Stability Analysis Of High-Formwork Support Systems With Couplers

With rapid development of social economy, high-formwork support systems are increasingly used in construction of large-space and large-span structures. However, high-formwork support systems belong to temporary bearing system, whose load paths and computing models are complex and affected by lots of factors. High-formwork support systems would induce various accidents such as collapse occurred frequently and cause huge casualties and property losses if their stability cannot be guaranteed. Hence, research on analysis model and stability bearing capacity plays an important role in design and safety evaluation of high-formwork support systems.In this paper, a analysis model which can capture semi-rigid connection characteristics and second-order effect of high-formwork support system was established according to mechanical characteristics of high-formwork support systems. Then stability bearing capacity and construction measures of high-formwork support systems were also investigated. The main contents are as following:1. Based on theoretical analysis, a finite element model of high-formwork support system was established by adopting two type elements, one is horizontal tube element which includes semi-rigid connection characteristics and second-order effect, and the other one is upright tube element which involves second-order effect. Then internal force and displacement of high-formwork support system were analyzed. The analysis shows that the coupling between semi-rigid connection characteristics and second-order effect has significant effect on redistribution of internal force and nodal lateral displacement.2.Stiff equation of stability for high-formwork support system was established by taking into account the influence of semi-rigid connection characteristics and second-order effect. Stability bearing capacity of high-formwork support system was computed based on the eigenvalue buckling analysis method. Meantime, the influence of initial rotational stiffness of semi-rigid joint and diagonal bracing on the stability bearing capacity of high-formwork support system was analyzed quantitatively. The analysis shows that initial rotational stiffness of semi-rigid joint has a significant influence on the stability bearing capacity of high-formwork support system, while diagonal bracing can significantly improve the stability bearing capacity of high-formwork support system.3. The influences of construction measures, such as lift height of horizontal tube, span of upright tube, height of bottom horizontal tube, length of vertical stretching out the top layer of horizontal pole and diagonal bracing, on stability bearing capacity of high-formwork support system was analyzed quantitatively. The construction measures of National Technical code for safety of steel tubular scaffold with couplers in construction (JGJ 130-2011) and Guangxi Safety and technical standard for the structure of crutches with steel tubes of construction template and working platform (DB45/T 618-2009) were analyzed and calibrated. Finally, recommendations for various construction measures were provided based on the results of quantitatively analysis.