Study On Hot Spot Stress Of Concrete-Filled Steel Tubular T-Joints And Y-Joints

Concrete filled steel tube is a kind of composite material formed by filling concrete in steel tube.When the steel tube is filled with concrete,the steel tube and concrete work together.Because the Poisson’s ratio of the two is different,the concrete plays a supporting role on the steel tube while the steel tube plays a restrictive role on the concrete.Therefore,the concrete filled steel tube as a new material to fully play the advantages of the two.Since the 1990 s,the development of the concrete filled steel tube bridge in China is very rapid,the construction of a large number of concrete filled steel tube Bridges,including the largest span has reached more than 500 meters,the concrete filled steel tube bridge construction level in China has reached the world’s leading level.In recent years,with the embodiment of the bridge fatigue problem and the deepening of people’s understanding of Bridges,the welded concrete-filled steel tube joints,as the weak link of the structure,have been gradually paid attention to,and the problem of stress concentration at the joints has become the key to the development of Bridges.Based on the research of domestic and foreign scholars on concrete-filled steel tube joints,this paper studied the T-joint of concrete-filled steel tube through experimental research and finite element analysis method,and studied the Y-joint of concrete-filled steel tube by using finite element analysis method.The contents of the study are as follows:(1)One hollow steel tube and seven specimens of concrete-filled steel tube were designed for experimental study.The difference of stress concentration between hollow steel tube and concrete-filled steel tube at joint position was analyzed.The trend of stress concentration and hot spot stress concentration factor at joint position of concrete-filled steel tube with diameter ratio,diameter-thickness ratio and wall thickness ratio was studied;(2)The finite element model was established by ANSYS Workbench for finite element analysis,and the results of finite element analysis were compared with the results of experimental research.The results are more consistent,which verifies the reliability of the model;(3)This paper use ANSYS Workbench to study the influence of concrete filled in the chord,the diameter ratio,diameter thickness ratio and wall thickness ratio on the joint stress concentration factor and hot spot stress concentration factor;(4)This paper make a comparative analysis the formula of hot spot stress concentration factor of concrete filled steel tube,and modify the formula of hot spot stress concentration reduction factor by the results of finite element analysis.