Analysis Of Mechanical Behavior And Effective Width Of CFST Joints With Exterior Stiffening Ring

With the development of steel structures in30years, concrete-filled steel tube structure with the advantages of steel and concrete has developed, and made great economic benefits; meanwhile, concrete-filled steel tube structure will become an trend from the situation of our country.In concrete-filled steel tube structure, external stiffening ring joint, as a kind of common joint, applise widely for engineering. The stiffening ring usually connects with beam flange, so bending moment is mainly transformed into tension loaded to the stiffening ring, then distributed to column limb and concrete. The value of effective width of looping pipe, how long the column limb can work with the stiffening ring, can be used as a reference, on the one hand, it has great differences between domestic and foreign in the quality of materials、the values of load and construction condition; on the other hand, domestic regulations defineded that it can be used as a reference for general industry and civil buildings, but whether it can be used still need a lot of practice and theory researches, and in recently years, column network of the workshop has became so large for meeting the requirements of production that specification of exterior stiffening ring can not accord with code and regulations, so it is essential for seeking the calculation method applied for the design of the stiffening ring joint in this structure in order to provide reference for the related code. Based on the background, the paper explored the value of effective width of looping pipe in elastic-plastic stage through a project, according to the study situation of domestic and international,1、Internal force of looping pipe is caculated using column analogy of statically indeterminate theory, and have an overall understand on the distribution of the stress and dangerous sections, finally, it is shown that validation rules for the value of effective width is too conservative.2、For outstanding advantages of external stiffening rings joint, this paper establishes a simple connected joint compared with exterior stiffening ring joint from their ultimate bearing capacity.3、Exterior stiffening ring joint of concrete-filled steel tube structure is tested through uniaxial load using simulation experiment of ANSYS, and mechanical behavior of exterior stiffening ring joint can be seen, finally, it is a fact that the column limb can work with the stiffening ring.4、Failure characteristic of exterior stiffening ring joint with different wall-thickness is studied for supplying reasonable diameter-to-thickness ratio.5、Simulation experiment of ANSYS on exterior stiffening ring joint of concrete-filled steel tube structure under cyclic loading is done for studying the effect of the value of width of stiffening ring on dynamic behavior of exterior stiffening ring joint, and it can supply reasonable ratio of width to thickness.6、Parameter analysis (width stiffening ring, thickness, diameter, wall thickness) on the value of effective width is done, and regression analysis of the data is also done for getting the calculation method applied for the design of stiffening ring joint in this structure.7、Comparing existing formula with the calculation method proposed by the paper, the paper verifies the validity of the calculation method, and the calculation method provided reference for the design of stiffening ring joint in this structure enlarges the scope of application about structure.