Study on overstrength of RC frame structures

Overstrength plays an important role in keeping satisfactory performance of structures during strong earthquake. Using a number of ground motions and the RC frame structures designed according to Chinese seismic code, the global capacity envelopes and overstrength of RC frame structures attributing to redistribution of internal forces are studied by means of incremental dynamics analysis and Pushover analysis. It is concluded that when using incremental dynamic analysis to determine the global capacity envelopes of structures, the difference between the capacity envelopes caused by different local site conditions is small. And the difference between the overstrength obtained from incremental dynamics analysis and Pushover analysis increases with the stories. Before further detailed investigations, it can be conservatively considered that the minimum overstrength factor of RC frame structures, which are designed according to Chinese seismic code, is 2.