Research Projects

Accurate estimation of seismic demands is essential in performance-based design to ensure the safety of structural and non-structural components. Past earthquakes have shown that both building configuration and soil conditions significantly affect seismic performance. Buildings on soft soils—such as loose sand, silt, or clay—often suffer more damage than those on stiff soils or bedrock. Irregular buildings, particularly with asymmetrical mass or stiffness, are prone to torsional effects, causing uneven force distribution and localized damage. This is especially critical in densely populated countries like India, where residential and commercial buildings commonly exhibit plan and elevation irregularities due to architectural constraints, functional requirements, or space optimization. For instance, open ground storey (soft storey) buildings—common in urban India for parking—have consistently shown poor seismic performance, as seen in the 2001 Bhuj and 2015 Nepal earthquakes. The combined impact of weak soils and building irregularity can lead to severe failures, resulting in costly repairs, economic losses, social disruption, and service interruptions—issues still insufficiently addressed in modern design codes, including ASCE 7, Eurocode 8, and IS 1893. The novelty of this study lies in its systematic investigation of the combined influence of soil-structure interaction and building irregularity on key seismic demand parameters—such as acceleration and inter-storey drift—and their impact on the probabilistic seismic risk of building to damage to both structural and non-structural components. The central hypothesis is that the soil structure interaction combined with torsional irregularity in buildings significantly amplifies building response and redistributes damage in ways not captured by conventional fixed-base models. To this end, the study proposes to develop a set of finite elements based numerical models in Opensees software for buildings with varying degrees of torsional irregularity, incorporating foundation flexibility through calibrated lateral and rotational springs across a spectrum of realistic soil conditions—from stiff to very soft—and to perform nonlinear time-history analyses under a range of bidirectional ground motion scenarios. Further, based on the obtained results, the study will perform a probabilistic seismic risk assessment by integrating structural and nonlinear structural response with seismic hazard using FEMA-P58 (2018), methodology for next generation Performance Based Earthquake Engineering (PBEE), propagating all sources of uncertainty. Based on these findings, the study will propose improvements to current seismic design provisions and offer recommendations for more risk-informed, site-specific building code guidelines. Reference: 1. Federal Emergency Management Agency (2018) Seismic Performance Assessment of Buildings: Volume 1 Methodology (FEMA P58). Washington, DC.