CFA Guidance Note: Anchorage Systems for Seasonal Decorations.

Transcription

1 Ensuring best fixings practice CFA Guidance Note: Anchorage Systems for Seasonal Decorations. Index Page 1 Introduction Background 1.1 Responsibilities Approach Terminology Implementation 3 2 Selecting anchors for the support of Seasonal Decorations Suitability of the structure Suitability of anchors for the substrate Avoiding corrosion 4 3 Loads 3.1 General Applied loads, allowable loads and design approach Loading direction 5 4 Anchor types 4.1 Eyebolts set in resin sockets Ring nuts attached to resin studs Square plates fixed with resin stud anchors Resin anchors - general points 6 5 Installing anchors 5.1 General Embedment depths Installation Anchor positioning 8 6 Testing anchors 6.1 Preliminary tests Proof tests Test procedures Test equipment Regular inspection 10 7 Labelling 11 8 Project documentation 11 Appendix 1 Test procedure examples 12 References 15 Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 1

2 1 INTRODUCTION 1.0 Background and scope This Guidance Note has been compiled jointly by the Construction Fixings Association [1] and the Institution of Lighting Professionals [2] (ILP) and forms part of more general guidance to be found in the Professional Lighting Guide No 6: Attachments and Seasonal Decorations to be published by the ILP on behalf of the Association of Directors of Environment, Economy, Planning and Transport [3] (ADEPT). This Guidance Note covers the use of drilled in anchors used to attach catenary wires used for the support of Seasonal Decorations to building structures across streets. For guidance on the fixing of brackets for e.g. the support of banners, hanging baskets, signs or other street furniture to concrete or masonry, refer to a Guidance Note Anchoring brackets to concrete and masonry. to be found on the CFA website at The security of the wire systems used to support Seasonal Decorations is dependent on a number of factors including the integrity of the structure to which they are attached, the correct choice of anchor in relation to both the substrate and the applied loads and the quality of installation of the specified fixings. This Guidance Note sets out the factors to be considered in achieving this. Guidance is given for all stakeholders in the installation of such systems in the widest context from designers of the system and specifiers of the anchorages to supervisors, installers and testers of the anchors. This Guidance Note provides specific guidance with respect to this particular application and follows, as far as possible, the guidance given in the British Standard BS 8539:2012 Code of practice for the selection and installation of post-installed anchors in concrete and masonry [5] which sets out the roles and responsibilities of all stakeholders in the use of construction fixings in all safety critical applications and allows for specific industry guidance. In the absence of guidance in this Guidance Note the recommendations of that code of practice should be followed. This guidance is given in good faith but where particular anchor types are discussed the guidance from the manufacturer concerned must take precedence. No liability can be taken by either the ILP or CFA for any adverse consequences arising from this guidance being followed. 1.1 Responsibilities In the context of carrying out the installation of the anchorages for the support of the catenaries between buildings one person should have overall responsibility for the project, referred to here as the project manager. Within the project various personnel may report to that person. Some of the activities referred to here may be carried out by the same person if, for instance, the project manager is a qualified structural engineer he may carry out the structural survey of each location to ensure that it has the integrity necessary to sustain the loads applied from the supporting catenary wires via the anchorages to the structures. The designer of the lighting display may also be the person to calculate the applied loads and select the most appropriate fixing the specifier. The variable nature of structures likely to be encountered in these projects means that from time to time the proposed anchor may be found not to be suitable as a result of proof tests carried out during the installation. It is important that all installers and supervisors understand the limits of their responsibilities and know who they should refer to for guidance when such cases occur. See 1.4 Implementation. In outlining the responsibilities of various stakeholders in these projects it is assumed all will be competent in the specific tasks they undertake. 1.2 APPROACH TO ENSURE SAFE FIXINGS Activity Check structure will support required loads Choose an anchor suitable for the base material Calculate the characteristic action and inform installer via project documentation Check the proposed fixing is capable of sustaining the characteristic action Install anchors Proof test all anchors Certify installed anchors as required by BS 8539 Responsibility Structural engineer Specifier Specifier Overall: Specifier Project Manager Installer Tester Supervisor Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 2

