I love your in-depth explanation and your break down of basic concepts, It's a good refresher and makes it easier if you understand them to not rely on formulas
OMG, I've been following you from Statics, Mechanics of Materials, Structural Analysis but never know that you do have videos on Concrete Design. What a relief. I'm taking both Steel and Concrete this semester (not that wise), I have no problem with steel but I do have a big problem with concrete. Please do more videos on this please they will be a BIG help to lots of students. I know this for sure because I always refer a lot of my friend to your channel and they always find your very helpful.
i need you to know that you saved me today, i am preparing for my FE exam and i was trying very hard to understand why do we use Yield strength for balancing the forces if at some point we need the steel to pass the yield strain , i never understand the concept till this moment ,,,,,,thank you alot for sharing your knowledge , sometimes one word can save you hours and hours of guessing. highly appreciated Rawan
U r the best on TH-cam by far , even the way u speak is professional u don't make us get bored at all and your videos are all short and easy to understand I am from the middle east and I can understand your lectures really really good , keep going hats off
@@structurefree Let alone the middle east, they reached remote areas in Africa :) A person is required to do good things wherever he/she is and God almighty will spread it to the farthest places that the person himself didn't imagine : )
Thanks you structurefree, this helped me a lot even though we use mainly the metric system in my country. I understand your explanations way more than my professor does.
The way you explain , I like it ,, your videos are very helpful , I learn regularly from you videos ,, thank you so much ,, Keep it up ... Love from Pakistan.
Structure free your video instruction is similar to what I learn with my professor in the concrete design in Cambodia, Phnom Penh city in South East Asia ! Thanks
Very good video for review. I'm using this to help me study for the FE so this was a good quick refresher of reinforced concrete design. Only thing I say was the #9 bar has a As of 1.128 square inch not 1 square inch. The #8 bar is set at 1 square inch
Hi Jose, thanks for your comment. The diameter of a #9 is 1.128 inches. The diameter of a #8 is 1 inch. The area of a #9 is 1 in^2 and the area of a #8 is 0.79 in^2. For US bar sizes...www.reinforcing-bar.com/technology/reinforcing-bar-sizes.html
Enlightening one structurefree :) great job. Thank's a lot, I know right now after long been confuse about this subject. Just a bit advice, to avoid mistake please make a different notation for 'depth of compression block' and 'width of the beam' which in this video denotes with the same symbol (a).
Hey structurefree! Thanks very much for your video! It's exactly what I needed to start with in concrete design. You have my subscription for more quality videos.
Nice video sir, it helps me and many people all over the world. But why do we need to assume that the steel yields? Is it to maximize its capacity? Thanks
@structurefree - This is a great video, you are helping me calculate beam size for a retaining wall I'm building. One thing i don't understand is we never apply the position of the rebar (3" from beam bottom) in this video. my intuition tells me that the rebar being 3" from bottom (where the beam is in tension) makes this stronger than the beam being 3" from the top. the reason i ask is I'm building beams by hand and i want the beams to be as small as possible. my "B" = 18, and my "D" = 6. due to the rule of thumb of having rebar ~ 3" from the edge of the concrete, I'm forced to put my QTY 3 #8 rebar in the center of the beam. My application is i'm building a beams for a retaining wall. this beam will be 8' Long, and be a retaining wall that i can pour into forms by hand and then move with a small tractor into place. the beams are supported by columns on 8' centers.
Awesome, one quick question please, sir. what would we do if after the third step, we verify that strain of steel has NOT yielded? Is it that we can't do the design because it doesn't satisfy the ACI code?
Hey Structure free! First I would like to say that I love your videos and I think I've soon watched them all! Would love some videos on Vlasov torsion and Bimoments! Haven't found much on the internet, find the subject kinda hard to grasp... Btw your channel rocks! /,,/
Christian, many thanks for all the support and comments you've posted on my videos! Based on your suggested topics, you must be in an advanced mechanics course....they are challenging topics to understand and even harder to explain well. I can't make any promises (my to do list of videos is over 80 topics) but i'll see what I can do over the summer....do you have any requests that don't involve differential equations? ha! ha!
