Bridge Expansion Joint for Bridges with Expansion Joints in Deck Prestressing

Bridges with transversely prestressed decks have a different structural behavior at the expansion joint location compared to conventionally reinforced decks. The transverse prestress affects the crack resistance and the movement behavior of the deck at the joint. Transverse prestress effects at the joint location include increased crack resistance due to the compressive stress from the prestress. The prestress reduces the tensile stress in the concrete under traffic loading, reducing the risk of cracking. However, the prestress also reduces the flexibility of the deck, which may increase the forces transferred to the joint. Prestress tendon layout at the joint location must avoid the anchor bolt locations. The prestress tendons must be routed around the anchor bolts to prevent interference. The tendon layout must be designed to maintain the required prestress level at the joint location despite the presence of the anchor bolts. Anchor bolt design for transversely prestressed decks must consider the interaction between the anchor bolt forces and the prestress. The anchor bolt forces create local tensile stresses that must be added to the prestress to determine the net stress in the concrete. The net stress must remain compressive to prevent cracking. Joint movement behavior of transversely prestressed decks may be different from conventionally reinforced decks. The higher stiffness of the prestressed deck may result in different movement distribution between the joint and the bridge structure. The joint must be designed for the actual movement, which may require a structural analysis of the prestressed deck. Maintenance of expansion joints in transversely prestressed decks requires careful inspection of the prestress anchorage zones near the joint. Any cracking or spalling in the anchorage zone must be reported and repaired promptly to prevent loss of prestress. The joint gap must be monitored to verify that the movement is within the design range.