CARESTechnical Approval Report TA2 5017Assessment of the Ancon Eazistrip Reinforcement Continuity System Product and the Quality System for Production

Ancon EazistripReinforcement Continuity System

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1.2 Design Considerations

In the UK, the use of continuity systemconstruction jointing methods, which requirethe site bending of in-situ reinforcement, is amatter for the engineer’s approval. Re-bendingof reinforcement is a matter of productsuitability and workmanship. This technicalapproval demonstrates that the performance ofconstruction joints designed to BS8110 is notadversely affected by the use of the Eazistripcontinuity system. Design for shear along theaxis of a joint of this type is not covered inBS8110 and some guidance on it is given insection 3.2 below.

1. BS8110 Paragraph 7.2 states “It ispermissible to bend grade 250 reinforcementprojecting from concrete provided that careis taken to ensure that the radius of bend isnot less than that specified in BS 8666.Grade 500 bars should not be bent, rebent orstraightened without the engineer'sapproval.”

2. BS 8110 clause 3.12.8.22 states “Endanchorages in the form of hooks and bendsshould only be used to meet specific designrequirements and should conform to BS 8666.”

1 Product Summary

Eazistrip is a reinforcement product designed tomaintain continuity across wall to floor and wallto wall construction joints in concrete structures.

Eazistrip consists of selected reinforcement, pre-bent and housed in a purpose-designedcarrier casing manufactured from indentedgalvanised steel.

The Eazistrip unit is fixed to the shutter and castinto the front face of the wall. After theformwork is struck, the carrier case lid isremoved to reveal the connection legs (or starterbars) lying inside the casing. These legs are bentout by the contractor, ready for lapping the mainreinforcement of the next concrete pour.

The casing remains embedded in the wall,providing a rebate and key for the subsequentpour of the adjoining member and eliminates theneed for traditional preparation such as scabblingat the joint.

1.1 Scope of Application

This approval covers use of the Eazistripreinforcement continuity system in reinforcedconcrete structures designed in accordancewith BS8110: Part 1, which are subject to staticloading in non-cryogenic environments.

Product

Ancon EazistripReinforcementContinuity System

Produced by:

Ancon Building ProductsPresident WayPresident ParkSheffieldSouth YorkshireS4 7UR

Tel: +44 (0) 114 275 5224 Fax: +44 (0) 114 238 1240

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3. BS8110 clause 3.12.8.24 states that in relation to theminimum radius of bends “In no case should this be lessthan twice the radius of the test bend guaranteed by themanufacturer of the bar, nor less than the radius required toensure that the bearing stress at the mid-point of the curvedoes not exceed the values given in 3.12.8.25”.

It is the designers responsibility to ensure that reinforcementis adequately designed in accordance with the code anddetailed to ensure end anchorages and bearing stresses areappropriate. However, rebending of reinforcement at theconstruction joint is a matter of product suitability andworkmanship. This technical approval demonstrates that theperformance of construction joints is not adversely affected byuse of the Eazistrip reinforcement continuity system.

1.3 Conclusion

It is the opinion of CARES that the Ancon Eazistrip issatisfactory for use within the limits stated in paragraph 1.1when installed and used in accordance with the manufacturer’sinstructions and the requirements of this certificate.

B. BowsherExecutive Director

November 2007

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2 Technical Specification

2.1 General

The Eazistrip reinforcement continuity system isa quick and easy way of maintaining continuity ofreinforcement at construction joints in concrete.The system is manufactured by Ancon BuildingProducts in a CARES quality assuredmanufacturing unit.

The system consists of a galvanised steel casingwith a dimpled surface to provide an effectivebond and key with the concrete. Pre-bent barsare housed within the casing and are enclosed bya protective steel cover; each end of the unit isprovided with a polystyrene block in order toprevent the ingress of concrete.

The type of reinforcement used is selected byAncon Building Products to provide a suitabledegree of ductility, ensuring that it complies withthe tensile requirements of BS4449:2005 GradeB500B after prefabrication and re-bending onsite. The material is CARES approved, assuringconsistent compliance with the product standard.Material processing is CARES approved toensure full traceability from steel mill tocustomer.

Eazistrip is available in bar sizes 10, 12 and 16mm, the bars are formed to a minimum bendradius of: (Table 1).

