Design assumptions on structural drawings?

[Kom3]

Has anyone ever put design load assumptions on their structural drawings? I am analyzing an existing pipe rack for additional loading and the client suggests the original loading is 20 psf. This seems reasonable as the pipes here are no more than 4". This is not a refinery where 40 psf is the industry standard. The original loading in this case is critical as I need it to do the 5%/10% utilization increase allowance for existing structures per IBC. Even though it is reasonable, I can't find the original drawings or calculations to verify this. Can/should I put this assumption and state it as "per client" on the structural drawings? I will put it in the calcs but few will keep/look at those calcs in the future.

Regards.

 

[WinelandV]

Since it's existing, I would have the client go out there and verify what size pipes are in the pipe rack, and what those pipes are transmitting. Tell them you'll start with 20psf to get rolling, but that your drawings will have a note along the lines of "CLIENT/OWNER TO VERIFY EXISTING PIPING IN PIPE RACK AND PROVIDE TO ENGINEER".

If I'm understanding your situation correctly, wouldn't you want the original loading to be 40psf b/c that would give you a 2psf-4psf allowable increase (instead of only 1psf-2psf)?

 

[phamENG]

Doesn't matter where the loading assumptions come from. If you use them, that means you've agreed with them and are taking responsibility for them. But yes, if I make a loading assumption I always put it on the drawings with the appropriate instructions for somebody to verify (contractor excavating a foundation, providing mechanical submittals with operating weights, etc.)

 

[skeletron]

Always put load assumptions. It helps track your work and helps anyone in the future.

 

[ukengineer58]

if your asssumptions potentially change your solution and you need them to be verified by others yes. If something is integral to design - such as phasing etc then yes. In UK we have CDM regs and i would say passing crucial design info like this is legally obliged here. and common sense to do anywhere