Study On Progressive Collapse Of Frame Structure Under Wave Passage Excitation

If part of the structure members failed and this failure spread form element to element, eventually leading to the collapse of the entire structure or a disproportionately large part of it, we call it “Progressive Collapse”. So far, scholars have done much research on progressive collapse, especially on the aspect of progressive collapse caused by blast and impact load. Progressive collapse caused by earthquake is little researched, and research on progressive collapse under wave passage excitation is without report. This paper mainly studies on progressive collapse of frame structure under wave passage excitation.The main research content of this paper as following:(1) Introduce the design codes for progressive collapse of structures. Summarize and compare the design methods and analysis methods of progressive collapse, choosing time history analysis method as the analysis method of this paper at last.(2) The analysis of uniform excitation and wave passage excitation of the model of a three-span, five-story reinforced concrete plane frame structure is carried out by using large mass method in finite element software ANSYS, and the time history curves of the column shear forces、column top moments、column base moments of side column and beam-end bending moments of side beam of the first floor are obtained through simulation respectively. The numerical results showed that for Central Calif-01 wave, the maximum value of four time history curves increased by 78%、93%、79%、29% respectively; for Hollister-01 wave, the maximum value of four time history curves increased by 138%、104%、95%、30% respectively; for Whittier Narrows-01 wave, the maximum value of four time history curves increased by 49%、52%、48%、14% respectively.(3) The collapse analysis under wave passage excitation of three reinforced concrete plane frame structures are carried out by using large mass method in finite element software ANSYS. The results showed that the collapse process is very fast; the collapse is start with the failure of side column of the first floor, then a sequence of beam fails and the later collapse also occurs in the side of the failed column, the other side of the structure is almost intact; comparing with the condition of dead load and earthquake action, structure collapses earlier and more quickly in the condition of dead load、live load and earthquake action.In this paper, we get the following two conclusions:(1) For the three-span, five-story reinforced concrete plane frame structure used in this paper, the column shear forces、column top moments、column base moments of side column and beam-end bending moments of side beam of the first floor obtained from the wave passage excitation increase remarkably comparing with the results of uniform excitation.(2) Large Mass Method in ANSYS can be used to study progressive collapse of structure under wave passage excitation.