Introducing an optimal method for macro modeling of nonlinear dynamic analysis in progressive collapse (A case study : OpenSees program)

Optimum implementation of nonlinear dynamic analysis (NDA) in progressive collapse is one of the most important issues that has not been addressed recently. Using detailed FE software like ABAQUS and ANSYS in progressive collapse analysis despite their accuracy is not appropriate because of consuming a lot of time. For this reason, many of researchers utilize the macro software such as OpenSees. In this study, authors tried to introduce an optimum and appropriate method for element removal in open program, OpenSees. Since nonlinear dynamic analysis shows the exact behavior of structure, this algorithm is developed for NDA. For this purpose, the developed algorithm has been compared with the other methods and it has been found that it has a high accuracy. Developed algorithm can remove one or more columns at the same or different time intervals and the effects of sequence column removals to their time durations can be seen. The application of the developed algorithm for nonlinear incremental dynamic analysis (NIDA) has been implemented and its application for an ultimate capacity of the structure has been shown. Analysis results showed that using of developed algorithm will lead to the speed and accuracy improvement of calculations in the sequence of columns removal and ultimate capacity of the structure using NIDA. At the end of this research, the application of this method has been shown for other element removal such as beams and infill walls.