Enhancing Seismic Resilience: Damage Characteristics and Mitigation Strategies for Reinforced Concrete Moment Resisting Frame Buildings on Hill Slopes

Buildings on hillside slopes have complex structural systems due to the existing topographical limitations. The seismic behavior and the failure pattern of these buildings are also observed to be peculiar in the past earthquakes such as Sikkim (2011) and Nepal (2015). Therefore, the mitigation strategy for such buildings must be delineated based on the detailed understanding of the typical damage characteristics exhibited. This study is focused on identifying the effect of critical parameters of configuration such as aspect ratio and slenderness ratio, that are usually imposed due to the topographical limitations, on the seismic response of the buildings on hill slopes. A total of 40 buildings are numerically modeled with varying aspect and slenderness ratios and the correlation between various member‐level parameters such as beam axial stresses, columns shear stress etc., are studied with the help of correlation matrices. Based on the observations, these parameters are categorized into three sets namely system parameters, behavior control parameters, and behavior verification parameters. Further, a suite of 11 ground motions recorded during the past earthquakes are utilized to verify the observations through nonlinear dynamic analysis. The response along the valley is predominantly governed by shear‐force concentration in the uphill columns, whereas the response across the valley is associated with differential flexible‐ and rigid‐edge deformations and the resulting torsional behavior. Lastly, three mitigation strategies are suggested and verified to improve the response and reduce the brittle failure modes, viz., (a) to limit the shear failures, (b) to improve the base shear distribution along the valley, and (c) to regulate the deformation of flexible edge that leads to reduction in the overall twist. Nonlinear analysis of the proposed model showed substantially reduced concentrated shear in short columns and improved deformations along and across the valley. The proposed methodology produced a more balanced structural response by improving stiffness distribution, deformation compatibility, torsional behavior, and force redistribution, with the flexible‐to‐rigid edge deformation ratio moving closer to unity.