Fixing the West Coast’s Busiest Bridge

Approximate design of the steel saddle fix for broken bolts. Saddles secure the shear key to the cap beam.

Broken shear key bolts.

Chiseled concrete awaiting steel saddle.

Crews on the pier work platform drill holes for dowels to bond the new concrete jacket to the cap beam.

Drilling into the concrete cap beam to prepare for steel saddle installation.

Drilling into the concrete cap beam to prepare for steel saddle installation.

Dowels and formwork installation at the underside of Pier E2 cap beam. The 1-in.-diamater T-headed dowels were used to transfer saddle anchorage forces to the crossbeam.

Epoxy and dowels installation.

Crews on the pier work platform drill the concrete cap beam in preparation for the bolt fix.

Formwork installation at the bottom of the concrete cap beam.

Shear key (middle) awaits broken bolt fix.

Shear key with broken bolts sits between two bearings with good bolts.

Applying liquid epoxy to seal the existing bolt locations at the shear key.

Pre-stressing trumpets. Conco crews installed PT anchorages supplied by Schwager-Davis Inc., San Jose, Calif. They mounted 260 PT bearing plates and trumpets onto custom blockouts. Each of the anchorages accommodate an alignment specific to each tendon, per design specs. The blockouts had to be easily removed after concrete placement to allow timely installation of the PT strand.

An upper saddle being delivered.

Saddles replace the broken bolts and are attached to the beam with PT cables.

Two upper saddles and one lower saddle installed.

Trucks on the road deck pump concrete to the bottom of the cap beam. The injectable SCC concrete mix was designed to reach 55 MPa in approximately 10 days. The high strength was specified in the design, and the short duration was requested by the construction team to allow PT to take place asap.

Pouring concrete base for the steel saddle retrofit. The geometry of the soffit concrete qualified it as mass concrete, and thermal cracking was a concern given the heat of hydration with the concrete mix. Conco installed internal cooling pipes in the formwork and bay water was circulated through the pipe network during the placing and curing process. This eliminated any potential for internal/external thermal differentials that could cause cracking.

Concrete in place at bottom of cap beam, encasing the web of PT cable ducts and steel reinforcing. After all concrete was placed, approximately 2,500 0.6-in.-diameter strands were installed in the ducts and tensioned.

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