Bhai.. everything u said is correct except the last part @6:01. Strain in steel at failure will be (0.002 + (0.87fy/Es))... Thus steel will fail before concrete crushes for under reinforced section...
Thank you for the informative video. I am building a load bearing house using red laterite stone and NO concrete. I would welcome a video on load and strees issues for such construction. 🙏
When the compression zone is "stronger" than the tension one, I would talk about an overdesigned compression zone, rather than an under reinforced beam. Similarly when the tension zone is "stronger" than the compression one, I would talk about an underdesigned compression zone. The reference that has to be taken into consideration is the value that was calculated. From there, if some reinforcement is added, which I would call overreinforcement, the only problem it results in is the additional cost. Not the risk of brittle failure of the compression zone. If this happens, the problem is not the over reinforcement but the under design of the whole.
I agree with what you are saying, but the decision of whether to provide an over or under reinforced beam depends primarily on site conditions and practical restrictions. An under reinforced section is preferred for its lower cost and safety factor(If higher depth beam is available) an over section is chosen when there are depth restrictions.
Thank you for that wonderful comment Harsha. There is no non destructive way of checking if a beam is over or under reinforced. You have to check the design of the member to confirm the type of beam design.
I would like to say just awesome videos.....sir just try to make video of other subjects also.....and we need to know what is probability distribution curve....etc.so plz make great animation over it....it will be great helpful for us......tx sir keep doing
@@ReactionTest0 great.. Can you please make a tutorial on that how these kind of animations can be made by Blender.. Please its a request... Thanks brother..
Sir if we provide same dia and amount of steel in top and bottom in beam so how do beam react at ultimate load does this thing is ok or safe ...??? Does beam shows crak before fail..??
More context is required to give any answer. For example, what is the magnitude and nature of load, the section size, bar size, grade of concrete and steel, etc. Manual design checks are then required to ascertain safety.
And what about the beam upper bars in compresion and stirups how do they act in under rienforced or over rienforced beam ..becaus in your video you only show bottom tention bars..???
Thoda parlo, hum civil engineer hai, kuch bhi bana diya toh logo ki jaan chali jaegi. Thoda parlo bhai aur accha building banao. Thank you video dekhne ke liye.
@@ReactionTest0 you are doing amazing by creating such videos, actually there's one of my favourite channel named The Efficient Engineer, they use similar animations so I got curious about where they draw these animations
It is wrong to say that under-reinforced bean is safer. there is nothing safer for a weaker beam than a stronger beam. In fact, the safety aspect depends on the actual load applied to the beams. this video fails to present that over-reinforced beams can bear higher loads than under-reinforced beams.
For a singly reinforced beam, under reinforced sections have better safety because, when under reinforced, the steel fails first and because steel is ductile in nature, there is visible deformation that gives a warning before there is complete failure. While in case of over reinforced beam, concrete will fail first and since concrete is brittle in nature, the section will fail suddenly without warning. This is the primary reason why under reinforced beams are preferred instead of over reinforced beams when singly reinforced. I hope this solves your doubt. Thank you for reaching out🙌
@@ReactionTest0 Whatever you said is exactly the same as mentioned in the TEXT books, but u have misunderstood it totally. The only 2 reasons why under-reinforced beam are recommended are: (1) visual warning under excessive load. (2) lower cost. But it is definitely not safer. Because visual warning only occurs under excessive load. And the level of excessive load is different for both under-reinforced and over-reinforced beams. Over-reinforced beam has more tensile strength than under-reinforced beams, so at a given load, the under-reinforced could start to break whereas the over-reinforced could still have tensile capability and withstand the load. So it is not definite that under-reinforced is safer. But it surely shows visual warning signs when it starts to fail.
I was looking at this as a reference for game development. We want to make more realistic environments and didn't know the difference between the X Reinforced Sections. Very nicely explained, and the 3d modelling definitely helps the demonstration!
In short, either rebar snaps first or the concrete at the top half of the beam suddenly crush. Ideal case is where the concrete crack becomes visible at the bottom so there is enough time to react, and in the mean time, the rebar holds the cracks .