3 1.3 Terminology In this Guidance Note the terms listed are taken to have the following meanings: Note: Terminology adopted here is that used in BS 8539:2012 and in CEN Technical Specifications [CEN TS which contain design methods for anchors] [9]. The most significant change compared with terminology traditionally used within the fixings industry is that loads are now referred to either as Actions (applied load etc) or Resistances (capability of the fixing). A Guidance Note published by the CFA Anchoring Terminology and Notation [6] sets out the meanings and relationships of the various terms used in relation to traditional usage. Anchor A component installed in the building structure to transfer the necessary forces between the catenary and the building structure, it may be temporarily or permanently fixed into the structure. Also referred to as fixing. The anchor may be a resin stud anchor or internally threaded socket to accept an eyebolt or another suitable configuration. Anchor point Point to which the catenary wire is to be attached, e.g. eyebolt or eye welded to a square plate. Anchorage The combination of anchor, a fixture, e.g. a bracket, and the immediately surrounding base material on which the anchor depends in order to transfer the relevant forces. Allowable Resistance N R,all. Safe working load determined from Preliminary tests (see 6.1) carried out on site. In designs carried out to Eurocode 2 there is no equivalent term.. The traditional industry term is Allowable Load. Characteristic action N Sk, Actual load to be applied to the anchor according to the design. It may be calculated from the catenary load. The traditional fixings industry term is Applied load. Catenary load Force expected to be present in the catenary wire in the worst case and on which the characteristic action (applied load) in the anchor is based. Determined according to information contained in Appendix 1 of the Professional Lighting Guide where it is referred to as the unfactored load. Installer Person or organisation who installs the specified anchors. Masonry unit Individual brick, block or stone within a masonry wall. Recommended Resistance N rec, The load which may be applied to the anchor as quoted by the manufacturer for a specific base material. In designs carried out to Eurocode 2 there is no directly equivalent term see [6]. The traditional fixings industry term is Recommended Load. Responsible Person Person responsible for the installed lighting display once in use. Specifier Person or organisation who designs the connection between the catenary and the substrate and is responsible for the selection and specification of the anchor. Tester Person or organisation who tests the installed anchors 1.4 Implementation This Guidance Note includes guidance for everyone involved in the installation of anchorage systems for seasonal decorations from managers and designers to installers and bodies who carry out regular inspections of such systems. Its implementation will require companies to set out and make clear to all staff their policy regarding the anchors they use, who is responsible for the design of the overall lighting display and who for the selection of anchors and generation of the Technical File, see section 8.0. It should state who is responsible for installing anchors on site, who for testing them and who should be referred to in case of problems with anchor capacity resulting from tests. It will require the training of staff as appropriate in the correct selection and installation of the anchors to be used and testing procedures. It will require method statements on installation and testing to be established and made available to those who need them. Test report formats will need to be established and made available to testing staff. 2 SELECTING ANCHORS FOR THE SUPPORT OF SEASONAL DECORATIONS Aspects which need to be considered in selecting anchors for attaching catenary wires to structures are: The suitability of the structure Suitability of the proposed anchors for the substrate Characteristic action (applied load) compared to the recommended resistance (recommended load) see section 3.2. Avoiding Corrosion Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 3

4 2.1 Suitability of the structure The suitability of the building structure to sustain the loads transferred from the catenary wires must be established and recorded within the project documentation, prior to any installation work, by a competent person e.g. structural engineer. In general, concrete elements which are part of the load bearing structure will be suitable. Masonry structures may be suitable if they are load bearing and of solid, rather than cavity, construction and composed of strong masonry units with sound mortar joints. Cavity brickwork constructions and cladding panels may not be capable of transferring the tensile loads involved. An engineer s advice should be sought before fixing into these structures and others which may not be load bearing e.g. areas under windows, parapet walls, etc. It must be noted that load tests as described in sections 6.1 & 6.2, will not indicate whether or not the structure itself has the integrity to sustain the loads involved. 2.2 Suitability of the proposed anchor for the base material The range of base materials into which anchors for supporting catenary wires are likely to be installed covers concrete and most masonry structures including brickwork, which may be solid or cavity (see notes above), stonework and occasionally rendered blockwork. In regard to blockwork only dense aggregate concrete blockwork will be considered here as any other sort of blockwork, be it lightweight aggregate, aerated or hollow blockwork, is unlikely to be capable of sustaining the required loads. Due to the varied strengths of base materials likely to be encountered resin anchors are most likely to be an acceptable solution in most cases as they exert no expansion stress in the base material and are therefore unlikely to cause cracking of weaker materials such as brickwork or stonework. Other systems may be suitable for concrete but a common solution is generally preferred. It is the responsibility of the specifier of the anchors to check that the proposed anchors are suitable for the base material according to the manufacturer. 2.3 Avoiding corrosion In cases where catenaries are to be installed in dry internal conditions, e.g. in shopping malls, the anchors used to attach the catenary wires may be of zinc plated carbon steel. For external installations the anchors should be stainless steel of at least Grade A2 to avoid corrosion. If installations are made in areas subject to exceptional corrosion effects such as high levels of atmospheric pollution and areas subject to sea water spray stainless steel to grade A4 should be specified. In cases where eyebolts designed primarily for fall protection and set in internally threaded sockets are to be used both eyebolts and sockets must be of stainless steel. When connections are made between catenary wires, connectors and anchorages involving contact between different metals the effects of galvanic (bi-metallic) corrosion must be considered. This is likely when fixing square plates, made of carbon steel - either galvanised or painted, using stainless steel anchors. Galvanic corrosion can be avoided by isolating the two components using neoprene washers and sleeves. For more information see [5 & 7]. Even if installations are required for short term usage anchors which will be left in the structure (resin studs and sockets) should be stainless steel as carbon steel anchors, even when plated or galvanised, will rust eventually and stain or damage the building structure. 3 LOADS ON ANCHORAGES 3.1 General Points to take into account are: Characteristic action (applied load) must be within the capability of the fixing. Loading direction The fact that applied loads are predominantly tensile means that anchor selection is to a degree simplified but installation becomes even more critical than in other cases. 3.2 Characteristic actions, recommended resistances and design approach Once the characteristic action is calculated (see examples in Appendix 1 of the Professional Lighting Guide where characteristic actions are referred to as unfactored loads) it must be compared with the capability of the fixing. For installations to be made into concrete standard selection methods may be used, these are set out in BS 8539 [5]. For this particular application the approach is relatively straightforward as loads are generally tensile and anchors are either individual anchors with no close spacing restrictions to be considered or, if the attachment is to be made to masonry, then the anchorage may use a single anchor or a group of four (in which case the load per anchor will be reduced). The basic requirement is that the Characteristic action, N Sk, is less than or equal to the Recommended Resistance, N rec, of the proposed anchor. Most anchor manufacturers quote Recommended (Safe Working) Loads for concrete and some for other base materials; these loads may be used for the selection of anchors against the Characteristic action as long as the base material of the structure concerned is known to be at least as strong as that for which the recommended resistance is quoted. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 4

