New Low-Rigidity Design for Widening of Elevated Bridges

A two-lane junction bridge connecting the Loop to a radial route on the Hanshin Expressway in Osaka was widened to a three-lane configuration by constructing an additional steel box girder bridge as a relief of chronic traffic congestion suffered at the site. This project was successfully completed, and remarkable mitigation of traffic congestion was achieved. The additional bridge support piers were built at the midspans of the original bridge, and the two bridges were not rigidly connected. Although a large longitudinal joint was installed to accommodate a differential deflection of 50 mm between the two bridges, it was found to be damaged by the heavy traffic of vehicles. An investigation was made to study a possibility of removing the joint and connecting the two bridges, and cross beams were adopted as the connecting members to achieve the desired connection.