Abstract：The duration of earthquake ground motions have insignificant effects on analytical results for performance-based seismic design of bridges (PBSD). The incremental dynamic analysis of a six span reinforced concrete continuous girder bridge was performed for decoupling the influence between duration, frequency content and amplitude on structural seismic demands by using several bins of real and artificial accelerograms that matched the same target response spectrum and had different probability distributions of the 5-95% significant duration. The correlation between duration and seismic demands of the RC girder bridge reveals that the mean, dispersion and probability distribution of the duration of earthquake ground motions have little influence on displacement engineering demand parameters (EDP) but important effects on the probabilistic assessment (mean), dispersion and probability distribution of energy EDPs or fatigue failure and cumulative damage parameters. If energy EDPs are used in PBSD, the mean, dispersion and probability distribution of the duration of earthquake ground motions must be in accordance with the real seismic hazard at the bridge site. An optimal method for rationally selecting real earthquake ground motions for PBSD based on total probability theorem is presented which can effectively consider the effects of the mean, dispersion and probability distribution of the duration on seismic demands of bridge structures and can significantly improve the precision of analytical results and computation efficiency.
2015, Vol. 34 
