Seismic Performance and Cost Optimization of Asymmetrical RC Buildings: A Performance-Based Approach

Asymmetrical reinforced concrete (RC) structures exhibit irregular mass and stiffness distributions, leading to torsional effects and complex seismic respons-es. This study examines the seismic performance and cost implications of three configurations, rectangular (symmetrical), L-shaped, and T-shaped, modelled and analysed in ETABS according to the IS 1893:2016 provisions. Key performance parameters, including base shear, story shear, story drift, and displacement, were evaluated for each model. It has been seen that asymmetrical forms demonstrate higher vulnerability, about 25-30% compared to a symmetric structure, when subjected to ground motion; however, their performance can be improved through strategically undertaken countermeasures such as optimal placement of shear walls, strengthening of diaphragm cores, and strategic stiffness balancing. Cost analysis was done based on material quantity and reinforcement estimates, which revealed that asymmetry generally increases construction costs due to greater concrete and steel requirements. Nevertheless, optimisation strategies such as selective shear wall installation or enlargement of the core column can also reduce displacement by 40% and increase cost by up to 11%. The research culminates in a design framework integrating performance-based analysis with cost efficiency, enabling the development of seismically safe, cost-effective asymmetrical RC buildings. The proposed approach offers practical guidance for residential construction in earthquake-prone regions, ensuring that architectural asymmetry can coexist with structural resilience and economic feasibility.