Seismic Performance Assessment of Regular and Irregular Reinforced Concrete Buildings under Long-Period Ground Motions in the Himalayan Region

Abstract

Long-period ground motions (LPGMs) generated by earthquakes in the Himalayan tectonic region significantly influence the seismic performance of medium- and high-rise Reinforced Concrete (RC) buildings, particularly those with structural irregularities. This study investigates the seismic response of regular and irregular RC building configurations, including Regular (R10), L-shaped (L10), T-shaped (T10), and Setback (S10) buildings, subjected to representative LPGMs. Three long-period ground motion records, namely the 2015 Gorkha earthquake, the 2005 Muzaffarabad earthquake, and a synthetic long-period ground motion, were selected and analyzed using nonlinear time-history analysis in ETABS v20. Structural performance was evaluated based on the Peak Inter-storey Drift Ratio (PIDR), Maximum Roof Displacement, Base Shear, and Plastic Hinge Formation. The results indicate that the regular building exhibited the best seismic performance, with an average PIDR of 1.08%, roof displacement of 136.6 mm, and base shear of 2213 kN. In contrast, the T-shaped building exhibited the highest seismic response, recording an average PIDR of 1.78%, roof displacement of 210.6 mm, base shear of 2424 kN, and the formation of 29 beam plastic hinges and 11 column plastic hinges, indicating significantly greater seismic vulnerability under long-period earthquake excitation.