How do you test anchors in accordance to BS 8539?
In our latest sound-out episode Stevan discusses how to test anchors according to BS 8539.
What is anchor testing?
Anchor testing is the process whereby an anchor/fixing is pulled to a designated test load. From this the performance of the anchor/fixing can be quantified. Test criteria is defined in Clause 9 of BS 8539:2012 ‘Code of Practice for the selection and installation of installed anchors in concrete and masonry’.
What types of anchor testing is available?
There are two main types of anchor testing available are:
- Allowable load (characteristic action)
- Proof testing
Allowable load testing (characteristic action)
An allowable load test is carried out where the application involved is not covered by a relevant ETA, or the strength and condition of the base material is unknown, with no published data.
Testing the substrate is quite simple for lightweight material however for blocks of concrete beam sections it can prove more problematic, as there is no clear way of highlighting the capacity of the concrete. If you do not know the capacity of substrate then it can be tricky to accurately determine the allowable working load.
How do you carry out an allowable load test?
Testing involves attaching a hydraulic pull tester to an anchor and pulling it to a designated test load, you then continue to turn the handle, gradually increasing the load until failure. You then divide the applied load by ¼ for a safety margin.
When carrying out an allowable load test the anchor should be tested five times and the resulting average should be recorded.
Ultimately, a proof test simply tests the quality of the installation. These tests are usually applicable when the specification stage of the anchor selection process has been completed. A test load is achieved based on the applied load.
MIDFIX often receive requests for on-site proof testing. What is often not known is that under BS 8539 if an ETA approved anchor is specified in a known substrate and has been installed by a competent individual then the anchor does not require a proof test.
How do you carry out a proof test?
To carry out a proof test simply attach the hydraulic pull tester to the anchor and gradually turn the level, gradually increasing the load (to the manufacturers safe working load).
If the anchor is flush-fixed (bolt head anchor or a frame fixing), it is not possible to test the anchor using this method.
Who is responsible for carrying out anchor testing?
BS 8539 states that the contractor is responsible for proof testing.
BS 8539 outlines the different type of tests available, how many tests to carry out, to what load and how results should be treated. According to BS 8539 the responsibility of the chosen tester is:
- To ensure tests are carried out to the correct procedures.
- Where relevant, anchors are installed in accordance with the manufacturers’ instructions, in the correct locations as required by the specifier.
- Results are recorded in a full and comprehensive manner and forwarded to whoever requested the tests.
- The tester should hold the relevant CFA qualification.
BS 8539 states there are two key areas of a project where anchor testing is recommended.
- To determine the allowable resistance when there is no manufacturer data and proof tests to validate the quality of installation.
- To understand the performance characteristic of ETA-approved anchors and those without ETA approval
What is the BS 8539 guidance around proof testing?
The CFA guidance notes highlights the following points of BS 8539 that should be considered.
- How many fixings should you proof test?
- What load should you test to?
- What is the percentage safety factor and what should it be going to?
If you are testing 1 in 40 fixings, you are only allowed a factor of 1.5x the applied load. The actual applied load must not exceed the manufacturer’s recommended load. If you test 1 in 25 fixings, the guidelines advise the applied load can be 1.25x the specified load requirement from the manufacturer.
Why should you carry out anchor testing?
To mitigate the risk of anchor failure. If you are a contractor and are unable to answer the following question: If challenged, can you demonstrate that the structure you have installed can take the service load applied to it, and that the supports and fixings are fit for purpose? then you may be liable if an anchor failure occurs on-site. Therefore it is very important to understand the applied service load of all anchors supplied and installed on-site.
How can MIDFIX help?
MIDFIX provide a comprehensive fixing policy covering the selection, supply, installation training and testing of post-installed anchors into concrete or masonry to BS 8539 standards. We hold a full range of ETA approved anchors alongside a team of CFA accredited advanced testers who can go out on site to test anchors.Take me to ETA approved anchors I would like to install and test anchors to the highest standards
Download and save our fixing policy to discover how MIDFIX can cover all anchor/fixing requirements for your project.
If you would like to discuss our anchor/fixing policy further then get in touch with our expert customer service team.
0115 922 1585
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The CFA have produced guidance notes that outlines the parameters that need to be met when carrying out an anchor test, how to set up the testing equipment, how to apply the load and monitor movement and finally how to record results.