Research On Ultimate Flexural Capacity Of CHS-H Rigid Connections

In recent years, steel structure, with its high strength, good toughness, ductility,short construction period, as well as environmental protection, etc., has achievedrapid development in China. Beam-column joint is an important part of the steel framestructure and research on beam-column joint of steel frame has always been very hot.Currently, domestic research has focused on the connections between H-column andH-beam and has get some achievements, however, research on rigid connectionbetween circle hollow section column and H-beam(CHS-H rigid connections) of steelframe structure is relatively less, and there is few relative codes or design manualguidelines about the design of these connections. As a result, research on this type ofconnections is significant. This thesis will do research on the ultimate flexuralcapacity of CHS-H rigid connections, and the main contents are as follows:(1) By finite element nonlinear analysis of CHS-H rigid connection with innerdiaphragm, this thesis studied the influence of different parameters on the ultimateflexural capacity of the connections, and the parameters studied include: the axialcompression ratio of tube column, the width and thickness of beam flange, thethickness of beam web, diameter to thickness ratio of tube column, vertical-horizontalratio of joint as well as the thickness of inner diaphragm. By analysis, this thesisfinally determined the impact of the parameters on the ultimate flexural capacity ofthe connections and gave project proposals about the design and calculation of theconnections.(2) This thesis build up finite element models of CHS-H rigid connections withexterior diaphragms, then conduct nonlinear analysis to study the impact of differentparameters of the joint on ultimate flexural capacity by changing model parameters,and the parameters studied include: the width and thickness of beam flange, thethickness of beam web, diameter to thickness ratio of tube column, vertical-horizontalratio of joint, the thickness of exterior diaphragms as well as the width of exteriordiaphragms. The studies have shown that failure modes of the CHS-H rigidconnections with exterior diaphragms vary due to different parameters. By parametricanalysis, this thesis finally provides a reference and practical engineering proposalsfor the design of the CHS-H rigid connections with exterior diaphragms.(3) In the ongoing revision of the code "Technical specification for steel structure of tall buildings", the ultimate flexural capacity of the CHS-H rigidconnections is considered to be bear by both flange and web of the beam, and newformula about web bending moment is added. By analyzing web bending moment offinite element joint model when the joint is in the limit state, the accuracy andapplicability of web bending moment calculation formula in the ongoing revision ofthe code "Technical specification for steel structure of tall buildings" can be verified.Finite element analysis results show that, as to CHS-H rigid connection with innerdiaphragm, the value calculated by specification formula is in good agreement withthe finite element results, and the formula can calculate web bending momentaccurately, however, as to CHS-H rigid connection with exterior diaphragm, the valuecalculated by specification formula is much less than the finite element calculations,so web bending moment calculated by the specification formula is more conservative.