Seismic Performance Analysis of Beam-Column Connections of Prefabricated Fiber Modified Concrete Frames

The influence of concrete reinforced with fibers in the post-cast region, including the connection region and beam service holes, was studied. An improved precast prestressed beam-column connection was designed by using fiber modified concrete in the connection area. For specimen SJ1 and SJ4, the influence of design parameters on the mechanical properties of connections was investigated systematically, which including the ductility and strength of concrete in the post-cast region, beam longitudinal rebar strength, and stirrup spacing in the post-cast region. The results showed that the reduction of compressive ductility of post-cast concrete had a more obvious promoting effect on the accelerated degradation of the connection strength and the reduction of displacement ductility of connections with a high reinforcement ratio. By increasing the strength grade of beam longitudinal rebars, the bearing capacity of connections would be improved significantly, while there was a drop in the displacement ductility. The displacement ductility of connections decreased with enlarging the stirrup spacing in the post-cast region. Moreover, the seismic performance of the connections with a high reinforcement ratio were more sensitive to the increase of the stirrup spacing of post-cast region.