Bond stress in grouted spiral connectors

Grouted connections are defined as the system used to join steel rebars available in precast components by means of grouting the splice sleeve and steel rebars together. The bond between the infill material and the steel bar is the key factor that governs the capacity and the performance of the connection. This study was carried out to investigate the parameters that affect the bond-slip relations in the connection. The variables in this study were the pitch distance of the spiral and reinforcement bar diameter. Altogether, 21 specimens were prepared in which 3 of them were the control specimens. Each splice sleeve utilized a spiral surrounding the main bars and 4Y10 steel splice bars which were welded to the inner surface of the spiral. All the grout filled splices were tested under increasing tensile loading. The experiments examined the bond stress-slip behaviour as well as the failure mode of the splices. The results indicate that by using the spiral without the vertical bars could not increase the bond capacity of the splices significantly. The results also showed that by reducing the bar diameter and the pitch distance of the spiral led to a higher bond strength. The highest bond stress was observed in the specimen with the lowest pitch distance and smaller bar diameter