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RE: Seismic - Isolating CMU infill wall

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Dr. Mr. Lema
Thanks for the reminder / opinion. I'll check that all the structures that
I'll design will not behave in an unsoundly manner. The frame might or will
lean against the wall because of the different stiffness properties of the
frame members and the loadings but only a part of the column will lean if it
really does.

If I would go for you suggestion which is acceptable, I may be inclined to
branded CHB and not the normal ones. These are a bit expensive and may
produce uneconomical design. It's much better here to isolate and provide
lean concrete than rely on some walls. 

> ----------
> From: 	Rodrigo Lema[SMTP:rlema(--nospam--at)]
> Reply To: 	seaint(--nospam--at)
> Sent: 	Monday, June 21, 1999 8:51 AM
> To: 	seaint
> Subject: 	RE: Seismic - Isolating CMU infill wall
> A. Yango wrote: "If  a gap is provided between the columns and the walls,
> the gap would only be minimized and not maintained since the wall would
> sway together with the beams / girders and columns"
> Not true.  The wall and the frame would have different deformation
> patterns.  The CHB wall deflects like a cantilever.  The frame will act in
> a much flexible way, so it would lean on the wall and it will get extra
> stiffness than assumed in your calcs.  
> As far as the CHB quality is concerned, we use clay bricks more often here
> in Argentina.  Problem (same as yours) is, the quality is not very
> reliable.
> But  when you have low buildings, with a lot of walls, why not use them
> -even not relying on the specified strenghts- to resist lateral forces? 
> You will be surprised to see how easily you can trust most of the lateral
> resistance to this very rigid walls.  
> By the way, the frame will then be no more than a knot helping to tie the
> CHBs together.  So you will get need less reinforcement.  The load path
> will be the wall, not the frame in bending.
> Try this one out;  it is very difficult to isolate the wall from the frame
> as I said before.  
> Rodrigo Lema.