×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?
4

Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

(OP)
Hello,

I am a mechanical engineer. I have been designing industrial equipment for the past eight years. I am somewhat of a reference book junky and I recently purchased the AISC STEEL CONSTRUCTION MANUAL (14th Edition). This book seems very useful, but it also seems like it might be over my head. On occasion, I need to design service platforms for our equipment. I thought this book might help me do a better job.

So here’s my question:

Is this book something that a mechanical engineer should be able to use; with a reasonable learning curve? Or, is this book very specialized and only useful to hardcore structural engineers? Right now, I am completely clueless. I don’t know anything about LRFD, ASD, etc. Also, I am worried this book will require the reference of other AISC standards. I don’t have an AISC membership and I don’t plan to buy any more structural reference books. If this book isn’t as complicated as it looks, does anyone have any advice on how to get up to speed quickly (i.e. how to learn the basic concepts, so I can take advantage of the various tables and formulas)?

Thank you for your help everyone!

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

It's very complicated to apply the specification direct from scratch. I've been doing steel design for 35 years and the code seems to have added a lot of new slenderness and other checks. Most of us use the tables, charts or other design tools as much as we can. These have accounted for almost all the oddball rules.
ASD is Allowable Stress Design (loads without load factors) and LRFD is Load Resistance Factor Design (loads with factors depending on their predictability and likelihood). They had to include both methods to get the old hardheads (like me) to use the "new" "improved" specification.
But I would be hesitant to cut you loose to use the tables. You need ASCE 7-10 to get the load factors and combinations. And interpreting bracing and fixities can be tricky. Even beam length can be misinterpreted. It's not of matter of other AISC Standards (thank god, they're all pretty much included, except seismic), but the nuances.
It's gotten more complicated, but luckily I've grown up with it.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Coming from scratch I can see how it would be a daunting task starting from scratch but once you get used to it, it's really not that bad.

If you are designing platforms now what code are you using? If you are in the US and you are using steel I would hope it would be the AISC.

As JedClampett points out, most designers use tables and charts located within the book or simple spreadsheets that were created using the specification. The specification is only about 200 pages or so w/o the commentary. Most of the other pages in the book are tables and charts that were derived from the specification. Most people warn about using the tables and charts w/o knowing how to calculate the values within the charts.

If you need to use the book on a regular basis to do you work, I would suggest looking into a steel design class at a local university. There they will show you the basics of designing steel members which would make using the book that much easier.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

In lieu of taking a class in steel design, you might want to purchase a good book on structural steel design. I found several on Amazon. Make sure the book you buy is written for AISC 360-10 (the latest steel specification - the one that is in the 14th Edition Manual that you purchased). Perhaps someone can give you a specific recommendation. Structural Steel Design (5th Edition)by McCormac & Csernak looks pretty good. The four general topics that you need to learn about are, beams, columns, stability and connections. (There are other steel design topics, but those are the primary ones.)

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Steel Structures - Design and Behaviour by Salmon is a good book. I saw it online in a bunch of places for <50$. I have the fifth edition but I'm sure a 4th edition wouldn't be much different and a lot cheaper.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

It's funny that you ask. I'm currently in the middle of the AISC Webinar called "Basic Steel Design - A Review of the Principles of Steel Design According to ANSI/AISC 360-10." It's eight 1 1/2 hour sessions. I can't imagine someone without a pretty sophisticated knowledge of the code sitting through this course. And this is just a refresher to bring the new aspects of the code to light.
Anyone else out there taking this course? In general I like it, but the sessions tend to get rushed, especially at the end of each one.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

(OP)
Thanks for the helpful responses guys!

It sounds like this is more demanding than “Machinery’s Handbook,” for example. As suggested, I will pick up an introductory structural steel design book. Unfortunately, this is a very small part of what my company does, so I doubt they would ever send me to classes.

Just so you know where I’m coming from, let me further clarify my situation. We are small OEM. Our equipment is very large and requires service platforms. Most of the time, we only create a platform layout and have an outside vendor do the detailed design and manufacturing work. However, these vendors are usually overseas (i.e. low cost) and I doubt they are familiar with AISC codes. They barely seem familiar with OSHA standards. In any event, the final product does pass the smell test (members look too heavy if anything), so we seem to leave it at that. I don’t really agree with this system, but I am low in the hierarchy and it is the way our company chooses to do things.

We have a small engineering department and we design equipment that requires a wide range of engineering skills. It’s a tough environment to work in because you never feel like you know what you are doing, but you have to find ways to make decisions and move on. I sense this is common at small companies.

