Research On Eccentric Compressive Behavior Of High Strength Reinforced Concrete Columns Based On Compressive Buckling Of Steel Bars

In recent years,hot-rolled ribbed high-strength steel bars with yield strength over600 MPa have been developed in China.If this kind of steel bars can be applied to concrete structures,the section size of members can be effectively reduced,the amount of steel bars used can be reduced,and the economic benefits can be improved.However,due to the existence of Compressive Buckling behavior,the strength of reinforcing bars may not be fully utilized in the compression process,which directly affects the performance of reinforced concrete compressive members.Therefore,by means of experimental research,numerical simulation and theoretical analysis,this paper studies the mechanical properties of 600 MPa high-strength reinforced concrete columns under small eccentric compression,analyses the strength exertion degree of the compressive steel bar,and on this basis,analyses the influencing factors of the Compressive Buckling of the steel bar,and focuses on how to avoid the pre-buckling behavior of the steel bar and ensure the full exertion of the strength.It mainly includes the following aspects:Experimental study on mechanical properties of concrete members with 600 MPa high strength longitudinal bars under small eccentric compression.Through the small eccentric compression test of 11 high strength reinforced concrete columns with 600 MPa longitudinal reinforcement strength,the failure process and failure mode of this kind of members are studied,the compressive behavior of longitudinal reinforcement during the test is observed,and the effects of stirrup strength,stirrup spacing,stirrup diameter,longitudinal reinforcement diameter and eccentricity on the mechanical properties and deformation properties of such members are analyzed.The stirrup spacing and diameter are discussed.And the influence of strength on the exertion level of compressive longitudinal reinforcement strength.Numerical simulation and analysis of 600 MPa high strength longitudinal reinforced concrete members under small economic compression.On the basis of the test,based on ABAQUS finite element analysis platform,the finite element analysis model of specimens is established,and the eccentric compression performance of specimens is calculated and analyzed.The failure mode,load-deflection curve and test results are compared to verify the validity of the model.On this basis,the factors affecting the buckling of compressive steel bars in high-strength longitudinal reinforced concrete columns are analyzed.The effects of stirrup spacing,stirrup diameter,stirrup strength and longitudinal diameter on the Compressive Buckling of steel bars are analyzed.Theoretical analysis of prevent pre-yielding buckling of compressive longitudinal bars.Taking the compressive longitudinal reinforcement in reinforced concrete columns as the research object,the restraint effect of stirrups on longitudinal reinforcement is simplified as lateral spring,and a simplified mechanical model of Compressive Buckling of reinforcing steel bars considering the influence of stirrups is established.The influence of stirrups’ axial stiffness and bending stiffness on the buckling of longitudinal reinforcement is comprehensively considered.The matching relationship between stirrup spacing and stirrup diameter is derived to prevent the buckling of longitudinal reinforcement before yielding.The calculated results are in good agreement with the experimental ones.