AISC 15th Ed. vs. 14th Edition 2

[Charred]

Can anybody provide a reference for an article or webinar that gives a comparison between the AISC 15th Ed. (blue) and 14th Ed. (maroon)? I know there were some major items that changed such as the HSS yield strength in the tables, but what about the overall content? Is it the same or are there a lot of smaller things that have changed too? Same questions for the 2nd & 3rd editions of the AISC seismic manual.

 

[jdonville]

HSS yield changed because they went from assuming A500B to A1085 due to the latter's increasing availability from AISC mills. You need to be careful with using the increased HSS yield strengths. AISC put on a webinar to discuss the new manual. Maybe it's available through the aisc.org website?

 

[dik]

It was...

Dik

 

[JoshPlumSE]

Lou Geshwindner has given a number of presentations on the subject:

http://web.engr.oregonstate.edu/~liujud/2017 StrCong Part1.pdf

The above link has some nice charts which show some differences in capacities based on the various specs.

 

[dauwerda]

HSS yield changed because they went from assuming A500B to A1085 due to the latter's increasing availability from AISC mills. You need to be careful with using the increased HSS yield strengths.

This is not correct. They went from A500 Grade B to A500 Grade C. If/when the HSS tables move to A1085 the design wall thicknesses will no longer be 93% of nominal and we will see even more strength (Also round HSS will go from 46ksi to 50 ksi).

Not sure why you need to be careful - HSS has been supplied as dual certified as Grade B and Grade C for quite a few years now, there shouldn't be any issues with sourcing A500 Grade C.

 

[Charred]

This is not correct. They went from A500 Grade B to A500 Grade C. If/when the HSS tables move to A1085 the design wall thicknesses will no longer be 93% of nominal and we will see even more strength (Also round HSS will go from 46ksi to 50 ksi).

Not sure why you need to be careful - HSS has been supplied as dual certified as Grade B and Grade C for quite a few years now, there shouldn't be any issues with sourcing A500 Grade C.

Agreed.

 

[Charred]

Main reason for me asking is the SE Exam is still under the 14th Edition (Manual) & 2nd Edition (Seismic).

I have been asked if it would be acceptable to use the new 15th instead of having to buy the 14th. My initial response was no - always use the standard the exam references. But other than the high points (a few noted above), what really does change from edition to edition? Are there enough small factors/equations that have changed to really constitute a pass/fail? The bigger items that have changed (HSS for example) can be noted and known by the user for the exam.

 

[sbisteel]

The tube yield strength change is due to the fact that A500 Grade C is equally as common as A500 Grade B, to the point that pretty much every tube out there is "dual certified" to meet the requirements of both. A500 Grade C is now shown as the preferred material in table 2-4. A1085 comes at a premium, and at least in my part of the world is still not a regularly used grade.

There are a lot of very small changes to flexure and compression checks for non-compact and slender elements. Single angle bending has been modified in chapter F as well.

There also has been some moving around of the HSS failure modes from chapter K into chapter J.

Some dimensions, mainly the fillet stuff (K1, K, and T) for WF shapes have been changed a bit to match current rolling practices.


Haven't even gotten into the seismic manual yet, myself.

 

[DrZoidberWoop]

The updates I've appreciated the most are on pages 9-14 and 10-153. They both provide guidance on connections to out-of-plane loads to plate elements and HSS walls. Also, for bolts w/ 1" diameter and above, the standard and over-sized holes have increased by 1/16", per Table J3.3. Other than that, I haven't changed the way I operate much since 14th edition.

 

[dauwerda]

I recently passed the SE exam and was initially studying using the 15th edition (mainly because I had it all tabbed out much better than my 14th edition) - I found that there were enough little changes (while working example problems) that I decided it would be best to use the correct edition (for both the SCM and the SDM). You could probably do it with the 15th edition, but it wasn't a risk I was willing to take.

I know that Ry's changed for some materials in the seismic manual.

 

[phamENG]

Another thing to be mindful of - they're pushing designers more and more toward the direct analysis method for stability in the 15th. Gone are the K factors from buckling equations in chapter E.

 

[jdonville]

Thanks to above responders for clarifying the HSS issue. I responded without checking my Manual.

@phamENG: k-factors are still in the Commentary, but yes.

 

[phamENG]

jdonville - yes, they are. Slowly phasing them out. I read somewhere that the intent is to remove them entirely in the next 1 to 2 revision cycles.

 

[KootK]

Are there enough small factors/equations that have changed to really constitute a pass/fail?

For me the answer would be no. The stuff that you'd need the manual for tends to also be stuff that isn't changing quickly (tabulated bolt capacities etc). I've done steel design on four separate exams now. For three of them, I used incorrect versions of the manual and, to my knowledge, didn't lose a single point on account of that. For one exam, I forgot my steel manual but did have the Structural Engineering Reference Manual. I tanked a couple of points as a result because I attempted something by hand that would have been much faster using values tabulated in the manual.

You'll have to decide for yourself. If you think that you'll be cutting it so close that you couldn't afford to miss a point or two, get the older manual. Otherwise, I feel that the newer manual would be a better investment. Just imagine if you fail and then require the newer manual for the next round after procuring the older one? That would suck.

- Nobody around with the older manuals that you could borrow from?

- Obviously, you could very easily print off the older specifications for free and inoculate yourself a bit that way.

 

[dauwerda]

I actually just remembered what the red flag for me was. It was prying action per chapter 9 of the SCM. In the 14th edition the tributary length, p is taken as 2b (45 deg angle). In the 15th edition it is taken as 3.5b (or even larger). I don't know how many subtle changes like this may have been made, and rather go through and try to find them all, I decided to go with the 14th edition (although I did not need to purchase a new one).

 

[EDub24]

Can you borrow the 14th edition or buy a cheap used copy? Maybe check with some bridge engineers who passed the SE exam and want to sell their steel code? Either way it’s best to have the referenced code. With the amount of time and money you put into this exam you shouldn’t take any chances.

 

[phamENG]

Here's another way of looking at it: how much of a pay raise can you expect after you pass your exam? With the bump I got, I think I would have considered purchasing three full sets of all the references a worthwhile investment (looking at a year over year return, of course).

Though of course, get them cheap/free if you can!