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Plastic Moment

Plastic Moment

Plastic Moment

(OP)
Hi,
How do I find the column shear that corresponds to a full plastic moment developed in a column assuming the column is fixed at top and bottom? My column is a W 8x21.
Thanks.

RE: Plastic Moment

Not completely sure that I understand your question, but there is no general direct relationship between moment and shear. You can have high shear and low moment, and vice versa.

RE: Plastic Moment

Not sure what you're after... but in the absence of any external forces along the member V = (M1 + M2)/L or it sounds like in your case V = 2Mp/L

Column being fixed is irrelevant if you are already assuming a full plastic moment.

RE: Plastic Moment

Not sure that a W8x21 is a class 1 Section.

Dik

RE: Plastic Moment

do you mean you have a doubly cantilevered beam with a point load applied (= shear) ?

or do you have a column, fixed both ends, with both axial and transverse (= shear ?) loads ? ie beam-column

both cases are available in Roark, etc.

i gather from Dik's post that this section may not be stable in compression (class 1 = stable in compression) so crippling of the compression flange might be the critical compression stress.

Quando Omni Flunkus Moritati

RE: Plastic Moment

W8x21 is equivalent to metric W200x31 and is a Class 1 section for Fy = 350MPa or 50ksi.

A column fixed top and bottom subjected to a normal force applied at mid-height would require force P where PL/8 = Mp or P = 8Mp/L in which case shear = P/2 = 4Mp/L.

A column fixed at the bottom and free to translate but not to rotate at the top would require a shear of 2Mp/L to produce plasticity at each end (same as bookowski).

BA

RE: Plastic Moment

Thanks BA...

Dik

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