Leaming Goal:

In a coplanar structure. the internal loading at a point is composed of a normal force $N$ a shear force $V,$ and a bending moment $M$ These intemat loads can be determined by analyzing intemal sign conventions and apphing equilibrium conditions using the following process

Deternine the support reactions for the entire structure

$2$ Keep all loadings exactly as they are specifed and pass an imaginary section through the member at the point where the internal toading is to be determined

Draw a free$-$body diagram of the segment with the least number of loads. Al the section, indicats the uninown forces $N$ and $V$ and moment $M$ acting in their positive directions $($descibed below$)$

$4$ Use the equations of equilibrium for the segment to solve for unknowns.

For the left$-$hand segment, the sign convention for internal loadings is as follows the nomal force $N$ acts to the right, the shear force $V$ acts dowmward, and the moment $M$ acts counterclockwise. $($Figure $1)$

Figure

$3$ of $4$

Part C $-$ Intemal normal force

The cantilever beam $($Figure $4)$ is subject to loads $P_1=24kN,P_2=12kN$ as shown. What is the intemal normal force at point $B?$ Use the standard sign comvention given in the Introduction.

Express your answer with appropriate units to three significant figures.

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