Seismic Performance Evaluation of an Irregular Steel–Concrete Composite Building Incorporating Steel Bracings and Shear Walls

Abstract

Objectives: Irregular buildings are highly prone to torsional effects and excessive lateral deformations during earthquakes due to the non-uniform distribution of mass and stiffness. Although in Reinforced Cement Concrete (RCC) frame steel bracing systems and shear walls are widely used to enhance seismic performance, comprehensive comparative studies involving multiple bracing configurations and shear walls with identical location and orientation in irregular Steel–Concrete Composite (SCC) buildings remain limited. This study evaluates the effectiveness of different seismic resistance techniques in improving the seismic behaviour of an irregular SCC building. Method: A G+15 storey L-shaped SCC building was modelled and analysed in ETABS 22.0. For the same SCC structure five steel bracings Diagonal, Inverted V, V, K and X bracing and Reinforced Concrete (RC) shear walls were incorporated at identical locations. Response Spectrum Analysis (RSA) was performed in accordance with IS 1893(Part 1):2016. Seismic performance was assessed using storey displacement, storey drift, storey stiffness, fundamental time period and torsional irregularity ratio. Findings: The integration of seismic resistance techniques significantly improved the seismic performance of the irregular composite building. Among the bracing systems, X-bracing showed the best performance by reducing storey displacement, storey drift and fundamental time period by 56.06%, 60.42% and 37.88%, respectively. Inverted V-bracing provided the highest storey stiffness, whereas K-bracing achieved the lowest torsional irregularity ratio. The shear wall system showed best overall improvement, reducing displacement, drift, fundamental time period and torsional irregularity ratio by 70.29%, 76.52%, 51.63% and 40.87%, respectively, while achieving the highest storey stiffness. Novelty: Unlike previous studies focused on RCC and regular buildings or individual strengthening systems, the present study provides a comprehensive comparison of SCC structure with five steel bracing configurations and RC shear walls placed at identical locations under identical modelling, loading and seismic conditions to identify the most effective seismic resistance strategy. Keywords: Steel-Concrete Composite structure, Plan Irregularity, Steel Bracing, Shear Wall, Response Spectrum Analysis