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ISSN 0974-5904, Volume 08, No. 03 June 2015, P.P.1260-1263
#02080327 Copyright ©2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Time History Analysis of Symmetric and Un-symmetric Buildings
Considering Soil Structure Interaction
VISHRUTH JAIN, K SARAVANA RAJA MOHAN AND P BHUVANESHWARI
School of Civil Engineering, SASTRA University, Thanjavur, Tamil Nadu, India
Email: vishu.jain9@gmail.com
Abstract: In the present study, earthquake response analysis is carried out for multi-storey buildings, treating the
foundation to be fixed. Both symmetric and un-symmetric plan of equal area are considered for the study. The
analysis is repeated by replacing fixed supports with different soil conditions like cohesive and cohesion-less soil.
Soil structure interaction effects due to earthquake excitation are observed. Four storey building models with total
height of 17.5m were subjected to El Centro earthquake excitations, to obtain the response under different soil
conditions. Time based responses are compared for structural members. Comparison of the results showed that
stiffness of the soil greatly affects the displacements, forces and stresses in structural members. Response shows that
unsymmetrical building found in cohesion-less soil is more vulnerable under earthquake excitations.
Keywords: Time History Analysis, Symmetric and Un-Symmetric plan, Soil Structure interaction, Seismic Analysis,
3D model.
1. Introduction:
Earthquakes due to sudden transient motion of the
ground, from release of elastic energy are one of the
most destructive of all natural hazards. The primary
hazards associated with earthquakes are fault
displacement and ground shaking. Secondary hazards
include ground failure, liquefaction, landslides,
avalanches, tsunamis and seiches.
In India, 59% of geographical area is vulnerable to
seismic disturbance with varying intensities and
magnitude. Data available from the year 1897 to 1991
indicates that India experiences an average of three
earthquakes of magnitude 6.0 or more every year. In
span of last 15 years, India has experienced six
earthquakes of moderate intensity.
There have been many studies carried out on seismic
aanalysis of multi-storey buildings. Sivakumaran (1990)
introduced new method of analysis to determine the
response of multi-storey mono-symmetric buildings
including the effects of soil-structure interaction and
sway effects. The numerical results indicate that the soft
soil conditions affect the response of the building.
Neelima et al. (2012) concluded that time periods of the
structure invariably decrease with the increase of soil
stiffness and it is seen that the displacement values
increase with the decrease of soil stiffness. Naida
Ademovic et al. (2013) conducted the pushover analysis
on typical masonry residential building without any
seismic guidelines and concluded the failure pattern of
typical masonry building. Hendramawat A Safarizkia et
al. (2013) concluded that steel bracing could be utilized
for seismic retrofitting of structures with poor detailing.
Pires (1996) proposed equivalent linearization technique
for the stochastic response analysis in the time-domain
of horizontally layered soil deposits under vertically
propagating random shear waves. Jenifer Priyanka
(2012) concluded that lateral deflection, storey drift,
base shear and moment values increases when the type
of soil changes from hard to medium and medium to
soft. Present study is focused on time history analysis of
buildings along with soil structure interaction to find
joint displacements, beam end forces and sway effects.
The types of failure in symmetrical and unsymmetrical
buildings are noted and forces to be considered for
aseismic design are also discussed.
Since the time history record is available for El Centro
city excitation, the same is considered for analysis.
2. Methodology
For the present study, two buildings of G + 3 storey
with total height of 17.5m and equal area of 91.0m2
were considered. One building is symmetrical in plan
whereas the other is unsymmetrical in plan as shown in
Figure 1. The dimensions of beams and columns were
0.4 x 0.4 m as per Indian codal provisions IS 456-2000
[10].
STAAD Pro V8i software is used for analysis of
buildings. Time history method of analysis was carried
out for finding sway effect, joint displacements, beam
end forces and support reactions.

