Sumitomo Mitsui Construction and Sumitomo Riko Co-develop 'Vertical Anchor Bolt-less Bearing' for Bridge Replacement Works

Sumitomo Riko Co., Ltd. and Sumitomo Mitsui Construction Co., Ltd. have jointly developed the 'Vertical Anchor Bolt-less Bearing' for use in bearing replacement work during bridge renovation and seismic reinforcement construction. By omitting the vertical anchor bolts for new bearings, this technology reduces the need for anchor drilling and removal of existing structures in cramped areas under existing girders compared to conventional bearing replacement methods, contributing to shorter construction periods and cost reductions.

■ Background of Development
Amidst the aging of road infrastructure, reducing construction periods, addressing labor shortages, and lowering costs are urgent issues in bridge renovation projects, including expressways. In conventional bearing replacement, anchor drilling into the top of the substructure is required when installing vertical anchor bolts for new bearings. In cases where the space under existing girders is narrow, this necessitated the removal and restoration of members like wrapped-around concrete for cross-beams to ensure construction space, leading to increased construction time and costs. To address this, the 'Vertical Anchor Bolt-less Bearing' was developed, which does not require anchor drilling on the top of the substructure.

■ Features of the Vertical Anchor Bolt-less Bearing
1. This structure uses the steel bracket utilized for jacking up as a permanent fixture. By extending the bearing base plate to the steel bracket on the front of the substructure and connecting it with bolts, horizontal forces during earthquakes are transmitted to the substructure, thereby omitting the vertical anchor bolts of the new bearing.
2. Members that restrict displacement are installed on the outside of the existing girder, where construction space can be secured, ensuring safety against horizontal forces in the direction perpendicular to the bridge axis.

■ Effects of this Technology
1. Compared to conventional bearing replacement methods that require the removal of wrapped-around concrete from cross-beams, this method involves less removal of existing structures, leading to an expected reduction of approximately 10% in both construction time and costs.
2. By eliminating anchor drilling on top of the substructure and avoiding work under existing girders where construction space is limited, this leads to improved workability and safety.

This structure is effective for bearing replacement work on small-to-medium scale bridges where the space under the girder is narrow and it is difficult to replace them with standard bearings.