CI/SfB Et6

September 2012

Punching Shear
Reinforcement
for the Construction Industry
2
2 Tel: 1300 304 320 www.ancon.com.au
Ancon designs and manufactures high integrity steel products for Used within a slab to provide additional
reinforcement around columns, Ancon Shearfix
the construction industry. Through continuous programmes of
is the ideal solution to the design and
new product development, inward investment and employee construction problems associated with
punching shear. The system consists of double-
advancement, the company is committed to maintaining the
headed studs welded to flat rails, positioned
highest level of customer service within a dynamic and around the column head or base.

challenging industry.
Masonry Support Systems Punching Shear 4
The Shearfix Solution 4
Windposts and Lintels Comparison with Shear Links 4
Sizes and Configurations 5
Wall Ties and Restraint Fixings Product Identification 5
Project Management 5
Channel and Bolt Fixings Design Program 6-7
Design Information 8
Tension and Compression Systems
Calculation Method 9
Stainless Steel Fabrications Typical Arrangements 10
Installation Procedure 10
Flooring and Formed Sections Applications 11
Other Ancon Products 11
Shear Load Connectors

Stainless Steel Reinforcement

Reinforcing Bar Couplers

Reinforcement Continuity Systems

Punching Shear Reinforcement

Precast Concrete Accessories

3
 Punching Shear Reinforcement

Punching Shear The Shearfix Solution Comparison with Shear Links

The weight of a slab supported on a column Used within a slab to provide additional Ancon Shearfix offers many advantages
induces shear stresses in the slab. These reinforcement around columns, Ancon Shearfix over loose shear links. Links can be time-
stresses, if sufficient and where additional is the ideal solution to the design and consuming to both design and install.
reinforcement has not been provided, would construction problems associated with A Shearfix system is easily detailed with
result in the column ‘punching’ through the punching shear. Ancon’s Punching Shear Reinforcement
slab. This punching shear is similarly induced Design Program (see pages 6-7). This program
The system consists of double-headed studs
in the footing on which the column bears. generates a layout drawing for inclusion in the
welded to flat rails, positioned around the
building plans and, rather than being installed
column head or base. The shear load from
individually, these studs are supplied to site
the slab is transferred through the studs into
welded to rails at the appropriate spacing.
the column.
When comparing links with studs, research
Shearfix is suitable for all column shapes and
has shown that any additional material costs
is easy to install either ‘top down’ or ‘bottom
incurred when purchasing a prefabricated stud
up’, depending on user preference.
system, such as Shearfix, are generally far
outweighed by the savings from a significantly
reduced fixing time; these systems being up to
Punching Failure ten times quicker to install (source: Building
Research Establishment, UK).
Although punching shear can be relieved by
localised thickening of the concrete with
downstand beams and enlarged column
heads, the construction of flat slabs offers
many advantages. A consistent head space
can reduce the overall height of a building and
provide significant time and material savings.

4 Tel: 1300 304 320 www.ancon.com.au

Sizes and Configurations Flat Rail
The Ancon Shearfix system comprises
double-headed studs welded to flat rails. It is
manufactured to suit the specific requirements
of each application. The quantity of each
component, the dimensions and spacings,
and the layout pattern around the column are
determined by calculation. Ancon provides
free software to determine the optimum
system design.
Double-headed Stud 12, 16, 20
Studs are manufactured in four diameters (12, and 24mm diameters
16, 20 and 24mm) from high strength steel
bar. The heads are hot forged to three times
the diameter of the bar. Studs are
manufactured in virtually any length to suit the
depth of slab, but are normally formed in
increments of 10mm within the 100-500mm
Top
range. The bar used in this system has Cover

characteristic yield strength of 500MPa.

The studs are welded to the rail at the centres
determined by Ancon’s software or a design
calculation. The rail performs no structural
function but ensures stud alignment and

Overall depth ‘D’

Stud length
positioning within the slab.
Shearfix rails are manufactured from strips of Stud
diameter
steel, 20mm wide.

0.5d 0.7(D - top cover - bottom cover - 5) 0.7(D - top cover - bottom cover - 5) 0.5d
Bottom
Note: d=effective slab thickness Cover

Project Management Product Identification

Please contact Ancon if you would like help Each rail of studs carries the following identification:
in creating a Shearfix schedule and a
Shearfix Code, Stud Diameter x Stud Length, Number of Studs @ Stud Centres, Rail Length
programme for delivery to suit progress on
Column/Grid Reference
site. If advised at the time of ordering,
Floor Level
pallets can be packed in priority order e.g
by pour number. e.g. SF12 x 230, 3 @ 180 c/c, 600 long
Call us on 1300 304 320 with your Shearfix K15
enquiry. Level 2
All dimensions are in millimetres.
230mm length

