Use of fibre sheet strip stirrups for internal shear reinforcement of concrete beams

In this research, experimental observations were made for the possible application of fibre sheet strips (FSS) as internal stirrups in place of fibre-reinforced polymer (FRP) rod stirrups currently being used for reinforced concrete beams. A total number of eight concrete beams were tested under three-point loading. Each beam measured 1200 mm long, 150 mm wide and 250 mm deep. Their shear span/depth ratios were 2.1. The beams were composed of different shear reinforcements: one without stirrups, one with steel stirrups and the rest with different types of FSS stirrups. Commercially available carbon fibre sheets were used for FSS stirrups. The main variables included strengthening bent portions of FSS stirrups, surface treatment and impregnation for FSS stirrups. Test results indicated that concrete beams reinforced with FSS stirrups enhanced shear strength over the beam without shear reinforcements. Moreover some of them could maintain comparable shear behaviour to that of the concrete beam reinforced with steel stirrups in overall load-deflection relationships, shear strengths, crack patterns and crack widths at maximum load.