In any event, my goal is to gain some basic structural design skills. Partially for personal development and partially to help me create more accurate platform layouts and help me better evaluate our vendor’s designs. Also, I have seen us take on large support structures in the past. These somewhat blur the line between mechanical and structural engineering. I believe these were analyzed with basic stress formulas and FEA (i.e. no AISC codes). Therefore, I thought some basic structural knowledge would be useful in case I get a similar project in the future.

Thanks again for discussing this topic with me.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I recommend Structural Steel Design (either ASD or LRFD) by McCormac. You can get used copies of past editions for about $2 on Amazon.com. The code references in them are not current, but you can get the introduction to the material that you are seeking for a competitive price and McCormac is very easy to read.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I work in a firm that has both structural engineers and mechanical engineers. Occasionally a mechanical engineer tries to do my job and I cringe when I see their designs, mainly for the following reasons:

1- They seem to think almost everything is a moment connection.
2- They completely ignore the stability provisions in the code.
3- They don't know how to properly apply load combinations.
4- They don't use industry standard connections.
5- They don't consider vertical AND lateral load paths.
6- They are unaware of ASCE 7's existence.

A manual might help you with a few of these items, but it's not a substitute for experience. If you want to design anything structural, a good place to test your "basic" ability is on the Civil/Structural PE exam. If you can pass that, you're might be competent. If not, you shouldn't practice structural engineering at all. It's outside your area of expertise.

I've been out of college and in the field now for 7 years, designing steel the whole time (working under several experienced SE's). I took several advanced steel design courses as part of my master's degree. I wouldn't dare say I had a "basic" understanding of steel design until about 3 years ago.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I agree with DCBII. There is way too much to consider and way too much at risk for a non-structural engineer to design even a basic system like a platform or a catwalk. I mean, I could probably fake my way through ASHRAE by applying the formulas in the manual, but the end result would likely be something that a practicing mechanical engineer would find to be non-standard and all wrong.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

(OP)
Thank you for the additional responses.

I appreciate the reality check from you guys. I kind of sensed that mechanical engineers have no business designing platforms. Unfortunately, management thinks we should be able to design anything mechanical. Regardless, I’ll be sure to avoid overextending myself on future projects (even if that involves speaking up). Proper structural engineering is clearly over my head. I should have figured as much. After all, structural engineering is its own separate field.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Quote (curiousmechanical )

Unfortunately, management thinks we should be able to design anything mechanical.

And maybe you can- mechanical that is. But I don't consider most structures to be mechanical. If my stuff is moving, I am in trouble!

The value of a modern engineer is in our high degree of specialization. How complicated could machines and structures and electrical systems be if we (engineers) all tried to do it all? Not very I figure. I call myself a structural engineer but there are numerous materials and systems that I am unfamiliar with, many things I would not be comfortable designing. Nothing to be ashamed of, we just all have our own specialties and experiences. It's the old "Jack of all trades, master of none" saying....

I would suggest finding a local structural engineer to work with when you need, one who is proficient in steel design. I have done quite a bit of this type of work for steel fabricators including equipment supports and platforms, and the fabricators don't assume any unnecessary liability and they don't have the volume for a full time SE. When some tricky aspect comes up in regards to building design or attachment, we can handle it since we have a full range of building and specialty structure design experience.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I started with the 8th edition (red book). The ninth edition (green book & my favorite) didn't change a lot of the technical stuff from the 8th edition but improved the format. Like JedClampett, Never really used LRFD much when it came out and still don't like it. The 13th edition, which combined LRFD and ASD has added a lot to the technical content. IMO, mostly an effort to trim down design. In some cases it may be worth the extra engineering involved, but in some cases not. I'd prefer to the option to still use the old 9th editin.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

To me, more complicated (LRFD) just means more room for mistakes and a need for insurance. I just use ASD too.

Mike McCann
MMC Engineering

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I had been designing with steel since 1974 (back in ASD days). I adopted to LRFD but have always used ASD on occasion, and now I use ASD exclusively because I design mostly wood structures and want to keep my ASD load tallies consistent if I need an occasional steel beam or post.

I have always heard in seminars where LRFD steel design that the LRFD method for steel beams was "calibrated" to result in the same result of beam size as when using ASD (for most commonly used ratios of dead load to live load), HOWEVER the LRFD method results in much shallower and moderately lighter beam sizes, and still be safe...however deflections have to be checked carefully. Also, using LRFD results in slightly smaller column sizes.

