So good evening friends welcome to JS Civil. How are you all? Class is late, but you came.
Come on, it will keep going. So today we were going to do a water tank question. So let's do the question quickly.
For always, then I will say whether you have read the theory or not, it doesn't matter. Do as much as you can here. Revise the PDF you get.
The maximum questions of the exam will be made. Because obviously there is a water tank and liquid storage structure, so the real design will be a little complicated. But the questions that come in the exam are based on simple code provisions.
So we will do as many questions as possible based on code. Along with that, we have always put the source, the provisions of the IS code, its screenshots etc. So that we can understand the structure of the system.
So, here is the first question of the day. The permissible concrete stress in direct tension. You know that if there is a cylindrical container like this and if there is water in it, then and if you cut it from the middle so if I see what will happen from here the pressure of water will go out due to which the cylinder will be what will be created in this? hoop tension so what is the way of hoop tension? as if you are feeling direct tension on it So the permissible concrete stress in direct tension of M20 in calculation relating to resistance to cracking as per IS33701965, water tank code.
So what is the answer of all of you? The answer of maximum is absolutely correct. 12 kg per cm2 or 1.2 N per mm2. So in IS code, clause number 8.2.1 is given.
Plain concrete liquid retaining structures or members may be designed by allowing direct tension in plain concrete. The permissible tensile stress for M20 and M25 concrete being 1.2 N per mm2 and 1.3 N per mm2 for direct tension and 1.7 N per mm2 and 1.8 N per mm2 for flexural tension. For bending 1.2 is 1.7 and 1.3 is 1.8 so it is different in direct and in bending however nominal reinforcement in accordance with the requirements given in IS 456 shall be provided for plain concrete structural members ok so here we have given permissible concrete stresses M25, M30 M35, M50, for direct tension these values were there and for bending. Here there is no M20 so we have done M20 separately.
So if you are asked for M20 then you can also be asked for your other grades. So from here you will study, you will get it in PDF. Okay, next question. Considering the concept of durability of water tanks, the minimum grade of concrete shall be? Yes, how much will the minimum grade of concrete be for water tanks?
If you want to memorize it, then read it 2-4 times. At least do the question that has come in the exam. So, the answer is C, M30 is absolutely correct. So, water tanks are generally in open areas, so they are exposed to severe rain. Read the provisions of the IS code.
Provisions given in IS 456 and IS 1343. for concrete cell apply for reinforced concrete and pre-stressed members respectively pre-stressing ka aagaya hai, khoi baad nahi, iske aage de rakha hai ye wala dekhega IS3370 part 1 ke according ye table mein saari values di hui hai Concrete, plain concrete, reinforced concrete, pre-stressed concrete Minimum cement content 250 for plain concrete 320 for reinforced concrete 360 for pre-stressed concrete This is the minimum cement content Maximum free water ratio 0.5, 0.45, 0.4 Minimum grade of concrete M20 for plain concrete M30 for reinforced concrete M40 for pre-stressed concrete You can find the PDF in the telegram group. Why M20 is not considered? If you consider M20, you will say why M15 is not considered.
So the first thing is that where IS codes are used, you don't have to use your brain. If IS code has said, then it has said. because on the basis of experience, these things will come in the field. Everything has no logic.
The second thing is that as we go towards higher grade, the strength of the concrete will increase. So in liquid storage structure, you will want a certain minimum strength so that cracks do not develop when stresses come. That's why you will want higher grade.
Zoom a little more. Then you will allow M15, why M10 is not allowed? This question is always asked.
When we talked about durability and decided 5 different conditions, mild, moderate, severe, very severe, then there was also a question that why don't we allow M10 in all? Okay, Maurya ji, Ganpati Bappa Maurya. Chali, ho gaya, aage bani?
Check. Next question. The circular ring beam to resist thrust from top dome in ints tank is designed for hoop tension, hoop compression, bending moment, bending moment and shear force.
So first of all, you will remember that if the question is coming from the ints tank, the question is from the water tank, then in maximum cases, the design is going to be hoop tension is going to be the answer. So, the question is, what is the most important thing in the design of the water tank? If it is a circular ring and when pressure is applied, you will cut it from anywhere.
When pressure is applied in this way, what will be created here? Tension. What do we call it? Hoop tension.
Now what is an Inns tank? Please understand one more thing about this. There are two domes in an Inns tank.
This is a top dome and this is a bottom dome. This is bottom dome. Let's understand dome shape. Whenever water is filled in it, its pressure is like this that the net pressure is vertically downward.
