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Study on Seismic Responses of Plan Irregular Buildings Due to Torsional Irregularity and Re-entrant Corners

Corresponding Author : A. Paul (arpice114@gmail.com)

Authors : A. Paul (arpice114@gmail.com), B. Morshed (azmorshed@ce.kuet.ac.bd), C. Parvez (zahid1998dec@gmail.com)

Keywords : Stress concentration, Re-entrant corners, Response spectrum analysis, Story displacement, Plan irregularity

Abstract :

Irregularly shaped buildings are susceptible to seismic load although it has an intrinsic appeal to humans. A lot of research on the irregular configuration of buildings has been conducted to understand seismic behavior but there are no widely accepted guidelines for it. Consequently, ensuring the desired performance of irregular buildings at seismic load is always a challenge for structural engineers. Therefore, to evaluate the seismic performance of irregular buildings, a study was conducted on G+12 storey buildings with four different plan configurations using the Extended 3D Analysis of Building System (ETABS 2016). The analysis included two symmetrical structures (a regular building and an H-shaped plan irregular building) and two asymmetrical plan irregular structures (C-shaped and L-shaped buildings). Then, the torsional behavior of structures and the amount of stress concentration were analyzed to detect the stability of re-entrant corners for plan (horizontal) irregular buildings by using two approaches: the equivalent static lateral force method (ESM) and a dynamic analysis technique. The findings suggested that having shear walls in the C-shaped model resulted in a 64% reduction in stress concentration, whereas H-shaped plan irregular buildings showed a 37% reduction. However, when considering the storey drift, C-shaped and L-shaped models described approximately identical values in both the X and Y directions of plan. Overall, the C-shaped model provided better performance considering storey displacement, drift, stiffness, stress concentration, and torsional irregularity, compared to any other configuration of structures under seismic loading. These findings will assist structural engineers and policymakers in enhancing guidelines for irregular structures.

Published on March 28th, 2025 in Volume 5 (Special Issue), Civil Engineering, Environment and Architecture