Experimental investigation on seismic performance of mechanical joints with bolted flange plate for precast concrete column

Abstract

The conventional assembled monolithic grouted sleeve connection of column–column joints continues to require in situ grouting, which has certain disadvantages, including the necessity of wet construction. Compared with cast-in-situ columns, its seismic performance is relatively insufficient in terms of deformation and energy dissipation capacity. In this paper, a new type of precast concrete column–column joint and its corresponding column base joint with a steel jacket for confining the concrete core and bolted flange plate is proposed to achieve rapid erection. Six specimens are tested at a high axial compression ratio and cyclic reversed loading, including three precast column–column joints with bolted flange plate, one column base joint with bolted flange plate, one grouted sleeve connection joint, and one cast-in-situ column. This study focuses on the effects of the ratio of longitudinal reinforcement to the gap between the steel jacket and upper concrete on seismic performances. Test results indicate that this new joint is reliable, and all failure modes involve the flexural failure of the precast upper column. The influence of tensile reinforcement on the out-of-plane deformation of the flange plate is minimal. Compared to the cast-in-situ column, the column with a flange plate connection has a more gradual crack development, a slightly higher resistance, an improved ductility, and a better energy dissipation capacity. With the increase in longitudinal reinforcement ratio, the confining effect of the steel jacket on the concrete core becomes more distinct. The gap between the steel jacket and upper concrete could effectively delay the compressive damage on the concrete surface. Finally, considering the confining effect of the steel jacket, the flexural capacity of the proposed precast column is determined using the fiber model. The predicted results approximate the test values and are all within the safe range.