Analysis and Comparison of R.C.C Conventional Slab& Flat Slab Under Seismic & Temperature Load

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 10 | Oct -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1370
Analysis and Comparison of R.C.C Conventional Slab& Flat Slab
Under Seismic & Temperature Load
Faria Aseem1, Waseem Sohail2, Abdul Quadir3
1,2Assistant Professor, Lords Institute of Engineering & Technology, Hyderabad, India
3Sr.Structural Design Engineer, PIL Limited, Hyderabad, India
--------------------------------------------------------------------------------***--------------------------------------------------------------------------------
Abstract— In today’s construction the use of flat slab has
become quite common. Flat-slab building structures
possesses major advantages over traditional slab-beam -
column structures because of the free design of space,
shorter construction time, architectural–functional and
economical aspects. Flat slab construction is a developing
technology in India. The conventional slab has more
stiffness and higher load carrying capacity. Due to
urbanization and aesthetic reasons flat slab have become
quite common. Because of the absence of deep beams and
shear walls, flat-slab structural system is significantly more
flexible for lateral loads then traditional RC frame system.
The performance of flat slab system under temperature
loading is also very poor. It is necessary to analyses seismic
behavior of buildings for various heights to see whatare the
changes that are going to occur for the conventional RC
frame building, flat slab building with and without drops. In
this comparative study, the seismic behavior of R.C.C flat
slab and conventional slab is evaluated by nonlinear time-
history analyses with different temperature loading with
the help of SAP 2000 v18 software. The main parameters
evaluated in this study are lateral displacement, inter story
drift, axial force, and bending moment. A total of 12 models
with three different structural systems i.e., conventional
slab system, flat slab system without drops and flat slab
system with drops are considered. For each structural
system 150mm and 200mm thickness oftheslab is taken, so
we have six basic models. For each basic model G+4, G+8
stories are considered. The performance of flat slab and
conventional slab has to be studied when subjected to
Seismic loading due to occurrence of varying magnitudes of
earthquakes having different frequencies. Thetemperature
loading is being considered due to frequent occurrences of
fire accidents and also due to the need for knowledge in
people about fire hazards. Fire will not onlycausecasualties
but also effect the structure predominantly leading to its
destruction. From results it can be concluded that
conventional slab of 150 mm thickness is more effective for
G+4 & G+8. For normal and high temperature 150mm
thickness is good for G+4, G+8.
Key words: Seismic Design, Temperature Loads, Flat
Slab, Conventional Slab, Non-Linear Time History
I. LITERATURE REVIEW
Kang et al. (2003) studied the constitutive model of
concrete subjected to elevated temperature. The model is
composed of four strain components: free thermal strain,
mechanical strain, thermal creep strain, and transientstrain
due to moisture. The thermal creep strain of concrete is
derived from the modified power-law relation for steady
state creep. Mathematical description on the multi-axial
creep behavior of concrete is also presented. The transient
strain component is made in order to consider rapid
irreversible strain change of moisture diffusion and
evaporation. Some applications for the proposed model are
carried out by a nonlinear analysis and compared with the
test results and it shows that the proposed model gives a
good agreement and the influences of inelastic strain
changes at elevated temperatures are very important for
the structural response at elevated temperatures.
Levesque (2006) presented a simplified design tool which
assesses the fire performance of reinforced concrete. An
Excel-based spreadsheet application was developed for
thermal analysis of concrete slabs. It accounts for different
aggregate types, slab thicknesses,andfireexposures.Several
analyses were performed with the spreadsheet application
to examine the affect slab thickness and aggregate types
have on the fire performance of concrete slabs in standard
and natural fires. The results were comparedwith published
test data and finite element software simulations to
benchmark the accuracy of the proposed tool. Furthermore,
methods for the design of reinforced concrete slabs in fire
conditions are presented. 11Wang (2006) studied that the
membrane forces and the redistribution of bending
moments in the slabs considerably affected the behavior of
the slabs in fire conditions. Consequently, the fire
resistance of the slabs can be enhanced if tensile membrane
behavior is mobilized. This thesis uses a non-linear finite
element program, SAFIR, developed at the University of
Liege, Belgium, to model reinforced concrete flat slabs and
one-way slabs at elevated temperatures. The slabs were
modeled as 3-D shell elements in the numerical structural
models. It was found that the location of the fire under flat
slabs and the arrangement of reinforcing bars in flat slabs
significantly affect the distribution of bending moments
and membrane forces in flat slabs. It was also found that
the worst scenario of fire exposure could be when the flat

slabs are exposed to fire with a decay phase or after the fire
was exhausted or extinguished. The fire resistance of flat
slabs is significantly increased if tensile membrane action
can be mobilized. However, the distribution of membrane
forces in the slabs is nonlinear.
