Field Demonstration of an Innovative Box Beam Connection

Previous research conducted multiple levels of laboratory tests and analytical studies and designed an innovative joint to resist joint cracking on the longitudinal joint between box girders. The joint design was165 mm (6.5 in.) wide and filled with shrinkage-compensating concrete and reinforced with transverse steel bars. Although the previous laboratory test and analytical simulation results indicated that the joint showed superior performance when resisting the joint early-age cracking and maintained the integrity of the bridge superstructure, its performance on a real onsite bridge was not evaluated. This paper documented the field evaluation of this new design on a single span box beam bridge. A bridge in Washington County, Iowa was selected to deploy the joint. To evaluate the performance of this first implementation, a 7-day field monitoring campaign was conducted during the early-age of the joint material. In addition, a live load field test and two bridge inspections at 6-month intervals were performed. During the field tests and monitoring work, temperature, strain, and displacement data were collected at critical locations and analyzed to evaluate the joint functionality on cracking resistance and load distribution. The visual inspections were conducted and focused on the condition and performance of the joint with a specific interest in the development of any cracking. The results indicated that this new joint was well suited to resist early-age joint longitudinal cracking, which is common in other joint designs. The joint was efficient in load distribution and the bridge superstructure behaved as an integral structure when the live load was placed. In addition, with an integral abutment, the construction of the abutment affected the strain distribution in the joint near the joint ends. This effect tended to provide compression in the transverse direction and reduced the potential of joint cracking.

This paper documents the field evaluation of the new design of a longitudinal joint between concrete box beams on a bridge in Washington County, Iowa. The joint was 165 mm (6.5 in.) wide and filled with shrinkage-compensating concrete and reinforced by transverse steel bars. The results indicated that this new joint was well suited to resist early-age joint longitudinal cracking, which is common in other joint designs. The joint was efficient for load distribution. The bridge superstructure behaved as an integral structure when the live load was placed. In addition, with an integral abutment, the construction of the abutment affected the strain distribution in the joint near the joint ends. This effect tended to provide compression in the transverse direction and reduced the potential of joint cracking. This design is recommended to be used in concrete box beam bridges to prevent longitudinal joint cracking and reduce the potential of bridge superstructure deterioration, especially in rural regions. Further research is recommended to deploy the design on a bridge with a higher traffic volume to investigate the performance of the joint under larger traffic loads.