Nonlinear-analysis On Joint Of Concrete-filled Square Steel Tube And H-shaped Steel Beam

Since the steel pipe concrete structure can make full use of twomaterials as steel pipe and concrete and has other merits like high strength,light weight, good performance of earthquake resistance, it is widelyapplied in high-rise buildings. Along with wide application of CFST(concrete-filled steel tube) structure, people have paid more attention to thedesign of CFST joint. Many foreign and domestic scholars have donemassive researches on CFST joint. The researches on the joints between theconcrete filled square steel tube columns and H shape steel beams mainlyfocus on the inner stiffened joints, especially on the tube column at present,but there is little theory and test research on the joints with outer diaphragmjoint.Based on joints in the national standard drawing betweenconcrete-filled square steel tube and H-shaped steel beam the nonlinearFEM model involving geometric large deformation and material nonlinear is established by using ANSYS and other3joint models of which thecolumn sections are changed are derived from above standard model. Thebehaviors of the4joints are analyzed under the monotonic loading andcyclic loading.The results indicate that there is little difference inperformance among the four models under monotonic load and thehysteretic curves attained are all full and show no obvious stiffnessdeterioration, and all connections have a good energy dissipation capacity.The paper mainly analyzes how the width of outer diaphragm, axis-pushratio and gradation of concrete to affect the performance of joint under themonotonic loading and cyclic loading. Results indicate that when thedecrease of the width of outer diaphragm, the elastic limit load-bearingcapacity of the model decreases, the exit standard is too much safe, thewidth of outer diaphragm can decrease about25%; axis-push ratio andgradation of concrete have little affect on joint behavior.Based on the analysis and summary above, the paper presents anouter diaphragm joint of concrete-filled square steel side tube andH-shaped steel beam. The nonlinear FEM model is established and thebehavior of the joint is analyzed under the monotonic loading by usingANSYS. The paper also does research on size of outer diaphragm andhysteretic performance of this joint.