Rizk (2010) studied the development in concrete
technology over the twentieth century covering materials,
structural systems, analysis and construction techniques
made it possible to build concrete tall buildings such as
PETRONAS towers(452m), jin Mao(421m) and bhurj Dubai
(800+) Manley (2014) presented the use of prescribed
solutions for fire design and has allowed engineers to
simply provide an assembly of elements which meets a
building codes required fire resistance without necessarily
understanding or evaluating the development of a fire in a
compartment, the corresponding temperatures reached
and the implications of such temperatures. A process is
presented which uses simple thermal and mechanical
models to determine the fire resistance of simply
supported reinforced solid concrete slabs. The calculated
fire resistance is compared to prescribed provisions for
slabs exposed to the standard fire and an equivalent fire
severity method for slabs exposed natural fires.
II. COMPARATIVE STUDY OF FLAT SLAB AND
CONVENTIONAL SLAB
The Flat slab building in which slab is directly supported by
columns, have been adopted in many building constructed
recently, due to the advantage of reduced floor to floor
height. Conventional slab system consists of thin beams
spaced at regular intervals in perpendicular directions,
monolithic with slab. The seismic performance of buildings
having conventional slab and flat slab is comparable but the
differences exist. Tall buildings with flat slab system are
weaker in shear whereas those with conventional floor
system are robust but taller and functionally less friendly.
Flat slab is quite common which enhances the weight
reduction, speed up construction, and economical.
Conventional slab has got features like more stiffness,
higher load carrying capacity, safe and economical also.
Conventional Reinforced Concrete (RC) frame buildings are
commonly used for the construction. The use of flat slab
building provides many advantages over conventional RC
frame building in terms of architectural flexibility, use of
space, easier formwork and shorter construction time. The
weight of flat slab structure is less compared to
conventional slab structure.
III. SEISMIC EFFECTS
Earthquakes are natural hazards due to which damage
occur to buildings and other man-made structures.
Experience has shown that for new constructions,
establishing earthquake resistant regulations and their
implementationisthecritical safeguardagainstearthquake-
induced damage. As regards existing structures, it is
necessary to evaluate and strengthen them based on
evaluation criteria before an earthquake. Earthquake
damage mainly depends on parameters such as intensity,
duration and frequency of ground motion, geologic and soil
condition, quality of construction, etc.
The April 2015 Nepal earthquake of India was an eye
opener killed over 8,000 people and injured more than
21,000. It occurred at 11:56 Nepal Standard Time , with a
magnitude of 7.8Mw or 8.1Ms and a maximum Mercalli
Intensity of IX . Its epicenter was east of Gorkha District at
Barpak, Gorkha, and its hypocenter was at a depth of
approximately 8.2 km (5.1 mi). It was the worst natural
disaster to strike Nepal since the 1934 Nepal–Bihar
earthquake.
IV. TEMPERATURE EFFECTS
With the increased incidents of major fires and fire
accidents in buildings;assessment,repairandrehabilitation
of fire damaged structures has become a topical interest.
This specialized field involves expertise in many areas like
concrete technology, material scienceandtesting,structural
engineering, repair materials and techniques etc. Research
and development efforts are being carried out in these
related disciplines. Any structure can undergofireaccident,
but because of this the structure cannot be denied neither
abandoned. To make a structure functionally viable after
the damage due to fire has become a challenge for the civil
engineering community. The problem is where to start and
how to proceed. It is vitally important that we create
buildings and structures that protect both people and
property as effectively as possible. Annual statistics on
losses caused by fires in homes and elsewhere make for
some unpleasant readings and sadly through these events
we learn more about fire safety design.
