Check concrete edge failure of an anchor or row of anchors in shear to AS 5216:2021 Clause 7.2.3, with every factor shown. Try it free on CalcTree.
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About this Concrete Edge Failure of Anchors in Shear Calculator
This calculator checks the concrete edge resistance of a single anchor, or a row of anchors parallel to the loaded edge, in shear towards that edge, to AS 5216:2021 Clause 7.2.3. The resistance of one anchor far from side edges is scaled by the area of the breakout body on the edge face, after neighbouring anchors, side edges and the member thickness have cut it down, and then by the factors for the nearer side edge, the thickness, the load angle, an eccentric shear and the edge reinforcement.
- Structural engineer checks base plates, brackets and handrail posts fixed close to a slab edge, where edge breakout usually governs shear.
- Facade engineer verifies bracket anchors near the edge of a slab or upstand under wind and dead load shear.
- Graduate engineer follows Eq. 7.2.3.1 term by term, with a plan and elevation of the breakout body, to understand how each factor moves the result.
It is an engineering-grade CalcTree calculation, with live equations that can be audited, reused for the next edge condition and kept with the project.
More info on Concrete Edge Failure in Shear
Basic resistance
The resistance of one anchor unaffected by side edges, thickness or neighbours follows Eq. 7.2.3.2, from the nominal diameter d_nom, the effective length l_f, the concrete strength and the edge distance c1, with k9 for cracked or uncracked concrete. The effective length is the embedment depth capped by a limit on d_nom, as Clause 7.2.3 sets out.
Projected areas
The breakout body of one ideal anchor shows on the edge face as a rectangle three times c1 wide and one and a half times c1 deep, giving A0_c,V. For the row, the actual area A_c,V is its width along the edge times its depth, with the end anchors limited by the side edge distances, spacings limited where neighbouring bodies stop overlapping, and the depth cut off by the member thickness.
Modification factors and narrow members
The side edge factor ψs,V (Eq. 7.2.3.4), the thickness factor ψh,V (Eq. 7.2.3.5), the eccentricity factor ψec,V (Eq. 7.2.3.6), the load angle factor ψα,V (Eq. 7.2.3.7) and the edge reinforcement factor ψre,V all multiply the area-scaled resistance. In a narrow, thin member, Eq. 7.2.3.9 replaces c1 with a reduced c′1 throughout.
Design check
The characteristic resistance V_Rk,c is multiplied by φMc to give the design resistance, and the page reports the utilisation against V* with a pass or fail for the verification of Clause 3.4.3.
Common Calculation Errors to Avoid
- Missing the narrow-member rule overstates the resistance where the larger side edge distance and the member thickness are both small against c1.
- Using the bolt diameter for a sleeved anchor understates d_nom. Take the outside diameter from the approval, which for a sleeved anchor is the sleeve.
- Claiming the edge reinforcement factor for bars alone is not allowed. The increase needs edge bars with closely spaced stirrups or mesh, and applies in cracked concrete only.
- Measuring the load angle from the edge instead of the edge normal inverts the load angle factor. Shear straight towards the edge is zero degrees.
- Checking the wrong row of a multi-row group misses the governing case. This page checks one row, and the shear on it comes from the force distribution.
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FAQs
What is concrete edge failure?
It is the shear failure mode in which an anchor near an edge breaks out a half-cone of concrete towards that edge. AS 5216:2021 Clause 7.2.3 gives its resistance, and it often governs anchors close to a slab or beam edge.
Can it handle a group with more than one row?
The page checks one row parallel to the loaded edge. For a group with more rows, decide which row is checked and how much shear it carries from the force distribution, then enter that row and that shear.
How do I enter a side edge that is far away?
Enter any distance of one and a half times c1 or more. Beyond that the side edge no longer cuts the breakout body or reduces the side edge factor.
Does the check cover steel failure or pry-out in shear?
No. Steel failure with and without a lever arm and pry-out are separate checks in AS 5216:2021 Section 7.2, and shear directed away from the edge is not covered.
What does the load angle factor do?
Shear inclined to the edge normal loads the breakout body less severely, so the factor ψα,V raises the resistance as the angle grows towards parallel to the edge.
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