Punching Shear Reinforcement - · PDF filecolumn head or base. The shear load from the slab is transferred through the studs into ... Design Sheet - Punching Shear Reinforcement Please

Embed Size (px)

Citation preview

  • Punching ShearReinforcementfor the Construction Industry

    CI/SfB (29) Et6

    July 2009

  • 22

    This brochure is printed on paper produced from 80%recycled post-consumer fibre and 20% virgin pulp which issourced from responsibly managed and sustainable forests(FSC certified). The printing inks and sealant are vegetable-based making the document fully recyclable.

  • Ancon designs and manufactures high integrity steel products for

    the construction industry. Through continuous programmes of

    new product development, inward investment and employee

    advancement, the company is committed to maintaining the

    highest level of customer service within a dynamic and

    challenging industry.

    Masonry Support Systems

    Masonry Reinforcement

    Windposts and Lintels

    Wall Ties and Restraint Fixings

    Channel and Bolt Fixings

    Tension Systems

    Stainless Steel Fabrications

    Flooring and Formed Sections

    Shear Load Connectors

    Reinforcing Bar Couplers

    Reinforcement Continuity Systems

    Punching Shear Reinforcement

    Insulated Balcony Connectors

    Refractory Fixings


    Used within a slab to provide additionalreinforcement around columns, Ancon Shearfixis the ideal solution to the design andconstruction problems associated withpunching shear. The system consists of double-headed studs welded to flat rails, positionedaround the column head or base.

    Punching Shear 4

    The Shearfix Solution 4

    Comparison with Shear Links 4

    Sizes and Configurations 5

    Product Identification 5

    Design Program 6-7

    System Design to BS8110 8

    Design Sheet 9

    Typical Rail Arrangements 10

    Installation Procedure 10Applications 11

    Other Ancon Products 11

    ISO 9001: 2008FM 12226

    ISO 14001: 2004EMS 505377

  • Shearfix Punching Shear Reinforcement


    PUNCHING SHEARThe weight of a slab supported on a columninduces shear stresses in the slab. Thesestresses, if sufficient and where additionalreinforcement has not been provided, wouldresult in the column punching through theslab. This punching shear is similarly inducedin the footing on which the column bears.

    THE SHEARFIX SOLUTIONUsed within a slab to provide additionalreinforcement around columns, Ancon Shearfixis the ideal solution to the design andconstruction problems associated withpunching shear.

    The system consists of double-headed studswelded to flat rails, positioned around thecolumn head or base. The shear load fromthe slab is transferred through the studs intothe column.

    Shearfix is suitable for all column shapes andis easy to install either top down or bottomup, depending on user preference (page 10).

    Punching Failure

    Comparison with Shear LinksAncon Shearfix offers many advantagesover loose shear links. Links can be time-consuming to both design and install.A Shearfix system is easily detailed withAncons free calculation program whichgenerates a layout drawing for inclusion in thebuilding plans and, rather than being installedindividually, these studs are supplied to sitewelded to rails at the appropriate spacing.

    When comparing links with studs, researchhas shown that any additional material costsincurred when purchasing a prefabricated studsystem, such as Shearfix, are generally faroutweighed by the savings from a significantlyreduced fixing time; these systems being up toten times quicker to install (source: BritishCement Association: Prefabricated punchingshear reinforcement for reinforced concrete flatslabs. BCA, Camberley, 2001).Although punching shear can be relieved by

    localised thickening of the concrete withdownstand beams and enlarged columnheads, the construction of flat slabs offersmany advantages. A consistent head spacecan reduce the overall height of a building andprovide significant time and material savings.

    Corner column using anorthogonal rail arrangement

    Top down installation. A row of studs is passed through the reinforcement grid as aunit and the rail is tied to the main reinforcement

  • 5

    Sizes and ConfigurationsThe Ancon Shearfix system comprisesdouble-headed studs welded to flat rails. It ismanufactured to suit the specific requirementsof each application. The quantity of eachcomponent, the dimensions and spacings,and the layout pattern around the column aredetermined by calculation. Ancon providesfree software to determine the optimumsystem design (see pages 6-7).

    Studs are manufactured in six diameters (10,12, 14, 16, 20 and 24mm) from high strengthsteel bar. The heads are hot forged to threetimes the diameter of the bar. Studs aremanufactured in virtually any length to suit thedepth of slab, but are normally formed inincrements of 10mm within the 100-500mmrange. The bar used in this system has acharacteristic yield strength of 500N/mm2.

