A Study of Reinforced Concrete Flat Plate-Column Interior Connections with Shearbands

Abstract

Because a flat plate system is a system whose columns support slab without beams, it allows for relatively small floor height and simple formwork

however, this system is vulnerable to seismic actions, as punching failure of flat plate-column connection may occur. To ensure its structural safety during earthquakes, an important design consideration is to obtain seismic ductility at the connection between column and slab. In this study, a shear band reinforcement is suggested as a method to improve overall performance of slab-column connections. The shearbands have many advantages over conventional shear reinforcement in terms of convenient installation and overall cost. An experimental study was conducted to estimate the seismic and punching shear performance of the shear reinforcement for flat plate slab-column connections. A total of six specimens were constructed on one-half scale slab-column connections and included slab-column connections without shear reinforcement and with stirrups / shearbands. Three specimens were tested under reversed cyclic lateral loading subjected to a constant gravity shear ratio of about one-third of the nominal concrete shear strength, and the remaining specimens were tested under only gravity load. The test results indicate that both shear reinforcements used in this study substantially increased the punching shear strength, the ductility of the slab-column connections, and the dissipation energy capacity. Although the connections strengthened with shear band were not as effective as connections strengthened with stirrup, they showed sufficient capacity for use in nonparticipating and lateral-force resisting systems. Most of all, the feasibility of the shearbands in the figure is promising because its installation process is quite simple.