| With the continuous advancement of China’s construction industrialization process,assembly building has become a new driving force and direction for the development of the construction market.In order to speed up the rooting and landing of assembled buildings and meet the requirements of mechanical properties of building structures,a new type of assembled composite concrete filled steel tube column-steel beam composite joint frame is proposed based on the advantages of good bearing capacity,plasticity,toughness and fire resistance.At present,the research on assembly CFST column structure mainly focuses on the joint research,and the frame research is insufficient.Therefore the CFST column assembly joint frame has been a new idea and direction to reserch,aiming at providing reliable reference value for the practical application of engineering.On the basis of reasonable design,carries out experimental research on the seismic performance of the joint frame,and uses ABAQUS to simulate and verify,and carries out parameter analysis on the bearing capacity and failure mode of the joint,and puts forward feasible improvement measures.The main contents and achievements:(1)Two composite concrete filled steel tube column-steel beam composite joint frame are designed and manufactured,one is the traditional Bolt-welded joint frame,the other is the assembled joint frame.According to the assembly design concept of "factory welding and field bolt connection",all the assembly joint frames adopt high-strength frictional bolt connection,which effectively avoids the shortcomings of traditional joint frames in field welding,and the joint layout is reasonable,connect is reliable,the transfer path of force is clear,and the construction is convenient.It provides a new way for the assembled composite concrete filled steel tubular column-steel beam connection.(2)Two frames were tested under low-cycle reciprocating loads.The failure modes and bearing capacity of traditional bolted-welded joint frame and assembled joint frame were explored,and the seismic performance indexes such as bearing capacity,stiffness and strength degradation,ductility of the two frames were compared.The results show that the hysteretic curves of the two frames is full,the ductility coefficient and the mechanical properties are good.(3)Through using finite element analysis software ABAQUS,considering material constitutive relation,boundary condition,mesh density and bolt loading mode reasonably,using trilinear strengthening model for steel,CDP model for concrete and three-stage steady loading method for bolt,the numerical simulation of two frames is carried out,and the resultsare compared with the experimental results.The results show that it is good enough to simulate the deformation form and load-bearing capacity of the frame under low-cycle reciprocating load,which shows the rationality of the model.(4)Based on the analysis of test and finite element results,the failure modes of the new joint frame are analyzed,and the existing problems are discussed,and the corresponding improvement measures are put forward.The parameters of the frame,such as the depth of weakened beam,the axial compression ratio,the thickness of the extended end plate and stiffening rib,the width of the extended end plate,the thickness and width of the steel tube,are explored when the values of different parameters are taken.The influence of monotonic loading on bearing capacity and stress distribution of joints can meet the seismic requirements of strong joints and weak members" and the requirements of composite concrete filled steel tubular column-steel beam assembly joint frame by reasonable methods,which provides direction for joint improvement.(5)In this paper,the seismic performance of the new type of composite concrete filled steel tube column-steel beam fabricated joint frame is studied,which lays a foundation for the research of composite concrete filled steel tubular fabricated structure and provides a reference for engineering application. |
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