New NY Bridge project uses precast pile caps with galvanized strands to prevent corrosion

March 06, 2017
New NY Bridge
New NY Bridge

Designed to meet the needs of this century, the New NY Bridge is built to last well into the next. To assure the longevity of the massive concrete structure, engineers and builders have added substantial precast concrete elements into the design. Bearing the load on the heavily trafficked road and supporting the bridge’s foundation are precast pile caps reinforced with low-relaxation galvanized PC strands from steel wire producer Bekaert. These 100% U.S. steel strands are essential components to achieve a 100-year bridge life.

The New NY Bridge project will be a 3.1-mile, twin-span, cable-stayed bridge across the Hudson River. The innovative construction replaces the Tappan Zee Bridge, which opened in 1955. Because the old bridge is no longer able to cope with the daily traffic load of approximately 140,000 vehicles, the New York State Thruway Authority and the New York State Department of Transportation decided on a complete replacement. When completed, the New NY Bridge will be the largest bridge in New York’s history.

Spanning the century

Like all new major concrete structures, the New NY Bridge needs to last 100 years or longer. To meet this goal, the contractors of this project incorporated substantial precast concrete components with galvanized steel reinforcement into the bridge’s design. The pile caps, in particular, play an important role in creating a strong base for the bridge’s foundation.

A major concern for Coastal Precast Systems, the company responsible for the design and production of the pile caps, was choosing a concrete reinforcement that is suited to the brackish waters of the Hudson River. Steel wire producer and coating expert Bekaert offered the best solution.

U.S. steel provides reliability

Bekaert produces low-relaxation galvanized PC strands that have been optimized for marine applications. Depending on requirement, the company offers zinc-coating levels up to 1 oz/sq ft, per ASTM A475. All galvanized strands have passed the ASTM A416 standard for 1,000-hour stress relaxation and are ASTM A1081 bond-test certified. The zinc coating provides a barrier and sacrificial protection to delay potential corrosion, thereby extending the life of the structure. To date, Bekaert is the only domestic manufacturer of galvanized seven-wire strands that meet the ASTM A416 standard specification, as well as the Buy America provisions.

A promising solution for future projects

Using Bekaert’s galvanized PC allowed Coastal Precast Systems to produce high-quality precast pile caps at a competitive price and at a considerably fast pace. Realizing the durability of the hot-dip galvanized steel, this project made a positive impact on the end-customers, the project contractor, the New York Department of Transportation and the Port Authority. While they had not commissioned many galvanized bridges prior to this bridge rehabilitation, they are now looking for ways to incorporate the corrosion protection system of galvanized products into future bridge projects.

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