Admiral Clarey Bridge/Ford Island Bridge
- Jun 22, 2012
In 1999, the US Navy completed the Admiral Clarey Bridge that connects the Hawaiian Island of Oahu to Ford Island in Pearl Harbor and offers a floating center drawspan to accommodate large ships.
Precast Bridge Improves Access
This nearly one-mile-long precast bridge was built to improve access to Ford Island. The 29-span bridge contains with a 930 foot long moveable floating concrete drawspan in the center. Two articulated steel transition spans ramp down to the floating section.
Moveable Floating Concrete Drawspan
The movable portion includes three prestressed concrete pontoon sections equipped with watertight access hatches, water sensors and piping to permit pumping. Its bottom slab was cast in place, the longitudinal and transverse walls were precast, and the top deck was formed with precast prestressed panels used as stay-in-place forms.
The pontoons support two transitional spans, weighing 16,500 tons, which are raised and lowered hydraulically to allow the pontoon to be withdrawn or extended.
Specifications included the requirement that all concrete contain a minimum of 5 percent silica fume by weight of cementitious materials and to have a maximum water/cementitious material ratio of 0.38. Durability was also enhanced by increased concrete cover to the reinforcement, zero tensile stress in all prestressed concrete, use of ASTM A934 epoxy for coating reinforcing bars and a maximum tricalcium aluminate content for the cement of 8 percent to improve sulfate resistance.
A key challenge came in needing to produce the various components at different sites, with the precast pontoons and beams being delivered from Tacoma, Washington, the precast piles and deck panels produced in Hawaii and the cast-in-place concrete made locally. All components matched perfectly in color, producing a bridge that is aesthetically pleasing, functionally innovative and highly durable for the long term.