It has always been an assumption of mine that LRFD is advantageous in designing large structures, to result in a moderate amount of cost savings due to less total tonnage of steel, and to compete with concrete because concrete design changed much earlier on to the ultimate strength (factored loads) in the 1971 ACI.

However, for designing an occasional service platform, I don't see any inherent advantage to use LRFD; and many handy Excel design spreadsheets offered free on the AISC website are in ASD.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Sorry, I should have checked my previous post


HOWEVER the LRFD method for composite beams results in much shallower and moderately lighter beam sizes

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

So that means there is less additional capacity for future additions too, emparting more expense for any future changes.

Mike McCann
MMC Engineering

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Well, it depends on the situation - if you are in a company that specializes in large structure and you are competing against another firm that proposes to design the same structure in concrete, you definitely would use LRFD in your steel design.

On the other hand, I did a large governmental steel structure back in ASD days and there was no competition - we used 100 psf live everywhere to be safe if there was a remodel of a floor and there were a lot of paper storage files, etc.

Otherwise we would have used the 50 psf "office" live plus 15 psf partition.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Just about everything I design is governed by serviceability requirements - ASD all the way.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

LRFD is good if you have to rationalize an underdesign by another engineer....ASD makes actual sense and is less prone to error. If it ain't broke, don't fix it. Back to the original question....yes, AISC is a pain in the ass and has gotten moreso over the years. Relevant, but a pain.

JAE...where are ya? You LUUUV AISC! lol

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Huh? Oh. Sorry, I've been busy updating my AISC manual via their erratae. That's plural for lots of errata.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I also aggree with Ron...but, unfortunately, the horse is out of the barn...

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Okay, sorry to hijack the thread (or hop on the on going hijacking) but I am going to take exception to the "ASD is so much easier" assertion. At this point in time there are almost no jurisdictions that incorporate the old 9th Edition ASD (two to be specific: Connecticut and USVI) All other US/IBC jurisdictions are either on the 13 Ed. or the 14 Ed, and while these do include ASD provisions it is simply a matter of multiplying by a number less than one verses dividing by a number greater than one. ASD uses the same limit states that LRFD does. Furthermore the "Load combinations defense" (the statement that the load combinations are so much simpler because all factors are one) that I have heard so many times is fallacious. The ASD load combinations are no longer that simple, and the suggested serviceablity combinations are different from both the LRFD and ASD. I will get off my soap box now.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I have on occasion, for the fun of it, compared results with the text book I used in university namely "Steel Construction Manual - 1957 AISC". I bet few have a copy of it in their library. LOL.

It has side tabs to mark the page of key topics.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

How did this discussion go from "I'm a mechanical engineer that is thinking about practicing structural engineering" to "ASD is better than LRFD". I swear every thread heads this direction eventually.

At the risk of drawing criticism; the 9th Edition died a long time ago. It was never meant to handle structures as slender as computer software now allows us to create. The stability provisions were primitive at best. ASD and LRFD are practically identical now. Applying load factors to steel is no more difficult than it ever was applying them to concrete. Move along people... Hyahhh!

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

(OP)
Even though this thread has taken a tangent, I've enjoyed reading the discussion. In the end, I did get what I was looking for. I now understand that structural engineering is for structural engineers. Also, I got a couple book recommendations in case I still want to learn about the subject (just for the sake of educating myself). Thanks guys!

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

DCB..."It was never meant to handle structures as slender as computer software now ALLOWS us to create"....computer software is just another tool....the engineer should be making the final engineering decisions...

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

The code writers are too removed from actual engineering practice. If I'm designing a stair, equipment platform, pipe rack or some other miscellaneous structure, I just want a quick and easy engineering analysis, not something as complex as the 14th edition is now.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Someone mentioned still using ASD. Be prepared for that to go away completely! It is my understanding codes will only have strength design in the near future. Everything will be a strength loads instead of allowable.

I steered away from LRDF for a long time. I have completely made the switch over and I love it. No more converting lateral loads back and forth between strength and allowable levels!

my 0.02.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

The 14th and 15th edition steel manuals include design methods for both ASD and LRFD. However, the 14th edition ASD method is not the same as the 9th edition ASD method. In fact the acronyms are for two different things. The 9th edition ASD refers to "Allowable Stress Design" while the 14th and 15th edition ASD refers to "Allowable Strength Design".

