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RE: CMU Wall Reinforcing[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: CMU Wall Reinforcing
- From: "Keith Erick Fix" <keith.fix(--nospam--at)redpepperconsulting.com>
- Date: Thu, 28 Apr 2011 13:25:40 -0500
You make a very good point: cost to detach a wall element from the lateral load path may exceed the cost to reinforce that element to behave resist in-plane shear loads. My thought was merely that we sometimes make shear walls of things we should not. Drew appears to be evaluating a pier.
That said, I am inclined to agree with you that ignoring this “shear wall” provision for a “shear pier” may be non-conservative. Missing from my ’05 copy of the code are alternatives to ordinary, intermediate, and special shear walls. It seems to me that a pier within a wall walls under the reinforcing requirements unless somebody can find an exception to the rule.
Assuming there are no seismic criteria to follow for piers within a masonry wall, I think Andre’s got the right idea – and it’s what I’ve done in the past: at least put all the shear (horizontal) reinforcing you might need into that wall so you aren’t in a pickle when it shatters during an earthquake. Even if you were to say this was a beam – not a special reinforced shear wall – you would need shear reinforcing spaced not more than half the beam depth (d), which in this case may be a little less than pier length, so I think you’re back where you started, generally speaking.
Of course, if you’re talking longitudinal (vertical) reinforcing, you may be able to justify a 4-bar solution, but you’re still going to have to address that bar diameter when setting your horizontal bar spacing. So, if you’re using #8 vertical rebar, you’re still facing 16” maximum spacing. No, that’s not under the pier design criteria, but it seems more than reasonable to get the pier reinforced similar to a either a column or a beam or a wall – but you’ve got to get close to something or Andre is right, you’ll have a problem under lateral load from earthquake forces.
Keith Erick Fix
Red Pepper Consulting, Inc.
10201 W. Markham Street
Little Rock, AR 72205
+1 (501) 227 7183 office
+1 (501) 350 3629 mobile
+1 (501) 319 7319 fax
- CMU Wall Reinforcing
- From: Andre Sidler
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