SHEAR BEARING CAPACITY OF STEEL REINFORCED RECYCLED CONCRETE COLUMN-STEEL BEAM COMPOSITE FRAME JOINTS

In order to study the shear bearing capacity of SRRC column-Steel beam composite frame joints, eight joint specimens were subjected to low cyclic loading tests. The failure process and failure modes of the specimens were observed and the strain of steel and rebars at each loading stage were obtained. The influences of the axial compression ratio and recycled coarse aggregate replacement percentage on the shear bearing capacity of joints were analyzed in detail. The results show that the shear bearing capacity of the joints decreases with the increase of replacement percentage, but the reduced magnitude of shear bearing capacity is relatively small. Appropriate increase of the axial compression ratio can improve the shear bearing capacity of the joints. Before the specimens became yielded, the shearing bearing force was mainly undertaken by the recycled concrete in the core of joints. After being yielded, the shearing bearing force was mainly undertaken by the steel webs and stirrups. Based on the test findings, the failure mechanism of composite frame joints was analyzed, and the expressions of shearing force of steel webs, stirrups and recycled concrete were proposed. Finally, the formula of shear bearing capacity for SRRC columns-Steel beams composite frame joints was established by in term of the superposition method. The calculated results agree well with the test results. The work could be used as a reference for the construction practice of the SRRC columns-Steel beams composite frame joints.