So net pressure is like this. force is vertically downward horizontal force is not coming here so the water will fill the bottom of this This is empty. The bottom is made in such a way that the net pressure of the water will not go down.
One ring is made here and the other ring is made here. You can see the rest of the detailed lecture for this. There are different parts of it. The criteria of design as per IS code is the dome at the top is usually 100 mm to 150 mm. thick with reinforcement along the meridians and attitude the rise is usually one-fifth of the span ring beam supporting the dome cylindrical walls a ring beam at the junction of the cylindrical walls and the conical wall okay okay next question Sir, please put a 3D photo in PPT from Google, Achiever sir. Let's put it.
You think you haven't seen the lecture of water tank. There are 3D images also there. Let's put it.
But today's class is starting from a long time. You should understand that how much time you will get. Okay. As per IS 456-2000, the minimum grade of concrete shall not be less than the following in structural reinforced concrete work in concrete water tanks. We have just said that because PSC has already come in this.
M30. Next question. As per the Indian standard IS33702009, the minimum grid of concrete to be used in liquid retaining structure? Again, what will be?
M30. UPA asked this, MPA asked this. Next question. Sir, when will you teach in vision batch?
Sir, when will you teach in vision batch? We have already taught in vision batch. A little more routine.
Let's see if it can be decided once. The permissible bending tensile stress in concrete for vertical wall of an RC water tank made of M25 concrete is 8.5 N·m2, 6.0 N·m2, 2.5 N·m2, 1.8 N·m2 So, what is it for? For bending.
So, for direct tension, and for bending 1.8. Now we are reading this question from the back. As I told you yesterday that the benefit of QRP sessions is that if you do one question and you have seen its solution well or the content that is being provided to you, by reading that new questions can also be made in your exam.
As I told you that M25P has direct tension of 1.3. So, this is the M25P. So 1.3 plus 0.5, 1.5 is plus 0.5, 1.6 is 0.6, then 0.6 is added here. So in the first two you did plus 0.5, plus 0.5, then plus 0.6, then plus 0.6, plus 0.6, and then plus 0.7.
So, if you add 0.5 for epoxy mate, then you can go to the answer. Next question. The allowable bending tension in M30 concrete of RCC water tank.
So, we just saw that for M25, it was 1.3, so M30. Okay. so here also we are adding 0.2 then 0.1 then 0.2 and the value of this should be more right let's go So this value was 1.5, now how much we were adding in both? We were adding 0.5, 0.5, so it will become 2. So you can remember any value of 1 row. If you remember this, then you will get this value.
If you remember the data of 3 grades, then M20, M25, M30 is sufficient. Because it depends on how many tables you remember. So, remember 1-2 values at the beginning, that's enough. Or it's a simple idea, don't remember the question that came in the exam, at least remember that much. If you have a question of M30, then you will do M30, M35, whether you remember or not.
Many times the question is done by elimination. Suppose this is the question. Now you know the range. The range is 1.8 to 2.8. 1.8 to 2.1 means less than 3. This is 1.3 to 2.1.
If you have read it once, then if you remember the range, then 8.5, 6.0. At least you can eliminate this. Ok, did you understand?
If you have studied, you can also make questions with elimination. Next question. This is done.
Next question. In case of designing a water tank with LSM method to control the cracking, the maximum stress in HYSD steel bar should not exceed. So remember 130 MPa.
In the IS code, it is given Table 4 Permissible Stresses in Steel Reinforced for Strength. Tensile stress in members under direct tension, bending and shear. For plain, 115 and for HYSD, 130. Compressive stress in columns, subjective, direct load, 125 and there, 140. So, 130 should be the answer.
Next question. the allowable tension stress due to bending for m20 concrete in rcc water tank season yes, for m20 how much in bending? 1.7 in direct how much? 1.2 First is plane concrete liquid retaining structures and members may be designed by allowing direct tension plane concrete. M20 is allowed in plane and M30 is there.
The permissible tensile stress for M20 and M25 concrete being 1.2 and 1.3. And it was in direct and for bending you will add 0.58 in both, so it will be 1.7 and 1.8. It was told to you in the starting. All these have been already told you. Next question.
