The Numerical Simulation On Collapse Mechanism Of Fastener Type Full Framing Support System

What we have concerned is the safety problems of scaffolding. But in recent years, scaffolding collapse accidents still occur in the constant. The accidents bring a serious threat to the life of the constructors. The aspects including design calculation, construction factors, material issue, site supervision adverse etc result in the accidents. Therefore, to find out the reasons that cause the collapse and to make corresponding measures for each factor is still the problems that we need to solve.This paper mainly studied from the following aspects:(1) Analyze and summarize the causes that may result in the scaffold collapses according to the related literature, reports and investigating the situation of the erection of the scaffold at the construction site.(2) Selecting the beam element to simulate steel pipe and the spring element to simulate semi-rigid characteristic of fastener establish comparison test model to verify the effectiveness of the finite model. Establish semi-rigid models of different lift height, space of upright tube, bottom reinforcing tube arrangement and diagonal bracing arrangement. First, analyze the influence of different structural conditions on bearing capacity of full hall formwork support. And then analyze the influence of the thickness of steel tube, corroded steel tube, bending steel tube, coupler failure and fastener tightening torque on the full hall formwork support capacity. Obtain the influence degree of structural measures and initial imperfection on the full framing support capacity.(3) Use the finite element software ABAQUS to establish finite models for progressive collapse simulation. In the model the fastener are simulated by rigid connection, using explicit dynamic analysis step, and point that the steel pipe lose its capacity when it get into the yield phase. According to each available factor including bottom reinforcing tube setting, steel corrosion, steel pipe thickness, loosen coupler and construction load this paper respectively analyze the simulation of progressive collapse. In the construction process local steel pipe of the support system first yield to fail, and then cause the adjacent pipe to fail one by one, finally result in the overall buckling collapse. And then put forward some safety and reinforced measures to prevent the collapse of the support system according to each factors.