Seismic Retrofitting Challenges Stimulate New Innovations for the Benicia-Martinez Bridge

摘要

The seismic upgrading of the Benicia-Martinez Bridge, now in the final stages of construction, is an excellent example of how a teaming approach spurs innovation to solve engineering challenges. The Benicia-Martinez Bridge is a high-level, deck-type, welded truss bridge with welded girder approach spans. This 6,215 foot-long structure carries traffic over Carquinez Strait between cities of Benicia and Martinez. New innovations to be shared with the profession in this presentation include: 1. Implementation of the friction pendulum bearing into the retrofit of long span bridges, which includes design, testing, fabrication and installation. 2. Anchorage of existing caissons by core drilling 150-feet down through the caissons into bedrock using innovative monitoring and coring equipment. 3. Load testing of a drilled shaft and pipe piling anchorage using the Osterberg test method. 4. Rocking by allowing axial elongations of the foundation piles. 5. Use of the world's largest friction pendulum isolation bearing. The concept of seismic isolation is combined with other strategies (e.g., strengthening, ductility, force limitation, etc.) to achieve critical lifeline performance for a maximum credible earthquake at a lower cost than could be achieved without isolation. If the bridge were strengthened without isolation, the full seismic inertia would be developed and transferred from the deck down through the truss system and bearings and reach to the substructure piers and foundations.