Hey SF! Awesome to hear from you! Yeah, I'm a gradstudent in CE at the Royal Institute of Technology in Stockholm so I've had a share of mechanics courses. >:) 80 topics in the to do list, wow! Can't wait to see whats comming up. If you'll run out of topics I would also love to see some on the Displacement- and Force methods for grids. Parhaps even Vianello's method for calculating critical buckling load! Love your work! Peace out, from cold Sweden!
in civil engineering the concept of R.C beam always the ACI code.within strain profile and stress profile always use together to calculate alls the ultimate problems in R.C beam.thanks.KPAD student.229.
thank you very much for the great video structurefree. your detailed explanation made it easy for me to understand the calculation & concept even i come from chemical engineering background. i have a question: it seemed your calculation didn't consider the effect of size / length of the beam. Do we need to consider the length of the beam? Is the beam length irrelevant because the cross section (concrete + steel) is same along the axis of beam length, considering uniform distributed load? appreciate your reply when you have a chance.
TheSnooex i'm assuming i'm looking at the critical section for internal moments along the length of a beam...or where the max internal moment would occur to design the cross-section.
Another question, what if you have a double layer tension bars? What would be its effect in your calculation? What will the strain and stress profile look like?
I know it's been awhile since you asked the question, but you just find the centroid of the area of the steel; meaning it doesn't matter if you have one, two, or three layers you just always find the area and the centroid of the area.
Awesome work @structurefree. I've got a question. I'm trying to understand what Phi*Mn actually means vs Mn. The equation for flexural beams is Phi*Mn> or equal to Mn. in this problem, Phi*Mn = 247.8 and Mn = 275.3. Phi*Mn is not greater than Mn. Can you please explain this, I'm a bit confused. Also, what do those values mean? Does it mean that this beam will fail at Phi*Mn? Cant thank you enough!! Thanks for all your great videos!!
Phi*Mn is the design moment strength or capacity. Mn by itself is the theoretical or nominal strength. We want the design capacity less than the theoretical so that there is some margin of safety.
+structurefree ok so if we want phiMn to be less than our Mn why is the equation written like phiMn should be equal or greater than Mn? If the beam Maximum moment let's say is 600 kpft we want to design the beam so it's actually less to have safety margin right? I guess my question is phiMn should be less than or equal Mn instead of it being phiMn is greater than Mn. Sorry for this stupid question just trying to wrap my head around it.
Thanks for the helpful video @structurefree It doesn't matter much but the area of #9 is 1.125 as the area = (n/8) => (9/8). #8 would have As=1.0 sq in
Hi Chad, thanks for the kind words. Actually the n/8 rule is for diameter of the bar and only works up to #8 bar. The #9 bar has a diameter of 1.128 inches which results in an area of 1 in^2. en.wikipedia.org/wiki/Rebar#US_sizes
Could you help me out with some architectural work for a building im trying to design and build . I want to figure out all the strengths but it is fairly overwhelming .
Hello. Could you answer a quick question. You found your strain to be 0.007 in the steel. By the hooks law E=stress/strain this would give a stress of 1400 mpa (203 ksi). This is far above steels ultimate stress capacity. I do not understand how we come up with a nominal moment capacity of 275 kip*ft which is based on a strain of 0.007 in the steel and still have a safe design.
+structurefree Thank you for that explanation. The only thing I am slightly unclear on is why isn't the strain we find through similar triangles the yield strain of the steel? Shouldn't it be this since we found the Neutral axis by setting the steel at yield and the Mu value is the moment the beam can take when the steel hits its yield stress?
should we use Fc instead of Fc- and Fs instead of Fy in equations..because we don't know is the section steel at yield or not ?? and for Fc also?? appreciate your quick response.
sorry, i really don't have a favorite when it comes to reinforced concrete design. i feel like they were all written for students in the 1970s or 1980s.
Why are you treating the compression load as a uniform stress load, instead of a profile proportional to the strain, like it is modeled for introductory homogeneous beams?
the equivalent stress block is used in reinforced concrete analysis and design to expedite calculations. You could keep the nonlinear stress profile and integrate numerically to get a very precise result.
