AISC Design Guide 24 2

[2457F]

Can someone please explain why on page 51, figure 5-5 (of AISC Design Guide 24)shows Mr = (P x e)/2? Why are they dividing by 2?

 

[Lion06]

Because the e for each individual P is e/2.

Instead of thinking of it the way they show it, think about it the way I show in the attached sketch.

You can quickly see that the e for a single P is e/2. The e for the moment is the e to the centroid, not the e to the opposing P.

 

[2457F]

Thanks. That helps.

 

[nutte]

The support on the left end is fixed against rotation but allowed to slide up and down. The support on the right end is fixed against rotation and fixed against upward displacement. If you sum moments about the right end, you get:

Mr (at left) + Mr (at right) = P e
2 Mr = P e
Mr = P e / 2