Seismic behavior of full-scale steel reinforced recycled concrete columns under high axial compression ratio

In order to promote the application of recycled concrete in structural members, the effect of recycled coarse aggregate (RCA) replacement ratio and inner steel on seismic performance of high-strength recycled concrete columns under high axial compression ratio was investigated. Low frequency cyclic loading tests on 6 column specimens, including 3 steel reinforced recycled concrete (SRRC) columns and 3 reinforced recycled concrete (RRC) columns, with a 600 mm x 600 mm cross section were carried out. Results show that high-strength RRC columns under high axial compression ratio have reliable seismic performance. The seismic performance of RRC columns is improved by adding inner steel, especially for specimens with high RCA replacement ratio. The replacement ratio of RCA has no obvious effect on SRRC column bearing capacity and ductility, but for RRC columns, it slightly reduces bearing capacity and energy consumption. When the specimen is damaged, the reinforcement and flange section in the compression zone yields, while the reinforcement in the tension zone approaches yielding. According to the plane assumption and considering the confining effect for the concrete provided by stirrup and steel, the crack load, yield load, and peak load are calculated, and calculated values are in good agreement with experimental values. This study provides a reference for the application of high-strength recycled concrete columns in practical engineering.