steel deck bracing steel beams

[bjb]

What are your opinions?

When the deck ribs are parallel to a steel beam, and the top of the beam is at the deck bearing elevation, can the deck be considered to brace the beam against LTB?

 

[dik]

If it were concrete filled... likely. For this condition, you would likely have joists or purlins providing the lateral support for non-filled deck.

HAPPY NEW YEAR

 

[haynewp]

You have to be careful about assuming that it is braced when the deck is parallel. I understand that collapses have occurred when concrete was being poured on composite girders that were designed as continuously braced by the parallel metal deck. I always check to make sure the option in RAM (or other program) that girders are braced by connecting beams only and not the parallel metal deck.





{Happy New Year from the land of cold cold beer}

 

[dik]

You know why the British drink warm beer?

British Leyland designs fridges, too... <G>

All the best in the New Year...

Dik

 

[bjb]

thanks and happy new year!

I agree that with deck paralle to the girder the safe thing to do is assume brace points at the infill beams. With the flange parallel to the deck ribs it's questionable that you will get good connections between the flange and the deck. Also, you would have to question that even if you did get good connections if the deck was stiff and strong enough to provide the bracing with the ribs parallel to the beam. I know engineers who do consider the beam braced when the ribs are parallel.

 

[dik]

I didn't mean to confuse things, but where the deck is parallel to the beam, the beam is braced by the purlins or joists that the deck is at right angles to. Once the concrete is placed and hardened, then the beam generally has full lateral support from the deck.

Dik

 

[DRC1]

Some decking is strong enough to provide lateral support, some is not. You must consult the manufacures litriture or better yet, speak directly to the company's engineer.

 

[bjb]

dik, I agree with you

 

[JAE]

DRC1 - I don't think that most deck manufacturers have that sort of concern or expertise relative to second order buckling of steel wide flanges. Rather - AISC is the place to go and/or the literature and research prepared by various profs - particularly Yura at Texas. Basically, the deck flutes, when parallel to a beam, have a fixed strength and fixed stiffness and these can be compared with the stipulated limits in the AISC spec using nodal bracing.

Having said that, I would say that the prudent engineer would not waste time trying to determine the accordian stiffness of a metal deck and would instead rely on the intermittent supported beams for the lateral stability.