1. The document describes a project seminar on parametric study of multi-storey reinforced concrete flat slab structures under seismic effects with varying plan aspect ratios and slenderness ratios. 2. 25 structural models are created with different plan dimensions, aspect ratios ranging from 1-5, and slenderness ratios ranging from 0.48-2.88. Static and dynamic analysis is performed using ETABS software. 3. Results for base shear, storey drift, storey stiffness, natural period, and maximum displacements are obtained and compared across the models to determine limiting aspect and slenderness ratios for seismic safety of the structures.

1. NAGPUR INSTITUTE OF TECHNOLOGY, NAGPUR
(Department of civil engineering Session 2015-16)
4th
Project seminar on
“Parametric study of multi storied R.C.C flat slab structure
under seismic effect having different plan aspect ratio and
slenderness ratio.”
Submitted by
Sourabh Kumar
Shubham Borkar
Under the guidance
Prof. Sudhir Kapgate

2. • Aim
• Objective
• Introduction
• Literature Survey
• Structural Modeling
• Result And Discussion
• Conclusion
• Future Scope
• References
CONTENT

3. AIM
Parametric study of multi storied R.C.C flat
slab structure under seismic effect having
different plan aspect ratio and slenderness
ratio.

4. OBJECTIVE
• To perform parametric study on behaviour of multi
storied R.C.C. flat slab structure having same plan area
but different plan aspect ratio (L/B) and slenderness ratio
(H/B), under seismic condition.
• To perform static and dynamic analysis using ETABS 15
software.
• To calculate and study the response of structure situated in
seismic zone IV and their comparison.
• To determine limit aspect ratio and slenderness ratio for
safe and stable structure.

5. INTRODUCTION
FLAT SLAB
A slab is a flat, two dimensional, planar structural element having thickness
small compared to its other two dimensions. It provides a working flat surface or
a covering shelter in buildings. It supports mainly transverse loads and transfers
them to support primarily by bending element just like flat plate. Hence in
warehouses, offices and public halls sometimes beams are avoided and slabs are
directly supported by columns. These types of construction are aesthetically
appealing also. These slabs which are directly supported by columns are called
Flat Slabs.
COMPONENTS OF FLAT SLAB
• Drops
• Column Head
• Column Strip
• Middle Strip

6. SEISMIC ANALYSIS
• Earthquake is unpredictable and massive damage causing phenomena of nature.
• Deals with dynamic forces.
• Large forces hence can not design structure economically.
• Various BIS guidelines are available for analyze, design and detailing.
• Response spectrum method is used for analysis.

7. Building Configuration
1. It is one of the most important parameter for Earthquake Resistant structure.
Because a great deal of resistance is provided by the basic configuration and
structural system of a building. The design of buildings for earthquake loads
requires an early and close collaboration between the architect and engineer to
arrive at the optimum structural design while still satisfying the functional and
aesthetic needs of the client.
2. As per BIS guideline in IS 1893:2002 {Clause 7.1} says “Regular and
Irregular Configuration to perform well in an earthquake, a building should
possess four main attributes, namely simple and regular configuration, and
adequate lateral strength, stiffness and ductility. Buildings having simple
regular geometry and uniformly distributed mass and stiffness in plan as well
as in elevation, suffer much less damage than buildings with irregular
configurations”.
3. In IS 4326:1993 {Clause 4.4.1} it is mentioned that “The building should
have a simple rectangular plan and be symmetrical both with respect to mass
and rigidity so that the center of mass and rigidity of the building coincide
with each other.” But the limiting “Plan aspect ratio” and “Slenderness ratio”
for the regular structure is not prescribed.

