Big Mistakes in RCC Slab - Lapping Mistakes - Reinforcement Mistakes - Civil Engineering

[@CivilEngineerss]

Remember Guys .. the Upper Bars Lapping should be Provided at the Mid but the tension Bars ( Positive Bars ) Lapping should not be provided at the mid but should be provided with L/4 Distance ... Thank you.

[@altain]

L/4 or L/3?

[@odecbuilders7655]

Since the problem is already there, What are the probable solutions? I am just curious. Thank you

[@arslanamar7011]

Well for bottom rebars of slab lap is on centre of support. For top reinforcement lap is in centre.

[@AbdulRaheem-kk8kv]

Sir I didn't understand that lapping length should not be done at the end of the support because shear stresses are more. What kind of lapping is that? Please clear my doubt

[@arslanamar7011]

@@AbdulRaheem-kk8kv for bottom bars laps are at support for top bars to cater negative reinforcement at supports there laps are at centre of span

[@khalidabdulrehman5742]

1. Same dia bars are used in two way solid slab. The distribution bars he was talking about are generally used in one way slab. 2. Lapping are provided at edges only, Moments are high at mid of span. Shear stresses are high at support he is correct but the bars he was showing was main bars (tensile bars) not the shear bars. 3. Lapping done at same point but it was done on alternate bars. so there is no issue. 4. Bleeding point he raised is correct. They might fix the holes during concreting. 5. As shear stresses are high at end support we keep the spacing less, no issues in the Slab reinforcement spacing.

[@jamshidpishgam3630]

If you provide lapping at the midspan it will have the same negative effect as they provide it at the face of support. The max shear is at the face of support and the max moment is at midspan so they should provide it somewhere between half distance from midspan to face of the support. I hope you got the point

[@muhammadmusab9952]

the lap should be near the support as there is high demand of moment in the mid span for shear support we have stirrups at the end. kindly review your knowledge.

[@jawidnikhat]

For a single mesh slab i agree with u Mr Muhammad but, if it is double mesh ,Any idia? Where should we provide lapping?

[@rawjor]

@@jawidnikhat areas of lowest bending.... there is not set rule that you cannot lap at the max bending but it is not recommended. (in canadian code) infact they recommend lapping bottom reinforcing @ the supports and extending a minimum distance into the support itself

[@starkey8616]

Lapping in a slab should be near the support, as the sagging moment is minimum. Lapping near midspan would make the slab less resistant to bending. Moreover, shear in a slab less than 200 mm is negligeable, the concrete shear strength is sufficient to resist it. Shear stress is resisted by shear links (if not negligeable) and not longitudinal bars. Please revise your theory as you could give wrong information to people!

[@nagahbk5746]

Yes i agree if lap is made in the middle there is a high chance for the failure of the slab

[@fayezali9351]

Bottom reinforcement must be spliced after L/3 distance & Top Reinforcement must be spliced with in the L/3 distance from support.

[@MrDangerousme]

As a QC Inspector i'm not really strict in terms of spacing as long as the number of bars required are provided. My main concern only is the bar lapping and the form shuttering opening that may cause bleeding and will weaken the concrete strength of the structures especially the elevated one/

[@barhomibrahim4828]

Isn't lapping must be a zone of zero Bending moment? If that so, the lapping of slab reinforcements here at the support is fine and not in the middle where maximum bending moment exist. If its a beam then the lapping should be done in middle for top bars only.

[@warrentyoso8391]

Barhom ibrahim Yes agreed to you. The bottom bar lapping must be near at support for a beam or low in bending but I think he care most of the concrete volume space rather than the lapping space reinforcement.

[@n.elosangeleskennels9062]

All I can say it's easier said than done. It's easy to get to the job site and say this should be built like this, or you built this wrong you made a Mistake. It's another thing doing the work and another thing to have control of the employees

[@warrentyoso8391]

N.E Los Angeles Kennels plans and specs must be followed, you can’t sacrifice safety and quality.