DONT EDIT YOUR VIDEO!!!!!!!! THere's no pause when im listening. It just goes on and on. Bro, I have no problem watching 20mins of a video. Just dont make it a non-stop-talking video. Your earlier videos with the little pauses, the uhs, the jokes, created a much more relaxed environment. Please dont edit your videos :( :(
![“อ.เบียร์ คนตื่นธรรม” มาตามคำเรียกร้อง แหกศาสตร์ฮวงจุ้ย เตือนสติอย่างมงาย | แฉ 7 พ.ย. 67 [1/3]](http://i.ytimg.com/vi/5fc4S3xBNfc/mqdefault.jpg)
![ค้างคืนโรงเก็บกระสวยอวกาศร้างกลางทะเลทราย [Around The World Ep. 3]](http://i.ytimg.com/vi/E5bWZQhABJE/mqdefault.jpg)
I love how warm and enthusiastic you explain things. It makes me listen to your voice non stop
I love your in-depth explanation and your break down of basic concepts, It's a good refresher and makes it easier if you understand them to not rely on formulas
OMG, I've been following you from Statics, Mechanics of Materials, Structural Analysis but never know that you do have videos on Concrete Design. What a relief. I'm taking both Steel and Concrete this semester (not that wise), I have no problem with steel but I do have a big problem with concrete. Please do more videos on this please they will be a BIG help to lots of students. I know this for sure because I always refer a lot of my friend to your channel and they always find your very helpful.
i need you to know that you saved me today, i am preparing for my FE exam and i was trying very hard to understand why do we use Yield strength for balancing the forces if at some point we need the steel to pass the yield strain , i never understand the concept till this moment ,,,,,,thank you alot for sharing your knowledge , sometimes one word can save you hours and hours of guessing.
highly appreciated
Rawan
U r the best on TH-cam by far , even the way u speak is professional u don't make us get bored at all and your videos are all short and easy to understand I am from the middle east and I can understand your lectures really really good , keep going hats off
Thanks! It's cool to know that these videos even help people in the middle east. I will definitely have to make more.
@@structurefree
Let alone the middle east, they reached remote areas in Africa :)
A person is required to do good things wherever he/she is and God almighty will spread it to the farthest places that the person himself didn't imagine : )
Only god knows how much you helped me through my degree... Thanks bro!!
Last semester I had structural analysis, and this semester I am taking reinforced concrete design. Its like you've been making videos for me!
Thanks you structurefree, this helped me a lot even though we use mainly the metric system in my country. I understand your explanations way more than my professor does.
Jesus Walks thanks for the kind words. let me know on facebook.com/structurefree if there are any topics you want me to do in the metric system.
structurefree How about Shear reinforcement design(either metric or english)? Did you make one already?
No, thank you, Jesus.
Jesus Walks I'll probably make one of those in the spring.
The way you explain , I like it ,, your videos are very helpful , I learn regularly from you videos ,, thank you so much ,,
Keep it up ... Love from Pakistan.
You sir ARE A LIFE SAVERR !!!!!!! I learn more in ur channel than my own uni !! Thank u so much😁
I refreshed my design in 18 minutes. Thank you!!!
Just watched your videos on RC Beams for my FE. AWESOME! Thanks
good luck with the fe!
Thank you so much!!!! Saving my bacon again as this previous sculpture major finishes MA in Arch
Thankyou sir! I hope i had a professor like you so that i could understand better
Ha! I wish I had a professor like me too. ;)
Structure free your video instruction is similar to what I learn with my professor in the concrete design in Cambodia, Phnom Penh city in South East Asia !
Thanks
i hope that is a good thing.
Very good video for review. I'm using this to help me study for the FE so this was a good quick refresher of reinforced concrete design. Only thing I say was the #9 bar has a As of 1.128 square inch not 1 square inch. The #8 bar is set at 1 square inch
Hi Jose, thanks for your comment. The diameter of a #9 is 1.128 inches. The diameter of a #8 is 1 inch. The area of a #9 is 1 in^2 and the area of a #8 is 0.79 in^2. For US bar sizes...www.reinforcing-bar.com/technology/reinforcing-bar-sizes.html
Enlightening one structurefree :) great job. Thank's a lot, I know right now after long been confuse about this subject. Just a bit advice, to avoid mistake please make a different notation for 'depth of compression block' and 'width of the beam' which in this video denotes with the same symbol (a).
i love all your lect and the creative way of teaching thanx alot , and keep going forward
Keep the RC videos coming, they are awesome
Structurefree you are absolutely legendary!
+Moses van den Berg thank you!
i learn from every fucking single word u said.i was swimming in the sea.now i got island..thanks man thank...U...SIR...
Hey structurefree! Thanks very much for your video! It's exactly what I needed to start with in concrete design. You have my subscription for more quality videos.
Thank you very much for this video. It helps me a lot to do my assignments. you are great sir
You are so better than my professor
You are a life saver
Great video!