V. OBJECTIVES OF THE STUDY
A. The present work aims at the following objectives:
To investigate and compare seismic behavior of RCC flat
slab and conventional slabusingtheNon-lineartimehistory
analysis with different thickness.
To investigate and compare the effect of Temperature load
on RCC flat slab and conventional slab with different
thickness.
To investigate and compare the behavior of both structure
for the parameters like lateral displacement, inter story
drift, axial force, and bending moment.
1) Flat slab and Conventional slab models are prepared.
Models are analyzed by nonlinear time history analysis

S.no Variable Data
1. Type of structure Moment Resisting Frame
2. Seismic Data Nepal Earthquake data
3.
Number of
Stories
G+4 & G+8
4. Floor height 3m
5. Plan Dimensions 18m x 24m
6.
Total height of
Building
15m & 27m
7. Live Load 3.0 kN/m2
8. Dead load
1 kN/m2 & wall load of 10
kN/m
9. Materials
Concrete (M30) and
Reinforced with HYSD bars
(Fe500)
10. Size of Columns
460x460 mm (for 4 & 8storey
frame)
11. Size of Beams 300x460 mm
12. Depth of slab 150mm thick & 200mm thick
13. Depth of drop 150mm
14.
Specific weight of
RCC
25 kN/m3
15. Zone II
16.
Importance
Factor
1
17.
Response
Reduction Factor
5
18. Type of soil Medium
Table 1: Preliminary Data Considered in the Analysis of
the Framed Structure for Seismic Load
2) Temperature load case is also considered of 280C and
4000C.
S.no Variable Data
1 . Type of structure Moment Resisting Frame
2 . Temperature Data 280C and 4000C
3 . Number of Stories G+4,G+8
4 . Floor height 3m
5 . Plan Dimensions 18m x 24m
6 .
Total height of
buildings
15,27 & 39m
7 . Materials
Concrete (M30) and Reinforced
with HYSD bars (Fe500)
8 . Size of Columns
460x460 mm (for 4 & 8storey
frame)
9 . Size of Beams 300x460 mm
1 0 . Depth of slab 150mm & 200mm thick
1 1 . Specific weight of
RCC
25 kN/m3
Table 2: Preliminary Data Considered for Temperature
Load
VI. RESULTS & DISCUSSIONS
1) Firstly, the results for Seismic effects are obtained by
using SAP-2000 software. In this models are
generated based on the variables assumed i.e.; flat
slab with and without drop and conventional slab.
Loads are imposed and after application of loads on
the structure, analysis of the models is carried out by
using Non-Linear Time History Analysis and the
results are obtained. Therefore, values for the
respective parameters are taken and graphs are
plotted.
2) Secondly, the results obtained by carrying out analysis
based on different Temperature effects fortheFlatslab
with and without drop and conventional slab are
illustrated. In this casetemperature effectsonbuildings
are observed by Normal (280C) and High (4000C)
Temperatures.
Subsequently discussions are made for the results obtained
for lateral displacement, inter storey drift, bendingmoment,
axial force.
A. Displacement of G+4 Storey Structure with 150mm
Thickness under Seismic Load
Storey Displacement
in mm for
Conventional
Slab
Displacement
in mm for Flat
Slab without
Drop
Displacement
in mm for Flat
Slab with Drop
1 9.4 16.4 14.9
2 23.5 52.3 46
3 35.7 93.7 79.7
4 44.7 132.5 108.8
5 50 165.7 131.5
Fig. 5.1: Displacement of (3+4 Storey Structures with
150mm thickness under seismic load
B. Displacement of G+4 Storey Structures with 200mm
Thickness Under Seismic Load.

