I appreciate the overview and wagering strategy but the SEOR is a friendly on this one and there's nothing conventional about this application. It's a tunnel, 40' below the street that communicates from one building to another across two public streets and an intervening block in DT San Diego. And crosses a fault, so a high likelihood of short waveform movement if there's ever an event. So we have the fault zone, the two building basement crossings and some other flexure points that we're trying to resolve. On top of all that, it's highly secure and there's limited space above detention-grade ceilings, so the required clearances for movement apparently can't be fully realized. The contractor has expressed a preference for the multiple 90s on this one because of space constraints and since this is a very sensitive project and everyone is earnestly working to get it right, I've been tasked with establishing what range of vertical movement the detail in the NFPA figure is capable of. Also trying to verify if it's been field tested (it has, apparently) and whether it's been lab tested or whether there is any particular requirement for vertical movement specifically. The language of 9.3.3.2 is confusing, with reference made to open and closing of the joint and also to, "...movement relative to the separation in the other two dimensions..." What "other two dimensions", time and space?
SML -----Original Message----- From: Sprinklerforum <[email protected]> On Behalf Of AKS-Gmail-IMAP via Sprinklerforum Sent: Tuesday, October 19, 2021 12:02 PM To: [email protected] Cc: AKS-Gmail-IMAP <[email protected]> Subject: Re: Seismic joint detail If we are referring to the six flexible coupling seismic separation assembly that every contractor finds an alternative, make a sizable wager with the structural engineer that the assembly provides vertical movement. Make sure the winnings cover the cost of six ½” pvc fittings and a four foot stick of ½” pvc pipe. Make the thing up and fool with it for some time before you present your case so that you can move it around to show it off like you know what you are doing, because at first it might look awkward enough that the engineer will cry foul. By the way, the details for this six coupling assembly show vertical accommodation in the elevation detail. You might obfuscate the demonstration by asking how much differential seismic movement this engineer is really expecting. Differential seismic lateral motion is due to how easy it is for one structural building section to be different in lateral flexibility than the next building section, i.e. across the seismic separation joint. Each building section will wiggle differently than the next. The difference shows up at the joint. Vertical differential flexibility, in other words “pogoing” differently than the next structural section is not happening very much, if any. Buildings are relatively much more vertically stiff than they are horizontally stiff. I might bet the structural engineer has not tried to calculate this. What might be the case, like this building is in Houston Texas which I believe has more seismic faults going on than any other US city, is that the structural engineer knows the building project has to span a known fault and so the structure is actually anticipating differential vertical movement at the joint. Allan Seidel St. Louis, MO > On Oct 19, 2021, at 11:45 AM, Steve Leyton via Sprinklerforum > <[email protected]> wrote: > > A question was raised by a project structural engineer about the NFPA 13 > seismic joint detail shown in Fig. A.9.3.3(a), 2016 edition for reference. > Does anyone know if this configuration has ever been tested/measured? Has > it been verified as an acceptable OMNI-DIRECTIONAL solution? The engineer > in question is looking at the detail and in his judgement, it's only a 2D > solution. There are lateral and longitudinal movements shown, but not a > vertical one. If there are installation or hanger/bracing committee people > who can chime in, I'm wondering if this figure has been vetted and that's why > it's still in the standard. Bottom line: Is Fig. A.9.3.3(a) equivalent to > a listed seismic loop? > > > Steve Leyton, President > Protection Design and Consulting > T | 619.255.8964 x 102 | > www.protectiondesign.com<http://www.protectiondesign.com/> > 2851 Camino Del Rio South | Suite 210 | San Diego, CA 92108 Fire > Protection System Design | Consulting | Planning | Training > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