5 Manufacturers recommended resistances quoted for concrete should not be used for masonry. If no load data exists or the strength of the base material is in doubt, e.g. masonry or old concrete, then it is normally CFA policy to recommend that Preliminary Tests (a series of at least 5) be carried out to determine the allowable load for the proposed anchors in the particular base material of the job, see 6.1, but on projects where a large number of different masonry structures may be encountered (e.g. a high street) and only a small number of anchors are required to be installed in each substrate, that approach is acknowledged to be impractical. In these cases the adequacy of the proposed fixings must be checked by proof testing every installation, see 6.2, and this process must start as soon as the first installation is available to be tested in order to avoid unsuitable anchors being installed in more locations than necessary. Many anchors are available with European Technical Approvals [9] (ETAs) and CE marking. This means anchors have been thoroughly proven against the most rigorous testing regime. Load capacities quoted in ETAs are based on ultimate limit state approach with partial safety factors quoted in the ETA; this involves a partial safety factor being applied to the Characteristic Action to get the Design Action. Care must be taken in using quoted load values or entering data into software to make sure that the values used are compatible with the Characteristic Actions of the project. For instance where, in the traditional anchor design approach, the Applied (unfactored) load must be less than the Recommended Load ; in the new approach the Design Action must be less than the Design Resistance. Bearing in mind that the design action is larger than the characteristic action by a partial safety factor of around 1.4 and the design resistance is larger than the recommended resistance, usually by a similar factor, see [6]. If in doubt refer to the anchor manufacturer. Load values quoted in ETA for anchors qualified for use in masonry may be limited if the quoted embedment depth is limited to a single brick thickness e.g. the front brick of a solid brick wall. In that case it may be necessary to select the anchorage on the basis of the embedment depth considerations of section 5.2 in which case the ETA will no longer be relevant. 3.3 Loading direction Catenary wires are normally attached to anchorages such that there is a defined, but generally small, sag in the wire. This means that the catenary load is directed into the anchorage at an angle, which is generally small such that the load may be regarded as a pure tensile load on the anchor point. The magnitude of the catenary load and sag in the wire can be calculated using guidance contained in PLG 06 section 6 and worked examples in Appendix 1. For eyebolts as described below (qualified to EN 795) the angle of load application does not affect the anchor capacity as these anchors are capable of supporting their rated load in any direction. For anchors set in square plates and α > 15 the load on each anchor should be calculated and resolved into tensile and shear components. It may then be necessary to check anchor capacity for the combined tensile and shear loads - refer to the anchor manufacturer for their approach in this respect or see CFA Guidance Note: Anchor selection for an acceptable approach. 4 ANCHOR TYPES α Force in catenary wire, F kn Catenary wire Note: Catenary wires should not be over tightened so as to make them straight which they will never be. The required tension depends on the temperature at the time of installation so that wires installed during summer months do not become too tight in cold weather and wires installed in winter do not become too slack in summer. The anchors discussed here are those currently used within the industry and considered suitable with the qualifications outlined. Other types may be equally suitable. Two types of anchorage are commonly used for this application: Eyebolts set in resin sockets, see 4.1 and square plates fixed with resin stud anchors, see Eyebolts set in resin sockets For single anchor points eyebolts inserted in internally threaded anchors and qualified to the requirements of Anchor Devices for Fall Arrest [9] (commonly known as safety harness eyebolts), see below right, are proven to be eminently suited to this application - with certain limitations. For fall arrest purposes these anchor devices are required to be marked with a reference to BS EN 795 [9] and while this application is not fall arrest, and eyebolts should be clearly labelled that they must not be used for fall arrest, (see section 7.0) the marking on eyebolts is a useful indication that they have been manufactured in accordance with a standard that means they will be capable of sustaining the load limits suggested below. Fall arrest eyebolts type tested and certified in accordance with BS EN 795 have an effective safe working load of 6kN which may be assumed as the Recommended Resistance for Seasonal Decorations (acting at any angle) in concrete only. They are also suitable for use in solid (9 thick) brickwork but, due to the generally weaker nature of brickwork and the lack of opportunity to prove the safety margin on a large series of tests in each substrate, characteristic actions should be limited to 4kN in solid brickwork. They are not suitable for use in cavity construction for which, if the structure is approved for the attachment of catenary wires, through fixed eyebolts qualified to BS EN 795 could be considered. Anchor devices for fall arrest in accordance with BS EN 795 used for Seasonal Decorations. Left - set in concrete with an applied tensile load limited to 6kN. Right set in solid masonry with an applied tensile load of up to 4kN. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 5