Eazistrip is available in a wide range of customerspecified shapes and options, refer to Figure 1.Eazistrip units can also be supplied radiused to suitcircular structural elements.

The manufacturer’s sales literature offersscheduling information for the engineer andcontractor.

All the manufacturing processes comply with ISO9001:2000 and the bars are cropped and bentaccording to BS8666:2005.

Table 1

Bar Bend Bend Size Form Radius Form Diameter

10mm 30mm 60mm12mm 36mm 72mm16mm 50mm 100mm

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Shape Types

Figure 1

(not available in 60mm and 80mm boxes) (not available in 60mm and 80mm boxes)

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Where VRd = design shear resistanceAs = area of continuity reinforcement normal

to the joint fyd = design yield stress of continuity

reinforcement (= 435 N/mm2 for grade 500 bars)

fcu = characteristic cube strength of concreteAc = area of concrete in contact

with rear face of casing.

(The tests were made with 190 mm widecasing in joints between parallel sections of 240mm wide walls. The upper limit in the equationis simply the value corresponding to the largestratio of reinforcement used in the tests).

Mechanical tests on the reinforcementshowed that the material, after bending and straightening, complied with the tensilerequirements of BS4449 Grade B500B,exhibiting values for Total Elongation atMaximum Load (Agt) of greater than 5%.

3 Product Performance and Characteristics

3.1 Reinforcement Tensile Properties

3.2 Strength of Joints

Wall to floor joints

Structural tests showed that the flexuralstrength and shear strength of constructionjoints formed with the Eazistripreinforcement continuity system are no lessthan those of equivalent traditionally formedconstruction joints.

Wall to wall joints

The resistance of a joint to shear along its axisdepends on contact between the dimples of thecasing and the concrete to either side of it and on theability of the continuity reinforcement (or externalactions) to resist the forces normal to the jointengendered by the shear transfer. The results of alimited series of tests, with effectively pure shearloading, are consistent with the design expression

VRd = 0.7 Asfyd � 0.4 �fcu Ac

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3.3 Serviceability Limit States

3.3.1 Deflection

The deflection of elements is not a function of thisproduct insofar as joints formed using Eazistripwere able to ensure full structural continuity duringtesting and did not exhibit any significant additionalrotation relative to the joint.

3.3.2 Cracking

In the tests conducted, the widths of flexuralcracks in the joint regions at reinforcementstresses of 300 N/mm2 were slightly over the0.3mm required for areas of constant bendingmoment according to BS8110. Although BS8110does not cover cracking at joints, e.g. corners atslab/wall interface, the value found is no worsethan that experienced in traditional constructionjoints.

3.3.3 Calculation of Crack Widths

Crack widths at joints are not generally assessed inBS8110 designs but where a calculation isrequired, the following equation can be used:

� =� �

�

�

4s

�s

s

s

�

2

�

s�

Where = the steel stress in the crack,= the bar diameter,= the average bond stress,= the crack width at the level of the

centre of the steel,= the elastic modulus of the steel.

s

�

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Nail the Eazistrip through the casing tothe formwork or alternatively securely tiethe projecting anchorage reinforcing barsback to the main reinforcement. In bothcases the Eazistrip boxes should besecurely fixed to avoid displacementduring concreting. The casing should betight against the formwork. Pourconcrete.

Strike the formwork to reveal thesteel cover.

Remove the steel cover to expose thepre-bent bars.

4 Installation

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Straighten the bars using theappropriate sized AnconEazistrip re-bending tool forthe size of bar. The barsshould be straightened onlyonce. To avoid damage toadjacent concrete, it isprudent to allow a concretecuring period of seven days.See “Straightening of Bars”for more information.

Once the bars arestraightened and alignedthey are ready for lappingwith the concrete elementreinforcement, provided byothers.

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The bars in the Eazistrip box must bestraightened using the appropriate sized AnconEazistrip rebending tool (Figure 2). This is asteel tube designed to fit over the bar, theinternal diameter being slightly larger than themaximum dimension over the ribs of the bar.One end of the tube has a section cut away;this provides support to the outside of the bendduring straightening of the bar and limits thepoint contact of the tube on the bar. Use of thetool allows the re-bending process to be carriedout in a smooth continuous action (avoidingjerky action), the tube being moved along thebar and around the bend as it is straightened.Scaffold tubes or similar must not be used tostraighten bar. To enable the re-bending tool tobe fitted on to the bar, the bar should be pulledthe minimum distance from the Eazistrip steelcasing to enable this. The re-bending toolshould then be slid along the bar to the start ofthe bend radius. The bar straightening processshould be smooth and progressive with thetube allowed to move along the bend towardsthe metal casing as it is straightened. The toolshould contact the Eazistrip steel casing at thecompletion of the straightening process.

