COMPARATIVE STUDY OF MASONRY INFILLED RC FRAME WITH AND WITHOUT
OPENING BY USING STATIC AND DYNAMIC ANALYSIS
NAGARAJA B.S1, Ms.HEMALATHA M2, Mr. DHARMESH N3 AND Mr. MADHUSUDHANA Y.B4
PG Student, 2Assistant Professor, Department of Civil Engineering (CADS), SIET, Tumkur, Karnataka, India.
3,4
Assistant Professors, Department of Civil Engineering, East Point College of Engineering and Technology, Bangalore,
Karnataka, India.
Abstract: Masonry infill frames are the most common structural systems in earthquake regions. They play a significant role in
resisting seismic forces when earthquake happens. The stiffness and strength contributions of infill frames are generally neglected
during practice. They are considered as non-structural components and usually added after the frame has constructed. In the
present study, two buildings of G+3 and G+12 are considered for seismic zone v consisting hard soil for the analysis. Totally 7
models are made for the analysis using software ETABS version 2013. The response parameters of 7 Models such as Base Shear,
Mode Period, Storey Displacement, Storey Accelerations and Storey Shear are studied and comparisons are made for both
Equivalent static lateral force method and Time history analysis. As the height and mass participation of the structure increases,
Base Shear and Mode Period also increase. If percentage of opening increases, the stiffness reduces. Simultaneously but the Mode
period and Displacement increases and frequency reduces due to which acceleration decreases for both G+3 and G+12 Buildings.
Compared to ESLM and TH analyses, the Time history analysis shows better performance than Equivalent static lateral force
method and G+3 building shows lesser displacement compared to G+12 Building.
1
Keywords: SMRF, Masonry infill, Equivalent Diagonal Strut Model, Equivalent Static Lateral force Method (ESLM), Time
History analysis (TH).
Model-2: RC frame with complete masonry infill strut.
Model-3: RC frame with open ground soft storey of
I. INTRODUCTION
complete masonry infill strut.
A. Infilled frames
Model-4: RC frame with 15% opening.
Generally Brick Infill panels or walls are provided
Model-5: RC frame with 30% opening.
in between Beams and Columns of RC frame Structures.
Model-6: RC frame with 45% opening.
This type of composite structures done by combination of
Model-7: RC frame with 60% opening.
moment resisting RC plane frame with brick infill wall
These seven building Models are analyzed for the
panel can be called as “Infilled Frame”. They are
following
cases.
economical also durable and having fire resistance character
a.
Effect
of masonry infill RC frame using above
and good thermal, sound insulation and they are considered
Models for both G+3 and G+12 buildings are studied using
as non-structural elements and provided for architectural and
Equivalent Static Lateral force Method.
functional reasons; their strength and stiffness consequences
b. Effect of Masonry infill RC frame using above
are ignored in analysis of structures, such as computer
Models
for both G+3 and G+12 buildings are studied using
technology and various modern computational resources.
Time
History
analysis.
Because of various complications included in the analysis
and uncertainties to the non-integral action in between
masonry infill and RC frame, so that analysis of buildings
are being based only on the frames.
In the RC frame, Infill walls add their self-weight
in static condition. When subjected to seismic forces, infill
wall interact with RC frame and shows energy absorbing
character. As seismic load increases, masonry infill tends to
separate from its boundary of RC frame, which can carry a
part of the compressed force by providing strut action of
infill to the frame. So, masonry infill frames are much
helpful during the time of earthquake.
B. Types of masonry infill provisions
Infill has provided completely or with openings
according to the need of provisions like partitions, windows
and doors. The following are four general types,
1. Bare Frame
2. Complete Infilled Frame
3. Infilled Frame with opening
4. Partial Infilled Frame.
III. OBJECTIVES OF THE WORK
The objectives include the following.
1. To find the response of 4 storey and 13 storey masonry
infill RC frame with above said Models. the storey shear,
base shear, displacement and using Equivalent lateral force
method and storey acceleration by time history analysis.
Numerical Modeling and analysis are carried out using
ETABS version 2013 software.
