Marwan Nader

Seismic Design Strategies on Major Bridges located in High Seismic Zones

Infrastructure Mega projects have become a norm across the world. With billions of dollars of investment, Owners are always looking for ways to maximize the design lifetime of their structures.

Big Bridges are often a major component of these Mega projects. This talk will discuss the how innovation and new technology are used in seismic design of new bridges.

In early 2000, Caltrans embarked on the replacement of the seismically vulnerable eastern spans of the San Francisco Oakland Bay Bridge (SFOBB). This marked a new era of seismic design and performance as the SFOBB is designated as a Lifeline structure and is engineered to remain operational shortly after a major seismic event. During an earthquake, shear link beams interconnecting the four legs of the single tower deform to absorb seismic energy while allowing the shafts to remain elastic – an industry first. Additionally, hinge pipe beams connecting the deck sections enable fusing, thereby dissipating seismic energy at designated, controlled locations. Designed to provide the highest levels of seismic safety, the SFOBB has transformed the Bay Area landscape and the bridge design industry. 

Across the globe, the Philippines government is currently undertaking one of the largest bridge crossings in the world. The Bataan Cavite Interlink Bridge (BCIB) Project is 32km and crosses the Manila Bay with water depth exceeding 100m. The BCIB seismic design employs innovations including isolated caisson foundations, seismic dampers and isolation bearings to mitigate large seismic loads. In addition to high seismicity, the bridge is subject to site-specific challenges including typhoons, vessel collisions, wave loads from tsunamis, associated scour, and the marine environmental conditions of Manila Bay. When built, the BCIB Project, regarded as a priority project of the Philippine government, will transform the region and will become an economic engine for Manila and Philippines.