How to ensure collateral load allowance isn't exceeded

[jochav52802]

I'd appreciate any insight in how one typically communicates collateral load limits for the electrical/mechanical contractors to follow to ensure that the supporting members aren't overloaded.

My experience has been that it's common for the contractor to determine routing out in the field without submitting prior plans to the structural engineer for review, so I'm curious how the structural engineer ensures that his/her allowance isn't exceeded.

I found the below resource that gives the example of how a 5-psf collateral load applied to purlins spanning 25 ft and spaced at 5 ft produces a slightly larger moment than a concentrated 300 lb load at center span. However, if I'm a contractor, and they're told not to exceed 5-psf in collateral loading, that would seem to allow them to apply a 625-lb, (5 psf x 25 ft x 5 ft = 625 lb) concentrated load at center span, which would produce a bigger moment than the load applied uniformly. Additionally, this would seem to allow the contractor to place a concentrated load near either end of the purlin, which would exceed the shear load produced by the uniformly applied load.

I'd appreciate any insight on how to ensure that the contractor doesn't distribute the collateral loads in a fashion that exceeds the moment/shear capacity of the supporting purlins. Many thanks in advance!

https://www.uop.edu.jo/PDF File/petra university

[Architecture_Ebook]_Metal_Building_Systems_-_Design_and_Specifications-20610-Part151.pdf

 

[RPMG]

The collateral load is not communicated to the electrical and mechanical contractors. Generally, the collateral load is selected high enough to allow the contractors free range. Collateral loads should also not be "stacked". For instance fire protection sprinklers are spaced out collateral dead load, but mass pipe runs should be coordinated and included in the design. Contractors typically do not accidentally bunch up heavy pipe runs, but if a pipe rack is available, they will make use of it.