Center for Transportation Research and Education

About the research

This project is a task order under the main Federal Highway Administration (FHWA)-sponsored project, “Infrastructure Research and Technology Deployment Program.”

There is evidence of the very successful use of Orthotropic Steel Deck (OSD) bridges both in the US and abroad. Particular examples include the San Mateo Hayward Bridge (1967) in California and the more recently constructed Millau Viaduct (2004) in France. OSDs are durable, redundant, and lightweight, making them a popular option for both new design and the rehabilitation of signature structures. However, complexity of design, sophisticated analysis requirements, large fabrication costs, and the possibility of owner-mandated experimental testing generally makes OSDs prohibitive for use with commonplace bridges. The FHWA’s 2012 Manual for Design, Construction, and Maintenance of Orthotropic Steel Deck Bridges (OSD Manual) aimed to address these shortcomings by introducing three design levels for OSD. These include Level 1 Design, which makes use of proven OSD solutions without the need for analysis, Level 2 Design, which makes use of simplified 1D or 2D analysis methods calibrated to experimental results, and Level 3 Design, which makes use of refined 3D analysis.

To further address the complexity of OSDs, in collaboration, the American Association of State Highway Transportation Officials (AASHTO) and National Steel Bridge Alliance (NSBA) formed a task group (TG-16) to evaluate and address the manufacturability of OSDs, the complexity of design, and the evolution of complex detailing. These parameters have been demonstrated to have a negative impact on the cost of the deck. Efforts of this task group so far have been to modify the overly specified rib-to-deck weld penetration requirements, propose research for a demonstration deck, and to evaluate the necessity of having a standard deck option. The latter effort is well-aligned with this task order from the FHWA.

With several team members participating in TG-16, the researchers are well aware of the negative perception of this deck type and the need for a more accessible process for designing and analyzing OSDs. Moreover, our team consists of OSD designers, fabricators, inspectors, and authors of the OSD Manual. It is that expertise that will successfully identify a list of candidate bridge OSDs and provide guidance for standardization.