Help for project looking into the amount of load's beams can take

[perfectchaos180]

Hi guys I was wondering if you could help me out with designing a project. I am looking into how much load different beams can take. How should I weigh down the beam? Should I put load on top of it or hang it from the bottom, or something else? If on top, should I just load it all directly on top of the center of mass or should I evenly distribute it about the beam?

Also after I measure how much load it could take, is that when I would use the Euler-Bernolli beam equation to interpret results?

 

[TVP45]

Do you have a copy of Machinery's Handbook?

 

[perfectchaos180]

no I don't

 

[perfectchaos180]

oh and does anyone know any sites that provide some info on structural beams? Like the common shapes used, and why they are commonly made out of steel, diagrams of them, etc.? anything would be appreciated

 

[TVP45]

This has about everything you might want. The challenge is sorting out the small amount relevant to you.
http://www.aisc.org/Content/NavigationMenu/ePubs/freePubs1/freePubs_Home.htm

 

[perfectchaos180]

Ok I really need a lot more help with this than I initially thought. I have been trying some internet searches but am not having much luck. If someone can basically give me a link that will tell me everything I need to know about beams, and how to measure things for them that would be great.

Or if you don't mind, give me some terms I should look up. Like, stress, load, etc. and I will try to build my searches off of that.

Thanks for any help, I really need some

 

[TVP45]

And here's one with a little less information
http://www.engineersedge.com/structural_shapes_menu.shtml

But, what's your background, education, and project. That might help tailor recommendations.

 

[perfectchaos180]

Wow thanks I will get to reading those.

Well, I am a high school Junior, and I am in an advanced program (above AP level) and we have to do a big research project for my senior year and we are putting together our proposals now. I am doing a project on how different shapes and materials of beams affect how much load they can take. I am very good with math and physics, but I do not know much about beams so I need to learn a lot about them for this project and I really just needed help getting started.

 

[TVP45]

OK, that's a pretty tall order, but you could limit it somewhat by, for example, looking at a beam supported at both ends, with a uniform cross-section, either a uniformly distributed load or the same load right in the center, maybe 3 different shapes in steel, 1 in aluminum, and 1 in wood (just for gasps!). That should take you maybe 40 or 50 hours. What's your time frame on this? Do you have any standard resources (Mark's Handbook, a Statics and Strengths textbook, or anything else). And, do you have a decent computer if I can get you a beam calculation program?

 

[perfectchaos180]

Well the project is supposed to be a big project, it is supposed to span across my whole senior year, I might look into that beam calculation program. But I can't really try steel and I don't know about aluminum. The problem is, I am just a high school student. I don't have the materials to test on a steel beam, first it would be hard to manipulate into shapes that I want, second it would take lots of weight to break. I was looking into using wood and maybe cardboard. I don't have any handbooks or anything either.

 

[KennyCivE]

Cardboard won't be much good. Definitely use wood in your case, because I'm sure there are numbers out there for calculations about its strength if you need to do that. It's easy to work with too (I'm assuming you have some wood shop experience and have access to equipment).

As for the setup, you probably want to support the beam on both ends, raised maybe a foot in the air. This way, things won't have too much of a wall when the beam breaks. Each end should be clamped down so its fixed. The way you load it can be a variable if you want to.

 

[TVP45]

I misunderstood your post. I didn't realize you wanted to test the beams. But, if you have a budget of, say, $100, you can buy (and bend) some steel and aluminum shapes. Otherwise, you're probably stuck with wood.

 

[perfectchaos180]

Well my variable is going to be the shapes of the beams, I am going to see how changing the shape affects the load. So I can't have the way I load it be a variable, that's what the shape needs to be. I wouldn't be able to get my own steel shapes, and I don't know how I would get different aluminum shapes. Any suggestions on that?

 

[FredGarvin]

Is there really a reason to do the testing? This subject is pretty well covered analytically.

If you can get aluminum shapes, you can get steel shapes. The nice thing about the aluminum shapes will be the lower loads you'll have to apply and thus a less extensive set up.

Go to any on line metal supplier and look at their assortments of structural shapes. 99% of the suppliers will have various shapes of box tubing, I-beams and angle irons if you so choose.

 

[TVP45]

If you really want to use shape as the variable, you're probably stuck with wood. You'll want to make sure you use really, really good joining techniques and a consistent wood. The mechanical properties of wood are (at best) loosely defined.

Here's a fair starting point to look at engineered wood.
http://www.awc.org/index.html

 

[ctjen]

Well the project is supposed to be a big project, it is supposed to span across my whole senior year, I might look into that beam calculation program. But I can't really try steel and I don't know about aluminum. The problem is, I am just a high school student. I don't have the materials to test on a steel beam, first it would be hard to manipulate into shapes that I want, second it would take lots of weight to break. I was looking into using wood and maybe cardboard. I don't have any handbooks or anything either.

This seems like a good project and I wouldn't shy away from using wood, cardboard and even styrofoam. The process of trying to assemble beams from these materials should be very instructional as to how the properties of cross section in both prismatic and non-prismatic beams effect the behavior of the beam in general. Assembly of composite wooden, cardboard and styrofoam beams using glues, nails, bolts, tape and any other means you can think of should give much insight into how beams succeed and fail particularly illustrating the way that shear strength comes into play. You can also create composite beams using simple and readily available metal shapes like flat bar and angle iron in both mild steel and aluminum. These can be assembled using only a hand held electric drill and pop rivets and/or bolts. You can also combine steel and aluminum shapes with wood shapes using bolts, screws and nails. Testing can be done using some standard weight lifting plates. Much could be learned with only two hundred pounds of weight. It would also be possible to use an ordinary bottle jack as a load. Part of your project could be devising a way to apply a variable calibrated load using a bottle jack as the load source and perhaps a motorcycle shock spring as the load indicator. In designing beams as you propose for gaining insight into their behavior it's always good to be able to apply a load that is sufficient to cause the beam to fail. Taking video of a beam operating in it's elastic region as well as when it is brought to failure is also something you could incorporate into your project. A good starting source text might be 'Mechanics of Materials' by Beer and Johnston. It has many worked examples using wood. Something else you could add to the mix is building beams using fiberglass cloth and polyester or epoxy resin. This may be more expensive than your budget will allow and could require some supervision regarding the use of the plastic resins if you are unfamiliar with their properties and safe handling requirements. Keep in mind that surf boards are beams and glass-resin composites are becoming prolific in industry replacing conventional materials where low weight and specific load paths indicated as seen in aircraft, boats and automobiles.

Chris