Longitudinal box-beam bridge joints under monotonic and cyclic loads

Longitudinal joints used for connecting box beams in bridge superstructures are prone to the formation and propagation of cracks, causing various structural performance issues and durability concerns. Among possible solutions, the use of shrinkage-compensating cement concrete along with joint reinforcement has been investigated in the current study through full-scale experimental tests and supporting numerical simulations. The shrinkage-compensating cement concrete offered the capability of producing controlled compressive stresses during the early stage of hydration, counteracting detrimental tensile stresses that originate from the shrinkage of concrete. Longitudinal and transverse reinforcements were also included in the joint to ensure the proper transfer of forces. The response of the full setup was evaluated under five million load cycles, including various loading protocols and boundary conditions. The measurements recorded from the experiments consisted of strains and deflections at critical locations. To expand the scope of this investigation and understand the effect of interfacial bond strength and joint reinforcement, a set of numerical simulations were also performed. Through a new combination of concrete mixture and reinforcement detail, this study provided a holistic strategy to resolve the long-standing issue of degradation of longitudinal joints in box-beam bridges.