Study On Hysteretic Behaviour Of Concrete-filled Double Tubular Slender Columns

Double concrete-filled steel tube is a new type of composite member formed by concentrically configuring a steel tube in the concrete filled steel tube member.Because the concrete is subject to the double cons traints of internal and external steel tubes,it shows better bearing capacity,stiffness and ductility than ordinary concrete filled steel tube members.In modern engineering,double steel tube concrete is mainly used as the load-bearing components of building structures,such as the load-bearing columns in buildings and piers in bridge structures.At present,scholars at home and abroad have carried out a lot of research on the static performance of this type of members,and have a relatively full underst anding of their axial compression performance and compression bending performance.However,there is little research on the hysteretic performance of this type of members,and there is also a lack of in-depth research and analysis on the failure mode and t he calculation of compression bending bearing capacity under reciprocating load.Therefore,it is necessary to conduct a more in-depth study on the hysteretic behavior of concrete filled double steel tubular compression bending members,in order to provide theoretical support for the engineering design of such members and promote their wide application in practical projects.In this paper,the hysteretic behavior of concrete filled double steel tubular compression bending members is studied by experimental research and finite element analysis.Pass test P-Δ Hysteresis curve is used to analyze the energy dissipation capacity and seismic performance index of the specimen,and a lot of parameter analysis is carried out through finite modeling.Finally,based o n the test results and finite element analysis results,the formula and P-Δ Resilience model.The main research contents of this paper are as follows:(1)In this paper,12 square sleeved circular double steel tube concrete compression bending members are tested for their hysteretic behavior.Is the axial compression ratio and the diameter thickness ratio of the inner steel pipe.The influence of different axial compression ratio and inner steel pipe diameter thickness ratio on the failure form of the test piece was discussed by observing the test phenomenon and the failure form of the test P-Δ Hysteresis curve is used to analyze the energy consumption capacity of the test P-Δ Skeleton curve analyzes the influence of the axial compression ratio and the diameter thickness ratio of the inner steel tube on the peak bearing capacity,stiffness and ductility of the specimens,and analyzes the seismic performance indexes of each specimen,and systematically analyzes the seismic performance of this type of members.(2)Fiber beam element subprogram i Fiber LUT based on the second development of finite element calculation software ABAQUS.The hysteretic performance of square CFDT members is simulated,and the parameters that may affect the hysteretic performance of such members are expanded and analyzed,mainly including axial compression ratio,slenderness ratio of specimen,yield strength of inner steel tube,wall thickness of outer steel tube and compressive strength of concrete.Through a large number of parameter analysis,the effect of different parameters on P-Δ The influence of skeleton curve and the change of inner steel pipe diameter thickness ratio on the peak bearing capacity under different parameters.(3)Based on the principle of superposition,the squ are sleeved circular double steel tube concrete is regarded as square steel tube concrete and built-in round steel The formula for calculating the bending bearing capacity of concrete-filled square and circular steel tubular members is proposed,which is c onvenient to calculate and has good accuracy;Based on the parameter analysis results,the P-Δ Resilience model.