2. 1261WANG JIAQI, JIN WENBIAO, GUO HUA, WANG XINYUE AND LIU JUNLIANG
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 03, June, 2015, pp. 1260-1263
3. Numerical Analysis
3D models were created to simulate both symmetrical
and unsymmetrical buildings. The dimensions for
foundation were determined by considering maximum
support reaction of 2700 KN, obtained with fixed
support condition. Foundations were first assigned with
fixed supports to represent the hard strata and analyzed.
In order to simulate soil structure interaction effects,
support conditions were changed to ‘Compression only
spring’ type. The dimension for foundation, obtained for
cohesive soil condition with safe bearing capacity of
200 kN/m2
was 3m x 3m. Similar value for cohesion-
less soil with safe bearing capacity of 350 KN/m2
was
2.1m x 2.1m. The safe bearing capacity was as per
Ramamrutham 2013 [5]. The subgrade modulus
considered was 60000 KN/m2
/m for cohesive soil and
235000 KN/m2
/m for cohesion-less soil as provided in
Arora 2011[6].
The buildings are subjected to load cases as dead load,
live load, seismic load and combination of load cases
with 1.2 times dead load, 1.5 times of live load and
seismic load. Dead load case includes the self-weight,
member load of 19 KN/m for floor beams and 5.4KN/m
for roof beams, floor load of 3.75 KN/m2
on all floors.
Live load of 5KN/m2
was considered for all floors
except for the roof with load intensity 1.5 KN/m2
.
3.1. Time History Analysis
3D models of the buildings with above mentioned
specifications were subjected to time history excitation
which was defined in time history definition. External
earthquake data was input as a basic data for analysis,
with damping of 0.05 as specified by IS 1893-2002 [9].
Analysis was carried out for fixed support condition and
repeated for different soil types by changing the support
conditions.
4. Results and Discussion
Improper planning and design of buildings is one among
the reason for its failure. Present study focuses on forces
and stresses developed in buildings due to seismic
loading and different types of failures to be considered
while designing earthquake resistant buildings.
4.1. Joint Displacements
Joint displacement for unsymmetrical building found on
cohesion-less soil was more as shown in the Figures 2.
Percentage increase in displacement is 13.8% compared
to cohesive soil and 68.6% compared to hard strata.
Similar increase in the value is only about 6.5% and
56.3% respectively, for symmetrical building.
4.2. Forces in beams
Comparisons of beam end forces are as shown in Figure
3. Unsymmetrical building found on cohesion less soil
gave more values. The percentage increase was 42.2%
more than that for cohesive soil and 98.6% more than
that for fixed support condition respectively.
4.3. Stresses in beams
Similar results were noticed for stresses in beams as
shown in Figure 4. Unsymmetrical building found on
cohesion less soil is more vulnerable showing an
increase in percentage of 78.2% in case of cohesive soil
and 98.9% in case of fixed support, compared to
symmetric building.
Comparison of result shows that soil condition and
unsymmetric in building plan, affects the stability of the
building. Cohesion-less soil leads to more deflection
and sway for the buildings.
4.4. Time based Displacement
Magnitude of displacement at different time interval is
as shown in Figure 5. Unsymmetrical building in
cohesion less soil is more vulnerable showing
percentage increase of 46.7% compared to symmetrical
building on similar soil.
4.5. Sway Pattern
Sway pattern of the buildings are as shown in Figure 6.
The un-symmetrical buildings have twisting or torsional
effect, when subjected to lateral seismic forces and
vulnerability is more in case of such buildings found in
cohesion-less soil.
5. Conclusion
Time History analysis of both symmetrical and un-
symmetrical buildings founded on different soil is
carried out considering soil-structure effect. Un-
symmetrical buildings were highly affected compared to
symmetric building. The following conclusions were
arrived
 Percentage increase for joint displacement for
unsymmetrical building found on cohesion-less soil
was 13.8% and 68.6%, compared to cohesive soil
and hard strata.
 Beam end forces are enhanced by 42.2% and
98.6%, compared to cohesive and hard strata.