Storey
Displacement
in mm for
Conventional
Slab
Displacement
in mm for Flat
Slab without
Drop
Displacement
in mm for Flat
Slab with Drop
1 10.6 18.4 15.6
2 25.8 57.6 44.9
3 38.5 101.2 74.3
4 47.4 140.7 97.5
5 52.3 173.7 113.3
Fig. 5.2: displacement of (3+4 storey Structures with
200mm thickness under seismic load
C. Displacement of G+8 Storey Structures with 150mm
Thickness under Seismic Load
Storey
Displacement
in mm for
Conventional
Slab
Displacement
in mm for Flat
Slab without
Drop
Displacement
in mm for Flat
Slab with Drop
1 16.1 35.3 26.1
2 41.4 116.3 83.2
3 66.1 216.9 151.5
4 87.6 321.1 219.9
5 107 419.7 282.2
6 123.7 510.7 335.4
7 136.7 590.2 377.9
8 145.8 656.1 409.7
9 151 709.9 434
Fig. 5.3: displacement of (3+8 Storey Structures
with 150mm thickness under seismic load
D. Displacement of G+8 Storey Structures with 200mm
Thickness Under Seismic Load.
Displacement Displacement Displacement
Storey in mm for in mm for Flat in mm for Flat
Conventional Slab without Slab with Drop
Slab Drop
1 18.3 49.7 27.2
2 46.3 161 81.3
3 73.4 296.6 141.7
4 97.5 434.4 201.2
5 118.1 562.9 256.3
6 135.1 679.6 304.3
7 149.4 777.5 342.9
8 159.4 855.2 370.6
9 165.1 916.1 388.7
Fig. 5.4: displacement of G+8 storey Structures
with 200mm thickness under seismic load
E. Displacement of G+4 Storey Structures with 150mm
Thickness under Normal Temperature
Store
y
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and without
Drop
1 1.2 1.5
2 1.1 1.4
3 1.1 1.4
4 1.1 1.4
5 1.1 1.4

Fig. 5.25: displacement of G+4 storey Structures with
150mm thickness under normal Temperature
F. Displacement of G+4 Storey Structures with 200mm
Thickness Under Normal Temperature.
Store
y
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and without
Drop
1 1.3 1.5
2 1.2 1.4
3 1.2 1.4
4 1.2 1.4
5 1.2 1.4
G. Displacement of G+8 Storey Structures with 150mm
Thickness Under Normal Temperature.
Storey
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and
without Drop
1 1.3 1.5
2 1.2 1.4
3 1.2 1.4
4 1.2 1.4
5 1.2 1.4
6 1.2 1.4
7 1.2 1.4
8 1.2 1.4
9 1.2 1.4
H. Displacement of G+8 Storey Structures with 200mm
Thickness under Normal Temperature.
Storey
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and without
Drop
1 1.3 1.5
2 1.2 1.4
3 1.2 1.4
4 1.2 1.4
5 1.2 1.4
6 1.2 1.4
7 1.2 1.4
8 1.2 1.4
9 1.2 1.4
Fig. 5.28: displacement of G+4 storey Structures with
150mm thickness under normal Temperature
I. Displacement of G+4 Storey Structures with 150mm
Thickness under High Temperature

Stor
ey
Displacement in mm
for Conventional Slab
Displacement in mm
for Flat Slab with and
without Drop
1 16.5 19.4
2 16.9 19.9
3 16.8 19.8
4 16.8 19.8
5 16.8 19.8
Fig. 5.43 Displacement of G+4 Storey Structures with
150mm Thickness under High Temperature.
J. Displacement of G+4 Storey Structures with 200mm
Thickness under High Temperature
Store
y
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and without
Drop
1 17.2 19.5
2 17.5 19.9
3 17.4 19.8
4 17.4 19.8
5 17.4 19.8
Fig. 5.44: Displacement of G+4 Storey Structures with
200mm Thickness under High Temperature
K. Displacement of G+8 Storey Structures with 150mm
Thickness Under High Temperature
Storey
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and without
Drop
1 16.5 19.4
2 16.9 19.9
3 16.8 19.8
4 16.8 19.8
5 16.8 19.8
6 16.8 19.8
7 16.8 19.8
8 16.8 19.8
9 16.8 19.8
150mm Thickness under High Temperature
L. Displacement of G+8 Storey Structures with 200mm
Thickness under High Temperature.
