Experimental study on the shear behavior of joints in precast concrete segmental foundations

By adopting the segmental precast post-tensioning method in foundations, the efficiency of constructing precast concrete structures can be significantly enhanced. To study the shear behavior of precast concrete segmental foundation (PCSF) joints, 13 double shear specimens were tested. The failure mode and shear carrying capacity (Vu) of the specimens were investigated. The parameters which were studied included the type of shear key, the confining stress, the type of bond for the internal post-tensioned bars and the application of epoxy resin. The results showed that design parameters changed the crack extensions of the joints. The Vu of the key unreinforced specimens was 29.14% lower than that of the reinforced specimens. After grouting of the post-tensioned ducts, the average Vu increased by 112.87% than that before grouting. With the increased in confining stress and the application of epoxy resin, the average Vu of the specimens increased by 21.9% and 48.45%, respectively. Finally, the test results were compared with the predicted results for the Vu of the joints. In predicting Vu for PCSF joints, the dowel action of the bonded post-tensioned reinforcement and the action of the reinforcement in the key must be considered on the basis of the existing prediction expressions.