Study On Performance Degradation Of CRB550 Stirrups Under Quasi-Static Load

Compared with traditional ordinary steel bars,cold-rolled ribbed steel bars have the advantages of high strength,light texture and low price.The application of cold-rolled ribbed steel bars in concrete structures can effectively reduce the slip between concrete and steel bars,which is very large.To the extent that the cracking of the anchorage position of the component is avoided,the bearing capacity of the concrete column member and the crack resistance of the house can be improved.However,based on the current use of high-strength cold-rolled ribbed steel bars in China,it is still in the promotion stage.In response to the concept of “green building” energy conservation and environmental protection advocated by the state,if it is applied to concrete structures in large quantities,it can not only reduce the project cost,but also bring huge social benefits.This paper refers to the requirements of steel grades in the Code for Seismic Design of Buildings(GB50011-2010),and adopts the principle of equal strength design to configure CRB550 grade cold-rolled ribbed steel bars with smaller cross-sectional area.As the built-in stirrup of concrete column members,the seismic performance of concrete frame column members under different working conditions is studied,in order to obtain the performance indexes of concrete column members such as stiffness,strength and ductility under seismic loading.This article mainly focuses on the following aspects:(1)According to the principle and requirements of seismic codes for buildings in China,the concrete column model is established by ABAQUS finite soft simulation software,and the mechanical indexes and component failures under different longitudinal reinforcement ratios,stirrup strength grades,stirrup cross-section areas are obtained.Morphology,verifying the rationality and accuracy of finite element software simulation by comparing the simulation results with the experimental results.(2)Comparing the hysteresis curve,skeleton curve,secant stiffness curve and ring stiffness curve of CRB550 steel bar and HRB335 steel bar simulation column member,the concrete column members are studied from three aspects: stiffness degradation,strength degradation and ductility performance.Seismic performance,verify that CRB550 grade cold-rolled ribbed steel can replace HRB335 grade steel as the builtin stirrup of concrete column member on the basis of meeting the requirements of standard construction.(3)In this paper,18 concrete column members with bending failure are designed.The ABAQUS finite element simulation software is used to simulate the quasi-static reciprocating loading,and the stiffness and strength of concrete column members with built-in CRB550 steel bars are determined.The index provides a reference for the application of cold-rolled ribbed steel bars in concrete structures.