Collapse Safety of Reinforced Concrete Frames Under Building‐Code Evolution

Seismic design provisions for reinforced‐concrete (RC) moment frames in Colombia have evolved substantially since 1984, yet their combined effect on collapse safety has remained unquantified. This study assesses typical low‐ to mid‐rise RC spatial frames from three eras: pre‐code (gravity‐only designs), early seismic code (CCCSR‐84, 1984), and modern post‐1998 code (NSR‐98/10). A database of over 250 two‐dimensional nonlinear index models, representing characteristic detailing and failure modes, is analyzed with hazard‐consistent ground motions for low‐, intermediate‐, and high‐seismicity regions. Collapse fragilities are derived at the building level and for 56 taxonomy classes, considering code era, building height, and detailing. Collapse risk metrics are computed regarding building height for three levels of seismicity. Modern designs achieve median collapse capacities ∼40%–100% (typically 50%–70%) above early‐code frames and reduce mean annual collapse frequency to ∼2%–10% of pre‐code levels. Mid‐rise risk is jointly influenced by design drift ratio, column‐to‐beam strength ratio, and confinement in high‐seismicity regions. The results highlight the conservative evolution of the Colombian seismic code, which is most effective for mid‐rise and taller frames, while indicating room for improvement to moderate the estimated risk in low‐rise buildings in high‐seismicity regions. These findings can support seismic risk modeling and code development across Latin American countries with similar reinforced‐concrete design and detailing practices.