[@zia2066]

I agree with you is better to let the lapping be by the beam crossing the beam on either side

[@jomaabuel1048]

For steel fixers to understand easily if there's no placing drawing provided by the rebar engineer: A.) For beams or slabs... just tell them where to have splices: 1) within L/4 each side of span near the support for bottom bars; 2) within middle L/2 for top bars. B) For columns - within middle L/2 of its clear height but not more than 50% at same splice point...the other 50% (others are 33%) shall be spliced at the next floor level (same at mid-height for multi-storied bldgs)..however if spliced at same level, 50% splicing is staggered at usually 1 meter minimum.

[@sonydawhoirabon4956]

Lapping is correct to provide at those end part, but not at the central of the slab. Reason: max hogging moment will take place at the near end. And max sagging moment will take place at the central part of the slab in which tension will be at the bottom of the slab, hence it will become weak to provide lapping at central part of slab. The best way to provide lapping is at zero bending moment. By analysis, you can find the zero bending moment. For distribution bar it's ok to provide lapping at central but not for the main bar in case of beam. Similarly slab, lapping should not be provided for main reinforcement bar at central part.

[@shreshthsuthar4692]

I m civil student Watched you video firsts time, It was help full. Keep it up 👍

[@javedmohd1043]

Beam stirrup hook angle is 90 degree which can not be earthquake resistant provide 135 degree hook angle

[@nitish10verma]

Please read .. If you design a rrc slab we never cheack for shear failure because rrc slab never failure in shear but failure in moment so we can't provide lap in middle

[@skibee50]

Hard Rock hotel nola

[@gurpreets55]

nicely explained thanks 1 point i would like to make is you did not mention about the concrete cover, the steel seem to be sitting directly on top of the formwork should that steel no be lifted to provide minimum cover 50 or 40mm ?

[@namelastname8872]

You can lap the bottom bars of the slab at the support if it is continuous, as the hogging moment is putting the top bars in tension. It is the top bars (bars in tension) where you shouldn't lap at the support.

[@Camhab]

The main mistake is where they have bent the bars over the conduits

[@TheStructuralWorld]

Can you site your reference code saying that the distribution bar should be lesser than the main bar? In this site, we cannot easily tell which is the main bar and the distribution bar. Nevertheless providing a distribution bar diameter same as the main bar is actually safer than the distribution bar with a lesser diameter. As an engineer, we cannot say right away that this is a mistake without investigating the slab design analysis.

[@chris_skiller2542]

Nice

[@naseerhussain3741]

There are no cover blocks under the reinforcement

[@govinpillay1165]

I was afraid that this video might be misleading in terms of lapping but almost got that lapping for a 2 way slab should be near the support due to the fact that there would be induced moment at the centre of the slab, and thus having a tensile force acting at the centre of slab. Also the lapping o reinforcement can be in the same place however, providing alternate lapping helps to reduce propagation of cracks if it was formed.

[@kirkwilliams5740]

Thanks for sharing this video with us, you're so Right.

[@sajjadahmed7702]

Agree with your two point. 1. Form work seems poor, Due to continious bleeding ( water falling from concrete ) disturbs water cement ratio the end result will concrete looses its required strength. 2. Bar and striups spacing.

[@stanley_official1171]

They should not work hard but work smart. It doesn't matter if you finish the job fast, if it doesn't even fit the right qualities. The people's life is in your hands so be careful.

[@mehulvaghela1103]

As per IS456:2000 the lapping length for beam in comparison reinforcement is development length or 24dia whichever is less and its can be provided at beam column junction to 0.25L of the beam length. For tensions reinforcement the lap length is development length or 30dia whichever is greater and its can be provided at beam column junction to 0.25L of the beam length and lappingreinforcement is always alternatively provided.

[@anilraghavan911]

In construction field what we are regularly do the mistakes you were tell about clearly its a good opportunity to we are correction of my self what ever we are mistakes in construction a buildings its increase the building life and quality of working and perfection of the work this very important thanking you sir you were gave good informations...