Storey
Displacement in
mm
for Conventional
Slab
Displacement in
mm for Flat Slab
with and
without Drop
1 17.2 19.5
2 17.5 19.9
3 17.4 19.8
4 17.4 19.8
5 17.4 19.8
6 17.4 19.8
7 17.4 19.8
8 17.4 19.8
9 17.4 19.8

200mm Thickness under High Temperature.
VII. RESULTS & CONCLUSIONS
Lateral displacement in column increases as the Storeylevel
increases. The lateral displacement will increase drastically
as the height increases. Lateral displacement will be
minimum at plinth level and maximum at terrace level.
Lateral displacement of conventional R.C.C Slab is less than
the flat slab buildings. About 68% to 70% of displacement is
less in conventional slab than in flat slab is observed
considering G+4 & G+8 with 150mm thickness of slab as
shown in Figures 5.1, 5.3 and Tables 5.1, 5.3
About 70% to 82% of displacement is less in conventional
slab than in flat slab is observed considering G+4&G+8 with
200mm thickness of slab as shown in Figures 5.2, 5.4 and
Tables 5.2, 5.4. It is because of the presences of beam in
conventional slab which has more stiffness compared to flat
slab. Conventional slab also has higher load carrying
capacity.
A. Conventional Slab and Flat Slab Subjected to Normal
Temperature:
When temperature load is applied to the structure, the
weight of the columns goes on increasing which makes the
lowest column bulge and at that point displacement is
maximum in the structure.
It is observed that Displacement of conventional slab of
150mm thickness is less, about 14%to21%comparedtothe
flat slabs building as shown in Figures 5.25, 5.27 and Tables
5.25, 5.27.
It is observed that 7% to 14% of Displacement of
conventional slab is less compared to Flat slabs of same
thickness 200mm as shown in Figures 5.26, 5.28 and Tables
5.26, 5.28.
Axial force in conventional slab will be more compared to
flat slabs. For 150mm thickness of slab about 76% to 80%
and for 200mm thickness of the slab 60% to 66% as shown
in Figures 5.37 to 5.42 and Tables 5.37 to 5.42.
Bending moment in conventional slab is less compare to flat
slabs. For 150mm thickness of slab about 9% to 10%and for
200mm thickness of the slab 6% to 8% as shown in Figures
5.31 to 5.36 and Tables 5.31 to 5.36.
B. Conventional Slab and Flat Slab Subjected to High
Temperature:
It is observed that Displacement of conventional of 150mm
thickness is less, about 15% compared to the flat slabs as
shown in Figures 5.43, 5.45 and Tables 5.43, 5.45
It is observed that 12% to 14% of Displacement of
conventional slab is less compared to flat slabs of same
thickness 200mm as shown in Figures 5.44, 5.46 and Tables
5.44, 5.46
Axial force in conventional slab will be more compared to
flat slabs. For 150mm thickness of slab about 76% to 80%
and for 200mm thickness of the slab 60% to 66% as shown
in Figures 5.55 to 5.60 and Tables 5.55 to 5.60. 91
Bending moment in conventional slab is less compare to flat
slabs. For 150mm thickness of slab about 9% to 10%and for
200mm thickness of the slab 6% to 8% as shown in Figures
5.49 to 5.54 and Tables 5.49 to 5.54.
REFERENCES
[1] Kang, Won, S., Hong and Gul, S. (2003). "Behavior of
Concrete Members at Elevated Temperatures
Considering InelasticDeformation." FireTechnology,39,
9–22.
[2] Levesque, A. (2006). Fire Performance of Reinforced
Concrete Slabs, Worcester Polytechnic Institute,
Massachusetts, U.S.
[3] Wang, G. G. (2006). Performance of reinforced Concrete
Flat Slabs Exposed to Fire, University of Canterbury,
Christchurch, New Zealand.
[4] Manley, D. M. (2014). "Design of Reinforced Concrete
Slabs Exposed to Natural Fires." Proc.,Conf.onFireEng.,
University ofCanterbury, Christchurch,NewZealandBIS
(Bureau of Indian Standards). (2002). “Criteria for
Earthquake Resistant Design of Structures, Part 1 –
General Provisions and Buildings.” IS 1893:2002(Part–
1), New Delhi

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