Civil Insight: A Technical Magazine Volume 3 | Page 41

Dongol N. et al.
Civil Insight (2019) 37-44
4) Results and Discussions
The building was analyzed for fixed base, spring base, and direct modeling, and the results were assessed.
The Table 5 presented below shows that considering SSI by spring modeling can increase the value of the
time period up to 8%, whereas the direct modeling can increase the value up to 9%. As shown in Table 6,
there is a decrease in base shear by 7% when soil parameters are considered through the spring-base
modeling. Likewise, a change in story displacement is observed from Figs. 2, 3, 4, and 5. It is observed that
there is an increase in roof displacement up to 6% along the x-direction and 12% along the y-direction on
spring-base modeling. Base displacements up to 24mm and 48mm are observed in static analysis and
dynamic analysis respectively while considering SSI in direct modeling. Fig. 6 and Fig. 7 present the
pushover curves of the building along the X- and Y-direction respectively.
Table 5. Time Period for the building
Base Condition Time Period in X-direction (sec) Time Period in Y-direction (sec)
Fixed Base (FB) 0.899 0.467
Spring Modeling (SM) 0.971 0.470
Direct Modeling (DM) 0.982 0.470
Base Condition Base reaction in X-direction (kN) Base reaction in Y-direction (kN)
Fixed Base 292.670 483.554
Spring Base 272.125 485.785
Difference (%) 7.020 0.461
7 7
6 6
5 5
Table 6. Base reaction of building at different base conditions
4
3
2
0
0
50
100
3
2
FB
SM
DM
1
4
FB
SM
DM
1
0
150
Lateral Displacement (mm)
0
50
100
150
200
250
Lateral Displacement(mm)
Fig. 2. Story displacement in static analysis along Fig. 3. Story displacement in static analysis along
x-direction
y-direction
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