# Math Help - Shigleys Indeterminate Beam Derivation

1. ## Shigleys Indeterminate Beam Derivation

Folks,

I am having difficulty deriving the moment expressions for a rigidly supported beam fixed at either ends and subjected to a point load as shown in the attachment.

The problem is that I want to derive the left hand fixing moment $M_1$ and $M_{ab}$ as in Shigleys. However, I believe my attempts are not leading to these expressions by shigley (engineering book).

My derivations are based on the free body diagram as attached with clockwise moments positive.

$M_{xx}=E*I \frac{d^2 y}{dx^2}$

Taking moments about the section yields

$M_{xx}+R_1 x-F(x-a)-M_1=0 \implies M_{xx} = F(x-a)+M_1-R_1 x$

Subjecting this to the curvature realtion and integrating twice will not lead me to the equations for $M_1$ and $M_{ab}$

Any ideas?

Thanks
bugatti

Please note that I have posted this at physics forum Shigleys Indeterminate Beam Derivation

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