Theoretical Study About Resisting Progressive Collapse Of Fastener Steel Tubular Formwork Supports

Along with the vigorous development of China’s construction industry, formworksupport system has become the indispensable one of the temporary facilities inconstruction site. Especially the fastener steel tubular formwork support, due to theadvantages of strong versatility, convenient assembly and disassembly, high bearingcapacity, good whole rigidity, reaches70%of the total amount of formwork supportsused in China, or even more. However, formwork support collapse accidents occurfrequently. It shows that we lack of detailed understanding about the relationshipbetween the bearing capacity and the structural factors, and our studies on the way offormwork support collapse are also inadequate, especially on the aspect of progressivecollapse. Therefore, the fastener steel tubular formwork support, the most common one,being looked as the research object, the progressive collapse problem is discussed andstudied by using finite element software SAP2000in this paper.In this paper, the research status of fastener steel tubular formwork support at homeand abroad is reviewed first, and the significance of research on the progressive collapseis put forward. Through introducing some collapse accidents of fastener steel tubularformwork support, the cause of collapse, influencing factors and preventive measuresare analyzed and discussed. Then, definitions and differences of progressive collapsebetween American standard and British one are introduced. Because that Americandefinition is more reasonable according to the definition and interpretation ofprogressive collapse in many articles, the study and analysis are based on the Americandefinition in the paper. Then, the calculation theory of progressive collapse and thetheory of semi-rigid node connection are emphasized as the theoretical basis foranalysis of finite element following.In the part of finite element simulation, two initial defects, the tube wall thinningand initial rigidity of fastener joint diminishing, are simulated respectively through twomodels. It comes to that the initial defect, the tube wall thinning, could cause formworksupport progressive collapse, and another initial defect, initial rigidity of fastener jointdiminishing, could not lead to progressive collapse of formwork support. This paperfocuses on simulating the first situation that the tube wall thinning leads to formworksupport progressive collapse. Through summing up the rod failure development law andthe relative features, two conclusions are obtained: the principle of falsework rod failure sequence and the law in the process of formwork support progressive collapse. Finally,some measures for resisting progressive collapse of formwork support are advisedaccording to the initial defect that the tube wall got thin. And the effects about fourkinds of structural factors on the bearing capacity of formwork support progressivecollapse were analyzed.