The Secrets of Development Length! | How to calculate the development length in reinforced concrete
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- เผยแพร่เมื่อ 6 ก.ค. 2024
- Development length is something that is commonly misunderstood in reinforced concrete design. This video explains the secrets of development length in reinforced concrete. First, the video shows a development length test and explains the theoretical basis of the development length equations. Next, the factors for the development length equations are explained and practical advice is given for development length design. These secrets will improve your fundamentals of reinforced concrete design.
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very informative and entertaining as well. it answers the why's on the formulas thus giving a better understanding and so have a "concrete" knowledge which is so essential to engineers.
Dr. Ley; excellent presentation, well done explaining the details. !!!
New way of teaching engineering subjects.not boring and so very informative.
Excellent video bro! Keep em coming. Thanks!
Thank you!!!
Man you are so great in Concrete Design!!!!!
Fantastic video, thank you very much professor.
Thank you for watching and your nice words.
Thank you for sharing
Dam, this was better explained than my professors did when I was in college. Great job.
Thanks man i was just eating up the equations and it simply made sense to me good to know I'm not the only one thinking about over engineering stuff so that it lasts rather than fails & the load factoring equation J hooks and L hooks adding more quality to the strength and performance of the pulled rebar and using more steel to redundancy make up for not using best strong patterns mnnn it tastes good to see
Your style is awesome, Thank You, are you going to make videos about the rebar overlap?
I used to just overengineer it by a factor of .2-.5., increased the sack mix and keep the water down to the minimum needed. Tried not to overwork the concrete. Made sure everything was in compression as much possible.( Some plans were a joke). Went with a thicker slab.
How did I cover the extr cost? Explained in detail the customer needed it. They always thanked me for the knowledge. Kind of like letting them into the secret club.😉
One more comment. Not a big fan of pea gravel. I know it's needed for pumping. But the aggregate size should be one third the size of the slab for maximum strength. That would be a problem pumping it up 40 floors.
I would use a larger rock if it was delivered by truck and could be dropped by shoot onsite.
@@georgemichaels2325 Thanks Geroge! It is cool to hear your experience. I am excited to go back to the field after things get a little more normal.
Thanks for the video, super informative. Do you have any videos that talk about development length for bars in compression?
Petition to start calling the "top bar effect" the "deep pour effect." The top bar factor applies not only to the higher bars in a pour but all horizontal reinforcement with 12" cast below it.
Seriously nice videos. I enjoy the education.
Thank you !!!
Wow...so much cool stuff...You know Tyler, we've studied all this stuff but our concept was not that good. You showed some cool slides and pictures which cleared the concept. The top bar effect image where the water comes up coz of its low weight is something which I learned from you. Thanks & keep it up. We expect more videos like this in the future...Stay safe...
Thanks GJ! We have more videos coming!!!
Some good insights are given in this video. I can of course think of variations on the theme where the U-shaped rebar goes around a vertical rebar in the wall to further distribute the load. This would of course make the calculations more complex.
Interesting is also the other video you have "what is epoxy coated rebar and why is it being banned". You did include a reason for it in this video though, but for anyone else watching I think it's worth a visit to that video too. However I can see a reason for some kind of coated rebar in aggressive environments where you may want to avoid replacing rebar but just resurface the concrete, but I'd keep that for flooring on the ground.
Thanks!
I agree that is a good way to anchor bars but most people don't use that technique or at least take that into account.
Nice explanation, Is there any explanation of the position of the development bar according to the aci code?
Wow you are a reinforced concrete designer god! I wish I had found your channel earlier. Insta subbed.
Question: does rebar hot dipped galvanisation impacts the development length?
Wonderful explanation. 10:53 But be careful under some condition like seismic loading you can not use this condition.
Very good explanation and video. I took concrete design with Milo Ketchum in 1974. I don't remember much from his course so, this was a nice review. Good Luck to Us All, Rick
Thanks Rick! Was that at the Univ of Connecticut?
@@TylerLey Yes. Got my BSCE from UCONN in 75 and then went off to be an Army Engineer. When I finished with the active Army I went back to study under Kent Healy in soils and got an MSCE in 82. I really enjoyed UCONN.
I stayed in the area and had long friendships with several of my old profs. In the 90s, Roger Ferguson asked me to help him with senior design projects. For 10 years I taught small groups of students the simple way to design bridges based on Army TM 5-312 and the AASHTO Codes. As a town engineer I provided them with real bridges that needed replacing. In several cases, I was able to replace the bridges the summer after the student's design and sent them pics. In 2000 Roger retired and went to teach at Idaho(I think). That ended my doing anything with UCONN.
so so thanks
Tyler,,i am trying to mix expanding cement,or concrete to make an insulation board, i need mix something able to produce bubbles of gas,like the yeast, have any reference about this?
