Car park deck loads 2

[ItsOnlyMud]

Hi, Geotechnical engineer looking at FNDs for single deck of car park, what sort of column loads could be expected for say 9m spans? The client is adding a raised car park deck to provide additional parking, so it's only one deck that will be supported.

Also, what sort of differential settlements are acceptable?

Thanks

 

[ErZaZee]

All the loads that will act on the structure. Use load combinations as per code and make a structural analysis to determine how much load will be carried by your columns. There are lots of loads to consider so please consult a structural engineer.

 

[ItsOnlyMud]

Thanks, I was hoping someone has experience in designing these things and could give me a ball park figure. KPa for the deck area would be fine, I could turn that into column loads based on the span...

I'm a geotechnical engineer not a structural engineer!

 

[ErZaZee]

It depends on the code you are using. Most specially you have to consider the effects of moving loads.

 

[ItsOnlyMud]

Eurocodes...

 

[MisterBill]

Live Load is 2.4 kPa (Car Traffic Only)

For Dead Load you need the slab thickness and topping.

 

[Once20036]

Don't forget snow, drifts, wind/seismic, etc, and the possibility of unexpected traffic loads (ie fire trucks)

 

[MiketheEngineer]

Typically in US the load is 50 psf plus dead plus snow/live plus wind, etc AND a 2,000 lb point load anywhere.

CHECK YOUR CODES!!!

 

[ItsOnlyMud]

Thanks for your help. I'm not actually trying to calculate the exact design loads, just trying to get an idea, 1kPa, 5kPa, 10kPa, etc. What I'm trying to second guess is whether the columns can be supported on pads, or will they need piling. Being a geotech, I have no real idea how much a car park weighs, but I do know what the ground will take.

 

[ErZaZee]

What is your bearing capacity and soil modulus?

 

[ErZaZee]

C4.8.3
"...vehicles, however, a design load of 40 psf is recommended
with no allowance for reduction according to bay area."

ASCE 7-05

 

[hetgen]

Light vehicles (≤ 25 kN gross vehicle weight) = 2kN/m2 or 15kN

Medium vehicles (> 25 kN, ≤ 160 kN gross vehicle weight) = 5 kN/m2 or 90kN

 

[hokie66]

ItsOnlyMud,
Just use 10kPa as a total of DL + LL. That gives an ample allowance for what you don't know, which is how heavy the structure will be. Probably less, but that is a good enough ball park figure for what you need at this stage.

 

[ItsOnlyMud]

Thanks, that's exactly the sort of answer I was looking for!

 

[ztengguy]

why not ask the architect to ask his structural guy to give you prelim loads?

 

[ItsOnlyMud]

Have tried and tried and tried...us Geotechnical engineers are bottom of the food chain, the STR guys don't think it's worth their time and effort to tell us things like loads, levels, settlement tolerances and all the other useful stuff that makes our reports a whole lot more relevant to their project and give much better value. Lucky to get a proposed layout dwg half the time!

 

[ztengguy]

well, if thats the case, state your assumptions, and bitch to your client. unless your working for the structural engineer, a owner usually can make stuff happen when he waves the project in front of someone.

 

[hokie66]

That is an irresponsible attitude on the part of the structural engineer. Your question about anticipated loading is entirely appropriate and standard practice.