The applicable IS code for RCC liquid retaining structure. I have asked so many questions in which I have given the IS code. Which is 1.7 in 25. See. 25 is 1.8 1.2 plus 0.5 is 1.7 for M20 This is direct and this is bending 1.3 is direct for M25 and 1.8 is bending Clear? So let's go to STATIS 70 Next question If a circular water tank resting on the ground has 275 mm thickness, thickness is given to you, 275, grade is given, M25, concrete and steel is given, Fe415, the minimum percentage of area of steel AST, okay, yes, how much will it be?
0.24 Is it a rata? Everyone has written rata In IS code, there is a clause written May be you didn't get to read it The minimum reinforcement in walls, floors and roofs in each of two directions at right angle shall have an area of 0.3% of the concrete section in that direction for sections up to 100 mm thick. So for 100 mm thick, if 100 mm thick is there then it is 0.3%. For sections of thickness greater than 100 mm and less than 450 mm, the minimum reinforcement in each of the two directions shall be linearly reduced.
from 0.3% for 100mm thick section to 0.2% for 450mm thick section. Means it is saying that if there is a section of 100mm, means if there is a section of 100mm, then for this percentage you will take 0.3. And if it is more than 100 mm, then you will take 0.2 mm.
And if there is a thickness in between, then you will reduce it linearly. You only say that something is acceptable and something is not. Actually, according to me, your answer is wrong. So you got the wrong answer.
Let's see, if the answer is wrong, then it may be that my answer is wrong. So, I have made the statement here in this way that 0.3% for 100 mm and 0.2% for 1.5% for mild steel and will decrease it linearly. But it also says that the minimum reinforcement specified in article this may be decreased by 20% in case of H by SD.
So, 20% I think you calculated that for mild steel. You have calculated 0.24 for mild steel. Whereas, what have you given in the question? You have given H by SD.
FE 415. So, these values will not work for FE 415. If you reduce them by 20%, then what will be left? 80%. This will be 0.8, this will be 0.8.
This will be 0.16, this will be 0.24. So now you will get these values, 0.3 x 0.8, it will become 0.24% for H by SD bars. So 100 for 0.24 and 0.16 for 450. Now I have told you the formula of interpolation. What is the formula of interpolation?
y2-y1 upon x2-x1 is equal to y-y1 upon x-x1. Now what value do I know? This value is at 450 and this value is at 100. This was 0.24 and this is 0.16. Let's consider this as x. So I know this value.
So, my x1 is 100, x2 is 450, y2 is 0.16, y1 is 0.24. And I need this value here. Or I have actually written x only. So, I will take this value as x for a while.
Which I need. Just thickness. And in the question, So I have made an equation with this concept that 100 is 0.24, 275 is x and 450 is 0.16.
So I should have written y but I wrote x so it doesn't matter. So I have written y2 as x. You should know how to write the equation.
So x-0.24. upon 275 minus 100 is equal to 0.16 minus 0.24 upon 450 minus 100. Okay. This way it will take plus minus by itself.
Straight line slope equation is exactly the same. The slope of the straight line is the same equation. So from here you will get the value of x is 0.2%. So you do this. You solve this and see if instead of 0.24, Instead of 0.24, you can take 0.3 and instead of 0.16, you can take 0.2 and see if 0.24 comes.
See, instead of 0.24, you can keep 0.3 and instead of 0.16, you can keep 0.2. Quickly tell me if 0.24 comes. Quickly tell me if 0.24 is coming.
If 0.24 is coming, it means that the data of mild steel has been solved. while in question you have to write FE415 after simple line interpolation is there, if anyone has this, then tell them we have taught this many times, because we do this in design for shear we do interpolation in steel also in column design So, the answer should be 0.2. Correct it. You can make readymade formulas, but it is not necessary to make readymade formulas.
You can do it with linear equations. So, this is the answer. So, the answer is 0.2. Correct I have already done this. I had done it with 0.3 and 0.2, so it was getting 0.25 value.
So that is for mild steel. Sameer Karan, what is this? Sometimes I remember that I forgot that I have also studied all this in Hindi till class 12. Samikaran, Vrat, Saralekha, Parvalaya, Ati Parvalaya, Vek, Karan Okay Nazarji, are you going to give the exam in Uttarakhand?
Those who are going to Uttarakhand, be careful, the roads are closed there, okay, in some places the clouds have burst, it is very rainy, so wherever you are, First of all, take care of your safety. Exams will keep coming and going. So take care of your safety. Don't force yourself to reach the exam center. A reinforced concrete cantilever porch has thickness T.
The main reinforcement steel will be placed. This is a question that has been asked. Where will you do it?
In the cantilever. Close to the top surface. Samikaran Bolet equation.
