Research On Progressive Collapse Simulation Analysis Of Spatial Truss String Structure

In recent years, due to the wide application and special function of truss string structures, in case progressive collapse of string structures happens, it will result in great disasters of major projects. Then it has very important significance to study the progressive collapse of the spatial truss string structures.The main contents of this paper include the following aspects:(1)First of all, this paper need to determine primary important levers based on judgment of structural concepts, then to analyze the whole structural levers by sensitivity in order to verify the rationality of primary important levers, and lastly this paper determines important levers of structures.(2)This paper use the method of unloading equivalent-loads instantly considering the initial condition through finite element analysis software ANSYS/LS-DYNA to carry on dynamic time-history analysis of single pin truss string structures and spatial truss string structures after failure of single important lever nonlinearly.(3)In conditions, single pin truss string structures are same, steel consumption of vertical-ties is equal, this paper carries on dynamic time-history analysis and progressive collapse analysis of the model 1 that vertical-ties are vertical-cross levers and model 2 that vertical-ties are trusses respectively. This paper reveals disciplines of spatial truss string structures’ progressive collapse according to variation of node accelerations、displacements、internal forces and energies when the structures collapse progressively.The conceptual analysis and sensitivity analysis of the whole structure show that there are important levers and secondary levers in the spatial truss string structures.The disciplines of spatial truss string structures’ progressive collapse after failure of single important lever show that vertical-ties trusses can improve bearing capacity of the whole structure, especially progressive collapse resistance of the remaining structure after failure of bottom-chord at the support.