2. To differentiate performance of masonry infill RC frames
with bare frame and some percentage of openings to
conclude the effectiveness of infill in RC frame.
II. PARAMETRIC STUDIES
A 3D RC infill frames with G+3 and G+12 storey
buildings have taken for Static and dynamic analysis.
Totally 7 Models are considered for comparison.
Model-1: RC frame without masonry infill strut (Bare
frame).
Fig 1: The details of Equivalent Diagonal Strut Model
IV. BUILDING DATA FOR ANALYSIS
Type of structure (building) = Commercial Building
Number of Storeys = G+3 and G+12
Storey height = 4 m for all storeys.
C. Load Considerations
Unit weight of RCC = 25 kN/m3
Unit weight of Masonry = 20 kN/m3
Unit weight of Steel = 77 kN/m3
Live load
3 kN/m2 for other Floors (as per IS 875 part 2)
1 kN/m2 for Terrace
Floor Finish
1.5 kN/m2 for other Floors
0.5 kN/m2 for Terrace
Seismic Zone = V
Response Reduction Factor for SMRF = 5
Damping in Structure = 5%
V. CALCULATION OF WIDTH OF DIAGONAL STRUT
Analysis has carried out using Mainstone R-J
formulae for calculating width of compressive diagonal strut
by assuming the thickness of strut is equal to thickness of
masonry wall.
W=0.175[λ H]-0.4 * √ (H2+L2)
(1.1)
Where, W = (4≤ λ H≤5)
d = √ (H2+L2)
4 𝐸𝑚 𝑡 sin 2Ɵ
λ= √
4 𝐸𝑐 𝐼𝑐 ℎ
Table 1: Width of Equivalent Diagonal Strut (for G+12)
Opening
Percentage (%)
Stiffness
Reduction
Factor (ƛ)
10 m
in X
axis
Width 7 m in
X axis
of
strut
8 m in
(W)
Y axis
10 m
in Y
axis
0%
15 %
30 %
45 %
60 %
1.0
0.47
0.26
0.16
0.14
1.543
0.725
0.401
0.247
0.216
1.12
0.526
0.29
0.18
0.157
1.255
0.59
0.326
0.2
0.176
1.543
0.725
0.401
0.247
0.216
Fig 2: Plan of G+12 and G+3 Buildings
A. Materials used
fm= Compressive Strength of Brick Infill = 10 MPa
Em= 550fm kN/m2
Ec = Modulus of Elasticity of Concrete = 5000√fck MPa
B. Section Properties
For G+3
Size of Column = 450*450 mm
Size of Beam = 400*500 mm
Depth of Slab = 125 mm
Infill Wall thickness = 250 mm
For G+12
Size of Column = 1000*1000 mm
Size of Beam = 400*500 mm
Depth of Slab = 125 mm
Infill Wall thickness = 250 mm
Fig 3: Plan and 3-D view of Model 6 (G+3)
Storey Shear (kN)
Storey Shear for different Models in Y-Y
direction using TH (G+12)
Model-1
80000
60000
40000
20000
0
0
5
10
No. of Storeys
15
Model-2
Model-3
Model-4
Model-5
Model-6
Model-7
Fig 8: Comparison of Storey Shear for different Models in Y-Y
direction using TH for G+12
Fig 4: Elevation of Model 6 (G+3) in X-Z direction and Y-Z direction
it can be found that the Storey Shear increases in the
range of 53% to 55% in Storey-1 compared with Storey-4
for G+3, 84% to 85% in Storey-1 compared with Storey-13
for G+12 in X–X direction, 53% to 55% in Storey-1
compared with Storey-4 for G+3, 84% to 85% in Storey-1
compared with Storey-12 for G+12 in Y-Y direction using
ESLM analysis and 60% to 79% in Storey-1 compared with
Storey-3 for G+3, 72% to 91% in Storey-1 compared with
Storey-13 for G+12 in X-X direction, 66% to 78% in
Storey-1 compared with Storey-4 for G+3, 72% to 92% in
Storey-1 compared with Storey-13 for G+12 building in YY direction using TH analysis.
