PSI - Issue 70

Aman Kumar et al. / Procedia Structural Integrity 70 (2025) 255–262

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the structure is subjected to higher seismic forces and deformations due to the amplification of ground motion by the soil. This leads to a substantial rise in the probability of damage across all damage states, particularly in extreme and collapse states, which are critical for life safety and structural integrity. The findings underscore the importance of considering soil-structure interaction and site-specific soil conditions in seismic design and analysis. The finding highlights the significance of considering soil amplification during seismic design and analysis along with the specific soil conditions of the site.

Fig. 6. Probability of damage to the building in x and y direction due to original and amplified ground motion

5. Conclusions The present study highlights the impact of soil amplification on the seismic response and vulnerability of unsymmetrical T-shaped RC buildings. Pushover, time history, and fragility analysis have been performed to estimate the capacity, response, and vulnerability of the building due to the amplified ground motion. • The study shows that ground motions significantly increase by up to 180 % in PGA due to the soil amplification effect. • The amplified response spectrum shows that the soil generally amplifies the ground motion most significantly in the low-period range (0 – 1 second). Beyond this range, the soil amplification effect gradually decreases, becoming negligible after 4 seconds. • The soil amplification significantly increases the seismic responses (base shear, ductility demand, and roof displacement) of the building for surface-level ground motion. The result shows that the base shear value of the building increased up to 168%, roof displacement increased by up to 96%, demand ductility increased by up to 55%, and spectral displacement value increased by 97% for surface-level ground motion as compared to the bedrock level. • The seismic vulnerability of the building has significantly increased due to soil amplification to the soil amplification effect. The results shows that the damage probability of the building has increased up to 38% in the extreme damage state and up to 18.3% in the collapse damage state for surface-level ground motion. These findings of the study underscore the need to integrate the soil amplification studies in the Indian standard, particularly for irregular RC buildings in high-seismicity regions, and suggest that seismic design standards (including the Indian seismic regulations) might require more explicit consideration of site-specific soil amplification effects to ensure accurate assessment and improved structural safety.