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Mechanical Unit Anchorage / fire ratings[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "SEAOC List" <seaint(--nospam--at)seaint.org>
- Subject: Mechanical Unit Anchorage / fire ratings
- From: "Paul Feather" <pfeather(--nospam--at)SE-Solutions.net>
- Date: Thu, 16 Jan 2003 11:41:23 -0800
We have been asked to look at some mechanical anchorage issues. In researching / investigating the issue I am developing as many questions as answers. Can any of the mechanical anchorage gurus out there provide references or points that will help me get a handle on the issues?
Ceiling suspended mechanical units. Steel frame / metal deck building, Type II F.R. with sprinklers. Post-installed (TI). All the typical mechanical systems from the mechanical supplier indicate spring isolated hangers and cable bracing. These systems are shown anchored to the metal deck in tension (the gravity supports) using expansion anchors.
1. Is the support of the mechanical unit required to be fire resistive construction? None of the available expansion or epoxy anchors are approved for use in fire resistive construction that I am aware of. If yes, how are others providing anchorage for these systems?
2. UBC Table 16-O footnote 14. Does this apply to suspended systems (I believe it does)?
3. UBC Table 16-O footnote 16. Does this apply to the attachment of a vibration isolator ( I do not think it does, the isolator removes the influence of operating vibrational loads on the anchorage)?
As an extended discussion:
This is an information search to assist an existing and valuable client for a TI project we were not involved in. I do not know about the rest of you, but we typically do not include anchorage of mechanical systems in our scope of work. Supporting structure for large roof or floor mounted equipment yes, but the anchorage attachment no. It has always been our view that the mechanical engineer and those responsible for the design and manufacture of the specified isolator or curb are responsible for the required attachment. In our experience, it is almost impossible for the project structural to know what unit type will eventually end up being used, never mind the bolt pattern / anchorage requirement. For tenant improvements and subsequent mechanical installations on buildings we have designed we are not usually involved at all.
How are others viewing and dealing with this issue? Apparently this is a hot topic in California. On two recent projects in completely different jurisdictions the only plan check comments we received were related to mechanical unit anchorage. I get the impression something must have happened.
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