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RE: Unreinforced masonry / stone building - which code?

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Nels,
 
This is not a Registered historical building.  I met with the local building official, and explained how I would retrofit the building using steel braced frames etc., using UCBC load, and it was agreed that this is acceptable.  After I came back, and read the UCBC again, and I start to wonder if this is valid, regardless of what the building official think, but from the do-it-right point of view.  These stone walls are 24" thick, and I can take a core sample, to get their shear capacity.  They must be good for something.  The building official I spoke with, will be retired in less than a month, and I'm afraid I might have to justify this whole thing again to someone else who might see it differently. 
 
Thanks.
 
 
Y i   Y a n g,   S. E.             
STRUCTURAL DIVISION
SUMMIT ENGINEERING INC.
707.527.0775.x15
Santa Rosa, California
 
-----Original Message-----
From: Nels Roselund [mailto:njineer(--nospam--at)att.net]
Sent: Monday, April 04, 2005 2:50 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Unreinforced masonry / stone building - which code?

Yi,

 

I would check with the local Building Official; many jurisdictions would allow the UCBC to be used in the case you cite.  The increase in occupancy would justify triggering of the UBC rules, but it would be a heavy handed way of retrofitting a stone building.  The UBC has no provisions for unreinforced stone masonry.  Using the UBC, you would have no way of taking of advantage of whatever strengths are inherent in the stone construction – you would have to assume the stone to be completely non-structural, and you could not take advantage of the DCR/flexible diaphragm concept so the of the diaphragm may become almost unmanageable.  UCBC is the only CA Building Code that written with unreinforced masonry in mind.  If it is a historic building, Section 8-705.1 of the CA Historical Building Code [Part 8, Title 24], which the Building Official is required to enforce, allows lateral load evaluation to not exceed 0.75 times the seismic force prescribed in the 1995 CA Building Code [1994UBC], and requires compliance with the UCBC.

 

Nels Roselund, SE

South San Gabriel, CA

njineer(--nospam--at)att.net


From: Yi Yang [mailto:YI(--nospam--at)summit-sr.com]
Sent: Monday, April 04, 2005 2:05 PM
To: seaint(--nospam--at)seaint.org
Subject: Unreinforced masonry / stone building - which code?

 

I have an unreinforced stone / mortar building (Napa county, California, very old), it is currently be used as storage.  The owner wants to change it to employee locker room / break room.   Is UCBC applicable?  From reading the UCBC, it sounds like UBC is required because change of occupancy.  Thanks for any advice.

 

Y i   Y a n g,   S. E.             

STRUCTURAL DIVISION

SUMMIT ENGINEERING INC.

707.527.0775.x15

Santa Rosa, California