Preliminary Design of Irabu Bridge
Bridges / Infrastructures / Asset Management
Okinawa Prefecture Japan, 2007-2008
Preliminary design work has been completed for Irabu Bridge, which will connect Miyako Island and Irabu Island over a marine channel in Okinawa Prefecture. The bridge will be 3,500m long, and its central span must be more than 180m long because it will be directly over the navigation route. The bridge’s durability requirements are severe because the site is over the sea in a region hit by several typhoons every year. At the same time, the bridge must have visual appeal because it will be a tourist attraction. CTI, which executed the preliminary design of the central portion of the bridge, decided on a main box figure. The design work utilized results of wind tunnel tests and sought to achieve smooth structural connection details without any convex or concave elements. No high-tension bolts will be used because they often trigger rusting in a salty environment. The completed design is for a three-span, continuous steel-box girder bridge.
