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RE: tilt-up concrete walls

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I've never seen the distrubution done any way except based on the inertia of the piers. I am unfamiliar with chord bars between the panels as I have always used a continuous angle (an L4x4x1/4 or something like that) as the chord for tilt.



Will Haynes, P.E.




From: "Bill Allen, S.E." <T.W.Allen(--nospam--at)cox.net>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: RE: tilt-up concrete walls
Date: Fri, 4 Feb 2005 15:22:50 -0800

Paul -



There are two schools of thought here.



Some believe that the stretching of the chord bars (particularly if they are
unbonded for some distance away from the end of the panel) between the
panels negate the distribution according to stiffness approach.



I'm not saying which is right or which is wrong, but I know a lot of people
on either side of the fence on this issue.



I think good judgment is required in any approach when substituting a
mathematical model for reality.



Regards,




T. William (Bill) Allen, S.E. (CA #2607)


ALLEN DESIGNS


Consulting Structural Engineers


 <http://www.allendesigns.com/> http://www.AllenDesigns.com


V (949) 248-8588

.

F (949) 209-2509



-----Original Message-----
From: Paul Feather [mailto:pfeather(--nospam--at)SE-Solutions.net]
Sent: Friday, February 04, 2005 2:32 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: tilt-up concrete walls



You need to distribute the shear based on relative rigidity of the wall
panels.  The continuous chord reinf is also a contributing drag element for
distribution of the diaphragm shear to the panels. Each panel will have a
relative rigidity, and then the individual piers within each panel.



If the panels are "reasonably" different, there is no valid justification
for assuming things will be evenly distributed. Relative rigidity
distribution will be more accurate and proper.  For the even distribution
idea to be valid, each panel would have to be able to deflect independently
along the diaphragm length with local deformation of the diaphragm and the
chord.



Paul

----- Original Message -----

From: Chris Campbell <mailto:ccampbell(--nospam--at)ofainc.net>

To: seaint(--nospam--at)seaint.org

Sent: Friday, February 04, 2005 11:25 AM

Subject: tilt-up concrete walls



I have what I think would be an interesting question.



I have a tilt-up project that I'm working on.  So far, it's going pretty
well - but I realized that I wasn't sure about distributing the in plane
shears in the wall panels.  The panels are 22' tall with the roof diaphragm
at roughly 19' (it varies with drainage).  At the plane of the roof
diaphragm the panels are solid (no major openings) but the openings for the
doors (which vary from 10' to 12') are placed such that each of the wall
panels is "reasonably" different.  In other words, the openings are of
differing heights and occur in different locations in each of the panels.
From the main elevation, the openings appear to be centered equally, but
when you figure out where the panel joints are located, the openings are NOT
in the same location for each panel.



I had two thoughts.  One was that since the panels at the height of the
diaphragm were solid and each virtually identical in length, the in plane
shear would be distributed equally.  The other thought was that I should
really think to distribute the shears based on the wall widths at the
openings.



Obviously the first method would be (much) simpler but I wasn't sure that
the second method would be much more accurate, if at all.  Any advice?







Thanks.



Chris!!





=================================
Christopher S. Campbell
O'Connor Freeman & Assoc., Inc.

916.441.5721     fax 916.441.5697



"They're only mad at me because I'm right"

=================================






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