Research On New Technology Of Steel Tube Strengthened Composite Column

Steel tube-reinforced concrete composite columns generally bearing a greater axial load,under a high axial compression ratio, the mechanical behavior is very different between theconcrete inside the steel tube and the concrete outside. Ductility of the outer concrete is poorwhile it is good for the core concrete. When stirrup ratio is low and the outer concrete crushed,the constraint of steel tube had not been fully exploited which resulted in reduced bearingcapacity of composite columns. This paper using the composite strengthened method, combinedwith CFRP and angle steel, to strengthen the steel tube-reinforced concrete composite column.The purpose is to provide lateral force for delaying the failure of the outer concrete, to get a fulluse of material, and raise the bearing capacity of composite columns. A finite element model isestablished using universal finite element analysis software ABAQUS, and the major contents aresummarized follows:On the basis of experiment, a finite element model is established, considering the influenceof steel ratio and slenderness ratio to the bearing capacity under axial load and eccentric load.The load-displacement curves and the bearing capacity are obtained. The finite element analysisresults and experiment results which are in good agreement show that simulation results aregenerally right. Load-strain curves are obtained, and the author elaborated on the failuremechanism of the specimen as well as failure characteristics. Order to understand the hightemperature performance of steel tube-reforenced composite column encased with angle steel, athermal-mechanical analysis has been carried using finite element analysis software ABAQUS.Temperature contour of each specimen and time-displacement curve have been put forward, aswell as the fire resistance of each column.This paper using the composite strengthened method, combined with CFRP and angle steel,to strengthen the steel tube-reinforced concrete composite column in Diechuitai project. Thebearing performance of steel tube-reinforced concrete composite columns combinationstrengthened with angle steel and CFRP has been studied in detail by finite element method. Theload-displacement curves and the stress contours are obtained. The influence of steel ratio andthickness of CFRP layers to the bearing capacity is analyzed too, as well as the eccentricity. Theresult shows that both the steel ratio and the thickness of CFRP layers have great contribution tothe axial load capacity. Based on the finit element analysis, the calculation formula of steeltube-reinforced concrete composite columns combination strengthened with angle steel andCFRP has been put forward. This paper discussed several methods for fire protection of steeltube-reinforced concrete composite columns combination strengthened with angle steel andCFRP. The temperature field of the column has been studied by finite element analysis software,and the appropriate thickness of fire protection is given.