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Re: Bridging for bar joist[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Bridging for bar joist
- From: Thomas Magnum <tm314052(--nospam--at)gmail.com>
- Date: Wed, 28 Oct 2009 13:58:11 -0400
'Positive anchorage with X-bracing' doesn't mean anything. 'Positive anchorage' with horizontal bracing doesn't mean anything either. Braces stabilize, not anchor. Welds and bolts anchor. You need to find out exactly what the manuf is talking about. X-bracing absolutely provides positive BRACING joist-to-joist and even joist-to-wall. However, it is thought to provide bracing that is too rigid when connected to a vertically stiff element, thus the requirement for horiz bracing (Vulcraft says '...shall be used...') in that instance. Just call them and clarify the comment.
You don't want to skimp on bracing because of a heavily reinforced wall. I've never seen anything short of a bank vault that was so heavily reinforced that you can't find space for a 1/2" post-installed anchor without coring.
Thank you for your responce. I have older Vulcraft standard Details that shows bridging both ways, attached to wall and X braced. I prefer not to attach to wall because of no coordination between bridging location and panel joints and some panels are heavly reinforced which would require core drilling. Also if this was a steel building with spanderal beam i would think X bracing of bridging required.
So does X-bracing provide positive anchorage as required in SJI?
Date: Wed, 28 Oct 2009 12:16:01 -0400
Subject: Re: Bridging for bar joist
My guess is that there is a misunderstanding. You do not use braces to provide positive anchorage. They stabilize, not anchor. It's now standard (page 33 of the '03 Vulcraft Catalog) to provide horiz bridging in the bay adjacent to a much stiffer element such as a wall. What sort of concrete panel is it? Could it be that the joist manuf thinks the bridging will be used to stabilize them? Are the panels more of a cladding than a support?
On Wed, Oct 28, 2009 at 11:50 AM, Kipp Martin <KMartin(--nospam--at)carollo.com> wrote:
Ed,I don't do a whole lot of work with steel joists, so keep that in mind. I've usually seen that X-bracing converted to horizontal bracing in the end bay. This is to allow the joist to deflect releative to the non-deflecting wall. I usually allow the use of either X-bracing or horizontal bracing, leaving it up to the joist manufacturer. But in answer to your question, I don't see how X-bracing does not provide positive anchorage. I'd ask the joist manufacturer to explain.--Kipp MartinCarollo EngineersPortland, Oregon
From: Edward Jonson [edjonson(--nospam--at)msn.com]
Sent: Wednesday, October 28, 2009 7:43 AM
Subject: Bridging for bar joistQuestion about anchorage of bridging. I have project where X-bracing of end bay of bridging is called out on plans rather than continuing bridging to concrete panels. Joist manufacture claims this X-bracing does not provide positive anchorage. So the question is does the X-bracing provide positive anchorage? Any comments much appreciated.
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