Effects of spiral on the bond stress-slip relationship in the splice sleeve connector

Abstract

Connections are defined as the system to transmit the forces among the precast element and provide the strength and ductility. Therefore, the connection system of the precast concrete structure must be designed in such way that its structural performance is equivalent to that of a monolithic concrete structure. Connections can exactly be as the critical points of a precast concrete structure especially when it involves in the aspect of bonding between reinforcement and concrete. Current study evaluates the relationship of the bond stress-slip of reinforcing bar joined by spliced sleeve connectors. Twenty one specimens in which three of them were control specimen with different variables such as pitch distance and spiral diameter. Those splice sleeve connectors utilized mild steel pipe, spiral surrounding the main bar and four steel bars as a shear keys that were welded into the inner surface of steel pipe. All the specimens were filled with Sika grout 215 and tested under incrementally tensile load. The experimental tests examined the bond stress, slip and failure modes. The results suggest that reducing the pitch distance and spiral diameter of spiral lead to higher ultimate bond stress. Also, the splice sleeve connector with pitch distance of 25mm contributed to the ultimate bond stress with lower amplitude of slip. It means that the pitch distance of 25mm has the main role to control the range of slip in comparison with the others. Thus, using the spiral with a smaller pitch distance will give the best performance of the splices sleeve connector.