Influence of slope angle variation in seismic performance of structures on slopy ground surface in hilly region

The present study considers a vertical irregularity generated by varying the angle of the slope of the ground surface. The influence of variation in the angle of the slope on the seismic response of structures has been investigated. The angles of the slope of the ground are taken as 0o, 15o, 30o and 45o respectively. Multistoreyed regular frames of six-storeys, eight-storeys, and ten-storeys are modified by introducing irregularities through a variable slope angle to generate a total of 12 configurations. A numerical procedure has been employed to estimate the responses of the structures under earthquake loading conditions. The analysis of the structures has been performed using the response spectrum method and the nonlinear time history method. The behaviors of the structures are evaluated in terms of the natural periods, drift ratio, and base shear. Fragility curves are plotted to investigate the vulnerability of structures with different slopes. The irregularities are found to influence the behavior of the structures considerably. The results obtained illustrate the criticality associated with the variation of the slope angle on the seismic response of the structure and would serve as an aid in designing irregular structures without compromising performance.