CollinW
Structural
- Mar 9, 2023
- 12
The thread linked below discusses a case with thermal and seismic loads on a pipe support. I have a similar case where loads are non-frictional and result from hard anchors/guides. It seems to be that people on the last thread stated that you must combine the seismic and thermal loads in the same case, but this goes against what I have previously heard.
My thought process is that this case is similar to pretensioned bolts. The force in the support is equal to the thermal case (like pretension) until it is overcome by the seismic force. At that point it is equal to the seismic force. So if you check the thermal case and seismic case separate, then that is enough.
I would love to hear people's thoughts. If anyone has some specific code references that would be preferred. ASCE is very vague and ASME B31.1 states "Supporting elements shall be capable of carrying the sum of all concurrently acting loads," which I would argue that they are not acting concurrently. The original thread quoted PIP STC01015, which does not seem to be required to be followed, but it states "Friction loads shall be considered temporary and shall not be combined with wind or earthquake loads. However, anchor and guide loads (excluding their friction component) shall be combined with wind or earthquake loads"
https://www.eng-tips.com/threads/pipe-rack-design-thermal-seismic-on-pipe-anchors.461740/

My thought process is that this case is similar to pretensioned bolts. The force in the support is equal to the thermal case (like pretension) until it is overcome by the seismic force. At that point it is equal to the seismic force. So if you check the thermal case and seismic case separate, then that is enough.
I would love to hear people's thoughts. If anyone has some specific code references that would be preferred. ASCE is very vague and ASME B31.1 states "Supporting elements shall be capable of carrying the sum of all concurrently acting loads," which I would argue that they are not acting concurrently. The original thread quoted PIP STC01015, which does not seem to be required to be followed, but it states "Friction loads shall be considered temporary and shall not be combined with wind or earthquake loads. However, anchor and guide loads (excluding their friction component) shall be combined with wind or earthquake loads"
https://www.eng-tips.com/threads/pipe-rack-design-thermal-seismic-on-pipe-anchors.461740/

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