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Unreinforced masonry testing

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Dear list,

 

I am working on a renovations and a seismic retrofit of an existing URM building.  The building is located north of San Francisco and is over 100 years old.  The building is a approximately 120ftx45ft in plan and is 1 story high with a partial mezzanine and partial basement.  It has an open front and a bunch of windows punched in the back but the longitudinal walls are solid.  The building's roof is being demolished after fire and new roof framing comprising of steel joists at 8feet on center and 2x6 rafters in between is being raised approximately 4 feet.  It is  going to rest on a new system of TS columns along the perimeter that will also provide lateral support out of plane to the solid longitudinal walls and rear wall.  Steel columns will get anchored into the mezzanine and 1st floor wood diaphragms.

 

The project was originally submitted last year as a fire repair and is currently being revised still using 2001 California Building Code.

 

The existing UM walls are supported on existing concrete walls (approximately 30%) and the rest is a mix of brick and stone masonry with various degree of mortar deterioration, some of it is pretty severe.  At some places these retaining walls are so bad that I think it will require adding a new shotcrete wall on the inside to stabilize them.

 

The lateral resisting system is comprised of 4 lines of moment frames transversely and 2 story x-braced frames longitudinally.  The longitudinal direction is where I have questions.

 

1. Do I design them to take the weight of the longitudinal walls, assuming that they are just a  very heavy veneer?  Can I assume that they can carry the loads from themselves and may be the existing first floor, while all other loads supported by Braced Frames?

 

2.  I need to develop a UM testing program to make sure that the walls can resist both in plane and out of plane lateral load.  SI there a good reference to that.  I have a copy of the current 2007 CBC code's chapter A1, (same as old UCBC) as  a reference for the placement and number of mortar shear tests.  Any other recommendations?  Can the testing be minimized if the masonry is only considered a veneer.

 

Thanks and I would appreciate your opinions,

 

 

Alexander (Sasha) Itsekson, SE

Enginious Structures, Inc.

Oakland, CA

510.272.9999

www.Enginious-Structures.com