Buying a Replacement Steel Manual

[DaveAtkins]

Like many of you, I design steel using ASD. I am still using my green ASD manual, which is 16 years old, and is starting to fall apart.
When I heard earlier this year that a new steel manual would come out this year with both LRFD and ASD, I thought, now is a good time to replace my old steel manual.
But further reading (mostly in Modern Steel Construction) has revealed to me that the new manual is not good old fashioned ASD, but a disguised version of LRFD (where you start with LRFD and divide by factors to get ASD).
So I am thinking of buying a new 1989 ASD, instead of the new manual, and continuing to design as I always have. Any opinions?

DaveAtkins

 

[archeng59]

we've had the same discussion in our office because we currently use ASD. we are going to adapt to the new code. don't know if we'll start using LRFD or ASD, but will use the new code. what else to do when AISC and academia are giving us no options?

 

[JAE]

If you use the "old" ASD on a project under more recent building codes, you will not be designing in accordance with the code and thus, technically, violating its provisions.

Now there is always the comment that "I've designed under this ASD for years and never had a structural problem" - but if you ever did have a problem, and a good lawyer found out you were using an old "antiquated" ASD spec, then you would be at a significant disadvantage.

 

[engphila]

JAE,

If the prevailing building code stipulates limit states as a design criteria, like what often occurs overseas, then you may have a valid point. However, IBC permits allowable stress for design.

engphila

 

[JAE]

Yes, it allows ASD, but the actual provisions within, say, the IBC 200x, will refer to the NEW ASD specification. So if you continue to use the 8th or 9th editions, the formulae for member capacities, connections, etc., will NOT be valid under the new code.

The combined ASD/LRFD specification has many sections which are revised and updated, especially the ASD portions as the ASD spec hadn't been updated for many years.

 

[bjb]

We are going to adapt to the new manual when it comes out too, although I will keep my green book around, and will probably look for another one on ebay as mine is falling apart. I can see using the green book to rough out things like crane girders and then checking the size with the new manual. I also plan on programming the equations for unbraced beams into my HP, and also increasing my usage of spreadsheets to deal with what I perceive as the added complexity of the equations. I'm just happy that they kept some form of allowable stress (strength) methodolgy, because I don't like dealing with one set of factored loads for strength, and a set of service loads for deflection.

 

[chichuck]

I've already had that problem with my ASD 9th edition. I went to a local bookbinder and had him put a new binding on it. Even though the binding was shot, the "block" (thats what the bookbinder calls the pages of the book) were still in good shape, so that meant he could put my book into his binding machine & put on a new cover very easily. It was cheap, < $20 per book, and he put on a very sturdy, good looking green binding on my manual. Now, it sits on my bookshelf and many colleagues come in and ask "do you have a green book". Its fun when I finally take it and show them: "....what the...???". That would probably be cheaper than a used one on ebay.

chichuck

 

[bjb]

That's an interesting idea about a new binding, I'll probably look into that. Mine is taped together with packing tape in several locations though. My office has copies of the 6th edition that have stood the test of time better than my green book. AISC probably thought, "we can build them cheap because soon nobody is going to use ASD anymore".

Although I'm going off the original topic of the post, does anyone know if the new manual will be the same size as the old ones, or will it grow to 8.5X11? I seem to remember filling out a survey from AISC where they asked about possible changes to the size of the manual.

Another question is, how many will buy it when it first comes out, versus waiting for a revised manual that catches the inevitable typos.

 

[cap4000]

JAE

My guess is that the 9th edition 1989 ASD version will be typically more conserative than the upcoming combined spec,thus making it structurally impossible and legally difficult (not impossible) to find an engineer at fault for a failure using an older spec. I have seen a recent article regarding a slight increase in unbraced lenghts for beam bending moments in the new ASD. It will be interesting after 16 years to see what changes have actually taken place.

 

[JAE]

cap4000 - I would think you are right that the newer ASD would tend to be less conservative, but unless you check every time for every condition, how would you know?

I've converted to LRFD anyway so I really don't care, but to just keep using the 9th edition blindly could possibly get you in trouble down the road....I was just pointing that out.

 

[chichuck]

you know, the new combined spec is available for download from the AISC website. You can get that to see what the changes are.

I did, and did some work trying to develop a Mathcad template that calculated combined stresses & interaction ratios for bending/compression in a W-shape. I did not run into any significant changes from the 1989 ASD.

regards,


chichuck

 

[mrMikee]

I’ve gone through the new spec a few times but it is not yet sinking in. However, doesn't the new ASD stand for Allowable Strength Design? Could there be three specs? The old ASD, LRFD, and the new ASD? I'll have to go to the ICC site and look at the 2006 draft.

Just a thought.

Regards,
-Mike