8. 4. Due to inadequate space available at important location of city, high land
rates and for economical utilization of space architects and engineers are
planning and constructing such buildings which are having larger aspect
ratio and higher slenderness ratio. The buildings, especially of
institutional or commercial use are having lager plan aspect ratio and
slenderness ratio.
With this background it is found essential to study the behaviour of buildings
having large aspect ratio and slenderness ratio under seismic condition to predict
maximum losses would occur and control measures to be taken to overcome this
problem. This is the primary motivation underlying the present study

9. LITERATURE SURVEY
1. Rucha S. Banginwar and M. R. Vyawahare, (2012) “Effect of Plans
Configurations on the Seismic Behaviour of the Structure By Response
Spectrum Method”
The study is carried on the effect of different geometrical configurations on the
behaviour of structure of the already constructed building located in the same area
during earthquake by Response spectrum method (RSM) in this paper, more emphasis
is made on the plan configurations and is analysed by RSM since the RSM analysis
provides key information for real – world application.
In the present study the response (i.e. behaviour) of already constructed three buildings
of college which are having different building geometric configuration in plan has
been studied with the help of response spectrum method and at the end out of these
three buildings, vulnerable building has been detected.
The conclusions of this study are briefly described as follows:
• The plan configurations of structure have substantial impact on the seismic
response of structure in terms of lateral deformation and storey shear.
• Effect of area on Storey shear; it was observed that the storey shear in ‘T’ shape
building was more though the irregularity in the plan configuration was less as
compared to ‘V’ shaped building.
• Torsion- Torsion was observed only in ‘V’ shaped building as the level of
irregularity is maximum. The building is symmetrical about one axis but the
orientation of block is oblique.

10. • Displacement – Large displacement were observed in the ‘V’ shape building and
least displacement were observed in rectangular building. It indicates that building
with severe irregularity shows maximum displacement and storey drift.
2. K S Sable (2012), “Comparative Study of Seismic Behaviour of Multi-
storey Flat Slab and Conventional Reinforced Concrete Framed
Structures”
This paper presents a summary of the study, for conventional R.C.C framed structure
building and flat slab building for different floor height. The effect of seismic load has
been studied for the two types of building by changing overall height of structure. On
the basis of the results obtained in this study, following conclusions have been drawn:
• The natural time period increases as the height of building ( No. of stories)
increases, irrespective of type of building viz. conventional structure, flat slab
structure and flat slab with shear wall. However, the time period is same for flat
slab structure and flat slab with shear wall.
• In comparison of the conventional R.C.C. building to flat slab building, the time
period is more for conventional building than flat slab building because of
monolithic construction.

11. • For all the structure, base shear increases as the height increases. This increase in
base shear is gradual up to 9th storey, thereafter, it increases significantly gives rise
to further investigation on the topic.
• Base shear of conventional R.C.C building is less than the flat slab building.
• Storey drift in buildings with flat slab construction is considerably more as
compared to conventional R.C.C building. This influences moment which is
developed during earthquake. In flat slab construction additional moments are
developed. Thus, the columns of such buildings should be designed by considering
additional moment caused by the Storey drift.
• A structure with a large degree of indeterminacy is superior to one with less
indeterminacy, this is primarily because of more members are monolithically
connected to each other and if yielding takes place in any one of them, then a
redistribution of forces takes place. As a result, the structure can sustain to take
additional load. Additionally, redistribution reduces as the number of member
reduces in a selected lateral load resisting system

12. 3. Arun Solomon (2013) “Limitation of irregular structure for seismic
response”
In this study, non-linear behavior of irregular structures. Because of the limitations of
available size and shape of land for construction of buildings some of the structures
become highly irregular as too long and too tall. The intension of this study was to identify
the limitations of the too long and too tall structures using the software SAP 2000.
Author’s aim was to show structure having regular building configuration behaves like
irregular structure when it is too long and too tall regular structure by performing non-
linear analysis (Pushover analysis).
From the investigation on the two types of too long structures the following results
are obtained. The aspect ratio of the building is
1. Type I Building aspect Ratio (85/15) = 5.66.
2. Type II Building aspect Ratio (145/25) = 5.8
Author has concluded that
• The too long structures does not meet the performance limit if one of the plan
dimension of the structure go beyond 5.6 times of another dimension, the
building. Hence such types of too long buildings should be avoided while constructing
in earthquake prone areas.
• From the study on too tall structure the subsequent result is obtained by author. If thr
slenderness ratio of the building is (92/15) = 6.13 then a too tall structure does not meet
the performance limit if the structure’s slenderness ratio exceeds 6.13.

