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Re: 97 ubc section 1630.8.2.1

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FEMA 273 has some suggested values for the ultimate strength of structural panel shear walls.  They are in Table 8-3 on page 8-20.   Don't know how accurate the values are or where they come from though.
 
Russell Berkowitz
 
Forell / Elsesser Engineers
----- Original Message -----
Sent: Thursday, March 15, 2001 5:45 PM
Subject: RE: 97 ubc section 1630.8.2.1

I'm not fully sure I understood the problem, but from the gist of it it appears that you need to transfer the compression and tension from the shearwall into the beam which will transfer the resulting moment (the couple created by each end of the shearwall) into each end of the beam.
There are a couple of issues:
  1. Designing the beam for the moment which would be the reactions times the distance between them.
  2. Insure that the uplift and compression are designed into the beam to avoid crushing from either the topside or the bottom of the beam (assuming that uplift if large enough might be restrained by a threaded rod and flat plate connection to the beam).
  3. Finally, how will you transfer the shear from the base of the wall to the next nearest lateral resisting element?
    1. would you do this by tying the ends of the beam to a cantilevered column at each end?
    2. Would you use the diaphragm below the wall to transfer shear to an adjacent wall line?
If I recall, there was a similar problem presented in the ICBO Seismic Design Manual Volume II for one of the Wood Design problems that either Bill Nelson or Doug Thompson had developed. You might check to see how they resolved the loads down to the foundation.
 
I would be very hesitant to try and load up the upper wall as it will create a larger problem trying to transfer the horizontal shear down through the diaphragm. But this would mean that you would need to use other walls to redistribute the forces and this does not even consider the Rigid Analysis.
 
The maximum value you can use for the shearwalls will be the table values, but I would check with APA to see if there are any publications that address this condition where walls are not stacked.
 
I'd be interested to see how others would handle this issue as well.
 
Dennis
-----Original Message-----
From: D.A. [mailto:dnae(--nospam--at)home.com]
Sent: Thursday, March 15, 2001 3:55 PM
To: seaint(--nospam--at)seaint.org
Subject: 97 ubc section 1630.8.2.1

 
Hi everyone
 
I'm trying to design wood beam under shear wall
by Applying section 1630.8.2.1
 
my question is
 
what the max. force can  be used for shear wall  to calculate
the uplift If I used 2.8 the force will exceed the shear wall capacity
and there is no publication to find the max. force can be transferred by the
shear wall
 
can I take the capacity of shear wall tables as max. force ?
 
thanks in advance for your input
 
 
D.A.