Stud
Stud length

diameter
12mm

0.5d 0.7(D - top cover - bottom cover - 5) 0.7(D - top cover - bottom cover - 5) 0.5d
120mm 180mm 180mm 120mm

SF12 x 230, 3 @ 180 c/c, 600 long

5
 Punching Shear Reinforcement

Design Program
Ancon Shearfix is designed to suit the specific
requirements of each application. Ancon
provides a design program to simplify the
specification and ordering of a Shearfix
system.
This easy-to-use program determines the
optimum design of Shearfix components and
generates a printable data sheet and a DXF file
of the specified layout. Solutions can be
created for all column sizes, shapes and
locations including columns offset from edges
and corners.
The program allows analysis to AS 3600 (Lim
and Rangan), BS EN 1992-1-1 (Eurocode 2)
and BS 8110-1.
The program requires the following
information:

• Column shape (circular, rectangular or ‘L’

shape)
Screen shot of a rectangular internal column
• Column dimensions

• Column location (interior, edge or corner)

• Slab thickness

• Concrete grade

• Any reductions to the critical shear perimeter

• Cover to reinforcement

• Shear load

• Applied moments
This program can be downloaded from
www.ancon.com.au.
The calculation method used in the Ancon
design program (Lim and Rangan) is shown on The DXF file generated
page 9.

The datasheet generated

6 Tel: 1300 304 320 www.ancon.com.au

Screen shot of a square column, offset from a re-entrant corner

The DXF file generated

The datasheet generated

7
 Punching Shear Reinforcement

Design Information
The analysis follows the specifications in the
standard AS 3600: 2009 clause 9.2, but the
major part of the design is based on the
research presented by F K Lim and B V
Rangan. Please note that AS 3600: 2009 does
not have a specific clause on shear stud
design. Therefore the software is based on a 0.7 (D - top cover -
research paper. We strongly recommend the bottom cover - 5)
shear stud design is verified against an 0.5d
alternate standard such as BS EN 1992-1-1 600mm
(Eurocode 2) or BS 8110. max
or D
The shear capacity of the slab is checked whichever
is less
against the design shear forces at the critical
shear perimeter (refer to AS 3600: 2009 for
further details on determining the critical shear Critical shear
perimeter) and if required Shearfix studs are perimeter
designed to increase the shear capacity of the
slab.
The first stud is positioned 0.5d from the face
of the column, i.e. along critical shear
perimeter, with the spacing between individual
studs taken at 0.7 (D - top cover - bottom
cover - 5) with a maximum limit of 500mm. Design Information
The Shearfix Program designs the rails, firstly
at 0.7 (D - top cover - bottom cover - 5) and Ineffective shear
then checks the shear capacity of the slab. perimeter
If the shear capacity of the slab is still below
the design shear force, the program will then
reduce the spacing until the shear capacity
of the slab exceeds the design shear force.
The maximum spacing between parallel rails
is 600mm or D whichever is less.
The number of studs along a rail is determined
Critical shear
by positioning the last stud 2.5d from the b0 perimeter
Opening
column face, and then spacing the studs
between the first and the last.
If more than one rail is required for each side
of the column, rails should be placed at the
corner of the column in the torsion strip.
Ineffective
A check is carried out for over reinforcement - shear
if this check fails, a warning message states perimeter
that failure due to punching shear is possible
and an increase in slab thickness will be
required.
Effect of Slab Penetrations
Where there are openings in the slab within
<2
.5

2.5b0 (b0 = width of an opening) from the

b0

critical shear perimeter (cl. 9.2.1.2), a section

of the slab will be ineffective and the critical
shear perimeter will need to be reduced. The Any opening within 2.5b0 of critical
shear perimeter must be considered
Ancon design program allows reductions to be
applied to the critical shear perimeter as
appropriate. b0

