Experiment Study On Seismic Design Details And Axial Compressive Performance Of Csrc Columns

Core steel reinforced concrete (CSRC) column is a new type of structural component which is developed from setting shaped steel with small size in the core region of a reinforced concrete (RC) column section. CSRC column has an advantage on seismic behaviour over ordinary RC column under high axial compression ratio and the application of this technology could enable the designer to exceed the limit value of axial compression ratio prescribed by the Code. The following studies on CSRC are carried out: (1) Five CSRC columns are tested under cyclic loading; (2) Four CSRC columns and two RC columns were tested under axially loading; (3) An analytical model of CSRC columns is established and a nonlinear numerical analysis simulating the whole test process is carried out.Based on the results of cyclic loading test, the failure patterns, hysteretic characteristic, skeleton curves, ductility coefficients, energy dissipation, stiffness degeneration and strength decay of CSRC columns are comprehensively analyzed. The effect of axial compression ratio and the truncated details of shaped steel on the seismic performance of CSRC columns are especially investigated.Based on the results of axial loading test, the failure patterns, P-Δcurves and axial load distribution of CSRC columns are comprehensively analyzed. The effect of core steel and stirrup reinforcement ratio on the axial compressive performance of CSRC columns is especially investigated.From the experiment results, the following conclusions can be derived: (1) CSRC columns have better seismic performance than ordinary RC columns under high axial compression ratio; (2) The anchorage details on the column base and middle truncation of shaped steel are rational; (3) It is found that the effect of seismic behaviour is indistinctness when test under the loading direction of the weak axial of the shaped steel; (4) The axial strength of CSRC column under axial compression test was increased by 30% approximately and the axial deformation capacity is almost doubled when the ratio of the core steel area to the section area was 2.88%. (5) Increasing the volume ratio of stirrups can effectively increase the axial deformation capacity of specimens and the brittle shear failure can also be changed into a more ductile way.A nonlinear numerical analysis simulating the whole test process is carried out by using the FEA program-ANSYS. Attention is paid to the different confinement conditions in the CSRC column section and the analysis results indicated that the results of calculation agree well with the test results.