The tube is then removed and the straightened barchecked for alignment and cover with the adjoiningreinforcement. The Eazistrip reinforcing bars shouldnot be straightened when the temperature of thesteel is below 5°C. Where straightening isnecessary below 5°C, indirect warming of the steelto a temperature not exceeding 100°C is permitted.The use of scaffold tubes, or other inappropriatetools will result in excessive kinks in the region ofthe bar bend and result in undesirable workhardening which may damage the bar and affect thestrength of the bar. Re-bending must be undertakenusing only the Ancon Eazistrip re-bending tool.Bending the bar in excess of the recommendationswill also result in work hardening of the rebar andshould therefore be avoided.

4.1 Straightening of Bars

Eazistrip should be suitably stored in order toprotect it from mechanical damage and corrosion.

4.2 Storage

Figure 2

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On-Site Cutting

Identify the location of the intended cut.

Slide the protective cover from the box and remove the barswhich pass over the cut location.

Cut through the steel casing using a disc cutter.

Replace the bars to face the opposite direction to their originalposition. Cut the cover to the same lengths as the steel casingand replace to protect the bars. The ends of the boxes must besealed, using polystyrene blocks, to prevent the ingress ofconcrete.

Note: Protective gloves should be warn when removing covers,straightening bars, cutting boxes and during general handling ofEazistrip.

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Normal practice is to palletise Eazistrip unitsfor mechanical handling. Attention should begiven to recognised manual handlingprocedures and regulations. Individual casingunits weighing up to 25kg may be handledmanually provided due care is taken; theweight of each unit is normally identified oneach casing label.

5 Safety Considerations

Heavier units may require mechanical handlingequipment. Protective gloves should be wornwhen removing covers, straightening bars,cutting boxes and during general handling.

Heat should not be applied to the Eazistripcasing as it is galvanised and may producedangerous fumes.

The Eazistrip reinforcement continuity systemwas evaluated in two stages:

6.1.1. The reinforcement was subject toindependent mechanical testing toestablish its suitability for bendingduring the prefabrication process andrebending through 90 degrees duringthe straightening process on site andsubsequent compliance with the tensilerequirements of BS4449.

6 Product Testing and Evaluation

6.1.2 Eazistrip reinforcement continuitysystem samples were subject to aprogramme of full scale structuraltesting in concrete to evaluate theperformance of the construction jointsunder combinations of high shear andhigh flexural loading.

The selected reinforcement was tested todetermine the appropriate bend radii.

Reinforcement was subject to the CARESbendability test, which consisted of bendingthe reinforcement through 90 degrees over asteel former, straightening and examination ofthe inside of the bend for signs of fracture.The test was conducted twice on eachsample.

Reinforcement was also subject to the CAREStensile test regime, which consisted of bendingthe reinforcement through 90 degrees over a steelformer and straightening with the Eazistrip toolprior to tensile testing to measure the UltimateTensile Strength, Yield Strength and Elongation atMaximum Load (Agt). The selected reinforcementwere found to comply with the tensilerequirements of BS4449:2005 Grade B500B.(Clause 7.2.3, Table 4).

6.2 Mechanical Testing

6.1 General

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Figure 4

Post load test, showing ultimate shearfailure mode; a continuous polystyrenestrip was cast into the wall beneath theEazistrip joint to simulate poorcompaction of the concrete. The wall/slabconnection remains essentially intact.

Figure 5

Longitudinal shear test arrangementwith Eazistrip cast into one side of thejoint. The load was applied by jackthrough the enclosed test frame.

6.3 Full Scale Structural Testing

Figure 3

General wall/slab test arrangementshowing jack, with load cells near thecentre of slab and at the support remotefrom the wall.

Full-scale structural tests have been conducted on construction jointsformed using the Ancon Eazistrip continuity system to determineflexural strengths, vertical shear strengths and crack widths forwall/floor joints and the longitudinal shear strengths for wall/wall joints.

