result obtained from etabs and manual calculation is analysed and compared

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
Comparison of Seismic Analysis of Multi-storeyed Building by ETABS
and Manual Calculation
Mohd. Aslam1
, Vishal Kumar2
, Saurabh Pandey3
Assistant Professor1
, Students2, 3
Department of Civil Engineering
ABES EC Ghaziabad, INDIA
Corresponding Author’s email: mohmmad.aslam@abes.ac.in1
Abstract
One of the major challenges faced by structural engineers’ across the globe is
earthquake which results in serious damage to structures and causes death
injuries, economic loss, and so requirement of effective and efficient
earthquake resistant building play important role in all over the world. So in
this paper an effort is made to analyse the response of symmetric multi-storey
building in earthquake by seismic coefficient method as recommended by IS
1893:2002 and compared the result obtained with the help of ETABS 2015.
Keywords: Seismic Analysis, ETABS, Manual Calculation
INTRODUCTION
With the availability of design software like
ETABS it is quite easy to design and
analyse the complex project as compared to
manually. So this paper provides
comparative analysis of result obtained from
analysis of multi-storey building when
analysed manually and using ETABS
software separately. In this case 20x20m, 12
storey structures is modelled using ETABS
software. The height of each is taken as
3.2m making total height of building
38.4m.analysis of structure is done and
result generated by ETABS are compared
with manual analysis of structure using IS
1893:2002.

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
PROBLEM DEFINITION
Case (A)
A 20mx20m, 12 storey multi-storey building is considered for study .story height is
3.2m.modeling and analysis of building is done on ETABS
Preliminary data
Table: 1
Length x width 20m x20m
No. Of storey 12(G+11)
beam 350mm x 500mm
columns 500mm x600mm
Slab thickness 160mm
Support condition fixed
Thickness of wall 1) outer = 230mm
2) Inner=115mm
3)Parapet=115mm
Grade of concrete and steel M25 and Fe415
density Concrete 25kN/m3
Brick 20kN/m3

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
Loading
Consideration loads acting on the structure
are dead load (DL), live load (LL) and
earthquake load (EL)
 Live load on floors 3kN/m2 and LL on
roof 1.5kN/m2
 Seismic zone: IV
 Zone factor: 0.24
 Soil type 1
 R=5
 I=1.5
 Damping=5%
 Time period=0.773second(calculated
as per IS 1893:2002)
Fig 1: Plan of the building

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
Figure: 2
A) Seismic Weight of Each floor= Weight
of (column+beam+walls + slabs)
= (384 +700+ 1344+ 1766.6)
=1766.4 KN
B) Seismic Weight of roof =2420 KN
C) Only 25% live load is considered in
seismic weight calculation as per IS
1893:2002(page no24) clause no.7.3.1
25% of live load on floors = 0.25x1008
=252KN
25% of live load on roof = 0.25x504
=126KN
D) Seismic weight calculation of building
as per IS 1893:2002
W1=W2=W3=W4=W5=W6=W7=W8=W9
=W10=W11=4446.4 KN
In the calculation of seismic weight, for the
roof 50% of the weight is considered for
walls and columns.
W12 (roof) =2546 KN

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
Figure 3: Seismic weight obtained by Etabs
E) Calculation seismic base shear
As per IS 1893:2002, page no-24
Design seismic base shear (Vb)is calculated
byVb=Ah xW
Where,
Ah=design horizontal acceleration spectrum
values as per clause 6.4.2,
Using the fundamental natural time period
T,as per clause 7.6 in the considered
direction of vibration
W=seismic weight of the building as per
clause 7.4.2
As per IS1893:2002,clause 6.4.2,page no14,
Ah=Z/2+I/R+Sa/g
Where
Z=0.24 for zone4
I=1.5
R=5
Sa/g is average response acceleration
coefficient
The value is determined by using graph
given on page no-16 of IS 1893-2002.
As per IS 1893-2002
Ta=.09H/sqrt d

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
Where
H=height of building in meters=38.4m
d=base dimension of the building=20m
Ta=.773s
Sa/g=2.2 from graph
Ah=(ZI(Sa/g))/2R=0.0792
Base shear(Vb)=Ah x W=.0792
x51456.4=4075.34 KN
F) Distribution of base shear to different
floors
Design base shear shall be distributed along
the building by using following equation
Where,
Qi=design lateral force at floor i
Wi=seismic weight of floor i
hi=height of floor from base
n=no. of storey in the building
Table: 2
Floor Height (m) Wihi2
Q Base shear
W1 3.2 45531.13 6.92 4075.34
W2 6.4 182124.54 27.70 4068.92
W3 9.6 409780.22 62.32 4040.72
W4 12.8 728498.1 110.8 3978.4
W5 16 1138278.4 173.1 3867.6
W6 19.2 1639120.8 249.3 3694.47
W7 22.4 2231025.6 339.3 3445.16
W8 25.6 2913992.7 443.2 3105.82
W9 28.8 3688022.0 560.9 2662.59

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
W10 32 4553113.6 692.0 2101.67
W11 35.2 5509267.9 837.9 1409.67
W12 38.4 3754229.7 571.0 571.0
Sum Wihi2
26792984.2
Figure: 4

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Advances in Civil and Structural Engineering
Volume 2 Issue 2
CONCLUSION
1) Comparison of seismic analysis result
obtained manually as per IS 18893-2002 and
ETABS software was done
2) Both in manual analysis as well as in
software analysis, value of lateral forces
increases from bottom floor to 11 floor and
decreases in 12 floors.
3) There is a slight variation in the value of
base shear in manual analysis and software
analysis.
4) Base shear value obtained by manual
analysis are slightly higher than software
analysis.
5) Results are compared and approximately
same mathematical values are obtained for
12 storey building.
FUTURE ENHANCEMENT
1) This paper can serve as a guideline for
any structural engineer for analysis of
multistoried building.
2) Result can be compared with time history
method and response spectrum method.
REFERENCES
1) IS: 1893:2000, Part 1, "Criteria for
Earthquake Resistant Design of
Structures - General Provisions for
Buildings", Bureau of Indian
Standards, New Delhi, 2002.
2) Kulkarni J.G., Kore P. N., S. B.
Tanawade, “Analysis of Multi-storey
Building Frames Subjected to
Gravity and Seismic Loads with
Varying Inertia”, International
Journal of Engineering and
Innovative Technology (IJEIT),
Volume 2, Issue 10, April 2013.
3) B. Srikanth, V.Ramesh,
“Comparative Study of Seismic
Response for Seismic Coefficient
and Response Spectrum Methods”,
Journal of Engineering Research and
Applications, ISSN: 2248-9622, Vol.
3, Issue 5.
4) Seismic Analysis of Multistoried
Building Mahesh N. Patil, Yogesh N.
Sonawane, International Journal of
Engineering and Innovative
Technology (IJEIT) Volume 4, Issue
9, March 2015.

9. 32 Page 24-32 © MANTECH PUBLICATIONS 2017. All Rights Reserved
Advances in Civil and Structural Engineering
Volume 2 Issue 2
5) Awkar J. C. and Lui E.M, “Seismic
analysis and response of multi-storey
semi rigid frames”, Journal of
Engineering Structures, Volume 21,
Issue 5, Page no: 425-442, 1997.