Small-Scale Investigation on Wide Longitudinal Joints Filled with Shrinkage-Compensated Concrete for Adjacent Box Beam Bridges

Adjacent concrete box beam bridges constitute more than 15% of bridges built or replaced each year and have been in service for many decades. A recurring problem with this type of bridge is cracking in the longitudinal joints between adjacent beams, which allows water and salt leakage through the joint and reflective cracks in the wearing surface. In this paper, a comprehensive review of the past literature is presented to identify potential reasons joint cracking is induced. An innovative connection was then designed with a wide joint, shrinkage-compensated concrete, a rough interface between the joint and box girder, and reinforcing steel that crosses the interface between the joint and box beam, to overcome the problems mentioned in the literature review. The design was evaluated on four small-scale specimens designed with different amounts of transverse reinforcement. The specimens were monitored for early-age joint behavior and then tested for ultimate capacity. A three-dimensional (3D) finite-element model (FEM) was developed to simulate early-age joint behavior and determine the stress distribution in the joint and at the interface between the joint and the box beam concrete. The shrinkage, temperature, and strain data collected during the early-age monitoring were used to validate the FEM. Both experimental and finite-element analysis results indicate that the innovative joint showed good performance in resisting joint cracking when subjected to joint material expansion and the heat of hydration. The results also indicate that the expansion of the joint material formed a compression-dominated joint, which would naturally inhibit crack formulation. The transverse reinforcing steel across the interface resisted the expansion of the joint material and resulted in some additional transverse compression in the joint.