EvaluatingRectangular Loadingpattern in NonlinearAnalysis ofCompositeBridgesSubjected to Blast Loading

While significant advances have been made on the blast analysis، applications of nonlinear analysis of structures under explosion have been limited to the frames and structural behavior of bridges subjected to blast is an issue that has attracted attention of researchers in recent years. Nonlinear dynamic analysis can be lead to the most accurate responses of the structure under blast but the use of it is not justified in many cases because of its complexity and excessive computing times. Pushover method is often seen to be a viable and attractive alternative to nonlinear analysis because of its simplicity and ability to estimate deformation demands with acceptable accuracy without the intensive computational and modeling effort of a nonlinear dynamic analysis. In this study، a rectangular load pattern is developed to estimate nonlinear responses of composite bridges subjected to blast using pushover method. For this purpose، first، an efficient method is proposed to determine equivalent static blast loading and then the accuracy of pushover analysis based on the developed load pattern is evaluated. It is shown that the proposed method can be easily used to conservatively estimate maximum displacement of composite steel girder bridges under explosion.