[@sahilamaan8691]

1) Shuttering material should be oiled 2) spacer should be put to make space between armature and shuttering material 3) if one more layer of armature is gonna lay first layer should pass inside the beam and the second on beam

[@freakyguyciviltech460]

I think lap length for top bars of slab should be at mid. But bottom rebar of slab should be near to support within L/3.

[@zachleonard258]

big mistakes with the formwork the concrete will cure too quick because of all the gaps and make it weak due to extra water loss and shrinkage

[@ronaldojimenez9953]

My opinion as an engineer this structure is rejected during inspection especially the formworks there should be no gap in between the formworks for the water wth cement will leak-out.use plywood formworks suitable thickness instead.

[@prakashgupta7735]

In ur videos it clearly show that both bar cross the beam ,not end before beam.That type of lapping is more stronger than any type.

[@satyaganesh2410]

Well said bro exactly

[@jacobkuriakosegmail]

Yeah it seems like an additional bar through the beam... Not just slapping

[@user-ry4sc4kg6u]

I really very love this video yours Because of live explanation

[@KingPassa96]

Hello,you haven't mentioned about crank bars in beam and slab as well.

[@sil3nt_love]

steel should not attach to the ground. there should be some space between ground and steel.

[@dankok531]

Yea aci318-11 requires dobies for clearance, also the down turn beam is missing a lot of stirrups, lap splices are usually called out on plans, but if not 24" staggered

[@northfolkshaq3054]

absolutely, we call them cover blocks in my country, and they vary between 30 to 50 mm, depending on the structure being constructed, and should have the same compressive strength as the structure

[@mohammedhamid1473]

Cover block

[@dhieylharold6590]

@@northfolkshaq3054 yeah...in my country we call that concrete spacer blocks...minimum of 20mm...

[@logiclessmind1525]

@@northfolkshaq3054 cover should be provide: For slab:20mm -30mm For beam: 40mm-50mm

[@VinodKumar-lf2rs]

1. Main bar and distribution bar can be of same dia and the C/C distance between distribution bars can be increased. That will anyway will be decided based on one way or two way configuration. 2. You should have shown the structural drawing for easy understanding of the mistakes you are trying to show. Without a drawing how the audience will get a picture? 3. Lapping length is not provided exactly at the end support . Yes the lapping should have been staggered but definitely not st the centre of slab. 4. Wood form work crack lead to bleeding. 👌 perfect 5. Some points you probably missed out....(a) No extra bar provided at end support of beam as top reinforcement. May not be required as per the design but seeing the span it seems an omission. (b) Stirrups not bent inwards at 135 degrees as per the codal provision.

[@samihaidari6686]

Mr. Vinod Kumar, u have pointed out the mistakes in a much better way than this guy...

[@tagingtaggutaggu1527]

Why no crank/bend up bar at slab?

[@darthvader5300]

Military code requires that standard 1 inch thick rebars be used and spaced apart by 1 to 2 inches. All hoops should be .5 inch thick and spaced apart by 1 to 1.5 inches. There should be no splice connections in any concrete floor slab and all splice connections must be done at the beam bending downward at right side of the beam and bending inward to form a U shape upward hook if coming from the left and vice-versa if coming from the right. There should be no splice connections in the middle. For the beams any splice connections should continue through the post steel rebar and be bent-hook at the right side of the post main rebar if coming from the left and vice-versa if coming from the right. The wire ties should be double-twisted double wires so as to increase hooking-holding power after being tied together to hold the hoops and rebars together and that of the main rebars.

[@sreenivaspeddisetty206]

nice description, Thanks for giving knowledge.

[@anuragkhati4547]

Why dia should not be same ??

[@toseefahmad7162]

Lapping should be provided at the end of the support not at the mid of slab because of there resistance against shear.

[@suyesuay9813]

Moment not shear

[@deniskimaro278]

I think lapping at the support is more convenient than lapping at the mid span...