You're a great teacher,dude! :)
Thank you for the comment. Yes...Yes, i am....although I'd rather think of myself as an "edumacator". word.
You are a life saver :D Amazing explanation
More concrete beam design! It's great!
Thanku Mr . Structure
You the man!
Nice video sir, it helps me and many people all over the world. But why do we need to assume that the steel yields? Is it to maximize its capacity? Thanks
Really helpful! Thank you!
+Gulipiye Abudukadier 😁
@structurefree - This is a great video, you are helping me calculate beam size for a retaining wall I'm building. One thing i don't understand is we never apply the position of the rebar (3" from beam bottom) in this video. my intuition tells me that the rebar being 3" from bottom (where the beam is in tension) makes this stronger than the beam being 3" from the top.
the reason i ask is I'm building beams by hand and i want the beams to be as small as possible. my "B" = 18, and my "D" = 6. due to the rule of thumb of having rebar ~ 3" from the edge of the concrete, I'm forced to put my QTY 3 #8 rebar in the center of the beam.
My application is i'm building a beams for a retaining wall. this beam will be 8' Long, and be a retaining wall that i can pour into forms by hand and then move with a small tractor into place. the beams are supported by columns on 8' centers.
Great video dude
Awesome, one quick question please, sir. what would we do if after the third step, we verify that strain of steel has NOT yielded? Is it that we can't do the design because it doesn't satisfy the ACI code?
Thanks very much for your video!
thanks for the upload .great video
dude youre amazing
🤗
Thank you that's good
Hey Structure free! First I would like to say that I love your videos and I think I've soon watched them all! Would love some videos on Vlasov torsion and Bimoments! Haven't found much on the internet, find the subject kinda hard to grasp...
Btw your channel rocks! /,,/
Christian, many thanks for all the support and comments you've posted on my videos! Based on your suggested topics, you must be in an advanced mechanics course....they are challenging topics to understand and even harder to explain well. I can't make any promises (my to do list of videos is over 80 topics) but i'll see what I can do over the summer....do you have any requests that don't involve differential equations? ha! ha!
Hey SF! Awesome to hear from you! Yeah, I'm a gradstudent in CE at the Royal Institute of Technology in Stockholm so I've had a share of mechanics courses. >:) 80 topics in the to do list, wow! Can't wait to see whats comming up. If you'll run out of topics I would also love to see some on the Displacement- and Force methods for grids. Parhaps even Vianello's method for calculating critical buckling load! Love your work! Peace out, from cold Sweden!
thank you.
in civil engineering the concept of R.C beam always the ACI code.within strain profile and stress profile always use together to calculate alls the ultimate problems in R.C beam.thanks.KPAD student.229.
I hope this will help me in my exam :) thanks
Genius
Awesome
thank you very much for the great video structurefree. your detailed explanation made it easy for me to understand the calculation & concept even i come from chemical engineering background.
i have a question: it seemed your calculation didn't consider the effect of size / length of the beam. Do we need to consider the length of the beam? Is the beam length irrelevant because the cross section (concrete + steel) is same along the axis of beam length, considering uniform distributed load?
appreciate your reply when you have a chance.
TheSnooex i'm assuming i'm looking at the critical section for internal moments along the length of a beam...or where the max internal moment would occur to design the cross-section.
very helpfull.... keep going sir
You are doing an awesome job! keep it up! :D
"Memorizing equations is going to get you in baaad plaaaces" - You've been there huh.
Great work @structurefree. I wonder if you can produce notes as pdf for us to be more handy, regards.
man you're awesome.. keep up the amazing work!
Great video! 👍🏼
Super very good explanation.. R u a teacher...
WOW....I DONT EVEN KNOW HOW TO THANK YOU!
Another question, what if you have a double layer tension bars? What would be its effect in your calculation? What will the strain and stress profile look like?
I know it's been awhile since you asked the question, but you just find the centroid of the area of the steel; meaning it doesn't matter if you have one, two, or three layers you just always find the area and the centroid of the area.
Thanks, your videos really help me, Im beginning to think that my professor doesnt get any of these
Thanks, this saved me!
THX sir!!!
Thank u sir u owe me once again :)
so helpful !!
