Chapter 6: AISC 13th Edition 1

[bootlegend]

I just now noticed this chapter and the tables for combined loading.
Does anyone actually use it? How can it be a simplification/"design aid" of Ch. H?
I thought Spec. Ch. H was about as simple as it gets. Am I just totally missing the benefit of CH 6?

 

[Lion06]

I've never used it, and I'm not sure I would. I haven't looked at it to examine it, though.

 

[271828]

I've tried using it, but find it to be more trouble than it's worth. By the time I refresh my memory on how it works, I'd be better off using beam and column tables plus the Ch. H equations to do the job.

The first time I saw those, my impression was that they were a total waste of space. After trying to use them, I still think that. I've heard them praised by a couple of the higher up AISC guys, so I'm sure they're not going anywhere.

 

[WillisV]

I use them all the time - but maybe not quite as intended. There are incredibly useful in my opinion in two ways.

1. To get an exact value of the moment strength of a beam at a certain unbraced length in lieu of trying to follow it through the Chapter 3 unbraced length graphs.

2. To get compression strength values for members that are not generally in the Chapter 4 column tables.

Examples:

1. Find PhiMn of W21x44 with 20' unbraced length:

PhiMn = (8/9)*(1/the bx value in the Chapter 6 Tables). From p6-49, bx = 8.46*10^-3. So (8/9)*(1/0.00846) = 105ft-k

2. Find the axial strength of a W18x40 unbraced for 15' in both directions.

PhiPn = (1/the p value in the Chapter 6 tables).
From p6-57, p=7.56*10^-3. So (1/0.00756) = 132.3kips.