Lateral Bracing for Steel Beams with Timber Deck.
Lateral Bracing for Steel Beams with Timber Deck.
(OP)
I'm completing the load capacity rating for an older steel beam bridge with a 4" thick timber deck. Steel beams are S15x42.9 @ 2'-4" O.C. Span length is 30 ft (Simple Span). As best I can tell, there is no connection between the timber deck and the steel beams and no intermediate diaphragms. Check of Lat. Torsional Buckling for 30 ft unbraced length severely reduces rating and drops posting requirement to 8 tons. I don't feel I can consider the compression flange to be braced with no physical connection between beams and deck, but I hate to tell my client that his bridge needs to be posted at 8 tons after it has stood for the past 70 years with no posting.
Any thoughts?
Any thoughts?






RE: Lateral Bracing for Steel Beams with Timber Deck.
RE: Lateral Bracing for Steel Beams with Timber Deck.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Lateral Bracing for Steel Beams with Timber Deck.
It won't be the first time that an old bridge has to be retrofitted to comply with current requirements.
RE: Lateral Bracing for Steel Beams with Timber Deck.
RE: Lateral Bracing for Steel Beams with Timber Deck.
Aside from that, the rating is what it is.We've all seen structures that shouldn't be standing yet they are for one reason or another. However, codes are codes.
RE: Lateral Bracing for Steel Beams with Timber Deck.
RE: Lateral Bracing for Steel Beams with Timber Deck.
You say "As best I can tell, there is no connection between the timber deck and the steel beams..."
Is there any chance you are mistaken? It seems unlikely that there is no connection. It may be worth a closer look.
BA