Bai Chay Bridge, Vietnam

The Bai Chay Bridge, spanning a strait within sight of Ha Long Bay, Vietnam's premier World Heritage site, has the world's longest center span length of 435 m, as a single plane cable-stayed prestressed concrete bridge, with a bridge length of 903 m. The foundations for the main piers were constructed by the pneumatic caisson method. Form travelers were used for the cast-in-situ box girder erection by the balanced cantilever method. The main pylons, which extend 91,5 m in height above the deck level and which incorporate 28 stay cables and anchorages each side, were constructed using a climbing formwork system. The design wind speed for the bridge is 50 m/s over a ten-minute averaging period at 50 m above sea level. Wind tunnel tests, using a three-dimensional (3D) full bridge model, were conducted to examine the structural stability against strong winds. The box girder is lightweight with internal steel pipe bracing and prestressing tendons. Technologically advanced vibration control devices, such as reduced-section high-density polyethylene (HDPE) ducts and internal radial dampers for the stay cables together with tuned liquid dampers for the pylons, were incorporated into the construction.