Contribution of dowel action to interfacial shear transfer in flat joints with unbonded posttensioned bars for precast segmental bridges

Dry joints are widely used in precast segmental bridge construction because they simplify assembly and accelerate erection. Incorporating fasteners crossing flat dry joints represents an innovative configuration for this type of connection. When fasteners are present, shear transfer results from the interaction between friction and dowel action, particularly when significant relative displacements develop. In dowel‐controlled behavior, failure may occur through flexural yielding of the fastener and/or local crushing of the surrounding concrete. Advanced materials have been proposed to enhance the performance of these joints. Fiber‐reinforced concretes, including high and ultra‐high‐performance concrete, improve the tensile behavior and crack control of the concrete matrix. This study presents 24 push‐off tests on flat joints with and without fasteners, analyzing the influence of concrete type, fiber reinforcement, confining stress, and fastener configuration. Results show that dowel action becomes dominant as sliding increases, fiber reinforcement improves ductility and shear resistance, and the number of fasteners significantly influences the shear capacity. Furthermore, the results provide experimental evidence to support the refinement of current design provisions for shear transfer in unbonded posttensioned connections.