13. STRUCTURAL MODELING
Modeling a structure involves the modeling and assemblage of its various
load-carrying elements. The model must ideally represent the mass
distribution, strength, stiffness and deformability. Modeling and analysis is
done with the help of ETABS 15 software. All 25 structures are separately
modeled and analyzed by RSM.
Template available for flat slab with drop are used to create models in ETABS
software, proper material properties and joint restrains are assigned and
column are assigned fixed support at base. Slabs and drops are assigned as
Diaphragms which resist in plane deflection.
Following table represents all 25 models classified in different groups and
named accordingly.

14. Sr.No
Model
Group
Model
Aspect
Ratio
Length
(m)
Width
(m)
Column
Spacing
(m)
No. Of
Storey
Storey
Height
(m)
Slenderness
Ratio
(L:B) L B X Z 3.60 (H:B)
1
M1
M11
1 30 30 6 6
3 14.40 0.48
2 M12 5 21.60 0.72
3 M13 7 28.80 0.96
4 M14 9 36.00 1.2
5 M15 11 43.20 1.44
6
M2
M21
2 41 22 5.85 5.5
3 14.40 0.69
7 M22 5 21.60 1.03
8 M23 7 28.80 1.37
9 M24 9 36.00 1.71
10 M25 11 43.20 2.06
11
M3
M31
3 50 18 5 6
3 14.40 0.85
12 M32 5 21.60 1.27
13 M33 7 28.80 1.69
14 M34 9 36.00 2.12
15 M35 11 43.20 2.54
16
M4
M41
4 60 15 6 5
3 14.40 0.96
17 M42 5 21.60 1.44
18 M43 7 28.80 1.92
19 M44 9 36.00 2.4
20 M45 11 43.20 2.88
21
M5
M51
5 75 12 6.25 6
3 14.40 1.11
22 M52 5 21.60 1.66
23 M53 7 28.80 2.22
24 M54 9 36.00 2.77

15. Sr.
No.
Design Parameter Value
1 Unit weight of concrete 25 kN/m3
2 Characteristic strength of concrete 30 MPa
3 Characteristic strength of steel 415 MPa
4 Modulus of elasticity of steel 2 x 105 MPa
5 Plan area 900 square meters
6 Slab thickness 200 mm
7 Drop thickness 300 mm
8 Depth of foundation 3.5m
9 Floor height 3.6m
MATERIAL PROPERTIES AND GEOMETRIC PARAMETERS

16. Sr.No. Design Parameter Value
1 Earthquake Load As Per IS 1893 (Part 1)-2002
2 Type Of Foundation Isolated Column Footing
3 Depth Of Foundation 3.5m
4 Type Of Soil Type II, Medium As Per IS 1893:2002
5 Bearing Capacity Of Soil 200 kN/m2
6 Seismic Zone IV
7 Zone factor (Z) 0.24
8 Response reduction factor (R) 5
9 Importance Factor 1
10 Percentage Damping 5%
11 Type Of Frame Special Moment Resisting Frame
SEISMIC DESIGN DATA

17. LOAD CONSIDERED FOR ANALYSIS OF BUILDING
Sr.No. Load Type Value
1 Self-weight of Slab and Column
As per Dimension and Unit
weight of concrete
2 Dead load of structural components As per IS 875 Part-1
3 Live Load As per IS 875 Part -2
4 Live load : on Roof and Typical floor 4.0 kN/m2
5 Floor Finish 2.0 kN/m2
CROSS SECTIONAL DIMENSION FOR COLUMN
Sr. No. Type of Structure Column sizes
1 G+ 3 (5 storey structure) 450 mm X 450 mm
2 G+ 5 (7 Storey structure) 450 mm X 450 mm
3 G+ 7 (9 Storey structure) 450 mm X 450 mm
4 G+ 9 (11 Storey structure) 600 mm X 600 mm
5 G+ 11 (13 Storey structure) 600 mm X 600 mm

18. BASE SHEAR (VB)
Design codes represent the earthquake-induced inertia forces as the net effect of such
random shaking in the form of design equivalent static lateral force.
Base Shear is total design lateral force at the base of structure. So, base shear is nothing but
the maximum expected lateral force that will occur due to seismic ground motion at the
base of a structure.
MAXIMUM STOREY DRIFT
Drift is the lateral movement of a building under the influence of earthquake induced
vibrations. Storey drift is the lateral displacement of one level relative to the level above or
below. It can also be defined as the drift of one level of a multistorey building relative to
the level below. It is difference between lateral displacements of adjacent storey.

