Seismic Behavior of Reinforced Concrete Frame with Split Columns

Abstract

Based on the success of the author's previous study, the seismic behavior of a 1/3 scale model of two-bay and three-story reinforced concrete frame with short columns being replaced by split columns at lower two stories is experimentally investigated under cyclic loads to present the seismic behavior of reinforced concrete frames by using the technology of split column. At first, a test model of two-bay and three-story reinforced concrete frame scaled to 1/3 of actual frame is designed, in which the original columns at lower two stories of the model frame are short columns and are replaced by the split columns, and is applied to constant vertical loads and cyclic horizontal loads at the top of the frame. The hysteresis curves between the cyclic horizontal load and the lateral displacement at the top of the model frame is obtained, from which it is seen that under the excitation of cyclic load, the model frame underwent the process of cracking, yielding, and maximum loading, and was destroyed under the ultimate load finally. It is also seen that the model frame with split columns represents better ductility; and the ductility factor, defined as the ratio of ultimate displacement by yielding displacement, of the model frame reaches 6.0. The yielding process of the model frame is obtained from the strain values of the longitudinal bars of beams and columns, from which it is seen that the frame with split columns can realize that the plastic hinges are generated at the ends of beams at first and then the columns begin yielding while the frame has still the load and deformation capacity. When the cyclic load reaches the maximum load, the columns begin yielding, but the deformation of frame may increase continually. It is demonstrated that splitting the sort columns can change the failure mode from shear to flexure, thus enabling a frame to have much better ductility.