Research On The Continuous Collapse Resistance Of The Core Tube Structure Of The Concrete-filled Square Steel Tube Frame-Steel Plate Shear Wall

Concrete-filled square steel tube frame-steel plate shear wall core tube structure is a new type of seismic force-resisting system,which has been applied in high-rise and super high-rise buildings in China recently.The Concrete-filled square steel tube has excellent behavior in terms of strength,stiffness and ductility.The steel plate shear wall structure has the advantages of light weight,excellent seismic performance and good economy.The combination of the two structures can give full play to their advantages,making this type of structure have broad application prospects.If the structure is subjected to accidental load such as large impact load or blast load,some key components will be invalidated,resulting in local damage of the structure and causing structural continuity collapse.During recent years,continuous collapse accidents have emerged in an endless stream,which has attracted extensive attention from scholars at home and abroad.At present,the concrete-filled steel tube frame-steel plate shear wall core tube structure has been applied in practical engineering.Most of the research conducted to investigate its seismic performance.Studies on resistance to continuous collapse have rarely been reported.In this paper,the anti-collapse performance analysis of this structure is carried out.The main research contents are as follows:(1)The seismic performance analysis of the steel tubular concrete frame jointed steel plate shear wall of the other side is performed.The hysteresis curve,skeleton curve and ductility,energy dissipation capacity,stiffness and bearing capacity degradation curves of the structural specimens are analyzed by low-cycle reciprocating load tests.Seismic performance of similar structures.(2)The numerical analysis model of the test specimen is established.The steel plate shear wall structure was simulated by using the diagonal rod model,and the plastic hinge parameters of the concrete-filled steel tube members were defined.Through the simulation of the test specimen,the correctness of the simulation method in this paper is verified.(3)A 15-story prototype structure was designed according to Chinese specifications,a spatial model was established in the structural analysis software SAP2000,and the failure of the first-level side column,corner column,inner column,cylinder column,etc.was selected as the analysis condition for nonlinear dynamic analysis.Analyze the vertical displacement time-history curve of the failure node and the internal force change of the beam and column within the failure column range,determine the structure's resistance to collapse,and analyze the structure's internal force response law and force transmission mechanism.The research shows that the vertical displacement of the structure is larger under the failure condition of the side and inner columns,and the beam mechanism and catenary mechanism are experienced.After the bottom column fails,the internal force distribution follows the principle of proximity,and the failure of a single column will not cause continuous collapse of the structure.The vertical displacement is the largest when the inner column of the ground floor is removed.Therefore,priority protection measures should be taken for the inner column of such structures in engineering applications.(4)Changing the steel content of the structural steel pipe,the strength of the steel beam material,and different longitudinal demolition positions to explore its impact on the continuous collapse performance of the structure.The study found that only changing the longitudinal demolition position has a greater impact on the structural collapse performance.The maximum displacement of the top corner column failure point is 521.1%different from that of the first layer,and the maximum displacement of the top cylinder column failure point is 738.7%compared with the first layer.