Investigation of closure-strip details for connecting prefabricated deck systems

This article describes how the Bridge Office of the Ministry of Transportation of Ontario initiated a research project to investigate the use of precast bridge technology as an innovative approach to bridge construction and rehabilitation in 2001. Two potential precast systems were investigated: precast composite slab-on-girder beam elements connected with cast-in-place concrete closure strips, and full-depth precast concrete deck slab panels laid across new or existing girders and connected with cast-in-place concrete closure segments. One of the main issues inherent in these precast systems is the presence of cold joints created by the closure pours and their potential effect on the overall deck system behavior. In addition, there is a need to develop effective connection details between the precast elements to provide continuity of reinforcement in the closure strips so that load sharing between girders is not compromised. This article presents the findings of a series of laboratory tests that were performed on 2/3-scale model of the closure strip system to study the serviceability and ultimate state behavior of the joint detail. Several types of reinforcement lapping systems were considered for the steel reinforcement in the closure strips: U-shaped bars, L-shaped bars, welded straight bars, and straight bars with full lap splice length as well as splices with reduced lap length but confined by steel spirals or stirrups. Scale models of the closure-strip connections were subjected to extensive cyclic loading and then tested to failure. Overall, the test results demonstrated the excellent performance of U-shaped, L-shaped, and welded straight reinforcing bars as connection details in the closure strips. The use of high-early-strength concrete in the closure pour was shown to have little effect on long-term performance, while a shortened lap length confined in a steel spiral was shown to be as effective as the conventional full-lap-length splice detail.