The largest bar 16mm bar was chosen for the majority of thewall/floor tests as being the largest bar size used in the Eazistripreinforcement continuity system and which imposes the greateststresses on the surrounding concrete and the most severe demandson the reinforcement in relation to bending and straightening.

The tests showed that flexural and shear strengths of wall/floor jointswere to the safe side of values calculated by BS8110 with safetyfactors removed, and that crack widths could be safely calculated bythe equation in section 3.3.3. The longitudinal shear strengths wereall on the safe side of the equation in section 3.2.

The test arrangements are shown in Figs 3, 4 & 5.

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8 Building Regulations

8.1 The Building Regulations(England and Wales)

Structure, Approved Document A

Ancon Eazistrip continuity system, when usedin BS8110 based designs using the datacontained within this technical approval, satisfythe relevant requirements of The BuildingRegulations (England and Wales), ApprovedDocument A.

Materials and Workmanship,Approved Document, tosupport regulation 7

This technical approval gives assurance that theAncon Eazistrip continuity system satisfies withthe material requirements of BS8110.

8.2 The Building Regulations(Northern Ireland)

Part B, Materials andWorkmanship

This technical approval gives assurance thatAncon Eazistrip continuity system satisfies withthe material requirements of BS8110 by virtue ofregulation B3, Deemed to satisfy provisionsregarding the fitness of materials andworkmanship.

8.3 The Building Standards(Scotland) Regulations

Part B, Fitness of Materials

This technical approval gives assurance thatAncon Eazistrip continuity system satisfies thematerial requirements of BS8110 by virtue ofClause B2.1

Part C, Structure

Ancon Eazistrip continuity system, when used inBS8110 based designs using the data containedwithin this technical approval, satisfies therequirements of The Building Standards (Scotland)Regulations 1990, Part C, C2.1 clause b.construction,ii.

The Ancon Eazistrip continuity systems areproduced under an ISO9001 quality managementsystem certified by CARES.

7 Quality Assurance

The quality management system schememonitors the production of the continuity systemand ensures that materials and geometry remainwithin the limits of this technical approval.

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9 References

• BS 4449: 2005: Steel for the reinforcement of concrete -Weldable reinforcing steel - Bar, coil and decoiled product- Specification.

• BS 8666: 2005: Scheduling, dimensioning, bending andcutting of steel reinforcement for concrete -Specification.

• BS8110: Part 1: 1997: (amended 2007) Structural Use ofConcrete, Code of Practice for Design and Construction.

• BS EN ISO 9001: 2000: Quality management systems -Requirements.

• CARES Appendix TA1-2; Quality and OperationsSchedule for the Technical Approval of ReinforcementContinuity Systems.

• Taylor Woodrow Technology Centre, Load testing ofAncon continuity reinforcement systems in concretesamples, Technical Report No N950/07.

• Prof. P. E. Regan, Evaluation of the results of tests of theAncon Eazistrip continuity System, Oct 2007.

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1. The quality of the materials and method ofmanufacture have been examined byCARES and found to be satisfactory. Thistechnical approval will remain validprovided that:

a. The product design and specification are unchanged.

b. The materials and method ofmanufacture are unchanged.

c. The manufacturer complies with CARESregulations for technical approvals.

d. The manufacturer holds a valid CARES Certificate of Product Assessment.

e. The product is installed and used as described in this report.

2 CARES make no representation as to thepresence or absence of patent rightssubsisting in the product and/or the legalright of Ancon to market the product.

3 Any references to standards, codes orlegislation are those which are in force atthe date of this certificate.

10 Conditions

4 Any recommendations relating to the safeuse of this product are the minimumstandards required when the product isused. These requirements do not purport tosatisfy the requirements of the Health andSafety at Work act 1974 or any otherrelevant safety legislation.

5 CARES does not accept any responsibilityfor any loss or injury arising as a direct orindirect result of the use of this product.

6 This Technical Approval Report should beread in conjunction with CARES Certificateof Product Assessment No 5017.Confirmation that this technical approval iscurrent can be obtained from UK CARES.

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CARES

Pembroke House, 21 Pembroke Road, Sevenoaks, Kent TN13 1XR

Tel: +44(0)1732 450000 Fax: +44(0)1732 455917

E-mail: general@ukcares.com

www.ukcares.com

Independent Product Assessments for the Construction Industry

Copyright UK CARES ©

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