6 4.2 Ring nuts attached to resin studs. 4.3 Square plates fixed with resin stud anchors An alternative to the safety harness eyebolt is a ring nut attached to a threaded rod set into resin which may be used in concrete (as shown here) or into solid brickwork in which case resin sleeves may be needed as shown below, see 4.4. Care must be taken to ensure adequate thread engagement is achieved within the ring nut and adequate stud embedment within the based material. Note: As safety harness eyebolts referred to in 4.1 are screwed into sockets, whose presence and therefore embedment depth is demonstrated at the time of future inspections, that technique is recommended. If the above load limits are insufficient or if proof tests on eyebolts set into masonry show that single anchors will not sustain the required proof test load (1.5 x characteristic action) then a square plate fixed back with 4 x M12 resin stud anchors can be considered, see left. Dimensions of the plate should be chosen such that the spacing between anchors will match brick courses i.e. 150mm. Maximum plate width of 250mm will allow readily available test equipment to stand over the whole plate, see section 6.5. In concrete the capacity of the plate will be determined from the recommended resistance of the proposed resin stud anchors in concrete as quoted by the manufacturer, taking account of limitations due to close anchor spacings and close edge distances, together with stiffness considerations for the plate the strength of the eye and welded joints. Embedment depths for M12 resin stud anchors set in concrete will be typically 110mm, check with the manufacturer. In solid brickwork with sound mortar joints using anchors with an embedment depth of 170mm (see 5.2) an applied load of no more than 3kN per fixing may be considered giving a total plate capacity of 12kN. Higher loads may be considered if the Preliminary test procedure recommended by the CFA [11] is followed. If this procedure fails to yield a loading capacity suitable for the application then the use of two plates may be considered with the catenary attached to both via a Y arrangement such that the load is shared evenly between the two eyes. More details of the use of resin anchors are given in section 4.4 below. Approved anchors Eyebolts qualified for fall protection to EN 795 should be marked accordingly. When choosing resin stud anchors preference should be given, where possible, to anchors which have been awarded an ETA [7] for use in the relevant base material as these will have been tested to prove their functioning in a wide range of site conditions and will have reliable and comparable load data. 4.4 Resin anchors general points. Resin anchors are suitable for use in concrete and hard masonry including brickwork, stonework and concrete blockwork as they do not stress the base material as would be the case with expansion anchors. Anchors set in concrete should ideally be set using spin-in resin capsules and while injection systems may be used in concrete they require more care. Resin stud anchor for attachment of plates to concrete. Resin injection systems are ideal for use in masonry. Special mesh sleeve systems are available for use in solid (9 ) brickwork, to cater for the lack of resin in the joint between leaves, and in perforated* or frogged bricks. The manufacturer s advice should be followed at all stages. *The presence of perforated bricks implies cavity construction. The suitability of such structures to support the characteristic action should be determined beforehand by a competent person. Resin stud anchor set brickwork using mesh sleeves. Solid (9 ) brickwork on the left, perforated bricks on the right. Curing time is a limiting factor which must be taken into account in the planning of these installations. New formulations with shorter curing times are becoming available. Curing times for all resin systems are set by the manufacturer to give a strength suitable for loading and tightening but they do not imply 100% curing at the stated time. Tightening or loading before the recommended curing time has elapsed may damage the resin bond and reduce safety margins and this damage may not be apparent, so the full recommended curing time relative to the temperature of the substrate - must be allowed. Resin materials should always be stored in temperatures within those recommended by the manufacturer for storage. If allowed to become too hot they will cure prematurely - if too cold they will take longer to cure. Resins should not be heated artificially to speed up curing. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 6

7 Resin anchors - Installation points to watch Hole cleaning is vital for all resin anchors especially injection systems. Remove all dust from the sides of the hole by BRUSHING using the correct stiff, round brush to the manufacturer s specification, as well as BLOWING using a large volume pump, all as per the manufacturer s instructions. With injection systems pump some resin to waste to ensure proper mixing before injecting into the hole. With all resin anchors allow the full curing time (ref. base material temperature) before loading or tightening. Do not over tighten! Always use a calibrated torque wrench set to the manufacturer s recommended installation torque which should be reached in approximately half a turn from finger tight. Torque values quoted for concrete should be reduced in weaker materials such as brick or stone refer to the manufacturer. 5 INSTALLING ANCHORS 5.1 General It is necessary for the contractor to be able to demonstrate that all anchors have been correctly installed. This means that anchors should be installed only by competent installers [10] - using the correct tools and strictly in accordance with the anchor manufacturer s instructions. Proof tests, as described in section 6.2, should be carried out on every anchor on every project. Key aspects are: Drill holes to correct diameter and depth Clean holes thoroughly (see above regarding resin anchors). Set in accordance with the manufacturer s setting instructions using the correct tools Allow resin anchors to cure for the curing time recommended by the manufacturer for the temperature of the base material. Tighten to the recommended installation torque* using a calibrated torque wrench. *When anchors are to be installed into masonry materials installers should check that the recommended installation torque to be used for tightening anchors, especially resin stud anchors, is appropriate for the strength of masonry of the job. Torques recommended for anchors to be set into concrete are usually excessive for most masonry materials. Refer to the manufacturer for guidance. In the absence of guidance from the manufacturer the installation torque should be reduced from that quoted for concrete in proportion to the reduction in base material strength or in proportion to the ratio of the characteristic tensile action in the masonry compared with the recommended tensile resistance for concrete. The appropriate installation torque should NOT be exceeded. See for 6.5 notes on the tightness of anchors at subsequent inspections. Where catenary wire spans are to be installed over the highway then the installer shall consult with the Highway Authority, Police and Health and Safety Executive as to the method and time of installation. 5.2 Embedment depths Embedment depths is usually referred to in manufacturer s data as h ef (the effective embedment depth and is the deepest point of engagement of the anchor in the base material) while the hole depth is referred to as h 0. For resin stud anchors there will be little difference between the two. Embedment depths for anchors in concrete Embedment depths in concrete are straightforward and should follow the manufacturer s recommendations. Embedment depths for anchors in solid brickwork. To gain maximum strength from anchors set into 9 solid brickwork it is important to achieve optimum embedment into the rearmost leaf which then benefits from load transfer via the front leaf, see (A) below. Maximum hole depth for anchoring into the rear brick of 9 structures is 170mm. Any deeper risks breaking the back of the brick out under the drilling action. Hole depths may vary with anchor type. The use of mesh sleeves should be considered see 4.4 above. Avoid setting the anchor with its effective embedment in the joint between leaves. Horizontal section through 9 inch thick solid brick wall. Up to170mm A Anchorage in the rearmost leaf benefits from interlock with the front. B Anchorage into headers may be made if bricks are strong and mortar joints sound. Reject if joints are cracked after drilling. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 7

