Comparing Seismic Collapse Safety of Modern and Existing Reinforced Concrete Frame Structures in California

In this study, the framework of performance-based earthquake engineering is used to predict the seismic collapse risk of California's older (non-ductile) and modern (ductile) reinforced concrete frame structures. Collapse performance assessments are conducted for two sets of structures, those designed according to an out-dated building code, the 1967 Uniform Building Code (UBC), and those designed according to modern building code provisions, the 2003 International Building Code (IBC). Each set includes 2, 4, 8 and 12 story reinforced concrete frame buildings, designed as space and perimeter frame systems. These preliminary results provide measures of collapse safety of reinforced concrete frame structures and are used to evaluate the level of safety provided by modern building codes, and to quantify differences in safety between older and moden structures, answering questions such as "how safe are code-conforming reinforced concrete frame structures?" and "how much more likely are existing reinforced concrete frames to collapse in an earthquake?"