A convergence of events including the
- increasing acceptance of beam bending by cold cambering,
- standardized design of steel bridges, and
- increased availability of domestically produced jumbo beams
all contribute to making steel the solution for bridges.
AASHTO (American Association of State Highway and Transportation Officials) has recently been revised its specifications to allow cold cambering of rolled beams.
Article 18.104.22.168.6 has been revised to read as follows – “Camber for rolled beams may be obtained by cold cambering (cold bending) or heat-cambering methods approved by the Engineer.” The italicized, underlined words have been added.
Because there are literally hundreds of machines operated by fabricators, service centers, and Bender/Rollers (sub-contractors who specialize in curving steel) across the continent that can camber rolled beams cold, this service is widely available and competitively priced with fast turn-around times and high quality.
State departments of transportation are developing standardized designs for steel bridges that will save time and money. Accelerated bridge construction (ABC) techniques, now in testing, will have a tool kit with standardized modular components, erection methods, specifications for construction and other critical information.
Lastly, mills such as Nucor Yamato have begun producing jumbo beams domestically. These beams are suitable as bridge stringers.
As these developments continue to reinforce each other, steel will increasingly be the choice for bridge construction.
There will be a session on cold cambering of rolled beams for bridges at the World Steel Bridge Symposium being held in conjunction with NASCC (The North American Steel Construction Conference) being held in Dallas TX April 18-21, 2012: The Science & Art of Cold Bending, Thursday 1:15 – 2:15 Grapevine Ballroom B. Speakers: Al Pense, Lehigh University; Jim Collins, MetalsUSA, and Dan Wendt, Chicago Metal Rolled Products. Moderator: Ronnie Medlock, High Steel Structures.