From: admin [mailto:admin@seausa.org]
Sent: Tuesday, November 15, 2011 3:00
To: Felker, Brian P CIV NAVFAC MIDLANT, IPTNE
Subject: seaint Digest for 14 Nov 2011
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seaint Digest for 14 Nov 2011
Topics covered in this issue include:
1: Unreinforced Masonry Wall from 1965
by Daniel Popp <drp181@yahoo.com>
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Dan,
It might not be feasible, depending on your boundary conditions, but masonry walls, depending on thickness, will undergo a compression arching response between flexural response and actual failure. In a simple spanning example, arching thrusts are created as two rigid panels (either side of midspan) rotate against each other. This response can provide a significant resistance, but is utterly dependent upon the strength and rigidity of the end supports.
Brian Felker, P.E.
From: Daniel Popp <drp181@yahoo.com>
Subject: Unreinforced Masonry Wall from 1965
To: seaint <seaint@seaint.org>
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List,
We have a renovation project in a low seismic area (SDC B). The 27-foot-tall exterior walls are unreinforced ungrouted (hollow) 8" concrete masonry interwoven with 4" brick face shells (12" nominal thickness). The occupancy is changing from Category 2 to Category 3 (>300 people in one space), so we are obligated to check the existing walls. However, due to the height, I cannot make them work using the "unreinforced masonry" provisions in MSJC Section 2.2.
Does anyone have any idea how the original engineer may have made these walls work in 1965? It strikes me that the code provisions for unreinforced masonry have probably not changed much in 50 years (seismic regions excepted). The owner is very sensitive to budget (who isn't these days?), so I'd like to find a way around an costly retrofit.
Thanks for your input,
Dan Popp, S.E.
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<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div>List,</div><div><br></div><div>We have a renovation project in a low seismic area (SDC B). The 27-foot-tall exterior walls are unreinforced ungrouted (hollow) 8" concrete masonry interwoven with 4" brick face shells (12" nominal thickness). The occupancy is changing from Category 2 to Category 3 (>300 people in one space), so we are obligated to check the existing walls. However, due to the height, I cannot make them work using the "unreinforced masonry" provisions in MSJC Section 2.2.</div><div><br></div><div>Does anyone have any idea how the original engineer may have made these walls work in 1965? It strikes me that the code provisions for unreinforced masonry have probably not changed much in 50 years (seismic regions excepted). The owner is very sensitive to budget (who isn't these days?), so I'd like to find a way around an costly retrofit.</div><div><br></div><div>Thanks for your input,</div><div>Dan Popp, S.E.</div></div></body></html>
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