Researchon The Mechanical Effect Of The Interface Between The Thin Steel-concrete-wrapped Composite Pipe Column

The outer thin steel concrete sandwich composite pipe column refers to a composite structure in which the inner and outer steel pipes are placed concentrically,and concrete is injected between the two pipes to form a combined structure in which the inner and outer steel pipes are subjected to common force.Compared with ordinary steel pipes,thin-walled steel pipes have better mechanical properties and corrosion resistance,energy saving and environmental protection,low cost,and a wide range of applications.In order to study the effect of the interlayer force(P)and the thin steel wall thickness(D_o)on the mechanical performance of the composite pipe string,this paper uses the outsourcing thin steel concrete sandwich composite pipe string as the research object,and the numerical analysis method is combined with the theoretical research.With the help of ABAQUS software,a finite element model of the composite structure of the thin-steel-concrete sandwich composite pipe column was established,and the interface mechanical properties of the composite structure were studied to provide a reasonable basis for engineering applications.The main work carried out in this paper is as follows:First of all,according to relevant literature,using numerical analysis method,ABAQUS software is used to establish a finite element model of an axially compressed column with thin steel sandwich concrete,obtain its load-strain curve law,and compare it with the test results.It is found that the maximum error in the specimens CC2A,CC3A,CC4A,CC5A,CC6A,CC7A is 7.65%,which is not more than 10%,which verifies the rationality of the finite element modeling.Secondly,based on the axial compression column model,the influence of the interlayer force(P)and the outer thin steel wall thickness(D_o)on the interface mechanical properties of the composite structure is studied.Extract the load-deformation curve of the test piece and compare and analyze it.The results show that:under axial compression,the change of the interlayer force(P)basically has no effect on the bearing capacity of the composite structure;in the range of C40-C60,the thickness of the outer wall thin steel(D_o)is the optimal value It is 2mm.Then,a finite element model of the eccentric compression column with thin-steel sandwich concrete was established,and its load-deflection curve was obtained and compared with the test results.It is found that the maximum error in specimens B-1,B-2,and B-3 is6.78%,which does not exceed 10%,which verifies the rationality of the finite element modeling.Based on this model,the effect of the interlayer force(P)between the steel tube and concrete and the thickness of the outer thin steel(D_o)on the mechanical properties and bearing capacity of the composite structure is studied.The results show that:under eccentric compression,the interlayer force(P)can significantly increase the bearing capacity of the composite structure;when the concrete grade is in the range of C40-C60,the thickness of the outer thin steel wall(D_o)is the same as the axial compression The values of the bars are the same.Finally,based on the above research,a hysteretic analysis model of the composite pipe-column composite structure with thin-steel-concrete-enclosed sandwich is established.According to the calculation model,various indicators of the test piece are extracted and analyzed.The results show that the change of the interlayer force has a good improvement on the hysteretic performance of the thin-steel-concrete sandwich composite pipe column.