[@abidjaan7306]

Yah you right dear but it depend on designer but lapping at the support is correct.

[@ibrahimdahiru1584]

Exactly, because at the mid span the moment is at its greatest but at the support, the moment direction changes to top which the top reinforcement at support are provided to handle.

[@kondalraok6967]

Bro lap for slabs should be provided at ends only because slab is a flexure member

[@waynep343]

after a major earthquake near mexico city.. many building fell in mexico city.. including new hospitals.. they showed them starting to rebuild the hospital.. there were piles of sand, gravel and cement. and a guy with a garden hose.. each worker had a 5 gallon bucket and a trowel.. that is how they were pouring the footings for the new hospital. i called the mexican embassy.. actually got to talk to somebody about this. they had seen the same footage. thought how great it is to have so many working.. i said every time there is an earthquake that building will collapse.. that is no way to mix structural concrete.. it won't flex it will crumble.. they changed the work rules in mexico.. buildings are now only poured using batch mixed and tested cements. no longer hand mixed like you could do on a single story house..

[@kurulusosman8727]

после крупного землетрясения недалеко от Мехико.. многие здания рухнули в Мехико.. в том числе и новые больницы.. они показали, как они начинают восстанавливать больницу ... там были груды песка, гравия и цемента. и парень с садовым шлангом ... у каждого рабочего было 5-галлонное ведро и совок.. именно так они заливали фундамент для новой больницы. я позвонил в мексиканское посольство ... вообще-то мне нужно было кое с кем поговорить об этом. они видели те же кадры. подумал, Как здорово, когда столько людей работают.. я сказал, что каждый раз, когда происходит землетрясение, это здание рушится.. это не способ смешивать конструкционный бетон ... он не будет сгибаться, он будет крошиться ... они изменили правила работы в Мексике.. здания теперь заливаются только с использованием серийно смешанных и испытанных цементов. больше не смешивать руки, как это можно было бы сделать на одноэтажном доме..

[@bhagrathprakash7713]

Awesome understanding your voice and you are good at every pronouncian as well have good knowledge 👌👌👌

[@bolajiaiyegboyin3579]

You really think so?

[@ricagnes-w7o]

what letting len mistakes? thanks to your informative videos.

[@mehulvaghela1103]

Lap length of column is provided at mid span of the column and its lapping reinforcement is alternatively provided.

[@AMJADKHAN-do1nd]

Where are the bars for negative moment???

[@aakarfashion8062]

To confusing....you are talanted but need a graphical representation for us to get your idea clear.....

[@emmanueldeiparine9672]

Your are good engeener for inspection

[@coops6621]

Slab bottom steel laps at support with 40% minimum steel area through support, top steel laps .15x & .3x span length beyond face of support.

[@kuldeepsinghbisht5907]

If both bars dia is 12mm then what's the problem why it is wrong?

[@mazlytius1227]

Wastage myb, main bar and support bar

[@hypehype1982]

What about no bar chairs the rebar is just sitting on the form work, so it almost has no coverage after the formwork is striped leaving the rebar without any protection from corrosion.

[@ajmeeraugendar]

Excellent job Sir

[@walshakmyalshak9021]

I guess I am guilty of lapping at the support, can we see an example of lapping at the mid please

[@bakkiyaraj170479]

no my friend for slab is ok

[@mohammedali808]

No my friend. Lapping is best done where there is support. The narrator in the video was totally wrong.

[@jiban-100]

Bottom bars are lapped at supports..

[@toniebenbunao906]

@@mohammedali808 good thing took time to read comments since im in doubt with the other pointer he was referring to.

[@QubitBrain]

Slab and beam bars should not be lapped at center, it should be lapped at supports because because at center there is sagging bending moment and to resist shear at end extra top bars are provided to resist it and in columns lapping should be provided at centre not at ends. The reason for this is that the lapping must not be provided in tension zone of structural member. In beam and slabs, the tension is high at bottom mid span and in columns, the tension is high at top and bottom ends

[@CivilEngineerss]

Bro be careful don't provide lapping at the end.... Because we provide lapping length at mid.. BM is zero at the mid point

[@jinsonmemmanuel]

@@CivilEngineerss how can you even call yourself a civil engineer?? Please stop making videos like this

[@deniskimaro278]

@@CivilEngineerss Seriously... Who taught you that in the midspan, bending moment is zero...

