A Performance-Oriented Seismic Study of Vertically Irregular RC Structures on Hilly Terrains

This study investigates the seismic performance of reinforced concrete (RC) multistorey buildings constructed on sloping ground. Analytical approaches including Equivalent Static, Response Spectrum, Time-History, and Nonlinear Pushover analyses were carried out using ETABS for G+10 storey buildings with both regular and irregular (step-back, setback, and step-back–setback) configurations. The results reveal that slope-induced irregularities significantly affect seismic response, leading to higher storey displacements, drifts, and base shear compared to flat-ground structures. Short columns on the uphill side were found to be highly vulnerable due to stiffness concentration, attracting larger seismic forces and causing premature failures. Among the studied configurations, step-back–setback systems demonstrated relatively better performance. The findings emphasize the necessity of slope-specific seismic design, enhanced detailing of short columns, and consideration of height restrictions for structures on steep slopes.