Seismic Performance Evaluation of Low-Rise Open Ground Storey Buildings: Impact of Infill Walls and Code-Based Multiplication Factor

Structural Engineering

Abstract Open Ground Storey (OGS) buildings, commonly used in cities for parking, lack infill walls at the ground level—making them especially vulnerable during earthquakes due to sudden changes in stiffness. This study looks at how the presence and strength of infill walls affect the seismic behavior of low-rise OGS buildings, especially questioning the current design practice of using a 2.5 multiplication factor (MF) as per IS 1893:2002. A four-storey RC building located in Seismic Zone V was modeled in SAP2000 under both fixed and pinned base conditions, comparing structures with and without infill walls. Analyses included linear (static and response spectrum) and nonlinear pushover methods. Results show that infill walls significantly increase the overall stiffness, reducing the building’s natural period. However, applying the 2.5 MF tends to overestimate seismic forces, leading to uneconomical designs. The nonlinear analysis further showed that buildings with infill fail abruptly at the ground level, while those without infill walls behave more flexibly with better energy dissipation. These insights suggest the need to revisit seismic design guidelines, particularly for low-rise OGS buildings, to ensure both safety and cost-effectiveness.

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