r/StructuralEngineering • u/theVampire05 • 2d ago

Structural Analysis/Design Concrete breakout

Hi all,

Could someone explain me the concrete breakout as per the Eurocode 2. I am confused in understanding how to interpret the figures in the code.

And what if the breakout extends the length/width of the concrete base, how does it affect and basically how to check and satisfy the breakout of the concrete.

4 Upvotes

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5

u/Chuck_H_Norris 2d ago

Idk about the euro code, but the width of the breakout cone is certainly limited by the edges of the concrete

2

u/scodgey 2d ago

Edges are covered in the standard already (c vs c_cr,N for example).

What are you struggling with?

1

u/theVampire05 2d ago

I need to know how to verify it and what happen if the cone exceeds the edge of the concrete and spread/cuts the side lines of the cube or concrete member

3

u/scodgey 2d ago

Follow the equation for N_rkc.

N_rk,C0 is self explanatory.

A_c,N is the cone plan area accounting for edges. It's a square/rectangle in plan, with each edge 1.5 h_ef (c_cr,N) from the anchor or anchor group. If that overlaps with an edge, you use a reduced value equal to the distance to that edge (c, c1, c2 etc).

A_cN0 is just a square with sides 2h_ef. The rest you just plug in to produce reduction factors.

The diagrams are pretty clear no? Are you not looking at them?

1

u/Marus1 2d ago

The second part of the comment tells us you look at this from a theoretical point of view. What happens when the cone falls outside the edges of the slab, is fairly intuitive when you understand what happens instead of filling in formulas

Stop! Try to imagine a concrete cone failing, to see it in front of you

2

u/Board_Realistic 2d ago

The code sets out the area of an imaginary perfect cone and then you input the area of the actual cone as a reduction

-1

u/Abstract-tea Eur Ing 2d ago

I usually do those calculations through some kind of software and I havent really witnessed any of them take into consideration the REBAR inside the foundation. Without rebar, the foundation dimensions can skyrocket really fast. Im assuming you're probably designing RC foundations so it makes no sense to calculate the breakout as if the concrete is not reinforced.