Experimental Study On Seismic Performance Of Concrete Shear Walls With 600MPa Steel Bars

High strength steel bars can save resources and reduce the amount of steel per unit are.The concrete structure is developing towards the directions of large span and high rise,The general social environment in China is to promote green sustainable development and encourage supply-side reform.Therefore,the using of 600 MPa grade high-strength steel bars as the main forced steel bars has wide prospects.In order to promote the application of 600 MPa grade steel bars,systematically study on the main mechanical properties of 600 MPa grade reinforced concrete members is necessary.To this end,this paper conducts experimental research and theoretical analysis on the seismic performance of 600 MPa grade reinforced concrete shear wall,to provide theoretical and experimental basis for the application of the high strength steel bars.In this paper,4 concrete shear wall specimens were designed including 1 concrete shear wall specimen with 400 MPa grade ordinary steel bars and 3 concrete shear wall specimens.And the flexural failure specimens' longitudinal,horizontal and vertical distribution steel bars were replaced by 600 MPa grade high-strength steel bars according to the principle of equal strength substitution.The research parameters include steel bar strength grade,axis pressure ratio and damage form.Through the quasi-static test of the specimen,the following conclusions are obtained: As for the shear wall equipped with 600 MPa grade steel bars according to the principle of equal strength substitution,the flexural and shear bearing capacity of the wall reduced,however the peak displacement increase.When the horizontal force reached the peak point,the energy consumption capacity was lower than that of the ordinary reinforced concrete shear wall because the reinforcement area reduced and it was not easy for the high-strength steel bars to reach the yield strenth.The initial stiffness of the shear wall with high-strength steel bars was smaller due to the small reinforcement area.However,the stiffness reduced slowly with the increase of displacement.In addition,in the range of large eccentric compression,with the increase of axial compression ratio,the flexural capacity of high-strength reinforced concrete shear walls increases,but the deformation and energy dissipation capacity decrease.The shear-damaged shear wall specimen has poor energy-consuming capacity,presenting the characteristics of shear failure.In addition,the finite element models consistent with the experimental specimens are established.The numerical simulation results show that the test results can be better simulated when the confined compession and the tension stiffening concrete models are used in the constrained edge members.Based on this model,the specimens are expanded to further analysis the influence of parameters such as reinforcement ratio,axial compression ratio,concrete strength and length of restrained edge members on the bearing capacity of the shear walls quantitatively.According to the collected domestic and foreign experiments and the experiment of this paper,the calculations calculated by China's current codes show that the flexural and shear capacity of high-strength reinforced concrete shear wall is much discrete from the experimental values.Therefore,the calculation formula of the flexural bearing capacity is theoretically deduced according to the 600 MPa steel bars' characteristics.The paper also put forward the revise recommand on the calculation formula of the shear bearing capacity according to the experimental data.And the length requirement of the constrained edge members is theoretically deduced.The comparison between test results and calculations shows that the calculation formula proposed in this paper is much reasonable.At the end of the paper,the caculation method of bending moment-curvature skeleton curve and horizontal load-displacement skeleton curve are established to guide its application in seismic elastoplastic analysis.