Computational Seismic Evaluation of Existing RC-Building Structures in Karachi Subjected to Multiple Earthquakes

Abstract

This study addresses the vulnerability of reinforced concrete structures to multiple seismic events, considering the often-neglected effects of prior and subsequent shaking. The research emphasizes the need for a comprehensive evaluation of various structural systems to gauge the cumulative impact of multiple earthquakes, aiming to inform design processes for enhanced structural safety. The study specifically examines a mid-rise residential reinforced concrete building subjected to seven earthquake sequences, combining actual and artificial repeating events. The objective of the study is to investigate the response of an existing RC building structure located in Karachi, subjected to multiple shocks of earthquake. The scope of the current research covers the response evaluation of low to mid-rise RC building structures (engineered and non-engineered) located in Karachi. To this end, an FEM model has been developed with different sources of nonlinearities (Geometric and Material) and analyzed for recorded and simulated multiple sequences of earthquake. The research assesses the structure's response in terms of drifts, maximum displacements, and damage patterns. The results contribute valuable insights for understanding structural behavior under seismic conditions, with a specific emphasis on the percentage difference in displacement between the main shock and combined main shock and aftershock scenarios. The observed trends, including pronounced variations in displacement across different story levels, inform seismic vulnerability mitigation and retrofitting strategies, ultimately enhancing structural safety in earthquake-prone regions.