Study On Stability Of Tall And Large Steel Tubular Falsework Joined By Couplers

The fasten-style tubular steel scaffolding and falsework system is widely used in building construction in China because they are convenient/versatile/high carrying capacity/good overall stiffness and relatively inexpensive. It's said that they composite 70 percent of overall scaffold used in China. However, at the same time, instability phenomenon of that support system occurs from time to time, engendering template accidents happened frequently and that has now become one of the major sources of dangerous which can easily lead to group casualties in building construction. How to improve security and reliability of the system has been a new topic of the construction industry.Firstly, the dissertation enumerated the safety accidents of scaffolds in recent years and analyzed the reasons which cause these accidents, concluded the means to avoid the happening of these accidents. On the base of investigating the spot , Some problems which are easily ignored and easily become hazards are summarized. The dissertation also concluded the study fruit of scaffold and falsework both at home and aboard, the study fruit include computation models/ load and load combination/ on-site measurement and full-scale test, which is very useful for the following study.Making use of SAP2000 finite element analysis software, and analyses the mechanism deeply that how the factors effect the bearing capacity of buckling when the physical dimension is unchanged. The constitution factors of the supporting structure for tall and large formwork include lateral crossing struts/ viterical crossing struts/ the setting ways of floor members/ the hight of floor members/ steel tube thickness /semi-rigid/ and structure hight. It is found: vertical crossing struts is not important to bearing capacity of falsework when vertical crossing struts is setted in single direction of two lateral directions, but is an sensitive element when vertical crossing struts is setted in both of two lateral directions. Floor member and steel tube thickness are important elements to bearing capacity of falsework. The bearing capacity of buckling reduces when the hight of the structure or floor member increases or node stiffness reduces, the completeness of the floor members is important to the structure. The internal force and displacement of the nodes and elements have been discussed. According to the analyzing of the calculating result, the paper puts forward some suggestion and problems about the supporting structure for tall and large formwork during the design and the construction, which the designers and the constructors can refer to.By on-site examination for construction are researched formwork support .The rule of internal force variation of support poling and level pole in the construction are researched. The results show that poling and level pole experiences complex stress variation in the construction process without bridging, and some elements are under high bending moment without bridging .So the arrangement of bridging should be paid more attention to when carrying on the formwork support design.