Experimental Research On The Mechanical Properties Of The Reinforcing Bars FRP Tube Concrete Axial Compression Member

The object of the research is the reinforcing bars FRP tube concrete axial compressionmember. The methodology adopted is a combination of experiments and the finite elementnumerical value analysis. The research analyzes the caliber of FRP tube, the depth of the tubewall, the concrete intensity, the reinforcement ratio and other factors that would influence thefailure mode and mechanical properties of the reinforcing bars FRP tube concrete axialcompression member. The research results are expected to contribute to the engineeringdesign of the reinforcing bars FRP tube concrete axial compression member.12groups of reinforcing bars FRP tube concrete axial compression members have beendesigned. The variable parameters in the experiment are three kinds of calibers and threeforms of reinforcement ratios. The data arrived from the experiment include: the ultimate loadof the test pieces, the axial direction and the hoop strain in the middle part of the FRP tube,the axial strain of the steel and the axial displacement of the test pieces. Through theobservation of the experiment and the analysis of the data, it has been found that the FRPcaliber and the reinforcement ratio will influence the failure mode and mechanical propertiesof the reinforcing bars FRP tube concrete axial compression member.Through the use of large-sized finite element software ANSYS/L-SDYNA, the finiteelement modeling has been conducted on the the reinforcing bars FRP tube concrete axialcompression member. Comparative analysis has been conducted between modeling resultsand experiment results to testify the validity of the modeling. The reinforcement ratio, FRPcaliber, the depth of the FRP tube wall and the concrete intensity have been adopted asvariable parameters to conduct finite element analysis on the modeling. When analyzing eachfactor, comparative analysis has been conducted from two perspectives, i.e. the load strainrelation curve and the ultimate bearing capacity.The research has demonstrated that with the increase of the caliber, the overallmechanical properties of the reinforcing bars FRP tube concrete axial compression memberswill decrease; the existence of the steel interferes the constraint on the FRP tube, increases thetensility of the test pieces, restricts the lateral deformation of the concrete, increases the timeof the member entering plastic phase and enhances the ultimate bearing capacity; properlyincrease the depth of the tube wall will reduce the level of member deformation and increasethe rigidity of the member so as to improve the mechanical properties of the member; in spiteof the fact that the increase of the concrete intensity will improve the overall ultimate bearingproperty of the member, the overall mechanical properties of the test pieces will decrease inturn.