    The studs are welded to the rail at the centresdetermined by Ancons software or a designcalculation. The rail performs no structuralfunction but ensures stud alignment andpositioning within the slab.

    Shearfix rails are manufactured from strips ofsteel, 16mm wide. The gap between the stripsallows for the passage of concrete duringpouring and also enables the rail to be nailedthrough spacers to formwork when fixedbottom up i.e. prior to all other reinforcement.

    Double-headed Stud 10, 12, 14,16, 20 and 24mm diameters


    0.5d 0.75d 0.75d 0.5d






    rall d


    Note: d=effective slab thickness

    Tel: +44 (0) 114 275 5224 Web: www.ancon.co.uk














    m le



    Product IdentificationEach rail of studs carries the following identification:

    Shearfix Code and Stud Diameter - Number of Studs - Stud Length - Rail Length

    Column/Grid Reference

    Floor Level

    e.g. AS12-3-230-600


    Level 2

    All dimensions are in millimetres.

    PROJECT MANAGEMENTPlease contact Ancon if you would like helpin creating a Shearfix schedule and aprogramme for delivery to suit progress onsite. If advised at the time of ordering,pallets can be packed in priority order e.gby pour number.

    Ancons Products for Structural Concretedivision offers a dedicated service to theconcrete sector. Contact the team on +44 (0) 114 275 5224 with your Shearfixenquiry.

  • Shearfix Punching Shear Reinforcement


    DESIGN PROGRAMShearfix is designed to suit the specificrequirements of each application. Anconprovides a free design program to simplify thespecification and ordering of a Shearfixsystem.

    This easy-to-use program allows the optimumsystem design to be determined andgenerates a printable data sheet and a DXF fileof the specified layout. Solutions can becreated for all column sizes, shapes andlocations including columns offset from edgesand corners.

    The program allows analysis to BS 8110-1,DIN 1045-1 and AS 3600. For a Eurocode 2version please contact Ancon.

    Users can design a radial or an orthogonal raillayout. This feature, which is unique to theAncon program, allows the most economicaldesign (fewest number of studs) to beachieved for each application.

    Where there are openings close to the column,a section of the slab will be ineffective andperimeters will need to be reduced; the Ancondesign program allows these reductions to beapplied to each perimeter.

    The program requires the followinginformation:

    Column shape(circular, rectangular or L shape)

    Column dimensions Column location (interior, edge, external

    corner, re-entrant corner)

    Dimension to concrete edge(for offset corner and edge columns)

    Slab thickness Concrete grade Reinforcement size and spacing Cover to reinforcement Shear load Applied momentsThis free program can be downloadedfrom www.ancon.co.uk, emailed onrequest or supplied on CD. Contact Anconon +44 (0) 114 275 5224 for your copy.

    A hard copy of the calculation method toBS 8110 is available on request.

    Screen shot of a circular column offset from one edge, with a radial stud layout

    The datasheet generated

    The DXF file generated

  • 7

    Tel: +44 (0) 114 275 5224 Web: www.ancon.co.uk

    Screen shot of a rectangular column, offset from a re-entrant corner, with an orthogonal rail layout

    The datasheet generated

    The DXF file generated

  • 8

    Shearfix Punching Shear Reinforcement

    DESIGN INFORMATION:BS 8110-1:1997The shear stress is checked at a perimeter1.5d (d = effective slab thickness) from theface of the column (u0), further checks arecarried out at successive intervals of 0.75d (u1,u2 etc) until a perimeter is reached which doesnot require shear reinforcement (un).

    The first stud is positioned 0.5d from the faceof the column, with the spacing betweenindividual studs taken as 0.75d with amaximum limit of 500mm. The maximumspacing between parallel rails is 1.5d.

    When using the Ancon design program acheck is carried out for over-reinforcement; ifthis check fails, a warning message states thatfailure due to punching shear is possible andan increase in slab thickness will be required.

    Two layouts are available, radial and orthogonal.

    Radial LayoutRails are positioned on the two main axes toall available column faces with diagonal rails atthe corners; all perimeters have radiusedcorners, circular columns have circularperimeters. The spacing between theoutermost studs on the diagonal rails is kept toa maximum of 3d.

    Orthogonal LayoutRails are positioned on the main axes to allavailable column faces, additional rails arepositioned in lin