Check punching shear at a flat slab edge column to Eurocode 2, with link design and the outer perimeter. Try the free calculator.
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About this EC2 Punching Shear at an Edge Column Calculator
This calculator checks punching shear in a flat slab at an edge column to EN 1992-1-1 Clause 6.4. An edge column has slab on three sides only, so the control perimeter is open and the eccentricity factor is higher than for an internal column. The calculator works out the basic control perimeter, the design shear stress, the resistance without reinforcement, the crushing check at the column face, and where reinforcement is needed, the link area, spacing and the outer perimeter beyond which none is required.
- Structural engineer. Enter the column size, slab depth and support reaction, and read whether punching reinforcement is needed and what arrangement satisfies it.
- Design reviewer. See the control perimeter and eccentricity factor used, which is where edge and internal columns are most often confused.
- Engineer optimising a slab. Use the chart of stress against slab depth to see how much thickness is needed to avoid links entirely.
Every expression is shown with the clause behind it and units are carried through the calculation. It is an engineering-grade calculator you can audit, adapt and save to a project page in CalcTree.
More info on EC2 Punching Shear at an Edge Column
Inputs
Column dimensions, slab depth, cover, bar and link diameters, the design support reaction, the eccentricity factor and the flexural reinforcement in each direction. The reinforcement is entered per metre width and is used to form the geometric mean reinforcement ratio.
Control perimeters
The basic control perimeter sits at twice the effective depth from the loaded area and, for an edge column, runs to the slab edge rather than closing around the column. The column perimeter used for the crushing check is capped for an edge condition, which is one of the differences from the internal case.
Design checks
Three checks apply in sequence. The stress on the basic perimeter is compared with the resistance without reinforcement, the stress at the column face with the crushing limit, and where links are provided, the stress on the basic perimeter is capped at twice the resistance without them.
Reinforcement
Where links are required, the calculator gives the area needed per perimeter, the radial and tangential spacings with their code limits applied, the minimum link area, and the distance out from the column face at which reinforcement can stop.
Common Calculation Errors to Avoid
- Using the internal-column eccentricity factor. An edge column attracts a higher factor, and taking the internal value understates the design stress.
- Closing the control perimeter around the column. At an edge the perimeter is open and runs to the slab edge, which gives a shorter perimeter and a higher stress.
- Taking the reinforcement ratio in one direction only. The ratio is the geometric mean of the two orthogonal ratios, taken over the column strip width.
- Missing the crushing check at the column face. It is a separate limit from the basic perimeter check and often governs for a small column carrying a large reaction.
- Leaving the tangential spacing uncapped. Code limits on radial and tangential spacing apply, and the provided area must be based on the spacing actually adopted.
- Assuming links solve every case. Where the stress at the column face exceeds the crushing limit, more links do not help and the slab depth, column size or concrete grade must change.
Engineering templates
Common calculators
Design guides
FAQs
How does an edge column differ from an internal one?
The control perimeter is open rather than closed, so it is shorter for the same column, and the eccentricity factor is higher. Both push the design stress up, which is why an edge column often needs reinforcement where an internal one of the same size does not.
What if the stress at the column face is too high?
Adding links does not help. That check limits crushing of the concrete strut at the loaded area, so the fix is a deeper slab, a larger column or a higher concrete grade.
Which reinforcement ratio should I enter?
The flexural reinforcement in each direction over the column strip, entered per metre width. The calculator forms the geometric mean of the two, which is what the clause uses.
How far out do the links need to go?
The calculator reports the outer perimeter at which the stress falls to the resistance without reinforcement, and the corresponding distance from the column face, together with the number of link perimeters that implies.
Does this cover a column head or a slab with openings?
No. Openings near the column reduce the control perimeter under a separate clause, and slab-column connections with column heads are treated separately again. Both sit outside this calculation.
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