Steel press brake tub girders testing research

Steel Tub Girder High-Cycle Fatigue Testing Underway at West Virginia University

Topics: Innovation, Press Brake & Folded Plate, Research

Photo Credit: Dr. Karl Barth, West Virginia University

This week (December 5, 2022), sections of fabricated galvanized steel press-brake tub girders (PBTGs – pictured above) arrived in Morgantown for testing at West Virginia University’s (WVU) engineering lab.

Dr. Karl Barth, co-director of the Short Span Steel Bridge Alliance (SSSBA) Bridge Technology Center and professor at WVU, is working with several graduate-level students to conduct high-cycle fatigue testing on the short tub sections. Dr. Gregory Michaelson, co-leader of the SSSBA Bridge Technology Center and assistant professor at Marshall University, is also providing assistance with the research.

The research is funded by the SSSBA. The steel plate was donated by SSAB Americas and fabricated by Valmont Structures.

Karl Barth, Ph.D., the Jack H. Samples Distinguished Professor at West Virginia University, and Greg Michaelson, Ph.D., P.E., associate professor at Marshall University, have conducted research on press-brake tub girders for over a decade.

Dr. Barth and Dr. Michaelson have conducted extensive research on PBTGs over the past decade. The focus of their work has been finding ways to make short span steel bridge design more economical and efficient.

“We’ve come a long way since our team introduced the concept of the PBTG system in 2011,” said Barth. “PBTG bridges are now in service in 18 states.”

“This system saves significant costs and time,” said Michaelson. “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.”

A technical report on the results of the PBTG testing will be available in late 2023.

In the video below, Dr. Karl Barth, West Virginia University, presents information on the development of press-brake formed tub girders for short span bridges.

For more information:

Karl E. Barth, Ph.D.
Co-Leader, SSSBA Bridge Technology Center
Jack H. Samples Distinguished Professor at West Virginia University
Email: Karl.Barth@mail.wvu.edu

Gregory K. Michaelson, Ph.D., P.E.
Co-Leader, SSSBA Bridge Technology Center
Assistant Professor, Department of Civil Engineering at Marshall University
Email: michaelson@marshall.edu

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 to use in the free-to-use, web-based design tool eSPAN140.

The press-brake-formed tub girder system is open source.

Learn more about press brake tub girders→