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Re: wood frame bldg deformation and windows

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This is not entirely correct.  If you design a structure that is so loose
that it requires a caulk joint between a wall and window system that exceeds
(min. and max.) what the caulking manufacturer can warranty, you have a huge
problem on your hands.  Your drift has to be within the serviceable limits
of the curtain wall system being used.  You obviously must know what the
curtain wall system is since you had to account for it in the seismic
weight.

As part of the design team, it is our responsibility to explain to the
Architect/Owner the trade off between reduced steel tonnage (as say in a
steel frame situation) and taking the drift to the absolute limit and
potential effects on the curtain wall system and their bids.  I have been on
both sides.  On the one hand, you may sell your engineering prowess by being
able to produce a structure that yields less tonnage than your competitor,
but have to go back and stiffen your design because the precast/curtain
wall/glazing and caulking systems have tolerances that cannot accommodate
your design.  Or, there bids come in much higher than budgeted and everyone
is pointing the proverbial finger at the engineer.

But on a wood shear wall system!  Come on!

Keith De Lapp, P.E.
KDL Engineering


----- Original Message -----
From: Gerard Madden <gmadden(--nospam--at)duquette-eng.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, January 08, 2002 5:16 PM
Subject: RE: wood frame bldg deformation and windows


> Regis,
>
> I think what Conrad is saying that it is our responsibility as engineers
to
> comply with the drift provisions of the code - this is also true for the
> window contractor. It is not our responsibility to figure this out for
them
> (unless specifically retained to do so) and the architect should be
spec.'n
> a system or window frame design that can allow movement - in plane and out
> of plane if they want to avoid non-life safety damage.
>
> -gerard
> SF, CA
>
>
>
> -----Original Message-----
> From: Regis King [mailto:steelfishes(--nospam--at)hotmail.com]
> Sent: Tuesday, January 08, 2002 4:43 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: wood frame bldg deformation and windows
>
>
> You think non-conformance with the building code is a "non-issue"?  Seems
a
> little cavalier to me.  I'm sure the difference between 2x and 3x plates
is
> also a bit of a "non-issue", but you won't soon forget the experience of
> inadvertantly specifying 2x plates in a high-seismic area, believe me.
>
> Regis
>
>
> >From: "Conrad Guymon" <conrad(--nospam--at)karren.com>
> >Reply-To: <seaint(--nospam--at)seaint.org>
> >To: <seaint(--nospam--at)seaint.org>
> >Subject: Re: wood frame bldg deformation and windows
> >Date: Tue, 8 Jan 2002 15:35:49 -0700
> >
> >Are the windows the full story height?   If they are not, would it be
> >appropriate to use (window height/story height)*Delta M to obtain the
drift
> >differential between the bottom and top of the window?  Would this reduce
> >the value to something you could handle?  Do you have drift calculations
on
> >the wood shear walls?
> >
> >It sure seems like this is a non-issue.
> >
> >That's my two cents worth.
> >
> >Conrad
> >----- Original Message -----
> >From: "regis king" <steelfishez(--nospam--at)hotmail.com>
> >To: <seaint(--nospam--at)seaint.org>
> >Sent: Tuesday, January 08, 2002 4:42 PM
> >Subject: wood frame bldg deformation and windows
> >
> >
> > > Have any of the list members had to address the effect of seismic
drift
> >on
> > > the windows of a wood frame apartment building? I am not referring to
a
> > > large retail window wall system, but rather typical residential
windows.
> >UBC
> > > 1633.2.4.2 includes "elements that are attached to or enclose the
> >exterior".
> > > Most vinyl windows are attached with vinyl flanges on the outside. I
> >believe
> > > that the vinyl itself has some inherent flexibility, but this is
> >obviously
> > > difficult to quantify. I know that slotted holes can be used. However,
> >the
> > > slotted holes are not likely long enough to meet the code requirements
> >if
> >a
> > > residential window is included in UBC 1633.2.4.2. Note that this same
> > > section requires the greater of Delta M or 0.5 inches. The slot would
> >have
> > > to be 1" + the width of the screw to qualify. I have never addressed
> >this
> > > issue and it has been brought up on one of my jobs.
> > >
> > > Thanks in advance for any help.
> > >
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