Experimental and numerical investigation of prefabricated prestressed vertical steel strand core tube flange column connection joint

The core tube flange column joint is proposed to avoid field welding of traditional steel structures and to realize remote processing and efficient assembly. However, when the story drift is large, the joint will produce large deformation, and the flange bolt will be broken. Thus, in the present study, a prestressed vertical steel strand core tube flange column connection joint and design criteria were proposed to limit the large deformation at the flange connection. Both proposed prestressed vertical steel strand core tube flange column joint and core tube flange column connection joint were analyzed under low cycle reciprocating loading tests. It was found that the vertical steel strand can improve the hysteretic performance and ductility of the joint. Also, the vertical steel strand can increase the synergistic performance of the column connection joint, which changes the failure mode of the vertical steel strand. Based on the test results, the mechanism of the prestressed vertical steel strand core tube flange column joint was analyzed, and an effective numerical model for the joint was established. The analysis of the joints with different initial steel strand forces showed that increasing the initial short strand force will limit the deformation at the flange connection. Although this restriction has little impact on the joint's bearing capacity, it greatly impacts the strain at the column foot. Based on the numerical analysis, an optimal initial short strand force was obtained, which could provide a reference for engineering design. Note that the prestressed vertical short strand core tube flange column connection joint has excellent mechanical performances, breaking through the key technology of non-welded connection of vertical members. This proposed connection joint can achieve efficient assembly in practical engineering applications and realize the design goal of “strong joint, weak member”