Hey, Could you please do an example for a partially cracked RC section
Awesome work @structurefree. I've got a question. I'm trying to understand what Phi*Mn actually means vs Mn. The equation for flexural beams is Phi*Mn> or equal to Mn. in this problem, Phi*Mn = 247.8 and Mn = 275.3. Phi*Mn is not greater than Mn. Can you please explain this, I'm a bit confused. Also, what do those values mean? Does it mean that this beam will fail at Phi*Mn? Cant thank you enough!! Thanks for all your great videos!!
Phi*Mn is the design moment strength or capacity. Mn by itself is the theoretical or nominal strength. We want the design capacity less than the theoretical so that there is some margin of safety.
+structurefree ok so if we want phiMn to be less than our Mn why is the equation written like phiMn should be equal or greater than Mn? If the beam Maximum moment let's say is 600 kpft we want to design the beam so it's actually less to have safety margin right? I guess my question is phiMn should be less than or equal Mn instead of it being phiMn is greater than Mn. Sorry for this stupid question just trying to wrap my head around it.
What will be the stress and strain diagram for a non-rectangular beam (ex. triangular)? Will it still be the same with the rectangular beam?
Thanks for the helpful video @structurefree It doesn't matter much but the area of #9 is 1.125 as the area = (n/8) => (9/8). #8 would have As=1.0 sq in
Hi Chad, thanks for the kind words. Actually the n/8 rule is for diameter of the bar and only works up to #8 bar. The #9 bar has a diameter of 1.128 inches which results in an area of 1 in^2. en.wikipedia.org/wiki/Rebar#US_sizes
You make concrete cool! Haha
You the best bro!
Could you help me out with some architectural work for a building im trying to design and build . I want to figure out all the strengths but it is fairly overwhelming .
is the nominal moment different from the yielding moment? If it is what is the difference in calculating the yielding moment and and yielding phi?
Hello. Could you answer a quick question. You found your strain to be 0.007 in the steel. By the hooks law E=stress/strain this would give a stress of 1400 mpa (203 ksi). This is far above steels ultimate stress capacity. I do not understand how we come up with a nominal moment capacity of 275 kip*ft which is based on a strain of 0.007 in the steel and still have a safe design.
Since 0.007 exceeds the yield strain of grade 60 steel, Hooke's law is not applicable...
+structurefree Thank you for that explanation. The only thing I am slightly unclear on is why isn't the strain we find through similar triangles the yield strain of the steel? Shouldn't it be this since we found the Neutral axis by setting the steel at yield and the Mu value is the moment the beam can take when the steel hits its yield
stress?
pls upload videos of column and footing design.
should we use Fc instead of Fc- and Fs instead of Fy in equations..because we don't know is the section steel at yield or not ?? and for Fc also??
appreciate your quick response.
hey dude, do you represent compression always on the upper side? Even if the positive axis is downwards?
were did you get the 0.85fc' is it standard??
+dollar bills it is from the equivalent or Whitney stress block.
Hey structurefree. What about in the equation where you have Phi*Mn is greater or equal to Mu. What does that mean?
That is the design relationship. Phi*Mn represents the design moment strength and Mu is the required moment strength.
I'm a consultant civil engineer and I really enjoyed the simplicity of the demonstration. Excellent job .
im having to do this in high school
sorry, i really don't have a favorite when it comes to reinforced concrete design. i feel like they were all written for students in the 1970s or 1980s.
Why are you treating the compression load as a uniform stress load, instead of a profile proportional to the strain, like it is modeled for introductory homogeneous beams?
the equivalent stress block is used in reinforced concrete analysis and design to expedite calculations. You could keep the nonlinear stress profile and integrate numerically to get a very precise result.
which text book you are recommending,,
thanx
Why is ACI ductility check performed
One answer would be to prevent brittle failure of a beam.
10:08, how if our assumption is wrong, that our epsilon s is lower than epsilon y?
Can anyone tell me which book should I refer
I like McCormac for a first course in Reinforced Concrete.
Thank you very much for your kindness and I will never forget your kindness
singly is such a strange word
Can anyone explain what you would do if the initial assumption was not true,
6:21
DONT EDIT YOUR VIDEO!!!!!!!! THere's no pause when im listening. It just goes on and on. Bro, I have no problem watching 20mins of a video. Just dont make it a non-stop-talking video. Your earlier videos with the little pauses, the uhs, the jokes, created a much more relaxed environment. Please dont edit your videos :( :(
Too fast ...........
Thanks, this saved me!