Next question. For sections up to a thickness of 100 mm, the minimum area of mild steel reinforcement to be provided in walls, floors and loops of water tanks. Now, I have made so much of this in the last question that it will be remembered automatically. The one who has asked the last question will remember it himself. For mild steel, we will take 0.3 mm for 100 mm, for 450 mm.
For HYSD, multiply it by 0.8, then it will be 0.3, 0.2, 0.4, 0.2, 0.1. You remember everything. You can do it from here. So how much will it be? 0.3% of concrete section.
For 100mm. And my, remember, first of all, remember the thickness that it is 100mm. And second, my list.
Sir, for this exam, how much is there in BTEC? I don't think there is anything like that. percentage of steel reinforcement of H by SD bars involves slabs and roofs of water retaining concrete structure as specified by Indian standards is Minimum percentage of steel reinforcement of HYSD bars in walls, slabs and roofs of water retaining concrete structures as specified by Indian standards. Is there any thickness here?
Is there any thickness? No. So the answer is 0.24%. Minimum reinforcement is I.S.
code clause number 8.1. The minimum reinforcement in walls, floors and roofs in each of two direction at right angles. within each surface zone shall not be less than 0.35% of the surface zone cross section as shown in figure 1 and figure 2, we will see later for H-by-S high strength deformed bars and not less than 0.64% for mild steel reinforcement bars the minimum reinforcement can be further reduced to 0.24% for deformed bars and 0.4% for plain round bars for tanks having any dimension not more than 15 m.
For tanks whose dimensions are not more than 15 m, it is 0.24% for them. In walls that have less than 200 mm thickness, the calculated amount of reinforcement may all be placed on one face. Both the faces need to be provided.
So you have to give the answer according to this. Next question. The permissible stress for Fe415 steel in tension used near water phase for water tanks is 150. Here you can see table 22.2.
Allowable stresses in reinforcement nature of stress. Allowable stress in MPa. This will be for mild steel for HYSD. Tension in steel placed within 225 mm from water face.
So, there will be water inside the tank. Now, the water tank will have some thickness. So if you have provided reinforcement within 225 mm from the inner surface, then for plain mild steel, it is 100 mm and for HYSD, it is 150 mm.
Steel has tension, i.e. tensile steel, but it is placed far from 225 mm. In that case, it will be 120 mm instead of 100 mm and 190 mm instead of 150 mm. And the same thing will happen in compression.
If it is far from 225mm, then it is tension or compression. Again, new table. New table means PDF will be there. If you have any question, then at least you can write it down. At least you don't have to design.
You have to do the counting type questions. The IS3370 part 2 code has all this in it. From here the table is made.
Oh, your class ended very quickly today. Okay, so the water tank was the question. I was very shocked today.
Very small by my side. This is your envelope. Whether it is edge of tech or JSC below, I think it will be the smallest class of history.
But the maximum codal provision is complete. I hope it will come soon. Good thing it's over. So tomorrow we will start pre-stressing.
Let's do one thing, tomorrow you read pre-stressing and start pre-stressing. Rest we will do miscellaneous later. And in advance I congratulate you all on Independence Day. You guys put a tranga at home and share the selfies. Make every home tranga and make it successful.
Jai Hind. See, this is a simple problem. Many students think this topic is difficult because if you go to study its theory, how to design the ring beam, dome, and load, it becomes very difficult.
So, they leave the topic. My method is that leaving everything is not beneficial, so do PYQ. Do the previous questions and see where the questions come from. If you do it 2-3 times, then the exam question will be made.
Don't leave the topic. Don't remember the whole table. Do the exam question. And you have seen that sometimes he does one question and 4 questions become his own. And sometimes he keeps asking the same question in the exam.
So don't worry about the table, read the question and remember your theory accordingly. And don't even think about it. Sir, I have changed the pattern of questions. Now the question is a TCS statement conclusion.
Okay, you prepare it as it is. We are a little bit of a fat-minded people, we do it like this. So, I do it like this. People say that Sir, paper TCS, that company's paper TCS.
TCS just gives a platform. Like if your offline center is somewhere, suppose your offline center is in a school, then will it set the school paper? Paper comes from outside. So, what does TCS do?
only one online platform because it has a system, software where exams can be conducted the paper that has to be feed in it will be of Aayuq if TCS or any company starts making paper and take the exam then they will know they will sell the paper and do anything so we will take small things which are in the exam we don't know what TCS is asking Thank you.