Analysis Of Mechanical Behavior Connected Of Joints And Stable Bearing Capacity Of The Bowl-Button Steel Pipe Supporting System

With the rapid development of modernization construction and the increase of tall buildings and long-span bridges with complex shapes,bowl-buckled steel pipe brackets are widely used in various construction projects because of the advantages of reasonable joints,high joint strength and good mechanical performance of the frame.However,in recent years,the frequent collapse accidents of scaffolding and formwork brackets have brought serious negative effects on social security and stability.Looking back on the past,it is found that there is little analysis on the mechanical properties of bowl-buckled joints and the stability bearing capacity of bowl-buckled steel pipe bracket system by experts and scholars,so it is necessary to conduct in-depth research on bowl-buckled steel pipe bracket system.In this paper,the mechanical behavior and stability bearing capacity of bowl-buckled steel pipe brackets are analyzed from the perspective of theoretical research and finite element analysis.The main research work is as follows:(1)Summarize the collapse accidents of scaffolding and formwork support in recent years,and find several main reasons leading to the collapse of formwork support:unreasonable analysis of support nodes;unreasonable calculation of overall stability of support;backward design and calculation methods;unreasonable simplification method of load,etc.(2)The basic calculation theory of bowl-buckled steel pipe bracket is introduced.It is found that the semi-rigid assumption of bowl-buckled joints can more truly reflect the actual stress situation,and the finite element analysis method of bowl-buckled steel pipe bracket is introduced in detail.(3)The mechanical properties of bowl-buckled bracket joints are analyzed.It is found that when the joints are subjected to vertical downward loads,the stress concentration area mainly distributes at the tail of the loading bar connected with the horizontal bar and the vertical bar,and the maximum tensile stress distributes above the tail.The number of cross bars has a great influence on the firmness of bowl-buckled joints.The more the number of cross bars,the better the firmness of bowl-buckled joints.(4)Midas Civil finite element software is used to analyze the factors affecting the stability bearing capacity of bowl-buckled steel pipe support,and the influence of each factor on its bearing capacity is obtained.Based on the bracket of a continuous box girder bridge,the overall stability bearing capacity of the frame is analyzed.It is found that the calculated value is more consistent with the standard value when it is regarded as a semi-rigid connection state.(5)It is found that the allowable stress method is more conservative than the limit state method by comparing the allowable stress method with the limit state method under various structural parameters,and comparing their advantages and disadvantages.