After almost six years of around-the-clock construction, the new east span of the San Francisco-Oakland Bay Bridge opened to traffic on Sept. 2, 2013. To ensure the 10-lane structure survives the type of earthquake that destroyed the previous cantilevered-truss design in 1989, engineering and materials innovations include:
- The world’s longest self-anchored suspension span (SAS) at 2,047 feet
- Joints that expand and contract up to 3 feet while keeping the frames solid. The joints accommodate hinge pipe beams, massive steel tubes that are designed to move within their sleeves during expansion or contraction of the decks. The beams accommodate minor movements, but they also absorb the energy of an earthquake by deforming in their fuse section. Deformed fuses can be replaced without affecting the rest of the hinge pipe beam or bridge structure. As a result, the replacement span is expected to withstand the largest earthquake predicted over the next 1,500 years and last 150 years with proper maintenance.
- Concrete that sets within four hours instead of the usual 28 days. Because a steel bridge can expand up to 3 inches in a single day, CTS Cement’s Rapid Set cement was used at the joints so the concrete achieved sufficient strength before bridge movement could occur.
To read more about the bridge, visit here.