jp99
Mechanical
- Dec 19, 2007
- 10
I have a question about applying ASD 9th Chapter H, combined axial and bending.
There is a factor accounting for the end moments, Cm, and the code states that Cm should be .85 for members restrained against rotation. I have a tubular member full penetration welded to a larger chord, so that seems correct.
But the code also states that Cm can be calculated from:
.6-.4M1/M2
When I calculate this factor using my end moments, which place the member in reverse curvature, I am obtaining Cm values much smaller than .85, around .2 to .5 depending on the values of the end moments. This doesn't seem right.
Does anyone have any insight into this calculation?
There is a factor accounting for the end moments, Cm, and the code states that Cm should be .85 for members restrained against rotation. I have a tubular member full penetration welded to a larger chord, so that seems correct.
But the code also states that Cm can be calculated from:
.6-.4M1/M2
When I calculate this factor using my end moments, which place the member in reverse curvature, I am obtaining Cm values much smaller than .85, around .2 to .5 depending on the values of the end moments. This doesn't seem right.
Does anyone have any insight into this calculation?