8 Anchors may be made into header bricks (B) especially if the remote leaf of stretcher courses appears weak during drilling, but only if bricks are strong and mortar joints sound. Care must be taken with all masonry installations to check that no damage is done to the brick or surrounding mortar joint by drilling, anchor setting or testing. Look for cracks across bricks and around mortar joints. If structures are rendered ensure the required embedment depth exists below the render. 5.3 Anchor positioning The recommendations of the anchor manufacturer should be followed regarding close edge distances and spacings between anchors used in pairs or groups. Anchor positioning in concrete All reputable manufacturers make detailed recommendations for edge and spacing criteria for anchors used in concrete. Eyebolts qualified for fall protection to EN 795 should be set no closer than 150mm from any edge in concrete and, if used in pairs, no closer than 300mm apart. Anchor positioning in brickwork Some manufacturers fail to make recommendations for these criteria in masonry. In the absence of such guidance the following should be observed for both resin stud anchors and eyebolts installed in resin sockets and qualified for fall protection to EN795: Anchors which are used to support tensile loads should be located at least one full masonry unit from a vertical edge, in brickwork this means at least 280mm. This distance may need to be increase substantially for lateral or shear loads the distance may depend on the magnitude of the load and condition of the masonry. A minimum edge distance of at least 2m should be allowed from a horizontal edge in brickwork for loads in any direction. Centre spacings between anchors should be chosen to avoid setting two anchors in the same brick. Diagram showing Location of fixings in brickwork and design of plate to avoid 2 fixings in the same brick. 2000mm - recommended minimum distance to horizontal edge (top of unrestrained wall). Ideal fixing location within brick on centre line, 55-70mm from end. 150mm mm min When drilling into brickwork the anchor should ideally be located in the solid portion of the brick rather than into the mortar joint. If the brickwork has been rendered the location of the centres of the courses of bricks should be identified by removing the render or by test drillings. If however anchors may not be fixed into the bricks themselves, e.g. as a result of a conservation order, then the following approach may be sanctioned by the responsible engineer if approved by the manufacturer: (resin anchors may provide a good solution for fixings into joints) Choose an anchor with a diameter significantly larger than the width of the mortar joints, e.g. >14mm in a 10mm joint. Fix into the base of the junction between bed and perpendicular joints PROOF tests must be carried out, on each individual anchor, see section Following installation all anchor points should be tested as recommended in section 6.2 and labelled as recommended in section 7. A Technical File should be passed to the client as per sections 6.5 and 8.0. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 8

9 6 TESTING ANCHORS. 6.1 Preliminary tests It is normally CFA policy to recommend that, in cases where anchors are to be installed in base materials of unknown strength and where there is no manufacturer s recommended resistance for the proposed anchor, i.e. in brickwork or stonework, then Preliminary tests should be carried out to determine the Allowable Resistance which should then be checked to be greater than the Characteristic Action. However, as this procedure involves the application of, typically, 5 tests, it is generally not practicable to carry out such a series of tests in situations where only one or two anchors may be needed in each substrate e.g. high streets where many different buildings are encountered, all with different base materials. In these cases the application of a proof load test (see 6.2) to every anchor is deemed sufficient as this ensures a safety margin of at least 50% on all fixings. Where buildings are sufficiently large that a significant number of anchor points are to be installed it may be deemed worth carrying out Preliminary Tests in accordance with the recommendations of the CFA Guidance Note [12]. In these cases proof testing should still be carried out on all working anchors as the load is applied in almost pure tension and the application is safety critical. 6.2 Proof tests. Following installation (after full curing time has elapsed in the case of resin anchors) every anchor should be subject to a proof test to a load of 1.5 times the characteristic action. At this stage for eyes set in square plates it is important that each anchor is tested individually to ensure it has the capability of supporting a safety margin of 50% rather than testing all four anchors at the same time via the eye as this could in theory apply the test load to only 2 diagonally oriented fixings - see 6.4 for suitable test rig arrangements. Acceptance criteria in Proof Tests: Anchors should sustain the test load for at least 15 seconds without significant displacement and without damage or deformation of the eyebolt or anchor under test and without damage to the surrounding structure, in particular there should be no cracks in brickwork or mortar joints. The failure of even one anchor in proof testing is a serious issue and requires the investigation of the cause(s) of failure and a review of the anchor specification and installation method. 6.3 Test Procedures Test procedures for either Preliminary or Proof tests should be carried out in accordance with the CFA Guidance Note [11] by suitably competent personnel (other than the actual installer of the anchors tested). Prior to carrying out any tests on anchors the tester should examine carefully the structure surrounding the anchor position and note any conditions giving rise to concern that the anchorage may not sustain the required load. Such conditions will include deterioration of masonry units or mortar joints and damage such as cracks across masonry units or in mortar joints. Where ever a tester is concerned that the structure may not be sufficiently strong then that concern should be reported in the test report and it made clear that any test results (even positive ones) do not imply that the structure can take the loads. Suitable test procedures are shown in Appendix 1. Test reports The Construction Fixings Association Guidance Note - Procedure for site testing construction fixings contains guidelines for site testing of anchors and the recording of results. Test results should be formally recorded and retained with documentation relating to the project. The Construction Fixings Association can provide sample report formats for the recording of tests and regular inspections of anchors for seasonal decorations, see also Test equipment Suitable arrangement for testing eyebolts In brickwork arranging the tester thus will test the mortar joints as well as the fixing.. Suitable arrangement for testing individual studs Eyebolt load spreading bridge Clevis Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 9

