Probabilistic Approach to Performance-Based Seismic Design of RC Frames

During the last two decades, Performance-Based Seismic Design (PBSD) was introduced as the preferred approach for seismic assessment and design of the structures. In recent years further developments have focused on using probabilistic approaches to arrive at an informed decision with regard to achieving the desired objective. This will also provide for a better control on the extent of economic losses during the earthquakes, which appears to be an important concern based on recent earthquake experiences. To this end, the next generation of PBSD has recently been proposed by Federal Emergency Management Agency (FEMA P-58). This paper reviews the pro and cons for probabilistic PBSD considering existing practical constraints and limitations. The randomness and uncertainties in demand and capacity parameters are discussed in some detail with regards to RC frames. FEMA P-58 performance assessment methodology is discussed and a review of recent research studies on RC frame structures is presented. It is concluded that, despite the powerful conceptual base and the provided guidelines, probabilistic approaches are still faced with considerable practical limitations and require additional efforts. However, for important structures, extra efforts may well be warranted.