Yup that's right. But this is for general case and educational purpose. In practice if the load is high enough, there is no option but go for Over reinforced beam as you can only increase depth to a certain amount.
kinda got clickbaited by the title i thought for sure it was a video that's gonna actually do utm testing on those different reinforcement types with actual beam sections.
If you then compare steel to concrete; would you say that concrete provides building material while steel holds it all together in the function of the two?
Both serve their own functions, concrete is exceptional in compression but barely contributes to strength when it comes to tension. Hence, in the tension zone, concrete provides strength. While in the tension zone, steel is responsible for strength.
If we make stronger concerete ratio in over rienforced beam so does it act like under rienforced beam ? and does the strain or yield of beam get high or stronger ..????
Great question, but there is no absolute answer to this. It is relative and depends on the load, area of steel provided initially and the increase in concrete grade.
I don’t know why this was in my recommended, I don’t know anything about this stuff and I am terrible at any kind of math. But I watched this anyway because the way you say “concrete” sounds really nice in your accent, and your animations and diagrams actually made these things make sense to me and I know nothing about this stuff, so there’s proof you’ve made a great video if you can make things make sense to a dummy like me! It was very interesting :)
Strain diagrams I don't know why you are changing the slope of the strain line for steel and concrete.... They should all be the same slope. Depending on the over-, under- or balanced reinforced sections, the N.A will change and determine which component reaches its limit state first.
Great video! The only point that you brought up in this video that I would contest is that 'overreinforced' concrete beams are more costly, less economical and more dangerous. That is not actually inherently true. Firstly, you might have height restrictions for your beam depending on what you are designing, and therefore must over reinforce the beam. You don't always have the option in real world design to make your concrete section bigger. Also, AASHTO LRFD and ACI specify a reduction factor of 0.65 for concrete beams with 'compression controlled failure', and a 0.9 reduction factor for tension controlled. I don't think it is fair to say that compression controlled failure is 'more dangerous', when you have a stronger section and a lower reduction factor. If you don't believe me, design two beams simultaneously (for same maximum bending), one for compression controlled failure and the other for tension controlled. The computations will prove to you my point on that. Whether one or the other is more or less economical, is completely dependent on what you are designing. That is a common misconception that compression controlled failure is either 'not allowed' or ' inherently less economical'.
I completely agree with you 100%. But I made this for students who are being introduced to this concept for the first time. So for explanation purpose I said you prefer an under reinforced section. But I don't mean to completely disregard the use of over reinforced section, they have their place like you've stated. I hope this answers the reasoning behind my statement. Thank you for bringing this up, others might also have had this doubt.
A designed height limit wouldnt result in an "over reinforced" beam. if the load requires a certain amount of reinforcement than it will be designed to such specification. an over reinforced beam would mean that it is unnecessarily strong for its intended use.
@@tamaninesauc Correct. Sometimes people use the term 'over reinforced beam' when they mean 'compression controlled failure'. I was simply using the same verbiage that was used in the video for clarity.
First, in under reinforced section, the failure begins with the yielding of steel before concrete crushing in top chord. Secondly, in case when the reinforcement ratio is too low, beams might fail due to steel rebar rupture without concrete crushing at top part. These two failure mechanisms are different to over reinforced section which is needed to elaborate.
Thank you🙌 I've also released a new video. It talks about the principles which dictate if an object will float or sink in water. Watch it and tell me what you think.
You say it's compression on top and tension on bottom, but then keep showing a fixed-fixed beam deformation instead of a pinned-pinned beam deformation. So 4 seconds into the video and you are already showing wrong information.
Good eye, thanks for pointing out the oversight. The deformation should have been for a pinned-pinned connection. Will make sure such errors are avoided 🙌
Bro.new subscriber here! Mera Q hy ke hard starta soil par load bearing type house keliye strip foundation magar without reinforcment banana hy tu kia strip foundation without reinforcment 40feet long 2 feet deep 2 feet wide bana sakte hy??
Always follow the code rules in regards to steel ratio, do not go beyond the limitations especially with large beams with long spans. Nice video mister.
Great video man! I will surely recommend your videos to my friends. One correction- you have to reduce the scale of stress strain curve of concrete with respect to steel.. Because, steel has higher yield stress value compared to concrete.