As RobertHale pointed out, the most notable differences between the two methods are 1) the way the loads are derived (according to ASCE 7) and 2) the way that the design/allowable strengths are determined. Calculation of the nominal strengths are similar for both methods. Chapter B, Sections B3.3 (LRFD method) and B3.4 (ASD method) give a brief overview of each method.

namanges

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Bagman...AISC does not apply to stair design. They specifically exclude it from being considered "structural steel"!

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

But I think the point he made still applies. My $.02 worth, at least.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Whoops, Ron, I saw after I posted that I was responding to you. Had I realized that I wouldn't have posted. I like to let my betters have the floor when they're participating in the discussion. Not attempted flattery, just reality.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I also design a lot of platforms for industrial use at my firm. The key to platform design is watching your deflections. The 100psf live load generally makes deflection govern over strength. The problem becomes clear when you walk across platforms designed for strength only- it's like walking across a rope bridge! The other consideration is rotational restraint of the beams that handrails and light fixtures are attached to. Again, platforms typically use light, thin wide flanges or channels and are susceptible to easily rotating- something you can feel while grabbing a handrail. The solution is torsion bracing every so many feet. All non-structural minds at my firm share the same viewpoint that these structures are simple. I do believe most people can design reliably safe platforms without much experience, but they generally are horrible designs in terms of serviceability.

Also- I vote for LRFD. The clear separation between service and ultimate load states does make designs more intuitive. If you do any seismic design you will stay away from ASD at all costs.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Archie264...I agree with you...his point does still apply and I agree with it. I should have said that in my post.
Code writers are not only "removed from engineering practice" ...they are often not engineers or architects. Code writing is a cumulative, political process that often loses sight of the technical need and importance...all for the sake of appeasing those lobbying for a particularly point or relief.

It is not a pretty process and is severely flawed...but it is what we have.

ps, Archie...I don't know any more than anyone else. While I appreciate your compliment, I have to admit that I've only been around long enough to learn a few things, one of which is how little I know. I learn from this site every day and thank those who teach me.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Ron and Archie,
I am curious why you believe that the people who write the code are not engineers. I googled about a dozen names listed on the specification committee at the beginning of AISC 360-10. Maybe half work (or are principles) for consulting firms. The others are professors along with a couple engineers working for federal agencies. I went to the steel conference in St. Louis earlier this year and heard presentations by several of the committee members. They seem to understand the needs of the practicing engineers as well as the needs of fabricators and erectors. Perhaps, there should be "when in doubt make it stout" guide to steel design for those that find the current manual to be too complex.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

Curiousmechanical, good for you for asking the question. It shows you're thinking. With the right guidance you could get the hang of it. A lot of mechanicals aren't even considering that they might not be designing structural systems correctly. Occasionally I'm asked to check a skid design and a trend I've noticed is that folks are using these really cool looking FEA programs that actually mesh the whole skid into a bunch of plate elements. Then all they do is find the maximum stress and say that it's less than the yield strength divided by a factor of safety. No consideration for things like columns buckling (like if they have a platform on legs connected to the skid) or lateral torsional buckling or nothing! It's just plain scary.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

wannabeSE....AISC 360 is not a code...it is a standard. Many standards are written by engineers, including AISC and ASCE 7; however,the building codes are often written by a cross-section of technical and non-technical people.

The standards are not too complex...just a pain in the ass for interpretation and interaction in some instances.

RE: Is the AISC STEEL CONSTRUCTION MANUAL as complicated as it looks?

I use the 14th edition manual exclusively. I have no difficulty keeping up with the pace of other engineers in the office who still use the 9th edition manual. I found that if you take the time to learn and understand it (and the learning curve is steep if you're coming from a spec. that was issued in 1989) it's not hard to apply. Different, absolutely; "removed from practice" no. If anything, it's in touch with the 24 years of computer technology and structural research that has developed since the 9th edition rolled out. It's a spec. for the computer age.

Sail3: I agree, the computer is not a replacement for good judgement, but in the end a computer does give the engineer the ability to design more slender structures. If I run a P-Delta/delta analysis (which is next to impossible by hand) and take my K factors as unity I'm going to find I can design more slender structures than I could using the old K alignment charts and Cm factors. The computer will also pick up stiffness from secondary elements that in the past were neglected.

Bagman2524: Certainly the 14th edition doesn't eliminate simple hand calculation methods either. Although a second order analysis is now required, good judgement can be used to identify whether it will make a difference or not. I certainly don't do a complex analysis on every stair stringer that comes across my desk just because I'm using the new edition.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources