Steel Girder Galvanization Prolongs Lifespan and Saves Maintenance Costs

PROBLEM

UDOT requires steel bridge girders that are within 10 feet of a body of water to be painted. However, painting girders in the field is expensive and poses environmental risks. For example, wind, precipitation, and temperature can make painting in the field problematic. It takes a lot of effort, planning, and expensive containment measures to keep paint overspray from getting on adjacent surfaces or into environmentally sensitive rivers or wetlands.

The use of weathering steel is not an option because constant moisture inhibits the naturally protective patina from forming. UDOT needed a better option for protecting steel girders located near water.

Hot dip galvanization, a common protective coating used on overhead sign structures, signal poles, and lighting fixtures, was not traditionally considered a viable alternative for protecting girders.

CHANGE

Through research and coordination with industry partners, UDOT Structures worked through their concerns regarding galvanized girders. The BFP Gramercy Bridge Project was selected as a pilot to verify that hot-dipped girders were feasible and would reduce project risks as theoretically anticipated.

RESULT

Galvanization is viable for short span (approximately 60') steel girder bridges and provides significant benefits. Galvanization involves less labor than painting, which requires three coats (two applied in the shop and the third in the field). Due to the cost of traffic control and environmental precautions, painting the third coat during initial installation or repainting the structure as it ages is expensive and impactful. All of this is eliminated by galvanization which is completed inside a factory setting.

Since galvanization (a metallurgical bond between steel and zinc) is long-lasting and durable, touch-up painting is eliminated, and less maintenance is required over the years.

Initial feedback has been so positive that galvanization of short-span steel girders is being considered for inclusion in the Structures Design and Detailing Manual (SDDM), where it would become a standard option for design teams.