Seismic Vulnerability of Non-Code-Compliant and Code-Compliant RC Buildings

This study investigates the seismic vulnerability of non-code-compliant reinforced concrete (RC) buildings compared to code-based structures. The research uses linear elastic and nonlinear pushover analyses (NPA) to evaluate critical seismic performance parameters such as natural periods, mass participation, base shear, capacity curve, ductility ratio, overstrength factor, collapse mechanics, and nonlinear hysteretic damping (NHD). Structures designed following standards like NBC 205 (old), RUD 205 new, and Indian standard IS 1893 are analyzed against non-code-compliant building samples (NES1-NES6) to highlight performance gaps. The findings reveal that code-compliant buildings demonstrate significantly higher seismic resistance, greater flexibility, effective earthquake energy dissipation, higher ductility, overstrength factor, and base shear capacity. Non-code-compliant buildings often exhibit soft-story failure, with initial damage observed in the columns, highlighting their vulnerability during seismic events. Meanwhile, code-compliant RC buildings (RUD) designed with seismic principles demonstrate better seismic performance, adhering to the “strong column, weak beam” philosophy and superior strength-to-capacity ratios, higher overstrength factors, and enhanced ductility ratios, highlighting their resilience under seismic loads. The results conclude that addressing the code provisions ensures earthquake-resistant buildings with warranted ductile behavior for structural systems, enabling the achievement of the intended collapse mechanism.