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RE: Seismic - Isolating CMU infill wall

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Dear Alfonso;

I think Mr. Gillian has answered most of your questions.  I have to add
something, though.

I suggested using the walls for lateral load resistance, but I also advised
considering the possibility that one or more walls could be removed.  It is
specially true if you're talking of interior walls, because sometimes the
use of the building could vary during its lifetime.  Then you have to check
the frame for both conditions.  And if you think there could be some major
changes in the building, then check the whole structure (torsional response
will be crutial).

As far as the quality issue is concerned, I can tell you what the local
practice is.  The seismic provisions tell us some allowable stresses the
bricks can handle.  They are quite conservative, but you can use higher
allowable stresses if you perform your own tests.  Nevertheless, usually for
buildings up to two or three stories high, you can rely on the code stresses
since the wall density is usually important (specially if you are in
residential construction).  Our code also specifies a.s. for concrete blocks
too.

Point is, that I don't think it's a good idea to try to "cheat" the
earthquake by telling that the wall is isolated.  Most of the time it is NOT
properly done and if so, it was really difficult to accomplish.

Rodrigo Lema.