Joint Design Optimization for Accelerated Construction of Slab Beam Bridges

Abstract

The Florida Slab Beam (FSB) has been developed by the Florida Department of Transportation (FDOT) to be used for short-span bridges [less than about 19.8 m (65 ft) long]. The FSB system consists of shallow precast, prestressed concrete inverted-tee beams that are placed adjacent to each other and then involve reinforcement and concrete being placed in the inner joints and deck all in one single cast. Ultra-high-performance concrete (UHPC) is becoming more widely used in bridge construction applications as a result of its remarkable structural performance. Many departments of transportation have tested and deployed the use of UHPC in bridges around the United States. Most of these applications have been to connect precast members (e.g., slabs to beams and slabs, adjacent beams, caps to columns, etc.). A modified FSB design is desired to eliminate the cast-in-place (CIP) deck and allow for UHPC to be used in the joint region, which will allow for accelerated construction and decrease the impact of construction on traffic. Different joint details and cross-section geometries were analyzed and experimentally evaluated to determine feasible joint details with UHPC for slab beam bridges used in accelerated construction. Results from numerical modeling, strength, and fatigue experimental testing of the transverse joint performance of four different UHPC joints in two different depth slab beam bridges are presented. Straight-side and shear-key UHPC joint details were found to behave similar to or better than the current FSB joint detail.