Fig 5: Plan and 3-D view of Model 6 (G+12)
This is because of as the No. of Storey increases; the
Seismic weight of the Structure also increases. Hence top
floor has minimum Storey Shear and maximum at the
bottom floor. The Time History values show maximum
Storey Shear compared to ESLM analysis.
B. Base shear
Base Shear for G+3
Fig 6: Elevation of Model 6 (G+12) in X-Z direction and Y-Z direction
VI. RESULTS AND DISCUSSIONS
A. Storey shear
Storey Shear (kN)
Storey Shear for different Models in YY direction using ESLM (G+12)
Model-1
14000
12000
Model-2
10000
Model-3
8000
Model-4
6000
4000
Model-5
2000
Model-6
0
0
5
10
15 Model-7
No. of Storeys
Fig 7: Comparison of Storey Shear for different Models in Y-Y
direction using ESLM for G+12
Base Shear (kN)
15000
ESLM X-X
10000
ESLM Y-Y
TH X-X
5000
TH Y-Y
0
1
2
3 4 5 6
No. of Models
7
Fig 9: Comparison of Base Shear along X-X and Y-Y direction for
different Models (G+3)
It can be observed from table 5.1 and 5.2, the base shear
decreases in bare frame Model in the range of 44% to 35%
for G+3 and 55% to 46% for G+12 building along X-X
direction and in the range of 44% to 35% for G+3 and 64%
to 57% for G+12 building along Y-Y direction using ESLM
analysis. It can be also observed that from the above tables,
the base shear decreases in bare frame Model in the range of
56% to 30% for G+3 and 87% to 84% G+12 building along
X-X direction and in the range of 51% to 13% for G+3 and
90% to 84% for G+12 building along Y-Y direction using
TH analysis compared to other Models. The Model 2 of G+3
building has high base shear compare to other Models
because of increase in seismic weight of structure and also
mass participation factor. But in Time history analysis,
4
5
6
7
4
43.2
5.1
15.8
9
14
19.6
21.4
3
35.9
4.3
15
7.6
11.8
16.6
18.1
2
23.9
2.9
13.7
5.2
8.2
11.4
12.4
1
9.7
1.4
11.8
2.5
3.8
5.2
5.6
Table 3: Comparison of Storey Displacement along X-X direction
for different Models using TH (G+3)
No. of
Storeys
4
3
2
1
1
83.3
72
50.4
20.9
Storey Displacement (mm)
No. of Models
2
3
4
5
6
10.7 41.2 16.7 23.8 33.4
9.4
40 14.8 20.8 29.4
6.9 37.7 11.3 15.2 21.4
3.4 33.2 5.9
7.5 10.4
7
45.4
39.3
28
13
It can be discussed that there was increase in
Displacement nearly in the range of 25% to 77% in X-X
direction, 24% to 77% in Y-Y direction in Storey-4
compared to Storey-1 for G+3 building and 76% to 98% in
X-X direction, 69% to 98% in Y-Y direction in Storey-13
compared to Storey-1 for G+12 building in ESLM analysis
and 19% to 75% in X-X direction, 18% to 74% in Y-Y
direction in Storey-4 compared to Storey-1 for G+3 and
70% to 98% in X-X direction, 63% to 96% in Y-Y direction
in Storey-13 compared to Storey-1 for G+12 building in TH
analysis for all the 7 Models (i.e. Model-1 to Model-7).
This shows the Displacement value is increased in top
floor compared to bottom floor because of increase in Mode
period from bottom storey to top Storey and Stiffness
Participation factor is less in top floor compared to bottom
floor in both X-X and Y-Y directions for all the Models of
G+3 and G+12 buildings.
0
Model-6
0
5
10
No. of Storeys
15
Model-7
Fig 11: Comparison of Storey Acceleration in Y-Y direction for
different Models (G+12)
It is observed that, Acceleration was increased in
Storey-4 compared to Storey-1 nearly in the range of 15% to
50% for G+3 building and 35% to 76% in Storey-13
compared to Storey-1 for G+12 building for all Models (i.e.