19. NATURAL PERIOD
Natural Period (Tn) of a building is the time taken by it to undergo one complete cycle of
oscillation. It is an inherent property of a building controlled by its mass m and stiffness k.
Its units are seconds (s). Thus, buildings that are heavy (with larger mass m) and flexible
(with smaller stiffness k) have larger natural period than light and stiff buildings.
NATURAL FREQUENCY
The reciprocal (1/Tn) of natural period of a building is called the Natural Frequency fn; its
unit is Hertz (Hz). The building offers least resistance when shaken at its natural frequency
(or natural period).

20. RESULT AND DISCUSSION
PARAMETER FOR COMPARATIVE STUDY
Following parameters are considered for comparative study of analysis results
of all 25 models.
• Base shear
• Storey drift
• Storey stiffness
• Maximum storey displacement
• Natural time period
Results obtained from software analysis of all 25 models were filtered and then
arranged to compare it with respective values of other models. For better
understanding of results graphs are plotted.

21. RESULTS FOR MODEL M11
SN STOREY Shear X Drift X Stiffness
X
Shear Y Drift Y Stiffness Y Displacement
X
Displacement
Y
kN Mm kN/m kN Mm kN/m mm mm
1 2 3 4 5 6 7 8 9
1 STOREY5 1029.721 3.8 274140.2 1029.721 3.8 274140.2 28.7 28.7
2 STOREY4 1595.299 5.8 274828.4 1595.299 5.8 274828.4 25.6 25.6
3 STOREY3 1962.43 7.3 270623 1962.43 7.3 270623 20.4 20.4
4 STOREY2 2311.962 8.1 286026.4 2311.962 8.1 286026.4 13.5 13.5
5 STOREY1 2583.759 5.4 475483.2 2583.759 5.4 475483.2 5.4 5.4
6 BASE 0 0
RESULTS FOR MODEL M21
SN STOREY Shear X Drift X Stiffness
X
Shear Y Drift Y Stiffness Y Displacement
X
Displacement
Y
kN Mm kN/m kN mm kN/m mm mm
1 2 3 4 5 6 7 8 9
1 STOREY5
1031.403 3.4 302630.2 1022.38 3.3 312406.5 26.5 25.5
2 STOREY4
1618.888 5.3 303751.8 1614.999 5.1 315708.7 23.7 22.8
3 STOREY3
2009.261 6.7 299344.3 2010.987 6.4 312635.9 18.9 18.2
4 STOREY2
2367.846 7.5 316271.8 2370.341 7.2 330083.3 12.4 12
5 STOREY1
2635.777 5 525762.1 2635.779 4.9 541599.8 5 4.9
6 BASE 0 0

22. Results for model M31
SN STOREY Shear X Drift X Stiffness
X
Shear Y Drift Y Stiffness Y Displacement
X
Displacement
Y
kN Mm kN/m kN mm kN/m mm mm
1 2 3 4 5 6 7 8 9
1 STOREY5
1035.748 3.2 320199.7 1048.994 3.5 302434.6 25.6 26.7
2 STOREY4
1640.546 5.1 321193.3 1646.386 5.4 306086.5 22.9 23.8
3 STOREY3
2045.088 6.5 316728.9 2041.164 6.7 302978.8 18.3 19
4 STOREY2
2410.73 7.2 333205.4 2406.145 7.5 320973.6 12.1 12.5
5 STOREY1
2680.553 4.9 545329.7 2680.553 5 532491.7 4.9 5
6 BASE 0 0
Results for model M41
SN STOREY Shear X Drift X Stiffness
X
Shear Y Drift Y Stiffness Y Displacement
X
Displacement
Y
kN Mm kN/m kN mm kN/m mm mm
1 2 3 4 5 6 7 8 9
1 STOREY5
1061.909 3.6 295525.2 1033.535 3.2 325995.6 27.7 24.7
2 STOREY4
1656.292 5.6 295899.6 1643.993 4.9 332708.6 24.8 22
3 STOREY3
2046.92 7 290892.1 2052.612 6.2 331574.2 19.7 17.6
4 STOREY2
2412.306 7.8 307906.7 2420.332 6.9 350073.1 13 11.6
5 STOREY1
2690.351 5.2 517051.7 2690.352 4.8 565040.2 5.2 4.8
6 BASE 0 0

