Plastic Section Modulus Calculation

Plastic Section Modulus Calculation

I'm embarrassed to even ask this, but how are the plastic section modulus about the weak axis values calculated in Table 1-16 of the AISC Steel Construction Manual, 14th Ed.?

When I try to recreate these values, I come up with different answers.

For example: the first shape is 2C15x50. I calculated the Zy as…

Zy = 2 * ((dist from PNA to back of channel /2) + xp) * Area

Zy = 2 * ((0, 0.375, 0.75)/2 + 0.49") * 14.7 in2

Z.y = 14.41 in3, 19.92 in3, 25.43 in2 for each spacing, respectively.

However, the values shown in the table are 23.5 in3, 29.0 in3, 34.5 in3 for each spacing, respectively.

I know there must be a simple answer to this, but I'm at a loss.


Submitted June 21, 2017 at 11:37AM by BACON_LASER
via reddit

Plastic Section Modulus Calculation

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