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IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 09, 2014 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 852
Study on Seismic Responses of Masonry Brick Infill Walls in Slender
Structures Geo.Davis
Department of Civil Engineering
KMEA Engg College, Aluva, ErnakulamAbstract— RC framed buildings are generally designed
without considering the structural action of masonry infill
walls present. These walls are widely used as partitions and
considered as non-structural elements. But they affect both
the structural and non-structural performance of the RC
buildings during earthquakes. In this present study, the
seismic responses of brick masonry infill wall in slender
structure were studied. The assumed slender structure
havingG+10storey. There are two models are created for the
analysis such as bare frame and RC frame with masonry
infill wall. The structures modeled and analyzed by ETAB
software. Static analysis, Modal analysis and Time history
analysis are done and the results were compared. From the
results has been established that masonry brick infill walls
influence the response of RC framed structures.
Key words: Brick masonry, Brick strut, Infill frame, bare
frame, Seismic analysis
I. INTRODUCTION
In the analysis of earthquake frames without masonry brick
infill wall is considered in most of the study. The purpose of
present study is to evaluate the seismic influence of masonry
brick infill walls on the RC framed structures.
While building collapse is the primary cause of loss
of life in most earthquakes, other contributors to earthquake
loss include equipment and contents damage, business
interruption, and damage to lifelines, such as water, power,
gas, communications, and transportation.
To limit these losses to acceptable levels,
earthquake engineering involves a process of
Seismic hazard identification,
Structural analysis, design, and retrofitting to
prevent structural collapse,
Reduce property damage, and
Review of equipment and operations to prevent
disruption due to earthquakes that is, an integrated,
comprehensive program of facility seismic review,
analysis, retrofit, emergency planning, and risk
transfer, involving the expertise of mechanical
engineers, operations specialists, emergency
planners, and insurers, in addition to geoscientists
and structural engineers.
In fact the presence of infill wall changes the
behavior of truss action, thus changing the lateral load
transfer mechanism. The frame with unreinforced masonry
walls can be modeled as equivalent braced frames, braced
frame with infill walls replaced by equivalent diagonal strut.
A. Effect of Infill Wall in RC Frame
A great majority of reinforced concrete (RC) structures were
severely damaged or collapsed during ground motions.
Thousands of people died after recent earthquakes. The
main reasons of these losses originate from the fact that the
average of the structures is not well engineered and also
some of them are constructed illegally.
Besides the mentioned cases, existing structures
still have similar deficiencies for future hazardous
earthquake loads. Reliable strengthening methodologies and
rehabilitation procedures should be established as quickly as
possible to minimize the expected loss in the future.
Different strengthening methods (addition of shear
walls, pre-cast panels, steel bracing, concrete jacketing of
frames, etc.) have been used. Among these techniques,
addition of RC shear (infill) walls was found practical and
economical. RC infill frame increases the lateral load
capacity of the RC frame and reduces the lateral
displacement (drift) at ultimate load.
However, the construction work for these
applications lengthens the retrofit time and occupants of the
rehabilitated buildings have to be relocated. Reconstruction
may disturb the ongoing building facilities and new
structural elements may affect the architectural aesthetics of
the structures. These restorations may add considerable
mass and cause high seismic (lateral) loads during an
earthquake. And also, altering the dimension of the RC
frame leads to take more loads of the RC frame members. In
order to overcome these deficiencies, new alternative retrofit
strategies are needed. Infill walls are commonly used in low
and mid-rise constructions. They are generally used as
interior partitions or exterior walls in buildings.
Partition walls are usually treated as non-structural
elements and often ignored in design. Recent studies have
shown that infill RC frames can be superior to a bare RC
frame in terms of stiffness, ductility and energy dissipation.
By recent improvements in polymer composite
technology; the infill walls can be strengthened and
retrofitted with fiber reinforced polymers (FRP). FRP brings
logical solutions because of their small thickness, ease of
application and advantage of high strength. Moreover, the
strength and stiffness of a structure can be increased with
little mass. Nevertheless, use of fiber reinforced polymers is
limited due to economic factors, lack of standards and some
doubts of serviceability life.
As a matter of fact, it is known that most of the
people live in inadequate economic conditions. Thus, the
usage of fiber reinforced polymers (FRP), as being a reliable
strengthening method, may not be an option to most of the
home owners, simply because of its high cost. Assessment
of strengthening the large number of infill walls could be
economical and would be superior to other techniques. If
confinement location and detailing are standard this system
has performed excellently under very intense earthquakes.