23. Results for model M51
SN STOREY Shear X Drift X Stiffness
X
Shear Y Drift Y Stiffness Y Displacement
X
Displacement
Y
kN Mm kN/m kN mm kN/m mm mm
1 2 3 4 5 6 7 8 9
1 STOREY5
1076.337 4.2 253617.5 1053.084 3.9 272967.9 31.6 29.1
2 STOREY4
1638.553 6.5 252628.1 1628.855 5.9 275226.1 28.2 26
3 STOREY3
1993.066 8.1 247292 1999.221 7.4 271845.6 22.5 20.7
4 STOREY2
2347.955 8.9 262573.4 2355.789 8.2 287630.2 14.8 13.7
5 STOREY1
2636.396 5.9 447252.8 2636.39 5.5 476117.9 5.9 5.5
6 BASE 0 0
SN Mode Period Frequenc
y
Period Frequenc
y
Period Frequency Period Frequenc
y
Period Frequenc
y
sec cyc/sec sec cyc/sec sec cyc/sec sec cyc/sec sec cyc/sec
M11 M21 M31 M41 M51
1 1 1.561 0.641 1.488 0.672 1.492 0.67 1.523 0.657 1.523 0.657
2 2 1.551 0.645 1.459 0.685 1.462 0.684 1.434 0.697 1.434 0.697
3 3 1.438 0.695 1.374 0.728 1.42 0.704 1.384 0.722 1.384 0.722
4 4 0.495 2.02 0.473 2.116 0.474 2.111 0.482 2.073 0.482 2.073
5 5 0.493 2.03 0.465 2.152 0.466 2.146 0.458 2.183 0.458 2.183
6 6 0.453 2.209 0.434 2.303 0.449 2.229 0.44 2.275 0.44 2.275
7 7 0.276 3.622 0.264 3.788 0.265 3.779 0.269 3.724 0.269 3.724
8 8 0.275 3.634 0.261 3.837 0.262 3.816 0.258 3.87 0.258 3.87
9 9 0.249 4.011 0.241 4.158 0.248 4.027 0.245 4.077 0.245 4.077
10 10 0.187 5.335 0.179 5.572 0.18 5.547 0.182 5.503 0.182 5.503
11 11 0.187 5.344 0.178 5.607 0.179 5.574 0.178 5.607 0.178 5.607
12 12 0.167 5.999 0.162 6.175 0.167 5.98 0.167 5.989 0.167 5.989
Variation in period and frequency

24. RESULTS FOR MAXIMUM DIFLECTION
0
1
2
3
4
5
6
0 5 10 15 20 25 30 35
storey
Displacement in mm
Displacement in X
m11
m21
m31
m41
m51
0
1
2
3
4
5
0
1
2
3
4
5
0
1
2
3
4
5
0
1
2
3
4
5
0
1
2
3
4
5
0
1
2
3
4
5
6
0 5 10 15 20 25 30 35
NOOFSTORY
Displacement in mm
Displacement in y
m11
m21
m31
m41
m51
FOR G+3 STOREY
FOR G+5 STOREY
0
1
2
3
4
5
6
7
8
0 10 20 30 40 50 60
NoofStory
Displacement in X (mm)
Displacement in X
m12
m22
m32
m42
m52
0
1
2
3
4
5
6
7
8
0 10 20 30 40 50
NoofStory
Displacement in Y (mm)
Displacement in y
m12
m22
m32
m42
m52

25. FOR G+7 STOREY
0
1
2
3
4
5
6
7
8
9
10
0 10 20 30 40 50 60 70
Storey
Displacements IN X (mm)
Displacement in X
M13
M23
M33
M43
M53
0
1
2
3
4
5
6
7
8
9
10
0 10 20 30 40 50 60 70
Storey
Displacements Y (mm)
Displacement in y
M13
M23
M33
M43
M53
FOR G+9 STOREY
0
2
4
6
8
10
12
0 20 40 60 80
Storey
Displacements mm
Displacement in X
M14
M24
M34
M44
M54
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70
Storey
Displacements mm
Displacement in Y
M14
M24
M34
M44
M54

