Research on resisting progressive collapse mechanism of post-tensioned energy dissipating steel frames
Aiming at the progressive collapse of post-tensioned energy dissipating(PTED)steel frame structures,a refined finite element model was established by using ABAQUS software,and the behavior of unbalanced load redistribution was studied after the load-bearing members were removed.The accuracy of the model was verified by comparing the finite element results with test results of the quasi-static push-down of the 1/3-scale PTED steel frame.On this basis,further research on the mechanism of resisting progressive collapse of the PTED steel frame was carried out.The effects of four factors,namely,initial post-tensioned,number of post-tensioned steel strand,material strength of steel members,and the width-thickness ratio of beam flange on the resisting progressive collapse mechanism of steel frames were analyzed.The results show that there are three stages in the process of resisting progressive collapse of the PTED steel frame:the initial stage,the favorable stage and the unfavorable stage of arch compression mechanism.The collapse resistance is provided by the tensile force of post-tensioned steel strand and the vertical force between beam and column.Increasing initial post-tensioned force,number of post-tensioned steel strand,yield strength of steel and decreasing the width-thickness ratio of beam flange will increase the peak load.With the increase of the number of steel strands,the frame can provide greater resistance when the displacement of the failure column is small.Strengthening the ability of resisting local buckling deformation of beam-column members will improve the ability of resisting progressive collapse of PTED steel frames.
self-centering structurepost-tensioned energy dissipating steel frameprogressive collapse mechanismresistance force