 Beam stresses are increased by 78.2% and
98.9%,compared to cohesive soil and fixed support
condition
 Time based results also show similar increment of
46.7% for displacement, compared to symmetrical
building.
 Sway in unsymmetrical building is accompanied by
twisting or torsional effect due to mass irregularity.
The effect is again reinforced due to cohesion less
soil.

3. 1262 Experimental Study on Ammonia Nitrogen Absorption Performance of Zeolite Powder
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 03, June, 2015, pp. 1260-1263
The time based joint displacements, beam end forces
and beam stresses shows enhanced values for un-
symmetrical buildings found in cohesion less soil. It is
concluded that un-symmetrical buildings should be
constructed with symmetrical shear walls for preventing
twisting effect. For buildings to be constructed on soft
soil the soil must be stabilized and design of foundation
should be carried out accordingly.
Acknowledgement
Support and guidance provided by Shanmugha Arts,
Science, and Technology & Research Academy is
gratefully acknowledged.
References
[1] K.S. Sivakumaran, “Seismic Analysis of Mono-
symmetric multi-storey building including
foundation interaction”, Computers & Structures,
Vol. 36, Issue No. 1, pp. 99-107, 1990.
[2] B. Neelima, B. Pandu Ranga Rao, P. Kodanda
Rama Rao and S.R.K.Reddy, “Earthquake
Response of Structures under Different Soil
Conditions”, International Journal of Engineering
Research & Technology, Vol. 1, Issue No. 7, 2012.
[3] J.A. Pires, “Stochastic seismic response analysis of
soft soil sites”, Nuclear Engineering and Design,
Vol. 160, Issue No. 3, pp. 363-377, 1996.
[4] Naida Ademovic, Mustafa Harasnica and Daniel V.
Oliveira, “Pushover analysis and failure pattern of
typical masonry residential building in Bosnia and
Herzegovina”, Engineering Structures, Vol. 50, pp.
13-29, 2013.
[5] S. Ramamrutham and S. Narayan, Design of
Reinforced Concrete Structures (Revised
Seventeenth Edition), Dhanpat Rai Publishing
Company (P) LTD, 2013.
[6] K. R. Arora, Soil Mechanics and Foundation
Engineering, Standard Publishers Distributors,
2011.
[7] Hendramawat A Safarizkia, S.A. Kristiawanb, and
A. Basuki, “Evaluation of the Use of Steel Bracing
to Improve Seismic Performance of Reinforced
Concrete Building”, Procedia Engineering, Vol. 54,
pp. 447 – 456, 2013.
[8] R. M. Jenifer Priyanka, N. Anand, Dr. S. Justin,
“Studies on Soil Structure Interaction of Multi
Storeyed Buildings with Rigid and Flexible
Foundation”, International Journal of Emerging
Technology and Advanced Engineering, Vol. 2,
Issue No. 12, 2012.
[9] IS 1893 (Part 1)-2002: Indian Standard Criteria for
Earthquake Resistant Design of Structures, Part 1–
General Provisions and Building (Fifth Revision),
Bureau of Indian Standards, New Delhi.
[10]IS 456 – 2000: Indian standard code of practice for
general structural use of plain and reinforced
concrete, New Delhi.
(a) Symmetrical building
(b) Un-Symmetrical building
Figure 1: Plan of the buildings
Figure 2: Comparison of joint displacements

4. 1263WANG JIAQI, JIN WENBIAO, GUO HUA, WANG XINYUE AND LIU JUNLIANG
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 03, June, 2015, pp. 1260-1263
(3a) Fixed Support
(3b) Cohesion soil
(3c) Cohesion-less soil
Figure 3: Comparison of Beam End Forces
Figure 4: Comparison of Beam Stress
(5a) Symmetrical buiding
(5b)Un-Symmetrical building
Figure 5: Time vs Displacement graph for buidings in
cohesion-less soil