[@deniskimaro278]

@@CivilEngineerss You're not serious my Brother...

[@yoonhong9098]

@Civil Engineers Bending Moment at midspan is ZERO? You are stupid.

[@maalabbangi5451]

The steel bars are arranged like mat, there is no cranked bars and extra bars

[@ubaidkhan-hj7yg]

How can we provide lap in mid of slab, please review it..

[@nuskynus8824]

Is it lapping is providing middle of the slab? Middle of bottom bars have more tensile force if we provide lapping at the middle of slab then structure will failure on there

[@mahtab220]

There is no cover and surface should not have oil before casting

[@taffythegreat1986]

If you have a big slab. Can your slab be poured in two or three goes

[@krishnarao6242]

Very helpful video.thanx

[@jonahnewmai1428]

Awesome.... Can I use 16mm for 15ft distance between two columns?

[@fzlyanbu5374]

Re Bars should be 2 inch or 50mm higher from the form -It should have approx 50 to 70mm concrete covering all sides

[@yeboahthomas815]

I was thinking so too

[@ukghconst]

chair on internal floor min of 25mm on ground floor min 50mm, min 25mm cover inner beams columns, on out side wall min 50mm, in foundations in wet land min space out concrete to r bar .75mm

[@josephsivadon8592]

Good video.. please.move camera slower... for us green guys..

[@ShokiNHousE]

Good 🎉🎉

[@sadiq5681]

So what is the effective of that laping

[@gulzamanksaofficial4717]

Which international standard you are using for the lapping zone

[@beutifullcreation2411]

Hello dear hope u will be fine actually I noticed something in your vedio that the lapping bar which they provided is correct coz in slab bottom (B) we should lap the steel in the supported mean l/4 area and top bar we should lap in the mid of the Spain mean l/2 I am saying coz the same rule we are following here in dubai and as per the design, its corect coz that area is the critical zone area also compression tension occurring sory I just share my experience one thing more there is no cover block touching with shutter

[@sarthakmohapatra3738]

Excellent video sir. thnx a lot

[@hikikomorihachiman7491]

Why not using dhalan plastic ?

[@imranhasanrose9174]

Is 10mm*10mm steel bar is ok with 4.5 inch spacing, for 1 story building with a rooftop room?

[@javedmohd1043]

shuttering oil not pasting ??

[@sajjadahmad255]

Dear engineer. What is difrence between scafolding, Form work and shuttering

[@kenrich1779]

Scaffolding is set up at the perimeter of the building Form work is set up for pouring of concrete shuttering is for large scale excavation.

[@Well_boyz_media]

theres no way you have any certifications in the united states (ICC Reinforced concrete)

[@RNGunding]

Very informative. Thank you sir!

[@suhailali1895]

He should review his knoweldge

[@thebest9023]

This is helpful 👍 I subscribe you 😇

[@sataraqaie1957]

No reinforcement knowledge is seen on this video. Completely wrong

[@sourabhpandey9424]

It's very easy to talk about the mistakes What bout the solutions

[@nowazishahmed3592]

can u provide some solutions plzz

[@rajaramramalingam6158]

Hallo Please do not misguide with some technical words. By Rajaram Structural Engineer

[@rajaramramalingam6158]

@Jay Ho Pl Go through the basics for reinforcing applications.

[@dmichaelsf]

@ARVIND KUMAR the lap should be near the support as there is high demand of moment in the mid span for shear support we have stirrups at the end. kindly review your knowledge.