26. 0
2
4
6
8
10
12
14
0 20 40 60 80 100 120 140
storey
Displacements in X mm
Displacements in X
M15
M25
M35
M45
M55
0
2
4
6
8
10
12
14
0 50 100 150 200
storey
Displacement in y (mm)
Displacements in Y
M15
M25
M35
M45
M55
FOR G+11 STOREY
OBSERVATION
From above graphs points observed are as following
• Displacement for aspect ratio L/B = 5 is maximum.
• For first mode displacement in x direction is greater than y direction up to G+9
models.
• Displacement decreases with increase in aspect ratio up to L/B = 3.

27. RESULTS FOR MAXIMUM STOREY DRIFT
FOR G+3 STOREY
0
1
2
3
4
5
6
0 0.001 0.002 0.003
NoofStorey
Drift in x (m)
Drift in X
m11
m21
m31
m41
m51
0
1
2
3
4
5
6
0 0.001 0.002 0.003
NoofStorey
Drift in x (m)
Drift in Y
m11
m21
m31
m41
m51
FOR G+3 STOREY
0
1
2
3
4
5
6
7
8
0 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035
NoofStorey
Drift in m
Drift in X
m12
m22
m32
m42
m52
0
1
2
3
4
5
6
7
8
0 0.0005 0.001 0.0015 0.002 0.0025 0.003
NoofStorey
Drift in m
Drift in Y
m12
m22
m32
m42
m52

28. FOR G+7 STOREY
0
1
2
3
4
5
6
7
8
9
10
0 2 4 6 8 10 12
Storey
Drift X
Drift X
M13
M23
M33
M43
M53
0
1
2
3
4
5
6
7
8
9
10
0 2 4 6 8 10 12
Storey
Drift Y
Drift Y
M13
M23
M33
M43
M53
FOR G+9 STOREY
0
2
4
6
8
10
12
0 2 4 6 8 10 12
Story
Drift X
Drift X
M14
M24
M34
M44
M54
0
2
4
6
8
10
12
0 2 4 6 8 10
Story
Drift Y
Drift Y
M14
M24
M34
M44
M54

29. FOR G+9 STOREY
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12 14 16
Story
Drift X
Drift X
M15
M25
M35
M45
M55
0
2
4
6
8
10
12
14
0 5 10 15 20 25
Story
Drift Y
Drift Y
M15
M25
M35
M45
M55
From above graphs points observed are as following
• In case of flat slab structure Storey drift in x direction is more as compared to Storey drift
in y direction for same slenderness ratio.
• Maximum value of Storey drift was found out to be at second storey level in case of G+3,
G+5, G+7 structures where as in case of G+9 and G+11 storey structure the maximum
Storey drift was found on third storey level
• As per limitation laid by IS 1893 (Part 1) 2002, the maximum drift should not be more
than 0.004 times storey height which is 0.0144 m. This drift limit is exceeds in aspect
ratio L/B= 5 and slenderness ratio 3.32
OBSERVATION

30. 0
1
2
3
4
5
6
0 100000 200000 300000 400000 500000 600000
STOREY
STIFFNESS IN X
stiffness in x direction
M11
M21
M31
M41
M51
0
1
2
3
4
5
6
0 100000 200000 300000 400000 500000 600000
STOREY
STIFFNESS IN Y
stiffness in x direction
M11
M21
M31
M41
M51
0
1
2
3
4
5
6
7
8
0 100000 200000 300000 400000 500000 600000
Story
Stiffness X
stiffness in x direction
m12
m22
m32
m42
m52
0
1
2
3
4
5
6
7
8
0 100000 200000 300000 400000 500000 600000
Story
Stiffness YStiffness Y
Stiffness Y
m12
m22
m32
m42
m52
RESULTS FOR STOREY STIFFNESS
FOR G+3 STOREY
FOR G+5 STOREY

