ABK, “Methodology for Seismic Hazard in Existing Unreinforced
Masonry Buildings: Wall Testing, Out-of-Plane, Topical Report04,” ABK Joint Venture, California, December 1981.
[2] ABK, “Methodology for Seismic Hazard in Existing Unreinforced
Masonry Buildings: The Methodology, Topical Report 08,” ABK
Joint Venture, California, January 1984.
[3] FEMA 306, “Evaluation of Earthquake Damaged Concrete and Masonry Wall Buildings, Basic Procedures Manual,” Federal Emergency Management Agency, Washington, D.C., 1999.
[4] FEMA 307, “Evaluation of Earthquake Damaged Concrete and Masonry Wall Buildings, Technical Resources,” Federal Emergency
Management Agency, Washington, D.C., 1999.
[5] FEMA 356, “Prestandard and Commentary for the Seismic Rehabilitation of Building,” Federal Emergency Management Agency,
Washington, D.C., 2000.
[6] C. C. Simsir, M. A. Aschheim, and D. P. Abrams, “Out-of-Plane
Dynamic Response of Unreinforced Masonry Bearing Walls Attached to Flexible Diaphragms,” 13th World Conference on Earthquake Engineering, Vancouver, B.C., 2004.

Address:
Jr. Madre Selva Mz A Lt 09, Lima 12, Peru

Brief Career:
2009- Joined Japan-Perú Center for Earthquake Engineering Research andDisaster Mitigation (CISMID)
2011- Joined Faculty of Civil Engineering of the National University ofEngineering of Peru
2012- Study trip, Building Research InstituteAcademic Societies & Scientific Organizations:• Japan-Peru Center for Earthquake Engineering Research and Disaster
Mitigation (CISMID)• National University of Engineering of Peru

Name:
Cesar Fajardo Galliani

Affiliation:
Research Engineer, HAKI CT SA

Name:
Taiki Saito

Affiliation:
Professor, Toyohashi University of Technology

Address:
Ca Chiloe Mz D2 Lt 5 Los Cedros, Chorrillos, Lima 01, Peru

Brief Career:

Address:
1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Japan

Brief Career:
1990-1996 Research Associate, Tohoku University
1996-2000 Senior Research Engineer, Building Research Institute2000-2012 Chief Research Engineer, Building Research Institute2013- Professor, Toyohashi University of Technology

2008-2012 Assistant Researcher at Seismic Engineering Division,
CISMID, Lima, Peru
2012- Research Engineer, HAKI CT SA, Peru

Selected Publications:• “Seismic Performance Model of an Important Building in Peru
– Evaluation of a Hospital Structure by using non-linear analysis –,” Theinternational symposium for 25th CISMID Aniversary, August 2012.

Academic Societies & Scientific Organizations:• ACI-Peru

Selected Publications:• T. Saito, T. Takahashi, R. Hasegawa, K. Morita, T. Azuhata, and K.
Noguchi, “Shaking Table Test on Indoor Seismic Safety of High-rise
Buildings (Part 2. Movement of Furniture under Long Period Earthquake
Ground Motion,” Proceedings of 14th World Conference of Earthquake
Engineering, S10-014, 2008.10.

Name:
Koichi Morita

Affiliation:
Chief Research Engineer, Building Research InstituteAcademic Societies & Scientific Organizations:• Architectural Institute of Japan (AIJ)• Japan Association for Earthquake Engineering (JAEE)

Address:
1 Tatehara, Tsukuba, Ibaraki 305-0802, Japan

Brief Career:
1998 Joined Building Research Institute2005- Visiting Scholar, Purdue University

Selected Publications:• “Detection and Estimation of Damage to Steel Frames through Shaking
Table Tests,” Journal of Structural Control and Health Monitoring, Vol.12,
Issue 3-4, pp. 357-380, 2005.6.

Academic Societies & Scientific Organizations:• Architectural Institute of Japan (AIJ)• Japan Association for Earthquake Engineering (JAEE)

Journal of Disaster Research Vol.8 No.2, 2013311