18-12, Nishiochiai 2-chome,
Shinjuku-ku, Tokyo 161-8575, Japan
Phone: +81-3-5906-0211
FAX: +81-3-5906-0112

Transportation

BACKGROUND & PURPOSE OF PROJECT

This project was implemented to draw up a detailed design of the Kamihayashi Elevated Bridge (length: 647m) constructed at the location where the JR Uetsu Line crosses the Fuefuki River along the Coastal Japan Sea Tohoku Highway. The soft bed under the construction site is thick, and is in an area of little to no strata, leading to the adoption of a friction pile foundation (using cast-in-place and ready-made piles). Plans were drawn up taking into consideration the effects caused by proximity to railway lines regarding overpass sections.
The length of the bridge is 647m, it has a maximum span length of 93.5m, and the superstructure consists of 6 continuous narrow steel box girders and 4 continuous narrow steel girders.

CHARACTERISTICS, CONCEPT, STANCE & SKILLS OF PROJECT

To streamline construction and cut on labor costs we designed a superstructure that incorporated narrow-width box girders using a pre-cast PC deck. Considering that antifreezing agent will be used on the bridge, we also took the potential for salt damage into account, considering countermeasures applicable to Type 3 Salt Damage Areas. We carried out investigations into seismic isolation based on soil response analysis in consideration to the soft Type III Ground under the construction site, and based on these investigations we designed a structure that had multiple fixed points considering the potential for ground resonance. We conducted non-linear dynamic analysis to verify the safety of the overall bridge system in the case of an earthquake. As the level of strata on the construction site shifts from deep to shallow, we adopted a friction pile foundation setup and took the impact that differential settlement has on construction into consideration when verifying the design of the superstructure.

EFFECT OF PROJECT

We defined the plan so as to reduce the cost for the bridge construction by adopting the most rational, labor-saving structure that was simplified by using fixed points and reduced costs by using new technologies. The adoption of a pre-cast PC deck in the superstructure will also lead to improvements in durability and reductions to the work schedule, allowing for quicker construction.