Check steel failure of the highest-loaded anchor in tension to AS 5216:2021 Clause 6.2.2, from the approval or stress area. Open the template.
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About this AS 5216 Steel Failure in Tension Calculator
This calculator checks the design steel resistance of the highest-loaded anchor in tension to AS 5216:2021 Clause 6.2.2 and the verification of Clause 3.4.2. Steel failure is the fracture of the anchor itself, the bolt, rod or screw breaking before the concrete or bond gives way. Every anchor of a group has the same steel resistance, so the check is made on the anchor carrying the most tension.
- Structural engineer. Confirming that a chosen anchor size and steel grade carry the tension on the most heavily loaded anchor of a base plate or connection.
- Graduate engineer. Learning the anchor design sequence, starting with the simplest failure mode and seeing how the capacity factor is applied.
- Steel connection designer. Comparing threaded rod sizes and grades quickly by switching to the stress area route.
The page shows the characteristic and design resistances, the utilisation and a clear pass or fail. It is an engineering-grade calculator on CalcTree that you can duplicate and link to the other AS 5216 checks for the same fixing.
More info on AS 5216 Steel Failure in Tension
Two routes to the characteristic resistance
AS 5216:2021 Clause 6.2.2 takes the characteristic steel resistance N_Rk,s from the anchor's approval, and the standard has no equation for it. The page lets you enter that approval value directly, or, where the approval defines the resistance as stress area times ultimate strength (as for a threaded rod or bolt), compute it from the stress area A_s and the nominal ultimate strength f_uk. A selector chooses the route, and the inputs of the other route are ignored.
Inputs
Besides the route and its inputs, you enter the capacity factor φMs for steel failure and the design tension on the highest-loaded anchor. φMs comes from Table 3.2.4 or the approval, and depends on the ratio of the steel's ultimate to yield strength.
Design check
The design steel resistance N_Rd,s is φMs times N_Rk,s, checked against the tension on the anchor under Clause 3.4.2. The page reports the utilisation and a named pass or fail check.
Common Calculation Errors to Avoid
- Using the gross shank area. The computed route needs the stress area of the threaded part, which is smaller than the nominal bar area. Using the gross area overstates the resistance.
- Computing a resistance the approval does not support. The stress area route only reproduces the approval value where the approval defines it that way. For other anchor types, such as many expansion anchors and screws, use the approval route.
- Checking the average anchor. The design tension must be the tension on the highest-loaded anchor from the group's force distribution, not the total tension divided by the number of anchors.
- Taking a generic capacity factor. ΦMs varies with the steel's ultimate to yield strength ratio. Use the value stated in the approval or Table 3.2.4 for that steel.
Engineering templates
Common calculators
Design guides
FAQs
Does AS 5216:2021 give an equation for steel resistance in tension?
No. Clause 6.2.2 takes N_Rk,s from the anchor's approval. The stress area times ultimate strength route on this page is offered for approvals that define the resistance that way, such as threaded rods and bolts.
Why is the check made on only one anchor?
All anchors of a group share the same steel resistance, so the anchor carrying the most tension governs. Its tension comes from the distribution of the group's forces, assuming a fixture stiff enough to treat as rigid.
Can I use this for seismic or fatigue loading?
No. The page covers static and quasi-static loading. Seismic, fatigue and fire actions need the resistances the approval gives for those situations.
Which other tension checks do I need?
Pull-out, combined pull-out and bond, concrete cone failure and splitting are separate AS 5216:2021 checks. Each has its own CalcTree template, so you can build the full set for one fixing.
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