Hi Team,
Could you please help with a query about PROFIS in regards to the concrete edge distance requirement under fire. Our team is currently working on a project having are some cases that the anchors should be designed under temperature (600°C), and We are using Profis to do the design (Euro code). However, when the 6 anchor layouts was selected (4 anchors are fine), the concrete edge distance never works, an infinite edge distance has to be used which is actually not our case. So wondering is there any other solutions for this situation, or a maximum concrete edge distance can actually be specified?
Thank you !
Hi,
Thank you for your question,
To recap, there is no existing Australian standard available when designing post installed anchor under fire. Having said that, utilizing the world best practice approaches, you can use EOTA TR 020 “ Evaluation of Anchorages in Concrete concerning Resistance to Fire.”
Post installed anchors are subjected to testing under different fire resistance classes (30,60,90,120 mins etc). This testing is based on load application on the anchors under direct flame, as this is the most extreme case they will experience. Sample data from the testing will indicate the loads that can be reached based on the failures they experience (such as failure of steel component). This can be used as the ultimate design load and a marginal safety factor applied to determine the recommended load.
Hilti has conducted fire test in co-operation with renowned third party testing company on majority of our mechanical and chemical anchors. The fire resistance data for variety of Hilti mechanical anchors are available in their ETA document (attached).
When it comes to evaluating the performance of a metal anchor in concrete, concerning resistance to fire, the determination covers anchors with a fire attack from one side only. If the fire attack is from more than one side, the design method may be taken only, if the edge distance of the anchor is c ≥ 300 mm and ≥ 2 hef. The determination is valid for unprotected anchors.
Hence, if you are designing for an anchor system to be attacked by fire on more than one side, the minimum edge distance shall be ≥ 300 mm, as highlighted in table C6 of the attached ETA for HUS-3 anchors.
Hoping the above information proves useful,
Ask Hilti Team
Australia
