AASHTO Steel Grid Floor 2

[enginerding]

Can someone attach a photograph or diagram of an example of a Steel Grid Floor that is discussed in AASHTO? The spec refers to steel grid floors less than 4" and greater than 4" thick.

Thanks

 

[SlideRuleEra]

I'm not familiar with that portion of AASHTO, but it must be referring to grating described and shown in photos in the "Heavy Duty Metal Bar Grating Manual". Here is a link to the webpage of the National Association of Architectural Metal Manufacturers (NAAMM) that includes the free, .pdf manual:

http://www.naamm.org/mbg/literature.aspx

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[enginerding]

You are probably right. I don't usually do bridges. I am designing an alternate temporary access bridge to a site. It will be up just a couple of weeks. The cost of the rental bridge is upwards of $140K with installation. My customer wanted to see if we could design something using steel that he had in his shop and would be able to reuse after the project.

I was trying to come up with the distribution factors to size the beams and stringers using a 1-1/4" steel plate for deck. I thought maybe steel grid would be applicable, but I don't think so any more...

 

[SlideRuleEra]

Sounds like the traveling public would be using the temporary bridge. If there was an auto accident on it your design could be questioned in court.

If your client had ALL of the materials needed for a temporary structure then it "may" be cost effective to design something, using those material. If purchase of any major component (beams, piling, deck, etc.) were required the economics go BAD, quickly.

IMHO, probably best to pay the $140K and keep the overall project moving.

Good Luck

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[enginerding]

Actually, no, the traveling public would not use the bridge. The county will not let us build a temporary bridge over their existing posted bridge (10 tons); nor will they let us reinforce it. We need to get about a dozen concrete trucks and a 150,000# crane across a 25' (+/-) wide creek. So this is away from any roads, other than the gravel haul road on private property.

Anyway, the material he had in his shop doesn't work. We are going with the rental. It is just hard to believe they are willing to add about 30-40% of the total project cost just to build this bridge that will be up only a couple of weeks.

Thanks for your help.

 

[miecz]

Here's a look at an "Open Grid Deck" out of the IKG Greulich Catalog.

 

[enginerding]

miecz -

Thanks. This makes it pretty clear it is meant for HS20 loading and uses the terminology from AASHTO. This is probably what AASHTO is referring to by Steel Grid Deck.

 

[miecz]

For more info, try:

http://www.bgfma.org/