Statler College engineered bridge system met with commercial success

Karl Barth and the Bentley Street bridge in Lapeer, Michigan. The bridge is the first structure repaired with Barth's system under the Michigan Department of Transportation bridge bundling program. (Photo by OHM Engineers)

A Benjamin M. Statler College of Engineering and Mineral Resources led bridge system has progressed from mere concept to widespread commercial implementation. 

Story by Olivia Miller and Adrianne Uphold

Benjamin M. Statler College of Engineering and Mineral Resources

Karl Barth, associate professor in the Wadsworth Department of Civil and Environmental Engineering, has been working on development of a cost-effective accelerated bridge construction system for steel bridge since 2009. Barth, alongside Marshall University Associate Professor Greg Michaelson, have conducted extensive experimental testing to develop the press-brake-formed tub girder bridge system in conjunction with the Short Span Steel Bridge Alliance. 

According to Barth, the technical working group, which is made up of more than 30 partners from the steel industry, academia, government organizations and bridge owners, took the press-brake-formed tub girder system from idea to reality. 

The first press-brake-formed tub girder bridge was built in 2015. Today the bridge system is currently employed in 12 states for a total count of 19, with 59 prospective bridges in the works. The system offers several advantages over traditional short span steel bridge solutions like allowing a variety of installation and superstructure options, and it provides over 75 years of maintenance-free protection. 

“We are honored to see how rapidly this system has progressed from concept to commercial implementation,” said Barth. “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.” 

With the commercial implementation of the bridge system, the West Virginia University professor explained it will provide the broader opportunity to evaluate the condition performance of these systems.   

The system uses modular galvanized trapezoidal boxes fabricated from cold-bent structural-steel plates that can be constructed using either galvanized or weathering steel. The concrete deck is precast on the girder and the modular unit is shipped by truck to the bridge site. 

“The girder itself, which is available from the steel mill in standard plate thicknesses and widths, is simple to fabricate, requiring very little welding ― one girder can be produced in 45 minutes,” Barth said. “Because of the system’s modular composite design, there is a reduced need for additional details such as stiffeners or cross-frames. Due to its modular nature, the composite unit can be easily shipped to the bridge site, allowing for accelerated construction and reduced traffic interruptions.” 

The PBTG system uses standard plate widths that are optimized to achieve maximum structural capacity. With most of the steel in the bottom flange and increased torsional stiffness, it provides the system with stability.  

The girder system was selected for the 2021 American Association of State Highway and Transportation Officials Innovation Initiative, which will help implement the product nationwide. AII will invest resources to accelerate the adoption of the system among member associations, local agencies, and their industry partners to improve U.S. infrastructure. 

“The initiative allows us better work with state Departments of Transportation, and code specifying bodies to assess impediments to implementation of the system and to address those from a specification development perspective,” Barth said. “This has allowed us make changes to the U.S. Bridge Design Code that were unnecessarily punitive to the use of this system.   

Barth said they are continuing to assess needs for the economical implementation of the system including additional field testing, refined load distribution, capacity of skewered tub grinders and other testing as required.  

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