The reason why open beams can't handle torsion

This video investigates the stresses that arise in a beam element subjected to different types of loads. The focus is set on the torsional loads that cause twisting of the section resulting in the so called St. Venant Stresses. Furthermore the twisting gives rise to the warping action that induces large bending stresses in the beam flanges. The video concludes with an experiment of a 3D printed section subjected to eccentric and concentric loading.
References:
[1] J. M. Gere and B. J. Goodno, Mechanics of Materials, Cengage Learning, 2013.
[2] P. A. Seaburg and C. J. Carter, "Torsional Analysis of Structural Steel Members," American Institute of Steel COnstruction Inc., United States of America, 1997.
[3] P. H. Lin, "Simplified Design for Torsional Loading of Rolled Steel Members," Engineering Journal/ American Institute of Steel Construction, 1997.
[4] A. F. H. D. C. Iles and A. S. Malik, "Design of Steel Beams in Torsion," The Steel Construction Institute, Berkshire, UK, 2011.

[@tomsko863]

Those were some of the best graphics I've seen in these educational videos. Really fantastic job guys.

[@TheEngineeringHub]

Thank you sir!🙏 I put in a bit more consideration into the color scheme and overall graphic design for this video. I am glad it didn't go un-noticed.

[@nikevisor54]

Always great to get another lesson after school

[@hafeeznoormohamed1259]

Amazing summary. Ive taken full classes that couldnt explain this so well as it's done here in just 10 minutes!

[@samuelmuentes]

Excellent explanation and skillfully crafted visuals. Thank you!

[@465maltbie]

Great way to visualize this, thanks for sharing. Charles

[@bruce-le-smith]

The printed props made it really easy to visualize and understand the math, thanks!

[@xaviergonzalez5828]

Beautiful video!

[@billynomates920]

ibd to the 4 all i can remember. long long time ago. great video!

[@Goalsplus]

You're doing well. Keep them coming.

[@ddarkjared]

I would recommend you add a stiffener to the load application location and/or secure the wood to both the bottom and top flange. This should garauntee you see the effects on the section globally rather than locally

[@bridgeconstruction_irwansyah]

GOOD EXPLAINATION

[@Prando34]

Such an awesome video. Thankyou!

[@TheEngineeringHub]

You are so welcome Prando! Glad you enjoyed it!

[@stefanguiton]

Great video

[@rjserra5535]

Very good presentation. Next time, choose a physical model that has a smaller cross section and a greater length. Yo will get more deflection before failure and a better visualization of the deformation of the beam as you apply the test load.

[@TheEngineeringHub]

Yes, great feedback, thank you 🙏

[@bobmartin6055]

Very helpful!

[@foobargorch]

doesn't the local failure potentially confound the 15% difference?

[@angeloissa4088]

Good lesson, keep it up!

[@Edmund-kg7fp]

Thank you !

[@233kosta]

*a LOOSE bolt. Correctly tightened bolts are always in tension until the joint fails. A locating pin would have been a better example.

[@markterribile6948]

Excellent presentation, but it would be improved if you added a caption as soon as you introduced a new term.

[@TheEngineeringHub]

Amazing idea!! Thank you so much. This will be implemented in the future

[@RonJohn63]

0:57 Large scissors are (or used to be, 45 years ago) called "shears". That's how I remember what the shearing force is.

[@MFcitrous]

Steel gains strength in tension so the torsional effects are often self defeating in a sense. You can't 3d print a 'model' of a W beam and think that it will behave even remotely the same as quality steel. I subbed b/c your engineering math is very on point, but there are also large practical misses that I also see daily in stamped engineering out in the wild. Legally speaking I'm not an engineer; I merely present them with solutions to stamp.

[@m.5051]

What are you even talking about? I know 100% that you've never advised actual structural engineers

[@Golgi-Gyges]

The factor of different distances from the load to the base should be examined also (shear+torsional example has load positioned further from base).

[@Steamrick]

Does the 18% figure at the end include the shortening of the beam?

[@TheEngineeringHub]

No, so in reality, it would be a bit more than 18% if the beam was not shortened. Good question, cheers

[@asbestosfiber]

I assume that the offset load as shown in the last demonstration become higher as the load becomes more offset, I'll guess it is probably exponential or close to it.

[@Astroponicist]

I am interested in how to modify typical construction calculations for the design of structures on Luna, & Mars. Because Mass & weight are separate functions linked by G where typically we would think of G as always being a value of 1, on Luna G is The acceleration due to gravity on the surface of the Moon is approximately 1.625 m/s2, about 16.6% that on Earth's surface or 0.166 ɡ. but I don't know how that works for figuring out how much load an I-beam load bearing capacity should be expected to change, ect. can you make some videos to help us understand how to begin thinking about the design of larger structures on Luna, & Mars when the supplies become available? thank you.

[@paulkurilecz4209]

Another failure mode to consider is lateral buckling in beams. Even though the beam may be loaded through the centroid, if the beam is long compared to it's moment of inertia, lateral buckling can occur. Buckling is an elastic instability problem.

[@TheEngineeringHub]

Yup, we already made a video on that. You can find it in our library

[@yaaaaa.3]

Pllllz can you shaire with us the code w that you used it in the video about Magnus effect plllllz,i really need it

[@TheEngineeringHub]

I am missing some files but I can share what I have. You may need to fix it up

[@yaaaaa.3]

@@TheEngineeringHub oh that's ok , if you find it please share it with me 🙏

[@olgajoachimosmundsen4647]

Would a synonym for moment be force or load?

[@H34...]

A moment is a torque, or force/load at a distance from a pivot. Just physicists call it torque, engineers call it moment from my experience.

[@Mikiszub]

Normal bolt connections are not under shear stress- tension from nut forces 2 plates together and generates friction

[@m.5051]

Many connections actually are bearing/shear type connections for strength type loading.

[@Mikiszub]

@@m.5051 that is jist plain wrong. Only if you use shoulder bolts/screws like din 609/ iso 7379. Trust me, I do this shit for living

[@m.5051]

@Mikiszub Do you think your measly experience means anything? I design bridges for a living, and we design the connections as slip critical for service loads and shear/bearing for strength loads. I'm the engineer that tells you, the monkey, that bolt goes here.

[@Mikiszub]

@@m.5051 I' d better not drive bridges you design then. Additionaly- I design cranes and other transport devices for living.

[@m.5051]

@Mikiszub Hah, no you don't. And that's how all bridges are designed...go check out AASHTO bro.

[@mysticery]

sounds and looks like a spine.

[@jeanfrancoisbrodeur]

Your 3d printed beams and experiments could be sold as learning tools to engineering schools

[@TheEngineeringHub]

I'd happily donate them if any educators are interested (or share the model so they can print it themselves)!

[@melgross]

I don’t totally trust examples,especially that are made so differently from actual materials. For this to=o be more convincing, the beams should have been made in the solid. I know, of course, that it would use a lot more materials. But the fact that these are hollow meant the loading characteristics are much more complex. Additionally, the plastic has a different bending modality. Many plastics will crack, or break instead of bending as steel does, particularly A 36, used in most construction.

[@TheEngineeringHub]

Absolutely agree Mel, all of your points are valid. I will look into repeating this experiment with steel plates now that I have a 10t hydraulic press. Cheers and thanks for the valuable comment

[@melgross]

@@TheEngineeringHub I’ll be sure not to miss it.

[@TheEngineeringHub]

@melgross I'm testing some 2x4s currently and measuring the reduction in capacity when holes are drilled through them. That will be coming up shortly. Cheers

[@shack_67]

No shit......pretty common sense thing to me

[@tehsoonguan9343]

Thank you !