10 Tests and inspections should be carried out using a test meter with a gauge calibrated within the last twelve months to an accuracy of < 2% full scale deflection. It is important to use test equipment that applies the load to the anchorage in the most appropriate manner. Eyebolts should always be loaded individually. Individual stud anchors used in groups of four to fix square plates should also be loaded individually at the time of installation but at the time of regular inspections square plates may normally be loaded as a group via the eye, see above illustration. However, if there is any evidence of damage to or deterioration of any of the four anchors fixing back a plate then all four anchors should be tested individually. Possible problems may include bending of the studs, bending of the plate, cracking of mortar joints or apparent looseness of the anchors or nuts. (Testing the studs individually avoids the possibility, which exists when the plate is loaded via the central eye, - and if the plate is stiff - that only two studs on a diagonal are actually loaded, thus doubling the test load on those anchors and meaning that the anchors on the other diagonal are untested, or that possibly just three of the four anchors are loaded with a proportionate increase in test load and in this case one anchor of the four not being tested.) Obviously when the studs are tested individually the required proof load will be a quarter of that used to test the group of four. Test rig dimensions. Test rigs should be arranged such that the reaction loads are taken sufficiently far from the anchor so as not to influence the result. In the case of anchors set in concrete a distance of 50mm from the anchor centreline to the closest support of the test rig is sufficient (as proof loads only are being applied). In the case of individual anchors, e.g. eyebolts, set in brickwork this means ensuring the feet of the bridge do not rest on the masonry unit being tested, see bottom right on page 9. If stud anchors are tested individually with the plate in-situ, by spanning across the corner of the plate, care must be taken to ensure that the feet of the bridge do not sit on the plate or on the same bricks as the fixing under test. Alternatively the plate may need to be removed. For square plates tested via the eye a larger bridge may be used, as shown above right. 6.5 Regular inspection The regular inspection of all anchor points is required to ensure that the anchor points remain in serviceable condition, are capable of sustaining the required loads and have not suffered any damage or deterioration likely to affect this capability. The frequency of inspections should be determined by the body responsible for the catenary wires and will depend on factors such as the use to which anchor points have been put but it is recommended that, under normal usage, anchor points should be subject to an inspection at intervals not exceeding 12 months. If anchor points have not been used within the preceding 12 months the inspection may be deferred until prior to their next usage. The regular inspection should be carried out to a specification determined by the original Installer and stated in the Technical File see 8.0. If deemed necessary the test regime may be revised by the company responsible for the anchor points due to, for instance, a change of use involving additional loading of the anchor points at which time they become responsible for the inspection regime which should be updated in the Technical File. Following the inspection a report should be issued by the testing body to the client recording all aspects of the inspection including load tests carried out and reporting any negative results along with any recommendations that can be made regarding the remedial work required (this may be beyond the remit/experience of the inspecting body). The inspection report should be retained by the client and made available, along with the technical file, to companies carrying out future inspections. Generally the regular inspection should include the following aspects: Bridge large enough to span the plate to test all 4 fixings via the eye. Test loads to be applied*, usually to be the same as the proof test load applied at the time of installation. In the case of a square plate it must be made clear whether or not the test load is applied to the plate as a whole or to the individual anchors. Eyebolts to be removed and examined for corrosion wear or other defects and to confirm that they have been installed in an internally threaded socket. Eyebolts to be checked for tightness (e.g. that they cannot be unscrewed by hand) Nuts on stud anchors to be checked for nominal tightness (e.g. residual torque of approximately 10Nm). Visual inspection of componentry for rust. Visual inspection of surrounding substrate to check for damage including cracks in masonry or mortar joints. * When commissioning regular inspections the client should confirm to the inspection body that the usage of the catenary wires is unchanged since the last inspection and that the required test load is therefore unchanged. If the use has changed then the client should inform the inspection body of the new test load required. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 10

