| Diaphragm-through connection between concrete-filled square steel tubularcolumn and steel beam has been recommended in technical specification for structureswith concrete-filled rectangular steel tube members (CECS159:2004). Mostresearches on the mechanical behavior of the joints are experiments and there are sofew studies on the failure mechanism that calculating theory is not well developed.Since the lack of researches on capacity and design method of the joints, and theerrors between theoretical and experimental results are relatively large, that there isnot yet a unified calculation method of bearing capacity of diaphragm-through joints.So the backward research on the bearing capacity of diaphragm-through jointsrestricts its development and application.Based on introducing the concrete-filled square steel tubular column and steelbeam joints and its research status, the problems in its researches had been putforward.In order to investigate the flexural capacity of diaphragm-through joints,nonlinear finite element analyses of diaphragm-through joint are conducted undertensile loading. ANSYS was applied, which involved large geometric deformation,material nonlinearity and contact condition. The results indicated that main factorswhich influenced the flexural capability of joint were diaphragm thickness andwidth-to-thickness ratio of the tube, while the concrete had little effect on thecapacity.The yield mechanism had been proposed based on the finite element analysisstress diagrams of the joints. And through theoretical derivation, the calculationmethod of flexural capacity was also brought forward. According to the comparison ofcalculated results of the formula and the experiment results, it can be seen that thetested values and calculated values were in good agreement.The proposed formula of flexural capacity can provide reference for futureresearch and engineering application. |
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