31. FOR G+7 STOREY
0
1
2
3
4
5
6
7
8
9
10
0 100000 200000 300000 400000 500000 600000
Story
Stiffness X
Stiffness X
M13
M23
M33
M43
M53
0
1
2
3
4
5
6
7
8
9
10
0 100000 200000 300000 400000 500000 600000
Story
Stiffness Y
Stiffness Y
M13
M23
M33
M43
M53
FOR G+9 STOREY
0
2
4
6
8
10
12
0 200000 400000 600000 800000 1000000 1200000
Story
Stiffness X
G+9
M14
M24
M34
M44
M54
0
2
4
6
8
10
12
0 200000 400000 600000 800000 1000000 1200000
Story
Stiffness Y
G+9
M14
M24
M34
M44
M54

32. FOR G+11 STOREY
0
2
4
6
8
10
12
14
0 200000 400000 600000 800000 1000000 1200000
Story
Story Stiffness
Story Stiffness X
M15
M25
M35
M45
M55
0
2
4
6
8
10
12
14
0 200000 400000 600000 800000 1000000 1200000
Story
Story Stiffness
Story Stiffness Y
M15
M25
M35
M45
M55
OBSERVATION
From above graphs points observed are as following
• Storey stiffness increases with size of column
• For same size of column stiffness increases with no of column in respective direction

33. 0
2
4
6
8
10
12
14
0 0.5 1 1.5 2
Mode
Period
G+3
M11
M21
M31
M41
M51
0
2
4
6
8
10
12
14
0 0.5 1 1.5 2 2.5
Mode
Period
G+3
m12
m22
m32
m42
m52
0
2
4
6
8
10
12
14
0 0.5 1 1.5 2 2.5 3 3.5
Mode
Period
G+7
M13
M23
M33
M43
M53
0
2
4
6
8
10
12
14
0 0.5 1 1.5 2 2.5 3 3.5
Mode
Period sec
G+9
m14
m24
m34
m44
m54

34. 0
2
4
6
8
10
12
14
0 1 2 3 4 5 6
Mode
Period
G+11
M15
M25
M35
M45
M55
OBSERVATION
From above graphs points observed are as following
• For first 3 modes value of time period is maximum.
• With increase in no of storey time period increases.
• Sudden increase in time period for model M55 is noted.

35. RESULTS
BASE SHEAR
• From tables of results the value of the base shear is found out to be increasing with
increase in slenderness ratio & aspect ratio.
• The percentage increase in base shear for aspect ratio 4 & 5 is more as compared to other
ratio, as the column size increases seismic weight increases.
• In case of same number of storey base shear does not increases linearly with linear
increase in aspect ratio.
STOREY DRIFT
• Building with aspect ratio 1 have same drift in both the direction
• Increase in slenderness ratio Results in increasing maximum storey drift
• In case of flat slab structure Storey drift in x direction is more as compared to Storey
drift in y direction for same slenderness ratio
• Maximum value of Storey drift was found out to be at second storey level in case of G+3,
G+5, G+7 structures where as in case of G+9 and G+11 storey structure the maximum
Storey drift was found on third storey level .

36. • Value of maximum storey drift is exceeded in model M55 is 20.1 mm which is more than
limiting value 14.4 mm for storey height 3600 mm.
• Increasing lateral stiffness of structure by increasing size of column results in increasing
storey level of maximum storey drift.
• As per limitation laid by IS 1893 (Part 1) 2002, the maximum drift should not be more
than 0.004 times storey height which is 0.0144 m. This drift limit is exceeds in aspect
ratio L/B= 5 and slenderness ratio 3.32.
STIFFNESS
• With increase in lateral storey Stiffness fundamental time period decreases.
• Increase in lateral storey stiffness Results in decreases Storey drift and maximum storey
displacement.
• In same aspect ratio size of column are not fixed so stiffness changes with change in
column size. Results in change of behaviour of structure for lateral loading.
• Increasing lateral stiffness of structure by increasing size of column results in increasing
storey level of maximum storey drift.

37. NATURAL TIME PERIOD
• The value of time period increases with increase in slenderness ratio
• The numerical value for modal period and frequency shows that value of period
increases linearly with linear increase in slenderness ratio but not in the case of change
in aspect ratio.
• First three modes of displacement governs the response of structure for lateral loads.
In first three modes natural time period is more frequency is less hence for lower
values of excitation gives maximum lateral deflection.

