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RE: Differential temperature effect

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Could you describe what you are designing a bit? Sounds like a silo if you
are using ACI 313. The ACI 313 (Timoshenko) formula only computes flexural
stresses in simple plates. It would seem to me that boundary conditions
might effect your results in a more sophisticated model. Also, temperature
changes induce membrane forces in plates which would also have an impact on
the total force experienced in individual elements. What is the relative
difference in results from your two methods? Which one is giving you bigger
numbers?

-----Original Message-----
From: Bulent Deveci [mailto:bulentdeveci(--nospam--at)superonline.com]
Sent: Thursday, February 27, 2003 9:52 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Differential temperature effect


Lutz,
In ACI 313 clause 4.4.9 states that :
The thermal effects of hot stored materails shall be considered for circular
walls or wall areas with total restraint to warping (as at corners of
rectangular silos), the thermal bending moment per unit of wall height or
width shall be computed by
Mt = Ec*h2*alfa*DeltaT / 12(1-poission)
This is the same formula given by Timoshenko.

But as for Sap2000, there are two options. One "temperature t" which is
constant through the thickness and produces mambrane strains
The second, "temperature gradient t3" which is lineer in the thickness
direction and produces bending strains.
It is obvious that I have to use the second option. But unfortunately, my
results are very far from those I've obtained from the above given formula.





----- Original Message -----
From: "Lutz, James" <James.Lutz(--nospam--at)earthtech.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Thursday, February 27, 2003 7:17 PM
Subject: RE: Differential temperature effect


> I haven't done it, but it looks like it is possible. It wasn't clear if
you
> are just modeling a frame or if there are plate elements involved, but I
> think it will handle it either way. It's a pretty powerful program (once
you
> figure it out.)
>
> I think you may have to create a batch input file since the graphical
users
> interface is limited to more routine kinds of problems as far as data
entry
> goes. If you have already created a basic model using the GUI, you can
dump
> it into a text file and edit it to get the stuff you need in there. CSI's
> manuals aren't the greatest for figuring this stuff out. Good luck.
>
> -----Original Message-----
> From: Bulent Deveci [mailto:bulentdeveci(--nospam--at)superonline.com]
> Sent: Thursday, February 27, 2003 8:26 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Differential temperature effect
>
>
> List,
> Does anyone of you have any experience in designing a reinforced concrete
> structure
> having differential thermal conditions with SAP2000 software? I'm just
> trying to design a complicated RC structure with nearly 300 C differential
> temperature and I don't have the chance of insulating it due to the
process
> of the structure.
> I have tried to obtain the bending moments by means of SAP2000 software
but
> I'm not able to satisfy the results given in some text books such as
"theory
> of elasticity" by Timoshenko.
>
> Any comment would be appreciated.
>
> Bulent Deveci
>
>
>
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