Design objectives and collapse prevention for building structures in mega-earthquake

A mega-earthquake is one with an intensity larger than the most severe earthquake intensity category currently considered in design codes. For a mega-earthquake, the design objective of a given structure is to preserve living spaces for people in the buildings. In this paper, factors that may influence the collapse resistance of RC frames in a megaearthquake are analyzed based on seismic damage observed in the 2008 Wenchuan earthquake. Methodologies to improve structural collapse resistance focus on three aspects: global strength margin, global redundancy and global integration of the structural system. Fundamental principles and design concepts for collapse prevention under a mega-earthquake are proposed, and issues that need further research are identified.