Seismic performance of reinforced concrete buildings with shear walls under structural irregularities

Abstract

Structural irregularities can significantly alter the seismic response of reinforced concrete buildings by modifying stiffness, mass distribution and load paths. This study evaluates the influence of structural irregularities and shear wall placement on the seismic performance of mid-rise reinforced concrete buildings in Sri Lanka. A detailed literature review identifies a limited body of experimental and numerical research addressing the combined effects of shear wall arrangement and structural irregularity within the Sri Lankan construction context. To address this gap, a finite element (FE) model of a five-storey reinforced concrete building is developed in ETABS software and assessed using the seismic provisions of Eurocode EN 1998-1:2004. Different shear wall arrangements and horizontal and vertical irregular configurations are investigated through response spectrum analysis, with a particular emphasis on the fundamental period, lateral displacement, inter-storey drift, and torsional response. The results indicate that the introduction of shear walls significantly improves lateral stiffness and reduces both the fundamental period and lateral displacement, with reductions exceeding 40% across the configurations investigated. Furthermore, irregular configurations involving cornerplaced shear walls and discontinuities in the structural grid produce less favourable responses, primarily due to increased eccentricity and torsional effects. These results provide a strong foundation for future work, emphasising that scaled-down experimental testing is essential to bridge the gap between numerical predictions and physical structural behaviour.