Punching Shear in Foundation & Slab with 3D Animation

This video shows the punching shear failure and punching shear mechanism in foundation and flat slab. Punching shear also known as two way shear. It is the shear failure of the structure member due to high concentrated loads or high localized forces. For more detail please watch full video.
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#Punching #Shear

[@SomeshMathur92]

You could also add shear reinforcement in the area where punching is governing to prevent failure.

[@MIDNIMOJANAQOOW]

Smart engineer.
Concise and well explained content.
I appreciate you.

[@civilengineering94]

Thanks

[@klam77]

Champlain Towers bought me here! Punching shear. Those balcony slabs surely look very very THIN===> punching shear.

[@robertbrandywine]

The balconies had no columns to punch through. The initial punch through was caused by the 10,000 pound planters and the falling slab put lateral pressure on the building columns. I don't like this type construction.

[@klam77]

@@robertbrandywine yes, a lot of subsequent simulations have come out showing how even collapse of the pool deck (which was cross-tied to under designed main building support columns) helped start the collapse. Problem with RCC is its' like a daisy chain collapse!

[@robertbrandywine]

@@klam77 RCC?

[@klam77]

@@robertbrandywine some people call it "RCC" (re-inforced concrete cement) some people call it rebar built etc etc.

[@klam77]

@@robertbrandywine also, someone called @screamdoctor did visual analysis and it was actually marginally UNDER SPEC for load: "The remaining construction that was visible from photographs, showed a complete lack of thickened column caps at each column and where the columns punched through the pool deck, a complete lack of internal lateral closed loop ties that confine the top of column concrete core and the vertical column reinforcing bars. (2 are required at each top) Consequently, there was either a 2-way punching shear failure of the pool deck slab or an internal shear failure of the column tops, turning them into spears that easily knifed their way through the pool deck. No investigation would have likely discovered the completely absent lateral ties in the top of the columns unless the original plans omitted those lateral ties as well. But a simple 2-way shear stress investigation could have discovered the apparent overstress in the floor slabs at the columns since there was no column cap at each floor. For a 9 inch floor slab on 20'x30' column grid locations. The 2-way required design shear load would have been about 164 kips. However, the 2-way available shear capacity would have been about 154 kips. This assumes 18 inch square columns, 20 psf partition live load, 50 psf live load and 3000 psi floor slab concrete. So with no column caps, the floor slab appears to be overstressed in 2-way shear even before we consider cracks due to rusting rebar. The spear action represents an even greater overstress condition, and it took place with no live load on the pool deck. This rough analysis ignores the presence of cracking due to rusting rebar."

[@Phantom-sb2ld]

I fee like this was the cause of the Surfside Florida building collapse.

[@klam77]

Those balcony slabs sure looked THIN! Ideal for punching through.

[@dattatrayajantali4861]

Topic described is easy to understand very good experience of understanding difficult subject.

[@civilengineering94]

Glad to hear that

[@engrraufkhan3114]

Well explanation

[@civilengineering94]

Thanks for liking

[@vishwajeetbudruke2551]

Great Sir..We appreciate your efforts towards civil engineering lecture..All video's are very useful for us.. and provide more important lecture on RCC

[@civilengineering94]

Thanks

[@zaafraneomar1294]

Thanks for your simple explanation
I want to add also there is a punching phenomenon in the soil that usually supports big structures such as retaining walls

[@kingdomfor1]

You may have noticed that the example pictures of punching shear in various buildings on the internet, seems to be car parks or slabs exposed to the elements, this was also the case with the pool deck in Champlain towers in Florida, the evidence is pointing to the failure of the pool deck due to water penetration , which triggered the collapse of the main building , I think slabs that are exposed to the weather, should not be built slab directly on top of column, but should have pads on top of the columns or cross beams for extra support.

[@sivaji300]

For avoiding punching sheer in slabs. 1. Drop panel. 2. Column capital and 3. Increase the area of steel at top side of support (negative bending or tension area)

[@civilengineering94]

Yes exactly

[@annbrinda7253]

What should be approximately the span bw two column in flat slab? And the size of column to that span?

[@jlee29170]

Fascinating.

[@waisalam8630]

Thank you brother , it is very useful video

[@irfanaparari280]

Very helpful explanation. Thank you sir☺️

[@civilengineering94]

(Y) #Irfana

[@saisekhar5454]

Good explanation sir !!!!

[@civilengineering94]

Thanks and welcome

[@nithinchary3447]

good info from ur video

[@robertbrandywine]

How are the columns attached to the above ground slabs? Are they poured together? Is there rebar running across the join?

[@civilengineering94]

Yes they ar poured together.

[@hafizabdullah1312]

Sir do make a detailed video on column capitals and droo panels.
And great video 👍👍👍

[@civilengineering94]

Thanks dear Hafiz

[@dattatrayajantali4861]

Surprise handwriting similar to me !

[@civilengineering94]

That's cool!

[@sheikhkais4140]

It is so great sir
Thank u

[@shrutipattar6599]

Good explanation..

[@civilengineering94]

Thanks #Shruti

[@ssajid40]

Asalamualaikum..
Sir, I have seen on our site we use some columns which have a mushroom head. Is this to avoid punching shear?

[@civilengineering94]

Yes sure it helps in avoiding punching shear

[@gorillaau]

@@civilengineering94 I have seen analogy of a pushing a pen or pencil through a piece of paper. The point of the pen will go through the paper a lot easier than the blunt end.

[@Szhihihihihihi]

Thanks

[@civilengineering94]

Welcome #Teh Soon

[@Panther-]

Your explanation is very good,excellemnt in fact, but... you need to improve your drawing hahahahah

[@civilengineering94]

Ok. Thanks

[@Ordinary-person62]

Awful

[@mohanbabupm5778]

Best rxpln easily u.nderstood

[@civilengineering94]

Thanks