A chain is only as strong as it weakest link

 

Hi Subscriber

Recently I was poring over AS4084 – 2012 which is the Australian standards for pallet racking. I was trying to find specifications for the fixings that secure pallet racking to a concrete slab floor.

AS4084 – 2012 states that: “On racking serviced by mechanical equipment, a minimum of two anchors per base plate shall be used. Each upright-to-floor connection shall be able to transfer design ultimate actions of 5kN in tension and 8kN in shear”

The standard goes on to cite some mathematical formulas that use the symbol Fp. Fp I find refers to nine parameters relating to the concrete slab that the racking would be fixed down to. One of the parameters is the quality of the concrete.

This got me thinking. I had better check the specifications on the current 12mm diameter x 75mm long sleeve anchors. These fixings are used on all our pallet racking installations. My findings reveal 7.7kN in tension and 8.9 in shear. 

                                                                         

Phew, I’m ok I think to myself……or am I? The quality of the concrete from the Australian standards is nagging in the back of my mind.

I decide to ring my Hilti representative and he puts me onto one of their field engineers. Hilti are the global market leaders of fastening systems. After several phone conversations and many emails later I discover the following alarming information.

The figures that manufacturers of fixings use to rate their different fastening systems vary. They are all based on different concrete hardness.  The building code of Australia does not have a standard for designing anchor connections at the moment.

Hilti gave me a conservative or worst case scenario figures based on 20Mpa concrete. I find that the current specifications for sleeve anchors that I am using are based on 32Mpa concrete.

The Hilti engineer advised me that the 12mm diameter x 75mm long sleeve anchor has an ultimate tensile resistance of only 4.06kN in 20Mpa concrete. This is not enough to satisfy the 5kN requirement in AS4084 – 2012.

Now I don’t want to be an alarmist and I can let you know that most concrete slabs designed to handle forklift traffic usually are 32Mpa. Companies like LMATS (Laboratory Material Analysis Testing Services) can come out to site and test your concrete slab with tools like the Schmidt Hammer and other methods to identify the hardness of your concrete slab.

However, in case you are unsure there is another alternative and that is the Screwbolt pictured below. A 10mm diameter x 75mm long Screwbolt can transfer ultimate actions of 9.5kN in tension and 13.3kN shear in 20 Mpa Concrete. This is double the sleeve anchor’s capacity and more than satisfies AS4084 – 2012.

                                                                       

Not only is the Screwbolt a superior fixing it can also be used many times. This is a great advantage as most pallet racking will get moved or relocated. 

Have you ever been in the unfortunate situation where you have had to remove a sleeve anchor? A sleeve anchor can be almost impossible to remove once it has been tightened. It is normal for it to be cut off level with the surface. If the embedment hole has been over drilled the anchor can be tapped in level to the surface. A screw bolt is just unscrewed and removed

We understand that business owners have different needs and feel that City Shelving can cater for these individual requirements. Racking systems can be an expensive outlay and we like to be well informed with all the latest information and technology.

Want a great deal on a racking system?

Don’t hesitate to contact us on 1800 83 84 85 or    sales@cityshelving.com.au

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