Preliminary pull testing for ties

[Georgina Molloy]

Hi All,

When you are designing a scaffold and you will tie into reinforced concrete slab edges/RC walls do you specify that the scaffolder should do 5 preliminary pull tests (TG4:17) so that you can check the specified anchor is ok in that base material.
(Then proof tests would be specified after you have confirmed that this tie can be used).

Or do you only specify preliminary pull tests when you are tying into a base material that has unknown capacity such as old masonry where the tie manufacturer cannot give allowable loads due to unknown nature of base material?

I have the manufacturer's allowable loading for the particular tie into concrete and my applied wind load is 86% of the allowable.

Thanks.

[scaffcon]

I think its if you have the data for what you are tying into then you don't need preliminary tests or if the base material is in doubt (brickwork/mortar) then you need to do them.


Ive not read the guidance though, Doh! its been revised again to TG4:19 aswell!

[Georgina Molloy]

I think its if you have the data for what you are tying into then you don't need preliminary tests or if the base material is in doubt (brickwork/mortar) then you need to do them.


Ive not read the guidance though, Doh! its been revised again to TG4:19 aswell!

Thanks Scaffcon. I didn't realise there was a 2019 update.

[Nick-CDS]

I'll ask for preliminary tests for materials with unknown or unverified capacities such as old/damaged brickwork and some timber framed buildings but for concrete and other "controlled" materials, I'm happy to go with the supplied SWLs from the data sheets. So far, with just wind loading and notional horizontal forces, I haven't come any where close to hitting the max allowable loads into concrete so i'm happy with proof testing only.

[Georgina Molloy]

I'll ask for preliminary tests for materials with unknown or unverified capacities such as old/damaged brickwork and some timber framed buildings but for concrete and other "controlled" materials, I'm happy to go with the supplied SWLs from the data sheets. So far, with just wind loading and notional horizontal forces, I haven't come any where close to hitting the max allowable loads into concrete so i'm happy with proof testing only.

Thanks Nick, that seems reasonable.

[TG6]

One thing to watch in anchoring into slab edges (or thin columns) is edge distance which can decrease anchor capacity significantly. It is often difficult to get a fixing mid depth on a slab and I would always do a what if to check the effect of errors in positioning the anchors with slabs 250mm thick or less to make sure that the allowable load is achievable in a real situation.

[Nick-CDS]

I'm glad you mentioned that TG6. When I've been running through some Cat 3 checks, I've noticed that that is one thing that seems to be missed on the regular.

[Georgina Molloy]

Good point TG6, thanks for that.