How to learn to solve structural steel requirements?

[mikeysp]

Hi. I want to learn some better way to calculate steel beams, posts, trusses for projects. I am working on a design now to lift 5K + pounds of weight and I am trying to design in a way that is lightweight, so this question popped up again, how do I come up with the layout style (Big beam vs Truss vs?) and what shape and size tubing do I use? While it is nice to have folks help me by solving it, I would really like to be able to make some headway myself. I know there are a huge amount of variables, but surely there must be some basic design parameters that will keep me from using 1/4" wall when 14 gauge will work?

I have welded a few dozen projects together over the last few years. I tend to throw a heavy piece of steel that "ought to work" and this usually equates "P" for plenty, or really over engineering, or guessineering.

While I expect to add some extra steel to a structural problem, I hate the fact that I am just faking it.

Can anyone point me in the right direction for a beginners guide to steel math that would help me solve my current problem and aid me in the future?

I was not sure if this was the correct forum for this sort of question, so if it is not, please point me in the right direction.


Thank you.

-Mike

[N2 Welding]

Sounds more like a question for someone with a mechanical engineering background. I would like to know the answers to your question as this applies to many aspects of fabrication. Hope some one chimes in with a better answer than me :/

edit: there is probably some literature out there that provides this information but I have no idea of where to find it.

[Meltedmetal]

There are calculators available online but you need to think about safety factors, unexpected loading etc.,etc. Have fun.

http://www.atc-mechanical.com/calcul...al-properties/

https://www.amesweb.info/StructuralB...lculators.aspx

http://www.geocities.ws/richgetze/

[123weld]

i don't know, but i'd think that the state would want a lic'd structural steel contractor to kinda know stuff like that, which would make me guess, that if you found a used c-51 trade book somewhere, it might have what u want

[mikeysp]

Thank you gents.

I will look into those links and ideas.

-Mike

[ronsii]

And get yourself a copy of 'Machinery's Handbook' as it has tons of invaluable information on mechanics and strength of materials among hundreds of other subjects

[Bonzoo]

You'll get better info from an old school iron worker

[123weld]

nice collection ronsil. having one of them is worth its weight in gold

[ronsii]

Yes, they are extremely handy

I have just about every edition printed must be a collection sickness!!!!

[CAVEMANN]

I have a machinery handbook from 1989, I don't remember what edition, but they are awesome. I just don't see the need for every edition, unless for collectors value.

[henry42]

My dad was a licensed professional engineer who taught me that engineers didn't have to know crap, only where to find the answer.

And while it would be nice to learn where to find the answer, unless you're a licensed professional engineer you answer is only good for you. Anyone getting hurt by your design would own you.

[ronsii]

I have a machinery handbook from 1989, I don't remember what edition, but they are awesome. I just don't see the need for every edition, unless for collectors value.

Probably 24th edition


I don't have every edition(yet) but anytime I see one at a book sale or estate sale if it's one I don't have I just can't resist heh heh

Each new edition has some new data and other stuff in it - some more than others of course, I have a few I like better than others just because of the thumb index or print size

[mikeysp]

Thanks so much for those links. The second link: https://www.amesweb.info/StructuralB...lculators.aspx
was very helpful too me. I think i can use this to get smart on some terms and let the calculator do the math, then try to get an explanation, intepretation of the answer. Once I get this down, I will look into some truss design calculators - regular, then triangular and square.

I also found a PDF copy of the machinery handbook. Wow, that is a lot of pages. If you know that book cover-to-cover, you have a wee bit o knowledge, especially if you have experience using it.

Iron workers work off blueprints and when they build their own stuff, they throw steel at problems, from experience in some cases, but typically devoid of science. My good friend was an iron worker in California and Nashville for 35 years. He ran a company of 150 iron workers, and he does help me on projects, but it is "P" for plenty and way over engineered. Now, if I am constructing a steel building, he will have his preferred practices for assembly construction, but it would be a huge waste for me to seek his help on my goal of the minimum design for lightweight log lifting device as he would be without the experience in this specific problem and have to throw steel at it... way over engineer it, He did get a smile out of your comment though.

I don't think a licenced engineer factors in here, as the answer is valid for anything I build, unless I was needing a state stamp of approval to build my device. I am not anywhere near that need for my projects. A licensed engineer can get sued if their stuff fails too. The trailer manufacturer who does not need a licenced engineer is in the same boat if he has an an engineer or not. Some welders need to be licenced, so if you need a licenced welder, you need one. if not, you don't. The engineer, weather licensed or not, will know how to do the math I desire to do. However, if he is licensed, he will likely exceed industry safety margins in his design by 10% or more, so he protects his licence. Cost "him" nothing to add more to the design and helos him protect that licence. If I can figure out his math and do it myself, I am good to go.... unless I want to design a building in a code enforcement area, or some other thing that requires a licenced structural engineer approval, such as a bridge, etc..

Thank you all for chiming in.

-Mike

[CAVEMANN]

A friend used to tell people that I memorized the entire WORLD BOOK ENCYCLOPEDIA, LOL.

[N2 Welding]

I look at big books like those listed above and the Lincoln Electric welding books and my head starts to hurt. Way too much information to soak in. I like the KISS method

How about a youtube video showing how it's done using the calculator above. I can dig on that.

[mikeysp]

I look at big books like those listed above and the Lincoln Electric welding books and my head starts to hurt. Way too much information to soak in. I like the KISS method

How about a youtube video showing how it's done using the calculator above. I can dig on that.