Slab Penetrations

8 Tel: 1300 304 320 www.ancon.com.au

Calculation Method For the case where M* is zero – Minimum cross sectional area of stud
The design of Shearfix follows the Vuo = ud(fcv + 0.3σ cp ) reinforcement -
specifications set out in the Clause 9.2 of AS 0.35bs
Clause 9.2.3a, AS 3600: 2009 Avs ≥
3600: 2009, but the major part of the design is fvy
based on the research presented by F K Lim Where –
0.35as
and B V Rangan from the School of Vuo = shear capacity of the slab Avt ≥
fvy
Engineering at Curtin University of Technology σ cp = average pre-stress in concrete
in Perth. Fcv = concrete shear strength, where – Clause 8.2.8, AS 3600: 2009
The design calculations check the shear fcv = 0.17(1 + 2 βh ) f' c ≤0.34 f' c When using the Shearfix Design Program, the
stresses imposed on the critical shear βh is the ratio of the effective loaded program automatically determines the
perimeter surrounding the column, with area = X/Y (X≥Y) diameter, spacing and number of studs
Shearfix stud reinforcement provided as required.
required. For the case where M* is not zero –
Alternatively the user can specify the diameter,
Vuo
Design Actions Vu = spacing and number of studs and check
When checking the shear capacity of the slab, 1+( v* 8V* ad )
uM
against the shear capacity of the slab.
the design shear force V* and design transfer Clause 9.2.4, AS 3600: 2009
Detailing
moment from the slab into the support Mv* Where “a” is the dimension of the critical shear When using the Shearfix Design Program, the
must be taken into account. perimeter parallel in the direction of Mv* program automatically arranges the stud rails
In the Shearfix Design Program, these values If V* > φVu or φVuo, then Shearfix studs are around the column.
must be calculated and inputted into the required. When arranging Shearfix studs around columns,
program.
To determine the shear capacity of the slab the following limits should be implemented –
Critical Shear Perimeter
The critical shear perimeter “u” is the boundary
with Shearfix studs for the slab strip, the • The position of the first stud from the
following equation from Lim and Rangan is column face is 0.5d (d = effective depth of
of the effective area of a support or used – slab)
concentrated loads located at a distance of
d/2, (d = effective depth of the slab). Vu = Vuo(1 + kt ) • The maximum stud spacing is 500mm or
OR 0.75D or 0.7(D – Top Cover – Bottom Cover
For rectangular columns –
Vuo – 5mm), whichever is less (D – overall depth
u = 2(x + d/2 + d/2) + 2(y + d/2 + d/2) Vu = of slab)
1 + uMv*
Critical shear perimeter ks 8V* ad • The minimum spacing for 12mm studs is
(the lesser result of the two equations) 45mm, and 55mm for 16mm studs

d/
where – • The height of stud (hs ) is calculated as –
2 y ks = 1 Avs fvy d u hs = D – Top cover - Bottom cover - 5mm
Vuo sb
d/ Avs = cross sectional area of a row of studs in For 24mm Studs, the minimum stud height
2
the slab strip is 360mm
x
Fvy = Yield strength of the stud (500 MPa)
Where there are critical openings within 2.5 b0 s = spacing of the studs
• The cross sectional area for the headed
ends on each stud needs to be at least 10
from the critical perimeter, the projected width b = width of the critical shear perimeter times the cross sectional area of the stud
of the opening will be ineffective and will perpendicular to the direction Mv* diameter. (Clause 13.1.4, AS 3600: 2009).
reduce the length of the critical perimeter.
For the torsion strip, the following equations This ensures the stud is fully anchored to
b0 are used – provide full transfer of forces through the
Ineffective portion
of critical shear stud.
Vu = Vuo(1 + kt )
perimeter
<2.5 b0 d/
2 OR • The maximum spacing between rails is
Vuo 600mm or D, whichever is less
Vu1 =
d/ 1 + uMv*
2
1+kt 8V* ad
• The minimum spacing is 100mm

(the lesser result of the two equations) • The position of the last stud is located 2.5d
where – from the column face
kt = 1 Avt fvy d u
Vuo sa
• The minimum slab thicknesses for each stud
size with 20mm cover is as follows –
<2.5 b0 Avt = cross sectional area of a row of studs in
Stud Size Min Slab Thickness
the torsion strip
12mm 140mm
a = width of the critical shear perimeter parallel
b0 16mm 140mm
to the direction Mv* (the width of the torsion 20mm 180mm
Calculation of Shear Stress strip) 24mm 410mm
b
The shear capacity of the slab is determined in
accordance to Clause 9.2.3 for the case where For rectangular columns the areas of maximum
there are no transfer moments (M* is zero), or stress will be at the corners of the column,
Clause 9.2.4 for the case where there are Direction of Torsion because of this it is best to try and place rails at
transfer moments (M* is not zero). Bending Strip a the end of the column sides.

9
 Punching Shear Reinforcement

Typical Arrangements
Shearfix is suitable for all column shapes and locations.
Some typical arrangements are shown here.

Installation Procedure
Ancon Shearfix is quick and simple to install.
It can be fitted either ‘top down’ (after all other
reinforcement) or ‘bottom up’ (prior to other
reinforcement).

