6 Big Mistakes in Beam Construction

追加: 2026-05-14

[00:00:01]Welcome back to Civil Engineers YouTube channel. In this video lecture, I will guide you for six big mistakes in the construction of RCC beam. Guys, you can see clearly this is beam.

[00:00:14]And now let me guide you for details and this is RCC column.

[00:00:20]Column and these are two supports especially for this beam. So, we have six big mistakes in beam.

[00:00:28]So, let me guide you for these big mistakes. The first one is especially for the Guys, you can see for the hooks, right? Hooks which are we are Sorry, not hooks for the development length. The first one is for the development length.

[00:00:46]What is development length?

[00:00:49]So, this is development length. Guys, you can see here this is a beam and these are two support. So, guys you can see clearly this is RCC in beam. These are steel reinforcement. So, it should be bent to the downward side and this one also. So, now guys the bottom bars should be bent to the upward side like this. Guys, you can see like this and which are connected to these columns steel reinforcement. Like this.

[00:01:15]Guys, you can see here this is the steel which should be bent to the downward side and this is a bottom steel reinforcement which is called tension zone. It should be bent to the upward side. This is called development length.

[00:01:28]DL Right? So, this is development length.

[00:01:31]So, the development length should not be less than 12 in.

[00:01:36]Okay? But in many construction I saw them in six big mistakes they are not providing development length. So, it should be provided like this. So, this is the best way. So, don't do same like this. This is the wrong way for the development length. Right?

[00:01:49]Next guys, here as you can see guys this is a span. So, the span suppose which is 20 ft for example.

[00:01:57]This is 20 ft span, so the span should be divided by L by 4. L by 4 mean this is span which is called L. Right? The L is 20 ft, so the length should be divided by 4. Here guys, we have 20 ft divided by 4, where we have 5 ft distance, okay? So guys, you can see this is and this is This is called L by 4 distance. Here we have more chances of cracks. To resist cracks, here we should provide the stirrups closely, guys you can see like this. Look at here, and now you can increase like this.

[00:02:35]Okay? Again, at the distance of L by 4, it should provide closely.

[00:02:40]And we have big mistakes in this point.

[00:02:43]Wait, guys, you can see clearly. Let me guide you. This is a beam steel reinforcement. Inside this we are placing the uh what we can say, the stirrups. So guys, you can see here uh this is steel reinforcement.

[00:02:58]This is L by 4, right? And this is L by 4. Here we have one support, this is other support. Guys, you can see clearly.

[00:03:07]Look at here. So now we have more chances of cracks. To resist cracks, so here we should provide the spacing closely, same like this, guys, you can see to the distance of L by 4, same here.

[00:03:20]And you can increase here. So here, remember the die of the steel should not be less than 8 mm 6 mm minimum 6 mm minimum with the spacing of 6 in center to center, okay? But here guys, it should not be less than this, right?

[00:03:38]It should not be more than this, but the normally I'm recommending you use 4 in center center to center, right? Uh uh 4 in like this, center to center spacing. But here you can go up to 7 in.

[00:03:54]This is very important for you people to know about this point. This is and these are two big mistakes. Next, guys, you can see the third one. So, this is the first one.

[00:04:04]This is the second one. The third one, guys, you can see here. This is a beam section. So, the width of the beam should be less than its depth. So, guys, if this is 9 in, so the depth should be 12 in.

[00:04:19]So, the depth should be 12 in. But, normally, uh we are providing the same size, 12 by 12 in. So, the width should be less than depth. So, the depth should be more than width. So, this is the third big mistake that people are using like this. Now, let me guide you for the steel reinforcement. Suppose, guys, this is a beam.

[00:04:39]Right? So, they're providing two bars at the bottom and two at the top. So, this is the wrong way. Two at the top.

[00:04:47]Two at the bottom. This is the wrong way. So, what is the correct way? So, here, guys, you can see this is the correct way.

[00:04:54]Okay? Use minimum three bars at the bottom, two at the top. Because concrete is weak in tension, so therefore we should provide maximum numbers compared to the top portion and two at the top.

[00:05:05]Don't use two at the bottom, two at the top. If you are providing three at the top, so provide four at the bottom.

[00:05:12]This is very important for you people to know about these points. Next, guys, remember, don't use less than the uh other big mistake we have normally the people are using here uh 10 mm die of steel rod. Okay? So, don't use 10 mm.

[00:05:27]Use at the bottom minimum 12 mm. Also, at the top you should provide minimum 12 mm die of steel rod, which is very important for you people to know about this point. Next, guys, we are providing hooks. Guys, you can see here. This is the stirrup. So, it should be bent on 135°.

[00:05:46]Not same like this, guys. You can see.

[00:05:48]Normally, the people are using like this. So, this is the not correct way. This is the correct way. Okay? And the hooks length should not be less than 3 in. So, right? So, guys, you can see here. These are the details specially for the six big mistakes. Next, guys, in the beam, which is very important for you people to provide extra steel rods at the distance of L by 4. So, extra steel rods are important. Extra rods which should be provided at the distance of L by 4 as I discussed here.

[00:06:20]Uh because we have more chances of correct same like this, guys. You can see.

[00:06:24]Here we have negative bending moment.

[00:06:26]Here we have negative. Here we have positive bending moment. So, therefore, we should provide extra steel rods to resist negative bending moment specially in beam. So, guys, these are six big mistakes. So, you should avoid during construction site, otherwise, you will face more problems. Thanks for watching.

[00:06:42]See you in next video.

[00:06:44]Goodbye.