Study On Seismic And Axial Compression Behavior Of Concrete Columns With CRB600H High-Strength Stirrups

CRB600H high ductility cold rolled ribbed reinforcement has the characteristics of high strength,high ductility and low cost,has broad application prospects.In order to analyze the seismic and axial compression performance of concrete columns with CRB600H stirrups,the system research was carried out with the method of simulation.The main research contents are as follows:(1)In Open SEES,a numerical analysis model considering bending-shear coupling effect and bond-slip effect of longitudinal reinforcement was established by using nonlinear beam column element in series with zero-length shear spring and rotating spring element.The accuracy of the finite element model of reinforced concrete column established by Open SEES was verified through literature experiments.(2)The effects of axial compression ratio,shear-span ratio and other factors on the seismic behavior of CB600H stirrup concrete columns under reciprocating loads were studied by using the tested and verified FEA model,and the HRB400 stirrup columns were compared and analyzed.The results indicate that:The components under higher axial compression ratio,have better shear bearing capacity,but the ductility and energy dissipation are opposite.Higher shear span ratio of components,its horizontal shear bearing capacity decreases,but the ductility and resistance to collapse are better.The bearing capacity of CRB600H stirrups is similar to that of HRB400 stirrups,but the ductility and seismic performance of the former are better.(3)Expand the scope of parameter study by establishing experimental analysis model with ABAQUS software,systematic research the axial compression performance of CRB600H stirrup concrete short columns.The effects of stirrup form and concrete strength on the bearing capacity and ductility of CRB600H stirrup concrete columns were analyzed,and compared with HRB400 stirrup columns.The results indicate that:CRB600H stirrups columns have little difference in peak load capacity with HRB400stirrups columns,but the ductility of components with CRB600H stirrups is improved.The bearing capacity and ductility of well-shaped composite stirrup is better than that of diamond composite stirrup and rectangular stirrup;the load-bearing capacity and ductility performance of the components,which are improved with the reduction of the spacing of the stirrup;matching higher strength concrete with CRB600H stirrup,the load bearing capacity of the components is significantly improved,but the failure form is brittle failure,and the ductility of the component is weakened.Finally,the regression fitting by parameter analysis,and based on the effective restraint effect coefficient of stirrups(k_eλ_t),the calculation formula of axial bearing capacity of 600MPa high strength stirrup concrete column is presented.Compared with the bearing capacity calculation formula proposed in the code,the calculation method proposed in this thesis has better accuracy,and can provide some theoretical help for the application and popularization of CRB600H reinforcement.