032 CE342 Concrete Design: Torsion Design Example Pt1

[@goranadil8985]

Dr. Allen, I am not the type of ppl who comments a lot. During my PE structural review, I found your channel, and I like your channel. I hope you find the time to explain these excellent classes using digital methods rather than paper. Thanks again for sharing this with us.

[@jaythreeengineering]

Thanks for the very kind words. It’s my intent to someday update! These videos were all made during COVID for my students when time was really crunched. We were making 2-3 videos a day when we were forced on line. Admittedly the quality isn’t exactly what I would have dreamed, but was more a function of circumstances. Thanks for watching!

[@tawfikjdid]

I appreciate your explanation being so clear and precise. In the video, at minute 29, there was a limit where Vu was being compared to 0.5ΦVc. I have a question about that. Do you think the following applies generally? 1). If Vu < 0.5ΦVc then no shear reinforcement is required. 2). If 0.5ΦVc < Vu < ΦVc then Av,min is required. 3). If Vc > ΦVc then the following condition shall be checked: Vc < ΦVn ; Vn = Vc+Vs,max If ok then check the following condition: Vs = Vu/Φ - Vc < Vs,max = 8*SQRT(f'c) If ok then Av/s = Vs/fyt.d So far, is this how things are?

[@jaythreeengineering]

That’s a very succinct summary, and the way I always try to remember it. Well done! Thanks for watching!

[@misnadalmisnad8346]

Thanks; Great explanations; my question what do you consider when 0.75*Tn

[@joper8496]

When your'e given a beam that carries a cantilever slab will you not add the area of the slab to the area of the cross section of the beam when solving for Acp? Considering the weight of the slab will also be transferred to the beam?

[@jaythreeengineering]

In theory, if you can estimate the ability of the slab to resist the torsional behavior of the beam, you could probably add some some amount of it into the Acp value. But this slab is only 4.5 in. thick which is very small in most structural senses, so we decided to neglect this ability, which reduces Acp, which under estimates the torsional strength of the concrete, which will put more burden into the reinforcing steel (you'll be increasing your steel requirements). Also, the example in this video is also only for torsion and shear contribution, so the longitudinal steel requirements are the additional steel needed BEYOND the flexural requirements. Hope this helps. And thanks for watching / subscribing!

[@jimriseborough]

Is the critical section for Torsion at "d" away from the face, is that in the code anywhere for Torsion?

[@jaythreeengineering]

The critical section parameters are found in ACI318-14 Section 9.4 --- for shear it is 9.4.3 and for torsion its 9.4.4. Hope this helps! Thanks for watching!

[@moonisansari282]

Sir please cover one more example related to torsional design of RCC wide flange T beams....since you only covered rectangular beam torsional design unfortunately in my exam i got a question of T beam torsional design instead of rectangular beam due to which i was unable to solve that question

[@a.k.a2020]

🌹👍

[@jaythreeengineering]

Thanks for watching!

[@moonisansari282]

Kindly respond to my request sir

[@jaythreeengineering]

I do not have a video covering torsion design of t-beams or double stemmed t-beams or or even unsymmetrical flanged beams such as L-beams at this time. You could be grossly conservative in neglecting the flanges altogether and use the rectangular core for single stem t-beams to resist all of the torsional load if you were simply trying to size the member or get an upper bound feel for reinforcing requirements in the stem. In some situations this may be prudent in cases where the flange dimensions are very thin or very short in comparison to the stem i.e they carry a small amount of the torsional resistance. This will most likely result in slightly larger dimensions for the depth and width of a single core, but it would likely get you in the ballpark so to speak. We may decide to cover this topic in more detail in a future video but simply have not gotten to it yet for this course. Hope this helps and as always thanks for watching!