38. Based on the work done in this dissertation following conclusions are drawn:
 Limiting plan aspect ratio is L/B =5 and slenderness ratio is 3.32.
 Structure with aspect ratio more than 3 has higher magnitude of design base shear
along both X and Y direction though their seismic weight is lesser than structure
with aspect ratio 3.
 Curtailment in column size reduces the seismic weight of structure, hence less
seismic weigh and less base shear.
 Buildings having square plan shape i.e. aspect ratio 1, is safest because:
• Lower and equal amount of base shear is acting along both X and Y
direction.
• Fundamental time period for square plan structure is comparatively lesser
than rectangular plan building. Hence it will perform well during
earthquake with higher frequencies.
• Lateral deformation (i.e. lateral displacement and storey drift) for all the
storey level is same along both X and Y direction.
CONCLUSION

39. FUTURE SCOPE
• Present study is strictly restricted to effect of seismic forces on flat slab structure without
any lateral force resisting infill elements. To acquire in-depth knowledge about structural
behaviour we need to study structure with infill element which resist the lateral
displacement of structure or which does not resist the movement.
• Types of damage occur and points of critical damage are to be studied to save
unrepairable damage to lives of animals and human kind and other economic, strategic
losses.
• Behaviour of flat slab structure with different structural bracing elements under lateral
loads are to be found out.

40. • Prof. K S Sable, Er. V A Ghodechor, Prof. S B Kandekar, “Comparative Study of Seismic
Behavior of Multistory Flat Slab and Conventional Reinforced Concrete Framed
Structures”, International Journal of Computer Technology and Electronics Engineering
(IJCTEE) Volume 2, Issue 3, June 2012
• Rucha.S.Banginwar, M.R.Vyawahare, P.O.Modani, “Effect of Plan Configurations on the
Seismic Behavior of the structure By Response Spectrum Method” ,International Journal
of Engineering Research and Applications(IJERA),Vol2,May-June2012
• Arun Solomon A, Hemalatha G, “Limitation of irregular structure for seismic response”,
International Journal Of Civil And Structural Engineering Volume 3, No 3, 2013
• Mohit Sharma and Dr. Savita Maru(2014), “Dynamic Analysis of Multistoried Regular
Building” , Journal of Mechanical and Civil Engineering (IOSR-JMCE), Volume 11, Issue
1 Ver. II.
• Mayuri D. Bhagwat and Dr.P.S.Patil(2014), “Comparative study of performance of rcc
multistory building for Koyna and Bhuj earthquakes”, International Journal of Advanced
Technology in Engineering and Science Volume No.02, Issue No. 07.
• Dr. V.L. Shah and Late Dr. S.R. Karve, “Illustrated design of reinforced concrete
buildings”, Sixth edition, Structures publications, 36 Parvati, Pune-411009.
REFERENCES

41. • Paz. Mario. “Structural Dynamics" theory and Computation, CBS, Publishers and
Distributors Dayaganj, New Delhi.
• C. V. R. Murty, Rupen Goswami, A. R. Vijayanarayanan and Vipul V. Mehta, “Some
Concepts in Earthquake Behaviour of Buildings”, Gujarat State Disaster Management
Authority Government of Gujarat.
• BIS-1893, Criteria for Earthquake resistant design of structures-Part-1, General Provisions
and Buildings, Bureau of Indian Standards, New Delhi -2002.
• I.S-13920."Ductile detailing of reinforced structures subjected to seismic force" code of
practice Bureau of Indian Standards, New Delhi -1993.
• I.S. 456-2000, Indian Standard Code of Practice for Plain and Reinforced Concrete, Bureau
of Indian Standard, New Delhi.
• IS-875-1987.".Indian standard code of practice for structural safety loadings standards
Part-1, 2" Bureau of Indian Standards, New Delhi.
• I.S 4326 – 1993, Earthquake Resistant Design And Construction Of Buildings - Code Of
Practice, Bureau of Indian Standard, New Delhi
• SP-16-1980- Design Aids for Reinforced concrete to IS-456-1978-Bureau of Indian
Standards, New Delhi.
• SP 22 : 1982 Explanatory Handbook On Codes For Earthquake Engineering, Bureau Of
Indian Standard, New Delhi
• www.nicee.org, The National Information Centre of Earthquake Engineering
(NICEE - established 1999)

42. THANK
YOU