Seismic behavior of a new through-core connection between concrete-filled steel tubular column and composite beam

Abstract

Through-beam connections offer the effective performance in developing the rigid connection, but the practical applications often encounter concrete pouring difficulties at the through beam region. Then an advanced through-core connection between concrete-filled steel tubular (CFST) columns and steel-concrete composite (SCC) beams is proposed in this study. The modification emphasizes the reduced beam flange width to convenient the concrete pouring, and the penetrated slab reinforcement into the CFST column to make up the strength loss from flange reduction. To investigate the seismic behavior of the connection, quasi-static cyclic loading tests on four specimens are conducted, and corresponding finite element analyses are also performed. The failure modes, hysteretic response, skeleton curve, ductility, stiffness degradation, ultimate bearing capacity, and energy dissipation of these connections are all discussed in detail. The results indicated that the proposed new connection has a favorable seismic performance. Then with FE simulations, the varying trends of the seismic behaviors, including the strain at the core area, plastic damage at core concrete and the energy dissipation proportions in the connections are all analyzed. Moreover, the influencing patterns of axial load ratio and the flange reduction degrees (RD) are also investigated through FE simulations. To ensure a good seismic performance, the maximum flange reduction degree (RD) of the steel girder is suggested to be 0.4 for the upper flanges and the ratio of the flange reduction between the lower and the upper flanges should not exceed 0.8.