But severe damage was observed when confinement
detailing was substandard. For such cases, wall jacketing is
one rehabilitation technique suitable for improving its lateral
strength and stiffness. Jacketed specimens showed uniform
distribution of cracks and increased strength was seen
compared to the bare frames.
To achieve any benefit from wall jacketing, careful
and detailed installation of fasteners should be applied. Steel
Study on Seismic Responses of Masonry Brick Infill Walls in Slender Structures
(IJSRD/Vol. 2/Issue 09/2014/197)
All rights reserved by www.ijsrd.com 853
nails were used to fasten the steel wire mesh. Fasteners were
placed at the grid intersections of the wire mesh. They were
placed by hammering them into the wall. The nail head was
bent at the wire intersection to secure the mesh in position.
Spacers metal washers used between the wall and the mesh
according to fastening technique Infill-frames have been
used in many parts of the world over a long time. In these
structures, exterior masonry walls and interior partitions,
usually regarded as nonstructural architectural elements, are
built as an infill between the frame members.
However, the usual practice in the structural design
of infill-frames is to ignore the structural interaction
between the frame and infill. This implies that the infill has
no influence on the structural behaviour of the building
except for its mass. This would be appropriate if the frame
and infill panel were separated by providing a sufficient gap
between them. However, gaps are not usually specified and
the actual behaviour of infill frames observed during past
earthquakes shows that their response is sometimes wrongly
predicted.
Infill-frames have often demonstrated good
earthquake-resistant behaviour, at least for serviceability
level earthquakes in which the masonry infill can provide
enhanced stiffness and strength. It is expected that this
structural system will continue to be used in many countries
because the masonry infill panels are often cost-effective
and suitable for temperature and sound insulation purposes.
Hence, further investigation of the actual behaviour of these
frames is warranted, with a goal towards developing a
displacement-based approach to their design.
Different local materials are used to produce
masonry units with different shapes; they might be solid or
hollow units with different hole-sizes and whole
arrangements. The structural behaviour of an infill-frame
can be divided into two parts, in-plane and out-of-plane. The
simultaneous effect of in-plane and out-of-plane loading has
usually been ignored in the research conducted to date,
although in actual earthquakes this effect will usually be
present.
Predominant Truss Action in Infill Frame
Frame Action in Bare Frame
Fig. 1: Effect of Infill Wall in RC Frame
B. Objectives
To rusticated the effect of masonry brick infill walls in RC
framed structures of seismic response
To familiarization of software ETABS
To compare the response of bare frame and
masonry brick in filled structures
C. Methodology
Methodology employed is FEM analysis. Modeling of the
G+10 storey reinforced concrete frame and frame with
masonry brick infill walls done using ETABS and Modal
analysis, Static analysis and Time history analysis carried
out and results are compared.
D. Finite Element Analysis
The Finite Element Analysis (FEA) is a numerical method
for solving problems of engineering and mathematical.
Useful for problems with complicated geometries, loadings,
and material properties where analytical solutions cannot be
obtained. In this method model body divided in to smaller
elements and analyzed.
E. Details of Structure
F. Calculation of Strut
II. MODELLING
The structure is modeled by using ETAB software. Two
models are created bare frame and RC frame with masonry
brick in filled walls
Study on Seismic Responses of Masonry Brick Infill Walls in Slender Structures
(IJSRD/Vol. 2/Issue 09/2014/197)
All rights reserved by www.ijsrd.com 854
Fig. 2: Plan View
Fig. 3: Bare Frame
Fig. 4: RC frame with brick masonry infill wall
III. ANALYSIS ANS RESULTS
The modeled structures are modeled and analyzed. Static
analysis, Modal analysis and Time history analysis was done
by using ETABS
A. Static Analysis
The Static Analysis was performed for the two models. The
comparative results of storey displacement, storey drift and
storey shear are tabulated as follows.
