Experimental study on seismic behavior of different seismic grade RC columns

By quasi-static test on nine reinforced concrete (RC) column specimens with shear-span ratio of four, seismic behavior of different seismic grade RC columns and the influence of lateral loading cycle number on the behavior were studied. The test results indicate that: all RC column specimens fail in compression-bending. The lateral force-displacement hysteretic loops are plump. The ultimate drift ratio was from 1/48 to 1/32. RC columns with the same seismic grade have about the same seismic behavior, but the columns subjected to a higher axial compressive force ratio have a little bit smaller ultimate drift ratio and a little bit serious damage comparing with the columns subjected to a lower axial compressive force ratio. For RC columns which have the identical stirrup characteristic value, the elasto-plastic deformation capacity of the columns with higher seismic grade is larger than that of the columns with lower seismic grade. At the drift ratio 1/50, lateral loading cycle number does not have obvious influence on the lateral force degradation, tangent stiffness degradation and damage extent of RC column specimens. At the drift ratio 1/30, increasing lateral loading cycle number leads to an increase of the lateral force degradation extent and tangent stiffness degradation extent of RC column specimens, and also leads to more serious damage.