Live load estimation

[ramihabchi]

hi
Can any one give me offically approved way or reference to a way for determining live load an occupancy.I am not facing a specific case.I just want to know how to determine live load of an occupancy that is not listed in codes

 

[r13]

What is the building type, what is the expected use of floor areas, human activities, machine....

 

[dhengr]

Ramihabchi:
Use the building codes, bridge design codes, etc. as a guide or starting point. There are a number of commodity and materials weights tabulations around, and you can always weigh the material of interest. Machine weights, and the like, come from the machine builders. The loading conditions are almost always one of the first determinations which an engineer must make when starting the design of anything. Talk with your client about the intended use of the various spaces in the building. Then, of course, engineering experience and judgement comes into play too.

 

[Lomarandil]

For occupancies not prescribed in the codes, there are statistical methods -- the same as how the code values were determined. That's quite an undertaking.

Practically, the next best thing is to reference another code (e.g. another jusridiction, or bridge versus buildings), and use your engineering judgement to determine how directly applicable it is to your situation.

Many engineers also aren't aware of the supplementary table for live loads in the commentary of ASCE 7 that covers some more unusual cases.

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just call me Lo.

 

[ramihabchi]

@lomarandil is it usually accepted to use live loads given by another codes that are not applicable in own country?that is why I wanted to know the way live loads are calculated.if they are purely statistics, seeing many codes around the world will give me idea about live load of an occupancy.
For example I am trying to find live load of heavy and light storage rooms in hotel but can t find the answer in ASCE which is applicable in my country.

 

[dik]

Not likely a good idea... Baker's 'Steel Skeleton' about 50 years back had a discussion on design loads and the prescribed design loads were several times higher than those measured. Likely the same situation today... a parking garage has a prescribed design live load of 40 or 50 psf while you would have difficulty placing cars bumper to bumper in all isles and stalls and get more than 20 psf.

Best thing is to find an occupancy that comparable and use it or a factor of it (greater or less than 1).


Dik

 

[Lomarandil]

Good clarification dik.

I say statistics, and not just mathematical or measurement methods... because structural design loads do not only reflect the expected service load, they (as I understand it) reflect the combined dataset of past practices likely to produce a satisfactory building (strength, serviceability, localized overloads, alterations, lifespan, etc.), then distilled back to a simplified value of 'load'.

Yes, I would say that it is usually accepted to apply live loads given by codes in other countries, where one's own code is not specific. Engineering judgement is still needed.

Also note that this is somewhat straightforward for gravity loads, but not so simple for lateral loads (more statistics and design philosophies involved). Even for gravity loads, I may choose to check that more common load conditions match what is provided in your applicable code. Perhaps make adjustments where needed as dik suggests.

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just call me Lo.