Studies On Seismic Behavior Of Core Steel Reinforced Concrete Columns Considering Confinement Mechanism

As a new type of structural component,Core steel reinforced concrete column(CSRC)improve the axial compression bearing capacity and deformation capacity of the structural member by setting a smaller section steel in the core area of ordinary reinforced concrete column(RC),it can effectively inhibit the development of shear cracks,which can prevent the structure from causing more serious damage in the event of an earthquake disaster.Due to the good performance of the CSRC column and it can cost savings in the economy,therefore,there is a lot of room for promotion in the engineering community.In this paper,ABAQUS software is used to carry out finite element analysis on core steel reinforced concrete columns considering the effects of confinement on concrete.The influence of various parameters on its hysteresis performance was obtained,and compared the difference in seismic performance between ordinary reinforced concrete frame structure and core steel reinforced concrete frame structure.The main work is as follows:For core steel reinforced concrete columns,concrete was confined by both the steel section and the reinforcement bars.the concrete is divided into four zones,namely the steel highly confined concrete zone,steel weakly confined concrete zone,hoop restraint concrete zone and unconstrained concrete zone for calculation and analysis.The low-cycle reciprocating loading test data of the existing core steel reinforced concrete columns were collected,and the hysteretic numerical simulation of the specimens was carried out by using the above partitioning ideas.The rationality and accuracy of the finite element model proposed in this paper are verified by comparing the calculated results with the actual experimental results.Using the research method of this pape,19 core steel reinforced concrete column specimens were designed according to significant influencing factors,and modeled by the finite element method proposed above.The effects of different axial compression ratios,reinforcement ratios,volume ratio of stirrups,encased steel ratio and sectional form on the hysteretic behavior were investigated.The results show that the bearing capacity of the CSRC column increases with the increase of the axial compression ratio,when the axial pressure ratio reaches a certain limit,the bearing capacity decreases as the axial compression ratio increases,but the ductility ratio has been reduced as the axial compression ratio increases.Increasing the reinforcement ratio and volume ratio of stirrups can improve the hysteresis performance of CSRC columns.Within a certain range,encasedsteel ratio and section form of the steel have limited influence on the hysteresis performance of the CSRC column.A single-span two-layer frame of core steel reinforced concrete columns was designed,which compared with ordinary reinforced concrete column frames.The damage model,hysteresis curve,skeleton curve,displacement ductility,stiffness degradation and energy dissipation capacity were analyzed.The results show that the CSRC column is superior to the ordinary reinforced concrete column in terms of seismic performance.