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Re: Dead Load or Live Load?

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Isn't Cd = 0.9 for permanent dead load?  If these panels are going to be on
the roof permanently, Cd=0.9 would be more appropriate (combined with other
dead load only).  We also consider roof live load in these parts as snow,
sometimes in much greater magnitude than 20 psf (like 100 psf & up for Park
City), and Cd=1.0 because it sticks around longer than Cd=1.15 allows.

Conrad Guymon, P.E.

----- Original Message -----
From: "Peder Golberg" <peder(--nospam--at)jgpierson.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, November 21, 2001 3:13 PM
Subject: Re: Dead Load or Live Load?


> I haven't heard about the building type but if it is wood framing, this
> would considered a dead load based on duration of load with Cd = 1.
>
> We consider mechanical units as dead load.   If they change out the units
> 10+ years to something heavier, the framing gets reanalyzed for the
> increased loads.
>
> What about roofing material weights?  dead load
> The 2nd layer of roofing material?  These items are also stripped off
after
> 10 years or so.
>
> All of the above weights are used in the seismic calculations.
> Collateral load is probably a better definition and these loads are
treated
> as dead load (except uplift)
>
> Up here, we consider Roof live load as a thing called SNOW (>20 psf) that
> will fall right on top of the panels.
>
> Peder Golberg
> Portland, OR
>
> ----- Original Message -----
> From: "Bill Polhemus" <bill(--nospam--at)polhemus.cc>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Wednesday, November 21, 2001 1:47 PM
> Subject: RE: Dead Load or Live Load?
>
>
> > Okay, let's look at the other side of the argument.
> >
> > Say the "whackos" win and we have to depend even MORE on solar panels as
> > they mothball all remaining electric plants.
> >
> > Now, suddenly, you as the building owner decide you need BIGGER solar
> > panels. So you arrange to have 'em installed, knowing as you do that
> > "engineers always design conservatively anyway." Now, your "static dead
> > load" has just increased by 50%.
> >
> > When I was doing plant work, we considered ALL equipment, even if it was
> > "fixed," to be live loads for design of buildings, etc. We knew the
> > equipment was "here today, gone tomorrow," likely with something even
> bigger
> > to take its place.
> >
> > So, anything that isn't part of the structure itself, or the function
> > thereof, is "live load."
> >
> >
> >
> >
> > William L. Polhemus, Jr. P.E.
> > Polhemus Engineering Company
> > Katy, TX, USA
> > Phone (281) 492-2251
> > FAX (281) 492-8203
> > email bill(--nospam--at)polhemus.cc
> >
> > -----Original Message-----
> > From: Amy Ellis [mailto:EllisAL(--nospam--at)c-b.com]
> > Sent: Wednesday, November 21, 2001 3:01 PM
> > To: seaint(--nospam--at)seaint.org
> > Subject: RE: Dead Load or Live Load?
> >
> > The definition of dead load is the weight of the structure itself and
> > "permanent" attachments.  We consider floor coverings and roof
coverings,
> > which can be removed to be dead load so why wouldn't we consider
> "permanent"
> > solar panels to be dead loads.  The solar panels are static loads that
> don't
> > vary in weight or location. Sounds like a dead load to me - no matter
what
> > the "environmental whackos" decide.
> >
> >
> >
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