Fire truck loading 3

[steve1]

This is a pretty basic question. Do fire trucks produce structural loadings that are equilivant to standard truck loadings? Are there any references that discuss fire truck loadings? I looked in my states Highway Design Manual but could fine no specific mention of fire truck loads.

For the case in point we have several yard structures outside a power plant that must withstand a fire truck either driving across or being parked on them.

 

[JAE]

I know that in past years many engineers designed urban sidewalks that spanned over extended basements with a live load of 250 psf...very common in the 1940's - 1980's.

 

[JAE]

I found this on an old SEOINT website from 2001:

[blue]Fire truck loading will be significantly higher than HS-20. The normal fire truck axle and wheel loading will be within AASHTO HS 20 when it is traveling from point A to point B. But when they set up and set the outriggers, all bets are off.

The punching shear must be considered and will drive the thickness of the slab. The outrigger loading on aerial platforms is huge. The last time I checked Pierce, Seagrave, Sutphen, and E-1. A Pierce aerial had the largest outrigger loads at about 60,000 pounds (HS-20 wheel loads are 16,000 pounds). The only thing that NFPA says is that the outriggers are limited to 75 psi maximum bearing pressure under the outrigger.

There is NOTHING in any code on this. Fire apparatus manufactures are very tight lipped on maximum outrigger loading.
[/blue]

Hope this helps a bit.

 

[rmw]

As far as the fire truck loadings when they are riding on their axles, they are no different than any other type of truck. Axle loading limitations and axle load laws govern. They can't build a fire truck so heavy that it collapses bridges on its way to a fire. So, if your structure would handle a fully loaded concrete truck lets say, it wouldn't know that it was a fire truck that was passing over it.

Once you put the outriggers out, then the ball game changes.

rmw

 

[SlideRuleEra]

Requirements for fire trucks are covered by "NFPA 1901: Standard for Automotive Fire Apparatus", available at this link

http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=1901&cookie_test=1

Don't know if it covers highway loading, but the specification is affordable. Might be worth checking.

http://www.SlideRuleEra.net

 

[steve1]

Thanks JAE, rmw, and SlideRule for your replies.

 

[AUCE98]

steve1,

I have recently been faced with this same issue on a couple of projects. Working in Atlanta, we contacted the city fire department engineering office. They sent over a sketch of the largest truck in their fleet with axial loadings etc. Good Luck!
AUCE98