An Experimental Study On The Seismic Behavior Of Recycled Concrete Frame Columns

Owing to the insufficient study on the seismic behavior of recycled aggregate concrete (RC) frame columns, the experiments on seven RC frame columns and two normal concrete (NC) frame column were conducted under low-cycle reversed loading. The failure shape, force- displacement hysteresis loops and skeleton curves, characteristic load and characteristic displacement, loading capacity, ductility and ultimate deformability of RC and NC specimens were analyzed. The effect of axial load ratio, the amount of longitudinal steel and the amount of transversal steel in the plastic hinge region on the ductility and ultimate deformability of RC columns were discussed. The ductility factors of specimens gained by different ways of ascertaining yielding load were compared in the research. Finally, some design suggestions were advised. The research concludes that the hysteretic behavior and the ultimate deformability of RC columns are significantly influenced by the axial load level, improving the amount of longitudinal reinforcement as well as the amount of transverse reinforcement of RC frame columns could have a good effect on the ductility and ultimate deformability. When the axial load ratio is less than 0.2, the requirements of stirrup reinforcement in the plastis hinge region could comply with the requirements of Chinese code for seismic design of buildings GB50011-2001. However, when the axial load ratio is more than 0.2, the requirements of stirrup reinforcement in the plastic hinge region should be improved. In addition, the axial load ratio of RC frame columns should be controlled in the structural design since the RC frame columns are difficult to gain satisfactory behavior of ductility and ultimate deformability on the high axial load level.