Seismic performance of bolted flange splicing joints for CFST columns

Bolted connections are suitable to be applied in prefabricated structures and seismic resilient structures. A series of bolted flange splicing joints were proposed for square concrete-filled steel tubular columns, and six full-scale specimens with different flange thickness and flange stiffener layouts were designed and tested under cyclic loads to study the seismic performance. The stiffness, the ductility, the bolt tension forces, the strain distributions and the hysteretic behaviors of the joints were analyzed. Finite element models were established and validated by the test results, further analyzing the joint performances. According to the results, the joints with flange stiffeners or thicker flange plates could develop larger resistance, stiffness and rotational capacity. The joint yield moments would increase with the increase of the bolt diameter, the stiffener height or the stiffener thickness, and decrease when the distances between the bolts and the column walls increase. Parametric analysis of the joint was conducted, and calculation methods of the joint yield moment were proposed accordingly and validated by the test and finite element analysis results, providing satisfactory accuracy.