| Concrete filled steel tube structure(CFT structure) can give full play to their respectiveadvantages of steel and concrete, allow the CFT structure a unique advantage, and alsopromote the use of high-level multi-field and high-rise buildings and bridges which isdeveloping rapidly in recent years. However, research on the CFT is still relatively small,especially on the seismic performance of the CFT beam-column joint. Currently practicalapplications are still more to experience because of the lack of a complete theory of thesystem. As the key part of the structure, the joint is facing many problems in the actualdesign and construction. Therefore, it is necessary to carry out extensive research on the CFTbeam-column joints to accelerate the further promotion and application of the CFT structuresin the practical engineering.This paper is a research on the mechanical properties of the CFT and steel tubebeam-column joints. Based on the data acquired from the new CFT beam-column jointspseudo-static test, using different core concrete constitutive models of the CFT, to analyzethe CFT beam-column joints by the finite element method, screen and match theexperimental data more concrete constitutive models. Establish the six finite element methodmodels of CFT Structure and steel structure beam-column joints, to analysis on the jointscolumns in axial compressive load limit, a one-way end of the beam and the beam end loadapplied loading force performance in three weeks under low cyclic loading, etc. Obtain thedata of the stress distribution of joints, ultimate bearing capacity, energy dissipation, strengthand rigidity degradation and displacement ductility coefficient and others. Also, thedifference of joints and the advantages and disadvantages of joints connection forms havebeen analyzed. The result of comparative analysis shows the D-P model is much closer to theexperimental results among the core concrete constitutive models offered by the finiteelement method.Contrast the results of mechanical properties under columns axialcompression ultimate load and applicable uni-axial load, the analysis shows that the boltedconnection type CFT column-CFT beam joint has good mechanical performance. Contrastthe results of seismic performance under low cyclic load, and analysis shows that the outerand interior diaphragm type CFT column-CFT beam joint has good seismic performance.The comprehensive comparison of six kinds of the CFT structure under three kinds of loads shows that the bolted connection and outer and interior diaphragm type CFT column-CFTbeam joint has better mechanical and seismic performance. From the perspective of theconstruction，the bolted connection type joint is provided with easy assembly, no weldingsite and no high technical requirement. Therefore, the bolted connection type CFTcolumn-CFT beam joint is more conducive to promotion and application. |
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