The Axial Bearing Capacity Of Short Concrete-filled Steel Tube Column Constrained By FRP And Reinforced Concrete

With the common application of steel tube concrete members,Disadvantages of concrete-filled steel tubular components are also exposed,constraint concrete-filled steel tubular members which have more excellent performances have made up for the deficiency of the concrete-filled steel tubular members and have greater prospects for development.Concrete-filled steel tubular members constrained by FRP and steel tube-reinforced concrete column earn widely research of scholars because of their convenient construction,high bearing capacity,good durability,At present,the research on FRP-concrete-steel composite solid square column is less,the proposed calculation formula of axial bearing capacity of FRP-concrete-steel composite solid square column and square steel tube-reinforced high strength concrete column lack theoretical foundation and too much has been simplified.According to the characteristics of the stress of FRP-concrete-steel composite solid square column and square steel tube-reinforced high strength concrete column,The calculation formula of axial bearing capacity of the two kinds of members are deduced with the theoretical method and numerical simulation.The numerical simulation analyses of two kinds of members are conducted.The main contents of this article are as follows:Take FRP-concrete-steel composite solid square stub column as object of study.The sandwich concrete was divided into effective constraint region and invalid constraint region according to the different constraint degree of sandwich concrete.Whilst considering the double effect of restraint of core concrete,the square FRP pipe was equivalent to circular FRP pipe.Based on the unified strength theory and the influences of intermediate principal stress parameter,the material of tension and compression ratio,chamfering radius were considered,The calculation formula of axial bearing capacity of FRP-concrete-steel composite solid square stub column was deduced.Comparing the calculation results with relevant experiment results,the good comparison result can illustrate the correctness and rationality of the theoretical formula.And the influences of intermediate principal stress parameter,side pressure coefficient,chamfering radius,radius-thickness ratio are analyzed.Based on the unified strength theory and the influences of intermediate principal stress and the material of tension and compression ratio were considered when coming down to the ultimate bearing capacity of square steel tube-reinforced high strength concrete column,The constraint concrete outside steel tube was divided into effective constraint region and ineffective constraint region through introducing effective constraint coefficient and ineffective constraint coefficient to consider the different constraint functions of concrete derived from the stirrups.The square section was equivalent to circular section to consider the double constraint function to concrete in steel tube derived from steel tube and outer steel reinforced concrete.Then a new method for the axial ultimate bearing capacity of square steel tube-reinforced concrete column was deduced.The results were in good agreement through comparing the theoretical computational formula calculating results with the experimental results and the correctness of the theory formulae was proved.Influential effects of some parameters are analyzed and the analysis results show that the ultimate bearing capacity of square steel tube-reinforced high strength concrete column increases with the increase of the side pressure coefficient,Influence coefficient of intermediate principal stress,the material of tension and compression ratio and the longitudinal reinforcement ratio,while it decreases with the increase of radius-thickness ratio.The numerical simulation of FRP-concrete-steel composite solid square column and square steel tube-reinforced high strength concrete column are conducted through ANSYS software.Comparing the calculation results with relevant experiment results and theoretical calculation result,the good comparison result can illustrate the rationality of the numerical simulation.Mechanical characteristics,The parameters of Bearing capacity,Destructional form are analyzed based on the stress contours.