Experimental Study on Longitudinal Joints with Accelerated Construction Features in Precast Multibox Girder Bridges

Abstract

To accelerate bridge construction, U-bar details were proposed to connect the adjacent precast box girders and replace the original welded-loop details in longitudinal joint design. Static loading tests were conducted, and the failure mode, flexural strength, and cracking behavior of the specimens with welded-loop details and U-bar details were compared. The influence of the U-bar longitudinal spacing, the joint concrete strength, and U-bar lap length on joint performance was also considered. The test results show that although the specimen with U-bar details had the same strength as that of specimen with welded-loop details, it cracked earlier and faster, but it still met the code requirement on maximum crack width. Longitudinal spacing of U-bars has a significant influence on joint performance. Interface cracking occurred for all specimens, considering the actual construction sequence. The tested flexural capacities of specimens with U-bar details were compared with theoretical predictions based on two existing strut-and-tie (STM) models, and the accuracy of these two models was evaluated.