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STEEL: Lateral Support for Open-Web Steel Joists

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Greetings.

 

I have a job that requires adding on a couple of bays to a mezzanine level in an auto parts supply warehouse. The existing mezzanine level has steel bar grating supported on K-series steel joists. The real kicker is that the floor is rated (sign is posted) at 200 psf!

 

Yet the bar grating is attached to the top chords of the joists using typical “saddle clips” (e.g. http://tinyurl.com/6gkdp, illustration at upper left), which IMO will not provide adequate bracing against lateral torsional buckling of the joists under service load. Further, the bridging provided for the K-joists appears to be the standard for construction phasing before a solid deck is put down.

 

First, am I misinformed about the ability of the bar grating with only saddle clips to brace the joists? Of course the owner would say “hey, it’s worked this way for several years, never had a single problem yet! And will want me to put into the new addition exactly what is already there.

 

Second, what would be best: Use K-joists still, but make sure that the joist supplier puts adequate cross-bridging to assume there is no lateral torsional buckling problem? Or use wide-flange girders? I’m tending toward the first option because I could probably quietly slip it by without the owner’s curiosity being piqued.

 

Finally, what is my ethical responsibility with regard to the joist-supported floors which (if my assessment is correct) are not adequate for the posted load? This place is actually within the city limits of a small, well-to-do south Texas town that actually has a building official. Do I need to bring this up to the owner and inform the building official (thus possibly incurring wrath?)

 

This business is a high-profile outfit. I wouldn’t be surprised, in fact, if the building official didn’t choose to look the other way even if I did complain.

 

Sheesh.