Despite their popularity overseas, the percentage of orthotropic decks constructed in the United States remains low.
Over the last few decades, improved knowledge in regard to the design and performance of orthotropic decks has made them a popular choice for renovating older decks here in the United States," says John Fisher, professor emeritus of civil engineering at Lehigh University.
When first introduced in the United States in the 1950s and 1960s, orthotropic decks represented a new and relatively unfamiliar technology for bridge designers.
According to Benjamin Tang, with FHWA's Office of Bridge Technology, current research on bridge performance indicates that stiffer orthotropic decks with wider ribs, along with prototype testing, could result in good performance and long bridge life.
At Lehigh University, for example, Fisher and his colleagues conducted cyclical traffic loading tests on several orthotropic decks placed during retrofit projects on bridges in New York City, such as the Bronx-Whitestone and Williamsburg Bridges.
Rust-resistant paints and weathering steel, which rusts only to a given point while maintaining its structural integrity, are material options for orthotropic decks.
Previous experience on several bridges in North America showed that it was difficult for asphalt and concrete wearing surfaces to remain attached to the steel plates on orthotropic decks.
In addition, FHWA continues to support the advancement of high-performance steel technology used in orthotropic decks and other steel bridges.
By reducing the weight of the superstructure, orthotropic decks have less mass to excite during an earthquake; therefore columns and foundations have lower demands imposed on them from an earthquake's horizontal forces and displacements.
Orthotropic decks also may offer an alternative to cast-in-place concrete for projects in cold regions.
He specializes in the investigation of suspension systems of long span suspension bridges, in the design of orthotropic decks
, and he has made major contributions to the design of the San Francisco Oakland Bay Bridge.