Bridges
Tappan Zee Bridge,
New York
The new Tappan Zee Bridge is a precast concrete, steel girder structure that spans 3 miles across the Hudson River. The 584 EPS Triple Pendulum isolators reduce the seismic forces transferred to the substructure so that it will remain essentially elastic during the design earthquake.
Los Caras Bridge,
Ecuador
This 2 km bridge that spans across the Bahia de Caraquez was subject to extreme earthquake forces during the 2016 Mag. 7.8 Muisine Earthquake. Peak ground accelerations at the bridge site were between 0.5g to 1.4g. The 152 Triple Pendulum isolators, with a design displacement of 585mm, experienced displacements from 100mm up to 650mm during the earthquake shaking. The isolators remained safe despite the larger than expected displacements. The bridge was functional after the earthquake and provided a critical transport link in getting aid to the EQ damaged communities.
Dumbarton Bridge,
California
This 1.6 mile long bridge was part of the San Francisco Bay Area Toll Bridge Retrofit Program, which was tasked with identifying critical transportation links and seismically upgrading them so that they will remain functional after an earthquake. Six Friction Pendulum isolators were installed at the top of each pier. The isolators can accommodate 42 inches of expected displacement demand, and will prevent damage to the piers during an earthquake.
Columbia Bridges,
Columbia
The mountainous Zona Cafetera is the heart of the scenic coffee growing region of Colombia, but it is also seismically unstable and prone to landslides. Design-build contractor Grupo Odsina had to solve the problems posed by the region’s challenging geology when designing a new highway that links the region’s three main cities, called the Armenia-Pereira-Manizales Autopista. The highway includes several viaducts that had to be designed to withstand both earthquakes and landslides. Triple Pendulum isolators were used to safely mitigate the hazard of crossing active earthquake faults.
American River Bridge,
California
The 2,264 ft. long bridge at Lake Natoma, Folsom, California uses 48 Friction Pendulum isolators to allow it to elastically resist the safety level earthquake, with no structural damage. Seismic force demands for the non-isolated bridge design would have been more than twice the bridge’s elastic strength capacity. The use of seismic isolators saved $1 million in construction costs because of a reduction in the size of the drilled caissons.