‘Top down’ Fixing

• Fix all main reinforcement in position ‘Top down’ fixing

• Place Shearfix rails around the column to

the layout detailed on job drawings by
passing the studs through the
reinforcement grid and resting the carrier
rails on the top layer of reinforcement

• Tie rails with wire to main reinforcement

and pour concrete

‘Bottom up’ Fixing

• Clip rails to spacers in order to maintain
cover

• Place rail and spacer units around the

column to the layout detailed on job
drawings

• Fix main reinforcement in position and pour

concrete

‘Bottom up’ fixing

10 Tel: 1300 304 320 www.ancon.com.au

Applications Other Ancon Products
Reinforcing Bar Couplers
The use of reinforcing bar couplers can provide
significant advantages over lapped joints.
Design and construction of the concrete can
be simplified and the amount of reinforcement
required can be reduced. The Ancon range
includes BT parallel threaded couplers and
MBT mechanically bolted couplers.

Reinforcement Continuity Systems

Reinforcement Continuity Systems are an
increasingly popular means of maintaining
continuity of reinforcement at construction joints
in concrete. The Ancon Keybox system
eliminates the need to drill shuttering and can
Photo: Hyder Consulting

simplify formwork design, thereby accelerating

the construction process. It is available in both
standard units and special configurations.
Ancon KSN Anchors eliminate the need for
Westpac Place, Sydney, NSW on-site bar straightening and are available to
accept reinforcement of 12mm, 16mm and
20mm diameter. The system is also available
with a re-useable rebate former.

Shear Load Connectors

Ancon DSD and ESD Shear Load Connectors
are used to transfer shear across expansion
and contraction joints in concrete. They are
more effective at transferring load and allowing
movement to take place than standard dowels,
and can be used to eliminate double columns
at structural movement joints in buildings. A
‘Lockable’ dowel is also available for temporary
movement joints in post-tensioned concrete
frames.

Masonry Support Systems and Fixings

Ancon manufactures support systems for
masonry cladding on concrete and steel
framed buildings. A wide range of channels
and bolts are available to fix these systems to
Victoria Point, Melbourne, VIC
the structural frame. Cast-in channels and
expansion bolts are used for fixing to the
edges of concrete floors and beams.

Tension Systems
© Darcy Schack JAM Photographics Ltd

Tie bars are increasingly being used in

structures and buildings as an architectural as
well as a structural element. Ancon Tension
Systems comprise a range of components
which can be supplied in carbon steel or
stainless steel in a variety of sizes and finishes.
A variety of assemblies can be created from
simple tie bars to complex bracing systems
involving several bars joined at one point.

Special Fabrications
© Thiess, Energy Australia

Ancon is an ASSDA accredited specialist

fabricator and has a wealth of experience in
working with a variety of material grades. High
integrity steel components are supplied to a
wide range of industries including Civil
Beaumonde Apartments, Sydney, NSW
Engineering, Building, Infrastructure, Water
Treatment, Nuclear and Mining.

11
Masonry Support Systems
Windposts and Lintels
Wall Ties and Restraint Fixings
Channel and Bolt Fixings
Tension and Compression Systems
Stainless Steel Fabrications
Flooring and Formed Sections
Shear Load Connectors
Stainless Steel Reinforcement
Reinforcing Bar Couplers
Reinforcement Continuity Systems
Punching Shear Reinforcement
Precast Concrete Accessories

Ancon Building Products Ancon Building Products

114 Kurrajong Avenue 7-9 Second Avenue
Mount Druitt Sunshine
Sydney Melbourne
NSW 2770 VIC 3020
Australia Australia
Tel: 1300 304 320 Tel: 1300 304 320
Fax: +61 (0) 2 9675 3390 Fax: +61 (0) 3 9311 1777
Ancon Building Products Ancon Building Products
4/15 Terrace Place 82 Chisholm Crescent
Murarrie Kewdale
Brisbane Perth
QLD 4172 WA 6105
Australia Australia
Tel: 1300 304 320 Tel: 1300 304 320
Fax: +61 (0) 7 3395 6693 Fax: +61 (0) 8 9453 2300

International Enquiries: +61 (0) 2 8808 1111

Email: info@ancon.com.au
Web: www.ancon.com.au

Overseas Offices:
Ancon Building Products Ancon (Schweiz) AG Ancon (Middle East) FZE
Sheffield Ried bei Kerzers Dubai
United Kingdom Switzerland United Arab Emirates
www.ancon.co.uk www.ancon.ch www.ancon.ae
Ancon Building Products GesmbH Ancon GmbH
Vienna Nuremberg
Austria Germany
www.ancon.at www.anconbp.de

The construction applications and details provided in this literature

These products are available from:
are indicative only. In every case, project working details should be
entrusted to appropriately qualified and experienced persons.

Whilst every care has been exercised in the preparation of this

document to ensure that any advice, recommendations or
information is accurate, no liability or responsibility of any kind is
accepted in respect of Ancon Building Products.

With a policy of continuous product development Ancon Building

Products reserves the right to modify product design and
specification without due notice.
© Ancon Building Products 2012