Indiana SR 32 Bolt Together Press Brake Tub Girder Bridge

The bridge is the first built up press brake formed tub girder (built-up PBTG) bridge, representing a new approach to the rapid fabrication of resilient steel bridges. This concept is direct outcome of a 2018 National Steel Bridge Alliance workshop aimed at making steel more competitive in the short span bridge market. The concept of a bolted-up tub girder, where cold bent webs (bent via press brake) are bolted to the flange plates-was introduced as a strategy that could take advantage of the steel industry’s capability to fabricate components on demand with steel that was already in stock.

In 2019, this bolted tub girder research was pitched to INDOT by the University of Notre Dame in collaboration with HNTB Corporation. INDOT specified hot-dip galvanizing for this project based on prior successes of galvanized steel bridge projects in the state of Indiana. Selecting hot-dip galvanizing for this bridge was critical for the decision to move forward with this structure type.

This site represented a typical bridge in Indiana for which prestressed concrete girders would have been traditionally used. The tub girders for this project were half the weight of prestressed concrete girders, resulting in a much smaller crane and the ability to ship multiple steel girders on a single truck. This project brought together a collaborative team of engineers, researchers, steel fabricators and suppliers working together from a novel design concept to implementation in less than three years.