1) Maximum Storey Displacement
Bare Frame Brick infilled frame
Fig. 5: Storey Displacements
STOREY
LEVEL
BARE
FRAME
BRICK
INFILLED
Storey 11 17.4 7.2
Storey 10 16.7 6.8
Storey 9 15.8 6.4
Storey 8 14.6 6.0
Storey 7 13.2 5.5
Storey 6 11.7 5.0
Storey 5 10.1 4.5
Storey 4 8.5 4.0
Storey 3 6.8 3.6
Storey 2 5.1 3.2
Storey 1 3.1 2.6
Base 0 0
Table 1: Maximum storey displacement
Fig. 6: Comparison of values in graph
Study on Seismic Responses of Masonry Brick Infill Walls in Slender Structures
(IJSRD/Vol. 2/Issue 09/2014/197)
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2) Storey Drift
Bare Frame Brick Infilled Frame
Fig. 7: Storey Drift
STOREY
LEVEL
BARE
FRAME
BRICK
INFILLED
Storey 11 0.16 0.1
Storey 10 0.21 0.12
Storey 9 0.33 0.12
Storey 8 0.42 0.14
Storey 7 0.53 0.15
Storey 6 0.62 0.15
Storey 5 0.70 0.18
Storey 4 0.78 0.18
Storey 3 0.80 0.18
Storey 2 0.95 0.25
Storey 1 1.8 4.1
Base 0 0
Table 2: Storey drift
Fig. 8: Comparison of values in graph
3) Storey Shear
Bare Frame Brick Infilled Frame
Fig. 9: Storey Shears-Masonry
STOREY
LEVEL
BARE
FRAME
BRICK
IFILLED
Storey 11 110 200
Storey 10 220 400
Storey 9 325 630
Storey 8 420 870
Storey 7 515 1100
Storey 6 610 1300
Storey 5 680 1500
Storey 4 750 1700
Storey 3 800 1900
Storey 2 855 2100
Storey 1 875 2250
Base 0 0
Table 3: Storey shear
Fig. 10: Comparison of values in graph
Study on Seismic Responses of Masonry Brick Infill Walls in Slender Structures
(IJSRD/Vol. 2/Issue 09/2014/197)
All rights reserved by www.ijsrd.com 856
B. Modal Analysis
The Modal analysis was performed to two models and we
getting the periods of the structure
Fig. 11: Modal-5Bare Frame, Modal-5 Brick infilled Frame
Period-0.425 Period-0.937
C. Dynamic Analysis (Time History Analysis)
The time history analysis technique represents the most
sophisticated method of dynamic analysis for buildings. I
this method the mathematical model of the building is
subjected to accelerations from earthquake records. This
method consists of a step by step direct integration over a
time interval; the equations of motion are solved with the
displacements, velocities and accelerations.
1) Acceleration
Bare Frame Brick Infilled Frame
Fig. 12: Acceleration
TIME BARE
FRAME
BRICK
INFILLED
1 30.0 15.5
2 29.0 10.0
3 19.0 5.9
4 11.0 3.0
5 6.5 3.0
6 6.0 2.8
7 3.0 2.0
8 3.0 1.0
9 3.0 1.0
10 3.1 1.0
Table 4:.Acceleration
Fig. 13: Comparison of values in graph
2) Velocity
Bare Frame Brick Infilled Frame
Fig. 14: Velocity
TIME BARE
FRAME
BRICK
INFILLED
1 8 2.1
2 5.5 1.25
3 3.2 0.68
Study on Seismic Responses of Masonry Brick Infill Walls in Slender Structures
(IJSRD/Vol. 2/Issue 09/2014/197)
All rights reserved by www.ijsrd.com 857
4 1.9 0.49
5 1.7 0.45
6 1.0 0.40
7 0.8 0.22
8 0.8 0.20
9 0.8 0.20
10 0.9 0.20
Table 5: Velocity
Fig. 15: Comparison of values in graph
3) Displacement
Bare Frame Brick Infilled Frame
Fig. 16: Displacement
TIME BARE
FRAME
BRICK
INFILLED
1 1.4 0.20
2 1.1 0.14
3 0.6 0.08
4 0.3 0.07
5 0.2 0.06
6 0.1 0.05
7 0.2 0.03
8 0.2 0.02
9 0.2 0.02
10 0.3 0.02
Table 6:.Displacement
Fig. 17: Comparison of values in graph
IV. SUMMARY AND CONCLUSION
1) Investigated the effect of Masonry Brick Infill
Walls in seismic response of structure
2) Familiarized the software
3) Compared the results and find out Masonry Brick
Infill Frames having good response to earthquake
4) From Modal analysis Period of masonry brick infill
wall frame greater than bare frame
5) It can be concluded that brick infill walls is to be
included and carrying out seismic analysis of
multistoried frames
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