Press Brake Tub Girders Featured in “Bridge Structures” Journal
An article highlighting a new technology developed by the Short Span Steel Bridge Alliance (SSSBA) and its industry partners has been published in a key bridge technology journal. The article, “Fatigue Performance of Singular and Modular Press-Brake-Formed Steel Tub Girders,” appeared in “Bridge Structures,” Volume 16, No. 1, which was published on July 9, 2020.
It was authored by Karl Barth, Ph.D., the Jack H. Samples Distinguished Professor at West Virginia University, who headed the industry task group responsible for developing the technology; Greg Michaelson, Ph.D., P.E., associate professor at Marshall University, who was involved in the early research on the new technology; and Robert Tennant, Ph.D., engineering student at West Virginia University. Barth and Michaelson also provide expert assistance via the SSSBA’s Bridge Technology Center.
The article examines the modular testing of the press-brake-formed steel tub girder (PBTG) bridge system for short span structures of up to 60 feet. Specifically, it covers the scope of the testing, which includes:
- Fatigue testing of singular composite girders simulating a 75-year life in a rural environment,
- Evaluation of two slab edge treatment methods to determine the optimal option for the Ultra-High-Performance Concrete (UPHC) joint between modular tub girder units, and
- Evaluation of the system’s fatigue performance by connecting longitudinally two composite modular press-brake-formed tub girders with a UHPC joint.
The testing demonstrated that the press-brake-formed tub girders behaved adequately with respect to fatigue, as did the longitudinal joints composed of UHPC.
Dr. Barth stated: “We’ve come a long way since our team introduced the concept of the PBTG system in 2011. PBTG bridges are now in service in five states – Iowa, Ohio, Michigan, Texas and West Virginia. This system saves significant costs and time. It is a viable, economical solution to meeting the nation’s challenge to replace its aging bridge infrastructure, with the greatest need in the short span category of 140 feet or less.”
For more information or to purchase the article, visit IOS Press, Inc.. “Bridge Structures” focuses on practical issues and how certain techniques can be adopted in the work of the bridge engineer. It also narrows the gap between researchers and practitioners and provides state-of-the-art solutions to challenges faced by bridge engineers.
What are Press Brake Tub Girders?
Press-brake-formed tub girder (PBTG) is a new technology for short span bridge applications. It consists of modular galvanized shallow trapezoidal boxes fabricated from cold-bent structural steel plate (watch fabrication video). A concrete deck is recommended to be precast on the girder and the modular unit can be shipped by truck to the bridge site.
The system utilizes standard plate widths (based on availability) 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, since the girder is closed at the bottom. It is versatile for multiple-deck options.
The system utilizes Accelerated Bridge Construction practices, since it:
- Can be installed in one or two days
- Is modular, allowing the use of a precast deck
- Is cost-effective―as much as 1/3 less than a standard concrete girder structure
- Is simple to fabricate, requiring very little welding.
The Short Span Steel Bridge Alliance has developed standardized plans using standard plate sizes (60”, 72” 84”, 96”, 108”, 120”). The designs were developed to achieve maximum structural capacity and are available in eSPAN140.
The press-brake-formed tub girder system is open source.
Dr. Barth and Dr. Michaelson will provide a presentation on press brake tub girders at the 2020 International Bridge Conference.
West Virginia Department of Highways constructs states first press-brake-formed steel tub girder bridge.
SSSBA Publishes New Research Report in Technical Series On Innovative Press-Brake Formed Steel Tub Girder Bridge Technology
Research report on field evaluation that includes skew and superelevation.