Here, here. That would be most excellent... providing the definitions of esaticity and such and how to figure them is included in said video

I happened to sell something a day or so ago and the gentlemen who came for the item was a recently retired mechanical engineer from corporate america. I told him what I was trying to learn and he told me what he does is look around at what is already made and copies what is already proven.

-Mike

[theweldor]

What you want to accomplish is a lifetimes worth of work.

[zipzit]

Unfortunately everything has consequences. The well built awesome 5000# hoist you build today, gets sold to somebody else in the future (say after you pass on...) . And that somebody tries to lift too much weight. And stuff happens.

Accidents are never good. I personally know of two terrible accidents, largely related to engineering issues while I was in the military. (One was a tow rope which broke under exceptional load related to the collapse of a sand ramp during a river crossing training, the other a split ring truck tire not in a proper safety cage.) Permanent, life debilitating accidents. You don't want to be the person who possibly creates an adverse situation.

Oh, and I am a Licensed Professional Engineer. I know how to calculate moment, shear, stress, predict deflection, calculate center of inertia for different cross shapes. But after reading the details of such events as the Hyatt Regency Walkway Failure or other steel strength design issues, I don't even want to take jobs like that. Heck, I'm thinking of building something as stupid as a super low angle drive on oil change ramp for myself, wondering if the risk is worth it.. So I'll build a set of ramps, but you can be sure it will be over designed, and well marked with max load. But no, I won't share the design here in public forum. That sets me up for risk.

Color me nervous.

[Meltedmetal]

So Zipit,
We hire engineers to do specifically what you seem to be adverse to doing. I never thought negligible risk projects needed an engineer. No doubt I've seen poorly engineered structures fail but many of the failures I've seen result from lack of oversight on the project and poor quality work and materials or outright cheating the consumer by installing sub par material or leaving out components entirely. So what kind of project are you comfortable engineering?

For your oil change ramps, go look at one of those tipping ramp affairs the car dealers use to elevate cars on display in their lots and beef up the design if your manufacturing skills are up to it.

[zipzit]

Normally you are right. But anything that may have a human being on it, in it, or under it, or heck even next to it, ever, requires some thought.

On it (Hyatt Regency Walkway collapse)
In it (Elevator)
Under It (Florida Intl University Pedestrian Bridge Collapse)
Next to it (oops. Bad welds caused this failure. But why didn't engineering / management call out requirements clearly and inspect to standards? )

but you get the idea.

So Zipit,
... I never thought negligible risk projects needed an engineer. ... So what kind of project are you comfortable engineering?

Not much these days. I'm not soliciting work in this forum. I'm actually doing software freelance. I still do some design work, but not much, and nothing structural.

[William McCormick]

Over the years I have seen many an engineered project fail in actual practice. Now you can say well no one ever thought they were going to use it in mud, or that no one thought the plywood they were rolling it on would have given way like that. Or the cement that was supporting it would have cracked. But in reality that is just the stuff you have to think about. I was just in a newly built laundromat, instead of a six-inch pour for a floor, they got away with a four-inch pour. I was mounting a change machine base I made, to the floor for a friend, and I hit the dirt at 3 1/2 inches twice, and 4 inches two other times. The floor had already started to sink, crack and become unlevel.

Whenever anything moves, it has to be overbuilt, for reasons like the above. You have to be a pessimist and expect the worst; most young people in college are not up to thinking like that; they want happy thoughts. You also have to have in the shop, and in the field experience working with the tools and equipment that you wish to build. Otherwise, do not bother.

Years ago I built arched gusset "A" frames to lift boats in the warehouse. We used them for a year with no issues and even misused them with no issues, then someone either too lazy or just not too savvy locked the wheels on the "A" frame straight, as he was misusing them to move a boat with a forklift. The legs of the "A" frame tracked apart and set the ocean racer, on the ground as the "A" frame plastically deformed. No damage to the boat, but the "A" frame was toast. It could have been worse. You cannot expect common sense. And at some point, you have to agree to kill someone that is lacking common sense, to an extreme degree.

The reason we put locking wheels on the "A" frame was so we could aim the "A" frame unloaded at the place we wanted it to end up and then lock the wheels, we could push it from only one side of the "A" frame and move it to where we wanted it to go. We had warned all involved never to lock all four wheels under a load. But you know how good advice falls on deaf ears.

[farmersammm]

And get yourself a copy of 'Machinery's Handbook' as it has tons of invaluable information on mechanics and strength of materials among hundreds of other subjects

Machinery's is wonderful. I found the ideal tapping fluid for bronze in there. Lard, and mineral oil. I only had some bacon fat on hand, so made do with that.

Smelled so good, I was tempted to lick the tap

[ronsii]

LOL, yep.... hard to get much done right though when your mouth is watering and you keep thinking about food...

[Bonzoo]

In your original post( left pic) I use similar when I build but with 8" round, filled with cement and attached top and bottom to a concrete tie-beam and floor. The I-beam is for the rolling chain hoist....or electric. The upper is needed if it's roof, bracket arm to concrete wall, or other.Gusset that 90 with 3/8 plus.
Talk with the 'engineers' at a steel supplier. They've seen it all.

[lotechman]

If a person wants to learn a good source is the Design of Weldments which is a Lincoln book available from their knowledge site. The series of books by Blodgett is excellent. Apparenlty Blodgett was an engineer or Lincoln well into his nineties.

https://www.jflf.org/SearchResults.asp?Cat=81

The Lincoln foundation is a non profit that was set up many decades ago and the prices are fair. They are not out to gouge you.