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Allowable deflection...

Allowable deflection...

Allowable deflection...

(OP)
...in a beam used to support rooftop equipment. L/360 appears to be standard, however, what conditions allow for the use of L/240, L/180 and such. The metal framework (unistrut or aluminum profiles) will span equipment curbs/posts.

RE: Allowable deflection...

In roof installations, too much deflection will allow excessive ponding of water and build up of load, possibly leading to collapse.

The other larger deflection limits are allowed for interior floors and locations where persons and equiment are not sensitive to deflections and vibrations.

I might choose 1/240 for an office floor load, where there will be people working all the time, because I think vibrating floors are quite distracting, whereas for a warehouse with only a few people are entering at intermitant times, 1/180 might do very well.

For piping, this is the pipeline and fluid mech forum, you should not allow too much deflection which would interfer with free drainage of the pipe that would leave fluid in the low points in the middle of pipe spans.  

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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

RE: Allowable deflection...

Hi suncathr

What I would do as a starter is work out the deflection of a standard piece of unistrut supported as a simple beam, if needed I would add a support in the middle, however the deflection over a standard length should give you a reasonable starting point.

desertfox

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