11 Companies carrying out inspections should note that anchors originally set to a specified torque will, due to load relaxation, exhibit a lower torque when checked at a later date so a lower residual torque does not necessarily mean the anchor being inspected should be condemned. It is also likely that the condition of threads may have changed since installation making torque checks more difficult and less reliable. Torque checks with conventional torque wrenches are also difficult to carry out meaningfully. For these reasons the check recommended at the time of regular inspection is a simple check that the nuts of stud type fixings have a nominal tightness e.g. 10Nm. Effectively this means checking that they are not loose and may be carried out with a conventional spanner. If anchors are torque checked at the time of inspection the anchor should be retightened to the specified torque which should be achieved within a very limited number of turns e.g. half a full turn. To prevent anchors being over-tightened, with the danger of the resin bond being damaged, it is vital that a calibrated torque wrench is used and the specified torque is not exceeded, see also 5.1. Anchors subject to re-test should be clearly identified with a tag showing the detail required in section 7, any anchors failing the test should be tagged Do not use, their location recorded and a report passed to the client. The report should state the reasons for the failure of any anchors and any remedial action that can be recommended. Any wires temporarily removed for testing should now be permanently removed until such time as any remedial work has been completed and the anchorage put back into service. 7 LABELLING OF ANCHOR POINTS Each anchor point should be labelled with a tag, which may be attached via a cable tie or, in the case of eyebolts, by means of a disc set behind the eye. The label should state: The purpose of the anchor point e.g. For attachment of Seasonal Decorations only. NOT FOR FALL ARREST. Anchor point No... Date inspected The date of next inspection. Maximum applied (catenary) load...kn (F) Test load..kn Inspected by.. In the case of eyebolts and square plates tested via the central eye then the test load = F x 1.5kN. In the case of square plates where in the four anchors are tested individually the test load per anchor = F x.38kn Inspected by is intended to refer to the company carrying out the inspection rather than the individual. 8 PROJECT DOCUMENTATION Technical File Installers of anchors for supporting Seasonal Decorations should pass to the client a Technical File that will enable future examiners of the anchorages to fully inspect and load test them. Details which should be covered include: All loading calculations and the derivation of loads applied to the fixings For each building: Details of the anchors that have been installed (type and make), in the case of resin anchors the stud or socket diameter used, make and type of resin, hole diameter and embedment depth, installation torque applied. The test loads applied at the time of installation. Any restrictions regarding life expectancy. The requirements for regular inspections see 6.5 : The body responsible for the anchor points should maintain the technical file with records of all changes of use, inspections and any resulting remedial works carried out as a result of regular inspections. Inspection report The report of the regular inspection should include the following details: Details of the company and individual carrying out the inspection. Address of building Base material of structure into which inspected fixings are located Details of anchors e.g. eyebolt set in resin socket or studs set in resin, for each (as far as can be determined) the make and size of anchors found. Locations of anchorages tested Condition of eyebolts or anchors e.g. if rust or damage is found Confirmation that eyebolts were removable Tightness of eyebolt or stud anchors e.g. tight or loose. Condition of surrounding substrate e.g. cracks across bricks or in mortar joints Condition of plate e.g. rusting or damage to plate or central eye or welding Details of load tests applied, including test load, whether held or not, mode of failure if load not held. Statement to the effect that the anchorages may or may not remain in service. Recommendations regarding any remedial work which may be necessary. Details of test equipment including test meter, bridge, gauge Method statement for load tests indicating test rig arrangement. Gauge calibration certificate Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 11

12 Appendix 1 Anchorage Testing The following procedures may be adopted for the load testing of anchors as part of the regular inspection for which the full requirements are detailed in section 6.5. The test must be undertaken by a Competent Person who will issue a test certificate. The Promoter will be responsible for ensuring that details of the test are registered in the anchorage Technical File. Each anchorage shall be visually inspected before and after the application of the test load to ensure the anchorage, and surrounding base material are still sound and fit for purpose, e.g. no cracks across bricks or in mortar joints. Testing using a small bridge to span the brick, similar to the one shown in section 6.4 page 9, must be done when new anchorages are installed or existing anchorages modified, repaired or inspected. The load applied by the test equipment will depend on the purpose of the test but for tests immediately following installation and regular proof tests a test load of 1.5 x the characteristic action should be used. Test Procedure for eyebolts 1 Check that the eyebolt cannot be unscrewed by hand. Remove the eyebolt and check both it and the socket for any signs of corrosion and recorded the result in the test report. 2 If there are signs of significant corrosion i.e. sufficient to reduce the cross sectional area of the thread and therefore its strength, then the anchor device must be condemned. (The eyebolt should be left out to ensure it is not used). If only nominal corrosion is present then this should be drawn to the attention of the Responsible Person to ensure detailed checking is definitely carried out on an annual basis to monitor the condition. NOTE: ideally, for external installations, the eyebolts and socket should both be of stainless steel so there should be no corrosion present. If components other than stainless steel are present the specification should be reviewed. 3 Reinsert the eyebolt and tighten the eyebolt only sufficiently to ensure it cannot be unscrewed by hand. Swivel feet 75mm hex legs Clevis arrangement 150 load spreading bridge Eye under test (safety eyebolt) Reaction loads are taken away from brick under test. (Arrangement for concrete or hard stonework is the same.) 4 Assemble test rig as shown. Ensure hex legs, swivel feet and adjustment screws are firmly screwed together. Check that the clevis is fully engaged in the M12 locking adaptor within the tester body. 5 Place the bridge over the eyebolt to be tested. Locate the clevis on the eyebolt and fit the cross pin through the clevis and eyebolt. (Fit protection plate between wall and feet of bridge if necessary to protect soft finishes such as render.) 6 Adjust legs to take up slack in the system and to ensure the load is being applied axially through the eyebolt and structural anchor. Check that the primary and follower needles of the gauge are both set to zero. 7 Apply the tensile load gradually via the tension tester until the required proof load is reached or failure occurs (Check that the stroke of the tester has not been exceeded). Check that the eyebolt has not moved. 8 If the load is reached satisfactorily the certificate of installation and test/examination may be issued and. If the load is not reached the eyebolt must be removed, the reason for failure established and remedial work recommended. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 12

