Seismic design for plumbing connections

[idecharlotte]

Has anyone gone through the tedious process of analyzing / designing connections for overhead plumbing pipes as related to seismic forces? Being in NC, we've only had to deal with basic building seismic design. We've been hired to analyze the plumbing connections and 50 gal. water heater for something the plumbing contractor had already installed, as related to seismic. As small as this job is and the location, it's kind of ridiculous for the specs to require calculations etc. Although we piece together parts of the Code, there are sooo many calculations, some of which don't tell us anything and so many assumptions we have to make I question the accuracy of the calculations anyway. So I 'm basically wondering if there is a prescriptive guide to aid in this kind of design.

http://www.idecharlotte.com

 

[MiketheEngineer]

Some engineers just lock it all down to the building assuming that the building will move as one. And in simple cases that may be the case - like a house or small commercial.

But if you have a lot of corners, expansion joints, differing rigidities, etc - things can get real sticky.

 

[idecharlotte]

^Yeah, that's the easy part, using good judgement just to brace it to the building. The specifications require calculations to be submitted to the E.O.R. When you actually have to run calculations, there are so many design assumptions to be made, it seems to become a pointless exercise.

http://www.idecharlotte.com

 

[wannabeSE]

For a start, look at B-Line, Mason, Powerstrut or Unistrut's seismic bracing technical information. The documentation may be based on the 1997 UBC (or 2001 California Building Code), but the principals are the same.

 

[dhengr]

I’d start with large, concentrated, masses, such as boilers, water heaters, and water storage tanks. Certainly, on the larger ones they want them tied down, tied to the structure, and not supported by the piping itself, stressing the piping as a result of the lateral loads. Then large pipes with long runs or long spacings btwn. supports, and here you’re mostly checking support strength. Of course they are most concerned with steam or hot water, which could hurt people. I would assume that once you have done a few of these calcs. and kinda tabulated them and their attachment details, you will sign-off on this stuff by inspection.