Study On Seismic Behavior Of RC Columns With Ultra-high Strength PC Strands

In recent years,frequent earthquakes beyond the codes' level have caused the design of buildings based on the current seismic design codes to be not capable to meet the need for quick repair and post-earthquake relief work under large earthquakes.The concept of resilient concrete structure arises at the historic moment.Self-centering structure is a type of resilient concrete structure,which can reduce the damage of structures by controlling the residual deformation,making it possible for the building structure to quickly repair after the earthquake.In this study,ultra-high strength(UHS)PC strands is used as the longitudinal reinforcement of RC columns.By reducing the bond stress in surrounding concrete,the yield of longitudinal rebar is delayed under large deformation and the strain distribution over the length of the rebars is uniformly,thus put into full play to its high strength and ductility to achieve self-centering of the structure.To verify the feasibility of the self-centering under the great earthquake,a reversed cyclic lateral load while subjected to constant axial load test is carried out.The effects of longitudinal rebar,axial ratio,shear span ratio and restraint method at plastic hinge zone on the seismic capacity,the strain contribution of the longitudinal rebar,the ultimate deformation capacity,the residual deformation and the energy dissipation capacity are studied.Based on the measured mechanical properties of materials and with the finite element analysis program Open Sees,a fiber model considering the bond slip effect of PC strands is established,which is compared with the hysteresis curves obtained from the test.The comparison of the various earthquake resistance indexes with the measured values proves the accuracy of the model.Through the comparative analysis of test results and numerical analysis,it can be seen that the RC columns with PC strands can effectively control the residual deformation,and the main failure cracks are concentrated in the plastic hinge area,which is convenient for repair.When steel plate is used to restrain the plastic hinge transversely,the bearing capacity of the specimen is further improved.By studying the seismic behavior of RC columns with PC strands,it can be seen that the application of UHS PC stands can effectively control the residual deformation in the column and improve structural damage,so that the column can be self-centering.