Deicer Trucks on Parking Garages

[Forensic74]

Does anyone have any good references that talk about proper winter maintenance practices on parking garages? Specifically regarding how to address the weight of deicer/plow trucks? I find that the weight of deicer trucks will typically exceed code loading, and I am curious as to how the code anticipated top decks be plowed and deiced.

 

[oldestguy]

On how many parking ramps do you know of that have height restrictions that allow a typical deicing truck ? Some don't even allow my Suburban.

 

[EdStainless]

Here in WI top decks are plowed with heavy duty pickup trucks with blades, no way to get a tandem axle dump truck up there.
The pickups are heavy (F-350 and sometimes larger) with salt hoppers in the back, but they shouldn't be too much of a load concern.
Same reason that you don't design for firetruck load, they can't get there.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Forensic74]

hmm, GVWR of a F350 loaded with salt can be on the order of 14,000 lbs......spread over a 9'x16' is 100psf with wheel loads of up to 5000 lbs. How is this even close to the 50 psf in the code?

 

[JLNJ]

I took this picture a few months ago at an underground garage where the top floor was at grade. It looks just like a regular parking lot, expect for this sign:

Do you suppose every truck driver knows his wheel loads?

 

[Forensic74]

Again, so it would appear that there is a disconnect between the 40/50 psf in the code (limits you to about GVWR of 7000 lbs) and what any normal winter maintenance truck would be. So for those of you designing parking structures in cold climates, you're telling owners that they're limited to manual snow removal and/or bobcats and hand spreaders?

 

[hokie66]

It would behoove any structural engineer to find out what loading conditions are intended and/or possible.

 

[r13]

The 40/50 psf is applied to the entire floor area (parking spaces + drive ways), while the truck only occupy a finite space at infrequent occurrence, not to mention live load factor.

 

[Settingsun]

What's a typical magnitude of snow load?

 

[jayrod12]

Where I am, snow load is 36 psf.

 

[cliff234]

Here's an short 20-second video of a snow plow truck on a parking deck in Georgia, which might help visually illustrate the effects of concentrated wheel loads.

https://www.youtube.com/watch?v=sXS3mapwjH8

 

[KootK]

The PCI parking structure design guide mentions another design guide, prepared by the Colorado Prestressers Association, which apparently studies vehicular point loads in detail and concludes that the usual PSF design methods do an insufficient job of covering those cases. I've tried to track it down a few times, unsuccessfully. If I were involved in a related, forensic case... I might try a little harder.

 

[Forensic74]

PCI has a publication "Parking Structures Recommended Practice for Design and Construction" that talks about loadings, but gives zilch in the way of loadings from winter maintenance. ASCE published a study "Design Live Loads for Parking Garages" and it ignores any case over a normal passenger vehicle.

Just seems so strange to me and I guess it's not surprising why you hear of a truck going through a deck every winter.

 

[ACtrafficengr]

hmm, GVWR of a F350 loaded with salt...

I'm surprised no one has brought up the wisdom of chloride-based deicers on concrete parking structures.

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. -

http://xkcd.com/319/

 

[3DDave]

I expect the greatest likelihood of problems is where snow rarely accumulates - such as the deck failure in that video from Georgia. It would be very easy for typical plow operators to do a great deal of damage to a parking structure by either continuing to pile material to the point of failure or use the normal ram and jam to blow out perimeter walls or just rust the underlying structure to pieces with corrosive melters.

Those who are responsible for parking structures should be familiar with the original design limitations (spectacular exceptions aside) and will plan for snow removal/maintenance and line up qualified people and procedures. But where it rarely snows? Look at what happens to the local traffic at the same time and see that lack of familiarity will outpace any ability to engineer a flawless solution.