13 Test procedure for resin stud anchors. Test rig arrangement for resin studs Adjustable swivel feet 75mm hex legs Button adaptor Threaded stud set in resin Bolt Test adaptor Assemble test rig as shown. Ensure hex legs are firmly screwed to the bridge. Adjust swivel feet to ensure the pull is axial with the stud. Ensure the bolt test adaptor is located in the test meter via the M12 locking adaptor which must be locked into the tester without fouling the tester body. Stud anchors up to M12 diameter should be tested with button adaptors, M16 with a nut. TEST PROCEDURE 1. Screw a button adaptor of the appropriate size onto the anchor rod to be tested. 2. Locate bridge over the fixing to be tested by sliding the bolt test adaptor under the button adaptor or nut. In brickwork align the bridge vertically to ensure the feet locate on adjacent bricks and not the brick under test. Check that the primary and follower needles of the gauge are both set to zero. 3. Apply the tensile load gradually via the tension tester until the required test load is reached or failure occurs. Check that the fixing does not move during loading. (Check that the stroke of the tester has not been exceeded). 4 Record the load reached. If the fixing does not reach the required test load note any movement and any damage to the fixing and surrounding substrate e.g. cracking of bricks or mortar joints. 5 If the load is reached satisfactorily the certificate of installation and test/examination may be issued and. If the load is not reached the anchor should be removed, if possible, the reason for failure established and remedial work recommended. Note: If testing studs in a group of four fixing a square plate with the plate in-situ, by spanning across the corner of the plate, care must be taken to ensure that the feet of the bridge do not sit on the plate or on the same bricks as the fixing under test. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 13

14 Test procedure for square plate with central eye, fixed with four stud anchors. Swivel feet Adjustment screws Direct reading gauge Clevis arrangement Eye under test Bridge large enough to span the plate. Assemble test rig as shown. Ensure the clevis adaptor is fully located in the test meter via the M12 locking adaptor which must be locked into the tester without fouling the tester body. Test Procedure Reaction loads must not go through the plate under test. Prior to test inspect the base material around the fixings for cracks or other damage. Check the welding between eye and plate to ensure that it is sound and that the eye is undamaged. 1. Locate the bridge over the eye to be tested. Locate the clevis on the eye and fit the cross pin through the clevis and eye. 2. Adjust the legs to take up any slack and to ensure the load is applied at right angles to the plate. 3. Reset follower needle to zero. Apply the tensile load gradually until the required test load is reached or failure occurs. Check that none of the four fixings moves during the test, that that the eye does not deform during loading and that there is no damage to the weld, or other connection, of the eye to the plate. 4. If the load is reached satisfactorily that installation may be passed for use. If the load is not reached the plate must be removed and remedial action taken. 5. Note condition of surrounding structure. If cracked or damaged do not use. During testing: Check that the clevis does not jam against the underside of the bridge during loading. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 14

15 References: [1] *This is one of a series of Guidance Notes downloadable free from the CFA website at For more information contact: Construction Fixings Association Tel & Fax: By via the website. Registered Company address: 65 Deans St., Oakham, Rutland, LE15 6AF Company registered number: [2] Institution of Lighting Professionals Regent House Regent Place Rugby CV21 2PN Tel: Fax: info@theilp.org.uk Website: [3] Association of Directors of Environment, Economy, Planning and Transport (Formerly: County Surveyors Society) Website: [4] Drafting panel for the Professional Lighting Guide for Attachments and Seasonal Decorations Institute of Lighting Professionals Construction Fixings Association Lighting Column Technical Forum (a specific section of the ILP) Co-opted industry specialists. [5] BS 8539:2012 Code of practice for the selection and installation of post-installed anchors in concrete and masonry. Available at reduced cost from the Construction Fixings Association which is a BSI Distributor. [6] CFA Guidance Note Anchor Terminology and Notation. CFA website Section: Guidance Notes. [7] CFA Guidance Note Fixings and Corrosion. CFA website Section: Guidance Notes. [8] ETAs are issued in accordance with the appropriate ETAG (European Technical Approval Guideline). ETAG 001 Metal anchors for use in Concrete. Downloadable from [9] CFA Guidance Note ETAs and Design Methods for Anchors used in Construction is downloadable from the CFA website Section: Guidance Notes. [10] BS EN 795:1997 Protection against falls from a height - Anchor devices - Requirements and testing. BS 7883: 2005, Amended 2007, Code of practice for the design, selection, installation, use and maintenance of anchor devices conforming to BS EN 795. BSI [11] Training courses are available via the CFA for accreditation as Competent Installer and Competent Tester. The latter is part of the CFA Approved Tester scheme of Associate Membership. [12] CFA Guidance Note: Procedure for Site Testing Construction Fixings CFA website Section: Guidance Notes. Illustration on front page courtesy of Merlin Lighting Installations Ltd. Guidance Note Anchorage Systems for Seasonal Decorations Issue Page 15