Steel Press-Brake Formed Tub Girder System Selected for 2021 AASHTO Innovation Initiative Focus Technology

The steel press-brake-formed tub girder (PBTG) bridge system researched and tested through the Short Span Steel Bridge Alliance (SSSBA) has been selected by the AASHTO Innovation Initiative (AII) as a 2021 Focus Technology.

During 2021, AII will invest time and resources to accelerate the adoption of PBTG among AASHTO (American Association of State Highway and Transportation Officials) member associations, local agencies, and their industry partners to improve the U.S. infrastructure.

A PBTG bridge built for the Monroe County Road Commission in Michigan. Photo courtesy of Valmont Structures and Con-Struct Press Brake Formed Tub Girders.

PBTG is an accelerated bridge construction system for short span applications. It consists of modular galvanized shallow trapezoidal boxes fabricated from cold-bent structural steel plate. A concrete deck or other deck option such as a steel sandwich plate system may be placed on the girder, and the modular unit can be shipped by truck to the bridge site.

The PBTG system utilizes standard plate widths and is optimized to achieve maximum structural capacity, with most of the steel in the bottom flange and increased torsional stiffness. It is a closed system and versatile for multiple-deck options.

Press-brake-formed tub girder consists of modular galvanized shallow trapezoidal boxes fabricated from cold-bent structural steel plate.

“We are honored to have PBTG selected and thank the AII selection committees for their recognition of its economical and sustainable benefits,” said David Stoddard, Senior Steel Applications Engineer for SSAB Americas and Chairman of the SSSBA. “Since AII advances innovation from the grassroots up, this opportunity will fast-track this economical system further into the mainstream, providing an optimal steel solution to meet the nation’s infrastructure challenges.”

Guy Nelson, P.E., S.E, Business Development Director-North American Structures for Valmont Industries, Inc., said: “I am excited to be a part of this AASHTO Innovation Initiative focus technology and provide my AASHTO PBTG design experience. This system showcases the versatility and longevity of steel as a bridge building material. Not only are PBTGs an efficient and economical solution, but they are also helping to extend the service life of our aging bridge inventory.”

Matthew Chynoweth, P.E., Chief Bridge Engineer and Director of the Bureau of Bridges and Structures for the Michigan Department of Transportation, commended Guy Nelson for pulling together the AII application and providing outstanding examples of the benefits of the PBTG structure type. Chynoweth will be leading the effort with the AASHTO AII team.

Testing for the press brake tub girder was completed at West Virginia University.

Dr. Karl Barth of West Virginia University led the team organized by the Short Span Steel Bridge Alliance that initiated the PBTG system. Dr. Barth and Dr. Greg Michaelson, P.E. of Marshall University conducted extensive research on this new bridge technology, which was funded by members of the American Iron and Steel Institute.

Dr. Barth said, “We are honored to see how rapidly this system has progressed from concept to commercial implementation. It is truly a testament to the strength of the team comprised of members of all facets of steel production and bridge delivery that were integrally involved in advancing this system.”