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# Re: Shear center of L-shape beam

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Shear center of L-shape beam
• From: "David Topete" <d.topete73(--nospam--at)gmail.com>
• Date: Wed, 24 Sep 2008 08:18:53 -0700

Shear center for an angle is at the intersection of the horiz and vert legs.  The torsion constant, J, is equal to 1/3 (bt1^3 + ht2^3).  In your case, J = 113,333 in ^4.

On Wed, Sep 24, 2008 at 5:53 AM, Jordan Truesdell, PE wrote:
The reference I just checked (Beer & Johnson 1981), shows a force aligned with the centerline of a leg will produce no torsion. That's as much as they give for an angle. I'm sure someone has a better reference, but that tends to suggest your method makes sense.
`Jordan`

Wontae Kim wrote:
Hi,

I have a question on how to calculate eccentricity for torsion.

Let's take an example.
Here is a precast L-shape beam with web 10"(W)x24"(H) and 10"(w)x10"(h) ledge,
of which area is 340 sq in.
Personally, I used the center line of the web, 5" in this case, to calculate torsion.
I heard tihs approach is conservative.
I know some engineers use the center of mass, 7.94".

Which method is more realistic?
Where is the exact location of shear center in this case to calculate eccentricity?

If anybody knows  formula, please send me.

Thanks!

wontae

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