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# Re: Which method do you like for calculating deflection

• To: seaint-seaosc(--nospam--at)mail-list.com
• Subject: Re: Which method do you like for calculating deflection
• From: TJ Fu <tzujfu(--nospam--at)gmail.com>
• Date: Mon, 11 Mar 2013 18:21:49 -0400
• List-subscribe: <mailto:SEAINT-SEAOSC-on@mail-list.com>

```Yes, it is the Conjugate Beam Method.

1.     For example: 100' - 150' - 200' spans

2.     The moments: 1st interior = 500'k and 2nd interior support = 1000'k

3.     Span 1 (100') Deflection due to 500'k moment

·         Convert span into a Conjugate Beam

·         Simple support still simple support (our case)

·         Fixed end becomes free end

·         Free end become fixed end

·         Apply M/EI diagram on span --> a triangular load with M/EI at
right support and 0'k at left support, M=500'k

·         Consider span 1 as the Conjugate Beam, the total fictious load
is (M/EI)xL/2, L=100'

·         The reactions at the ends of the conjugate beam are thus ML/6EI
and ML/3EI

·         The moment at any point from that M/EI load will be the
deflection at that point

4.     Span 2 (150') Deflection

·         Same as span 1, you just apply one moment, one at a time

·         Apply 500'k first

·         Then apply 1000'k next

·         Add these two deflections up

5.     Span 3 (200') similar to Span 1.
TJ

On Mon, Mar 11, 2013 at 5:01 PM, Effland, Greg <
Greg.Effland(--nospam--at)bluescopebuildingsna.com> wrote:

> Isn't this M/EI approach the Conjugate Beam Method?  [Note changing Real
> Supports to Conjugate Supports in analysis]
>
> Greg
>
> -----Original Message-----
> From: seaint-seaosc(--nospam--at)mail-list.com [mailto:seaint-seaosc(--nospam--at)mail-list.com] On
> Behalf Of T. William (Bill) Allen, S.E. Sent: Monday, March 11, 2013 2:55
> PM To: seaint-seaosc(--nospam--at)mail-list.com
> Subject: RE: [SEAINT-SEAOSC] Which method do you like for calculating
> deflection
>
> TJ -
>
> Sounds too simple and easy!
>
> :o)
>
> Can you explain the approach? How does it account for boundary
> conditions?

Truncated 417 characters in the previous message to save energy.

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