Seismic Performance Research Of High-Strength Concrete Column With 600MPa High-Strength Longitudinal Reinforcement

HTRB630 grade rebar is a kind of high-strength rebar with yield strength over600 MPa newly developed in China,which is the main product of the replacement of rebar for concrete structure in the future.The popularization of this kind of rebar can effectively reduce the amount of rebar,reduce the structural weight,save resources and energy,and improve economic benefits.Promote the use of 600 MPa grade high strength reinforcement,the first should ensure that its strength can be given full play.However,due to the existence of buckling,the strength of steel bars under compression may not be fully developed,which directly affects the utilization rate of the strength of materials.Therefore,this paper adopts the method of combining experimental research and numerical simulation to study the seismic performance of 600 MPa grade highstrength reinforced concrete column,and analyzes the strength of 600 MPa grade compression longitudinal reinforcement in the members,including the following aspects:(1)Through the low-cycle repeated horizontal load test of seven concrete columns with600 MPa high strength steel bar under high axial compression ratio,the failure process and failure mode of high strength reinforced concrete bending members and high strength longitudinal reinforced concrete columns are studied.The horizontal load-displacement hysteresis curve,skeleton curve,bearing capacity,ductility performance and energy dissipation capacity are analyzed.The effects of volumetric hoop ratio,longitudinal reinforcement diameter and stirrup strength on the seismic behavior of high strength reinforced concrete columns are analyzed.The stress and strength of high-strength stirrups and high-strength longitudinal bars play a level.The results show that the plastic hinges formed by each test piece are in the root of the column,and the compression and fracture characteristics are obvious.The shape of the load-displacement hysteresis curve of the column top is full,and the test piece has good energy dissipation capacity under earthquake action;the displacement ductility coefficient is mostly greater than 3.0,between 3.0 and 4.0,the ultimate displacement angle is greater than 1/50,and the smallest is 1/36.The specimen has better deformation ability under earthquake action;the yield of the stirrup is generally After the specimen reaches the peak load,the yield of the longitudinal reinforcement generally occurs before the specimen reaches the peak load,so that the stirrup can better restrain the effect,and the stress level of the longitudinal reinforcement is fully exerted.(2)Numerical simulation analysis of seismic performance of high-strength reinforced concrete columns.Based on the ABAQUS finite element analysis platform,the high-strength steel bar adopts the constitutive model considering the buckling effect,and the nonlinear finite element model of the high-strength reinforced concrete column under low-cycle repeated horizontal load is established.Using the seismic performance test results of the high-strength reinforced concrete column,the validity of the nonlinear finite element model is verified.The effects of axial compression ratio,high strength longitudinal reinforcement strength,stirrup strength,stirrup diameter,stirrup spacing and concrete strength on the seismic behavior of high strength reinforced concrete columns are further analyzed.Numerical simulations show that:(1)Axial compression ratio for high strength reinforced concrete the seismic performance of the column has a great influence.Increasing the axial compression ratio is unfavorable for improving the energy consumption of the test piece,but it can improve the maximum bearing capacity of the test piece.(2)When other conditions are constant,increasing the strength of the stirrup will make the test piece The energy consumption capacity and bearing capacity increase;(3)when other conditions are constant,reducing the spacing of the stirrups will increase the energy consumption capacity and bearing capacity of the test piece;(4)the increase of concrete strength will also make the energy consumption capacity and load bearing of the test piece.The force is improved.In order to save steel,the 600 MPa grade high strength steel bar is used instead of ordinary steel bar as longitudinal reinforcement in reinforced concrete members.In addition,the buckling behavior of high strength longitudinal reinforced concrete is also studied,which lays a certain foundation for the further research of 600 MPa class high strength longitudinal reinforced concrete column.