Longitudinal Joints with Accelerated Construction Features in Decked Bulb-Tee Girder Bridges: Strut-and-Tie Model and Design Guidelines

Abstract

This paper focuses on the development of a strut-and-tie model (STM) that can be used in the design of previously developed longitudinal joints with accelerated construction features. Four joint specimens reinforced with tight bend diameter U-bars and previously tested under bending are summarized here to validate the STM. The validated STM is proposed to calculate the ultimate moments of the joints, which is capable of identifying the most critical parameters and yields safe and consistent predictions. It shows that the joint capacity increases with increasing of the concrete strength and overlap length, and the capacity reaches the maximum value when the U-bar spacing is twice the overlap length. Design recommendations to U-bar spacing, overlap length, diameter of lacer bars, as well as concrete strength of the closure pour material are developed for full-strength joints.