Could you please tell me what the the letters stand for in Ldh and Lbh ?
Tyler da 🐐
hey Tyler.. your videos are as always fantastic ..especially the way your talk about it and more specifically the tone you use in your talk ...fabulous. the only one thing though is ...the lighting that your face gets (in almost all of your videos) is a little bit too much. just FYI.
Hello Tyler,
Was this formula "designed" empirically?
Tyler - on a associated subject, just asking your insight on concrete window lintels. I purchased a 1957 single story block beach house in 2019 (one block from beach). When painting I noticed almost all concrete lintels are cracked due to rusting rebar. The rebar was burried in the middle of the lintel, but I guess salt intrusion still happens that deep. I chipped away what loose concrete, wire brushed the exposed rebar and patched with stucco mix. SInce it is a single story, I assume there is minimal load on the lintels. Does salt get two inches inside concrete? If so, I am guessing all the beach houses as well as older high rises have this potentially significant problem. Thanks!!!
Yes, salt permeates concrete. They made a concrete pier in Laguna Beach CA when I was a kid (Aliso Beach pier) that proceeded to come apart many years later [20 or so?] and they tried to save at high co$t and finally threw in the towel & tore it all out as a bad idea another 10 years or so later. [They could have saved a lot of hassle if they'd just listened to me, I could have told them it was a bad idea to put up that pier as a 6 y.o.... It's nice to have Aliso back to its uncluttered beauty!] Anyway, in a salty environment, you need to use some other type of reinforcement that won't corrode in a salt atmosphere...
@@nunyabidniz2868 thank you for your insight.
I agree with Nunya. If you give it enough time then the concrete will reach the rebar. BTW, I am not a big fan of using stucco to patch your rebar. If you want to slow the intrusion you could try and seal the concrete. Super cool you are close to the beach.
Good video.
Interesting how much structural engineering terminology differs between British and American English.
You are referring to lap length, of course (:
Yep. English is constantly evolving, and it's been over 230 years since we went different ways... What is the line again? "Two great nations separated by a common tongue...?" [Edit: Oscar Wilde! For the life of me, I couldn't remember his name at the moment. Anyway, it was his witticism...]
Thank you!!! What are some different terms that you use?
@@TylerLey well, this is worth looking into further. Can't really tell you of the top of my head, but I know I am often surprised by unknown terms when watching US videos or reading about buildings.
Can we draw a FBD diagram of the bar while it is undergoing pull-out test...
Sure! I talk more about this here:
th-cam.com/video/CpBsp9finmk/w-d-xo.html
@@TylerLey Suppose that the Bar is undergone corrosion inside a SS Beam, and due to corrosion volume of bar is increased to some amount, now due to the increase in volume, and the bar is restrained , stresses will be developed causing cracks, I would want to know in which direction and how much stress that would be?
6:54 I think that might be lambda, not gamma.
Sir are earthquakes and various environmental agencies has some sort of impact on development length
And also how developmemt length works out in prestressed concrete or structures
Thanks! The development length will allow the rebar to yield. This is good for earthquakes and extreme winds.
For prestressed concrete they have a term called transfer length. This is the distance that the prestressing steel transfers the load over. It is a similar concept to this. Thanks for the question!
Nice
Thanks!!
big Like
why is your lambda is out of place? It is not presented like that on ACI code
The West Seattle Bridge statement of findings timeline url:
www.seattle.gov/Documents/Departments/SDOT/BridgeStairsProgram/West%20Seattle%20Bridge/2020-03-20_WSP_WestSeattleBridge_UpdatedRecommendations.pdf Sure seems that a third-party could review this in-process failure and make an educated guess where or what is the primary cause of this failure rather than saying the failure does not fit the models... undoubtedly there is a lot of toilet paper being used regarding this problem because of the liability and repair expenses... OUCH! This is going to be a great study in concrete engineering for the history books. Comments welcome.
1 hour in development length saves 10 hours in production length ... wait - different development length
Nice!
I was gonna say about 6-7 inches is good
@ 6:54 -- Hey Ty, where'd you learn to read Greek, off the back of a cereal box? Tha's no a gamma, it be a lambda, ye ken? Two more brownie points lost a little later @ ~7:57 when you misspoke again as yet another psi. I know, I know, you were all aglee at the thought of the concrete coming undone... ;-)
Thanks for the corrections, mistakes happen!
@@TylerLey All in good fun, I know you know better. Very easy to misspeak when you're excited about a topic & trying hard to get the point across! :-)
Focus on the information rather than your excitement
Lambda bro...lambduh!