Model 1 to Model-7) in X-X direction and 17% to 56% in
Storey-4 compared to Storey-1 for G+3, 33% to 81% in
Storey-13 compared to Storey-1 for G+12 building for all
Models (i.e. Model-1 to Model-7) in Y-Y direction using
Time History analysis.
This shows that acceleration value is more at top floor
compared to bottom floor because of Mass Participation,
Stiffness and Frequency are increases in bottom floor,
acceleration also increases from ground floor to top floor,
along both X-X and Y-Y direction for all Models of G+3
and G+12 buildings.
E. Mode period
Mode period (G+3)
1.5
X-X
direction
1
Y-Y
direction
0.5
0
Model-7
3
Model-5
Model-6
2
Model-4
2
Model-5
1
Model-3
4
Model-4
No. of Models
Model-2
Model-3
No. of
Storeys
6
Model-2
Storey Displacement (mm)
Model-1
Model-1
Table 2: Comparison of Storey Displacement along X-X direction for
different Models using ESLM (G+3)
8
Mode period (sec)
C. Storey displacement
Storey Acceleration in Y-Y direction for
different Models (G+12)
Acceleration (m/s2)
Model 3 has high base shear because, when Exact
Earthquake conditions were simulated. The mass
participation factor reduces even the seismic weight remains
constant in both X-X and Y-Y direction.
Torsion
No. of Models
Fig 12: Comparison of Mode Period for different Models (G+3)
4
Storey Acceleration in Y-Y direction for
different Models (G+3)
Model-1
Model-2
3
Model-3
2
Model-4
1
Model-5
Mode period (sec)
Acceleration (m/sec2)
D. Storey acceleration
4
Mode period (G+12)
X-X
direction
3
2
1
Y-Y
direction
0
Torsion
Model-6
0
0
2
4
No. of Storeys
6
Model-7
Fig 10: Comparison of Storey Acceleration in Y-Y direction for
different Models (G+3)
No. of Models
Fig 13: Comparison of Mode Period for different Models (G+12)
The Mode Period of Model-1 of G+3 building is
decreases in the range of 71% to 40% along X-X direction
and 72% to 42% in Y-Y direction and 71% to 39% in X-Y
direction compared to other Models. Also The Mode Period
of Model-1 of the G+12 building is decreases by 90% to
86% in X-X direction, and 92% to 87% in Y-Y direction
and 93% to 87% in X-Y direction compared with that of
other Models.
This is because of, as Stiffness and mass of the
Structure increases, Mode period will reduces. So that
Model 1 has lesser Stiffness value and have larger value in
the Mode Period compared to other Models in both G+3 and
G+12 buildings.
VII. CONCLUSIONS
1.
2.
3.
4.
5.
6.
7.
8.
9.
As Number of Storeys increase, Seismic Weight of
Structure increases due to which Base shear is
gradually increased.
As the Mass Participation increases, Base Shear
increases.
As the Height of the Structure increases, Mode
Period increases.
As the Percentage of opening in Structure
increased, Stiffness reduces due to which Mode
period will automatically increase.
As the Mode Period of Structure increases,
Displacement increases.
Since Mode Period increases, Frequency decreases
due to which Acceleration also decreases.
It is observed that, Time History analysis shows
better performance compared to ESLM analysis.
Based on the results, the complete Infill frame
shows less damage (Displacement) compared to
other Models. As Percentage of opening increases
with increasing Displacement, the Stiffness
Participation factor (ƛ) is more in complete Infill
frame compared to other Models for both G+3 and
G+12 Buildings.
From the analysis, it is also concluded that the G+3
Building show lesser Displacement compared to
G+12 Building.
VIII. FUTURE SCOPE
1.
2.
3.
This project can be continued by replacing
Masonry Infill wall with different Lateral Resisting
Systems like Bracings and Shear Wall.
The Study on the performance of same Structure
continued through Soil Structure interaction.
The Study can be carried out by nonlinear Static
analysis.
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