Benicia-Martinez Bridge Retrofit

04 - 0440U4 PROJECT PHOTOS 1

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This is a picture of a pierwall and the footing below it (there is a timber fender system around the footing). A mile of water is bridged with 528-foot steel truss spans supported on these pierwalls and footings. To access the steel retrofit work, a scaffold has been suspended. The Union Pacific Railroad bridge is to the left.

This is a picture of the steel members supporting the traffic deck. The seismic retrofit will include strengthening existing steel members and connections. Approximately 3 million pounds of new steel will be added.

These existing bearings will be replaced by new seismic isolation bearings weighing up to 50,000 pounds. The new bearings will be of the "friction pendulum" type, with a concave disk up to 12 feet in diameter and a smaller articulated slider in the center.

Photo of one type of bearing (pendulum) that will replace old bearings.

The new bearings will be tested here, the testing facility in UC San Diego.

The seismic retrofit will involve strengthening the pierwalls and the footings. This picture shows access openings cut into an existing hollow footing where new 72" diameter caissons will be added and anchored up to 60’ into bedrock.

This is the drilling equipment used to drill out a 66" diameter test pile. This test pile is drilled 68 feet into bedrock. The bottom of this test pile is approximately 220 feet below sea level. Test piles are to determine the rock strength, which will be compared against the designer’s assumptions.

A test pile rebar cage has instrumentation to test stresses and displacements during a load test. The smaller 2" diameter PVC and steel pipes are for testing the integrity of the placed concrete. This will be done through gamma-gamma testing and cross hole sonic logging.

This test pile rebar cage has four hydraulic jacks (Osterberg Cells) in the center. These four jacks have a combined capacity of 4,800 tons. They will jack the upper portion of the rebar cage away from the lower portion of the rebar cage. The instrumentation will measure the rock strength.

Between the Benicia-Martinez bridge and the Union Pacific Railroad bridge, a barge-mounted crane is lifting a test pile rebar cage.

A test pile rebar cage is placed in a 72" diameter steel casing and lowered to the portion that was drilled into bedrock. The steel casing provided a "hole" through the water and soil so that the bedrock could be excavated.

These are the barges and equipment used while placing the concrete for a load test pile.