Live Load 6

[Robert-32]

Underground Car Parking of chain retailer with its slab accessible to loaded trucks and possible palet stocking. What is the logical number of live loads in this case? The owner did not specify what kind of material he might stock, but even if he says anything, how can the designer be on the safe side?

 

[Struct123ure]

Design for LL=12kPa (Garage for Vehicles exceeding 9,000kg gross weight).
Put the Design load on the drawings, you can't stop your client from putting pallets of lead on the slab(Happened before), if it collapses that's on him. You clearly specified what it was designed for.

 

[Robert-32]

Thank you Struct123ure for your answer. I will use 18 KPa to be more safe.

 

[JLNJ]

18kPa will cover you for most uses, but you might want to talk to your client about this assumption and how heavy it is going to make the structure. Let the client make the decision. It's his money.

The code has 125 psf for light manufacturing, 250 for heavy industrial, and you are considering 375. It will be an extremely stout structure.

Note that a loaded fork truck has heavy axle loads and those axle and wheel loads may control portions of the design, especially locally.

 

[Robert-32]

Many thanks JLNJ for your answer. The loaded forklift is a concern, and also the road roller when asphalting is another concern.

 

[BridgeSmith]

the road roller when asphalting is another concern.

Asphalt on a concrete parking garage slab? Why?

 

[Robert-32]

The slab is at ground level and looks like the parking in front of Walmart or Target.

 

[BridgeSmith]

Ok, I'm confused now. Is this a slab on grade, the top slab of an underground vault, or just a parking lot?

 

[Robert-32]

The top of underground vault and accessable to any kind of vehicles.

 

[BridgeSmith]

In that case, you should be using whatever bridge design spec is applicable in your locale. The design loads will be specified, and it will also give specifics for design of at grade 2-way slabs. The asphalt roller loading shouldn't control the loading. I've never been asked to review any of our bridge decks for a roller, and many of them are overlayed with asphalt.

 

[Robert-32]

Many thanks Bridgesmith for the answer. Can you please give me a number, assuming the building is in your area?

 

[Lomarandil]

I'll second BridgeSmith's comment about rollers. I did just check a number of bridges for rollers, and the standard size 10-15 ton rollers were no issue. Pavers can be an issue depending on how much mix is in the hopper.

 

[BridgeSmith]

In the USA, we're governed by AASHTO. For a small span, which I'm assuming yours is, we would design for a single 16 kip (71 kN) wheel load (HL-93 truck) or two 12.5 kip (56 kN) wheel loads 4ft (1.2m) apart. The distribution width of that load depends on a number of factors related to the support conditions and spans.

If this is accessible to public (i.e. commercial) traffic, it will need to be designed in accordance with the adopted code for the location where it is. If it's private property, not accessible to the public, then the owner should decide what size vehicle to design for.

 

[Enable]

Around these parts you'd be designing to CSA S413 - Parking Structures. Generally the design loads are either firetruck or garbage truck governed (in areas accessible to such trucks). Height restriction bars allow you to reduce the loading since it prohibits such heavier types of traffic.

Of course if you have specific direction regarding heavier trucks (or more importantly heavier axle loads) will be on the deck, then you design for that. However, if no direction is given you would be more than good to go with the firetruck/garbage truck loading (usually 250psf +/-). Ditto for stockpiling areas. If no direction is given you can give them the option of stockpile loading everywhere or nowhere; it's their call as long as you meet CSA S414 or whatever your equivalent code is.

BTW I agree that smooth rollers would almost never govern in a structure like this. Vibratory equipment on the other hand can be a disaster. I've seen it shred a roof deck to bits.

 

[Robert-32]

Thank you all for your contribution, I really appreciate your answers.