[@alfredosugano1199]

Location of lapping is ok...review your theory of structure subject because ...slab is treated as beam so there is tension part and compression part...so if ever avoid lapping at tension area if possible but if you cannot avoid it , apply what the code recommend

[@babafakruddin2425]

Respected sir Some deficiency exiting in your demo regarding lappinp of reinforcement kindly ref code sir

[@janingolgadoolgado1008]

I Enjoy love to watching this vds about how to build house.i hope soon i can make my own house

[@MasterCivilEngineering]

Good luck bro

[@gsraman8909]

Sir, why should have provided stirrpS closely at nearby the beam column joints???

[@Agrkhatree]

It's not a lapping mistake.. The steel bars crossed the beam and that is good practice.. Yes, if top bars of beam lapped at support , than it is wrong because negative moment at support needs continuous bars...

[@babucheekkoth2752]

Sir in this video i sow a main reinforcement is placing above Dist bar, as a third layer. Is it sufficient take any load, as its located in N A of section.? Is any justification about it?

[@civilengrzafariqbal71]

if we have two layers steel in slab where should provide overlap

[@ramildalina7056]

Do you understand the bending moment and the shear stress as you are lecturing on lap sections

[@gendelavega9160]

Hi Sir yes I can see the open wooden flat form they have to fix that it will make the slab weak.

[@MasterCivilEngineering]

Yes

[@rohitkong6027]

i could see three nos of bars 2 x- direction and 1 y-direction or say 1 x-direction and 2 - y direction. what is the reason behing this?.. as per my knowledge there are only one main rf and distribution rf or nowadays double bars .

[@taffythegreat1986]

When you point out these mistakes in the slab. Are they detrimental to the slab. Worse case scenario, What would happen?

[@gamieylno9085]

Lapping of bottom rebar should be provided near support which is correct as shown in this video. Lapping of bars must be alternate.

[@syedmessinaqvi5926]

Bro we should provide lap at corner for bottom steel and at mid for top steel

[@mawkishrich3851]

Sir, we are building a 2-storey house and the schedule of columns are 4 (16 mm steel bars) and 2 (12 mm steel brs), the schedule of beam used is 4 (16 mm)?Is that okay? The steel of the beam used are heavier than the columns? Total floor area is 162 sq meters. Thanks for answering.

[@mohammadnowfal2466]

Slab reinforcement should be pass over the beam top reinforcement then only slab load will pass through the beam. In your case provide alternative provided , there is no benefit. Please advice us if iam wrong....

[@jaimesandoval1988]

He is a foreman's nightmare 😱

[@ahmadtasabhji4127]

overlapping should be located at lowest moment NOT lowest Shear , that's located as it's designed . And it should be mention in drawings

[@shubhambanarase7246]

I like ur video nice sir but in two way slab reinforcement of same dia on both. Side

[@sidiquemukkannan2547]

still, there is no cover between steel and shutter

[@georgemichaels2325]

What about the most obvious mistake. Not enough spacing between the forms and the rebar.Where are the metal supports ( chairs) to raise up the rebar grid from the forms?

[@ikechukwuanyanwu2099]

You have max moment is in the span, the reinforcement shouldn't be bent around the pipe in the centre.. Span reinforcement should be continuous... I also can't find biscuits (concrete cover) for the reinforcement

[@ka09kempured78]

Thank you so much sir 🙏

[@toseefahmad7162]

Dear present lapping zone is in best position not wrong. The lap must be provided near to the beams not in center of the slab becaue of max bending moments.... Focus on Main structural Components how to stabilize all Components. Thanks

[@selvarajmurugan9996]

One video you said lap length provided near support but latest video you said lap length provided on mid span too much confusion

[@aruneesh4542]

Thank you bro, it's very useful of civil supervisors ,

[@masterhumayl]

Lapping should not be at center, as bending moment is maximum at center. Lapping should be at point where bending moment is zero and it is near the support at bottom face. Lapping should not be more than 50% of the steel at one section, They are using lapping in 50% steel at a point, so this is correct. Hence, lapping is correct in video.

[@GuestGuest-ik2jt]

Where is the temperature bars on the top of slab?