DOUBLE WALL LIFTING ANCHORS 07 - CFS Fixings

DOUBLE WALL LIFTING ANCHORS 07

DOUBLE WALL LIFTING ANCHORS

CONTENTS

Double Wall Anchors 07-03

Installation 07-05

Hoisting, Transportation and Relocation 07-06

Rules for using Flexi-X Lifters 07-07

General rules for Flexi-X Lifters 07-08

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DOUBLE WALL ANCHORS

Double Wall anchors are used for transporting and relocating precast concrete sandwich panels.

About Double Walls

Double walls consist of two thin precast concrete formwork layers which are joined by lattice girders. These form permanent shuttering and after installation on site, the core is concrete-filled.

The minimum edge distances given in this table are for the loadings given here. Please contact CFS if you have different conditions and we can provide a bespoke calculation.

Maximum Wall Weights

Dimensions of Double Wall Anchors

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Allowable loads Maximum wall weights

Axia

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≤ 45

°

Shea

r Loadcase 1 Loadcase 2 Loadcase 3 Loadcase 4

2 anchors

4 anchors

2 anchors

4 anchors

2 anchors

4 anchors

2 anchors

4 anchorsh ci c FV FVS FQ

N/mm2 mm kN tonnes

15 50 10 300 25.2 23.1 7.9 4 7.9 2.5 5 - - - -

20 50 10 300 29.1 26.7 9.1 4.6 9.1 2.9 5.7 4.2 8.4 2.9 5.7

25 50 10 300 32.5 29.8 10.2 5.1 10.2 3.2 6.4 4.7 9.3 3.2 6.4

30 50 10 300 35.6 32.6 11.2 - - - - 5.1 10.2 3.5 7.0

35 50 10 300 36.5 35.3 12.1 - - - - 5.5 11.1 3.8 7.6

15 65 15 300 35.5 35.5 11 5.6 11.1 3.5 6.9 - - - -

20 65 15 300 36.5 36.5 12.7 5.7 11.4 4 8 5.7 11.4 4 8

25 65 15 300 36.5 36.5 14.2 5.7 11.4 4.5 8.9 5.7 11.4 4.5 8.9

30 65 15 300 36.5 36.5 15.6 - - - - 5.7 11.4 4.9 9.8

35 65 15 300 36.5 36.5 16.8 - - - - 5.7 11.4 5.3 10.5

Anchor widthLeg bar diameter

Crossbar diameter LengthSmooth steel S235

L1 d D2 H1

mm

≤ 200 14 20 450

200 - 310 14 22 450

310 - 360 14 25 500


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DOUBLE WALL ANCHORS INSTALLATION

Loadcase 1 – Factory – Axial loading only

• Rotate to vertical using tilting table and then axial lifting with a lifting beam• Concrete strength 15 to 25 N/mm2• Dynamic factor = 1.3 (tower crane, mobile crane)• No demoulding• All axial load, no angled and no shear lifting

Loadcase 2 – Factory – Axial, angled and shear loading

• Stripping without tilting table. Tilting the walls in shear from the horizontal to the vertical using the anchors

• Concrete strength 15 to 25 N/mm2• Dynamic factor = 1.3 (tower crane, mobile crane)• Lifting chains at an angle ≤ 45°

Loadcase 3 – Site – Axial and angled loading

• Delivery of double wall standing vertically• Concrete strength 20 to 35 N/mm2• Dynamic factor = 1.3 (tower crane, mobile crane)• Lifting chains at an angle ≤ 45°

Loadcase 4 – Site – Axial, angled and shear loading

• Delivery of double wall lying flat on the bed of the truck• Concrete strength 20 to 35 N/mm2• Tilting of the walls in shear to the vertical using the anchors• Dynamic factor = 1.3 (tower crane, mobile crane)• Lifting chains at an angle ≤ 45°

Edge Distances and Spacing

To use the load tables shown here, the minimum distance from the edge of a panel and from any recesses is 300mm and the minimum distance between anchors is 600mm. If you have a different situation contact CFS for a bespoke calculation.

Concrete Cover

The concrete cover towards the outside of the panel must be determined by the engineer according to the durability requirements of the wall. To the inside, the concrete cover should be as stated in the table. If the contours of the stirrup are visible on the inside surface of the wall, the capacity of the anchor is not guaranteed and the anchor should not be used.

Reinforcement

Minimum reinforcement should be determined by the engineer. The manufacturer’s data has been generated from tests with 1 layer of A252 mesh, please provide at least this level of reinforcement.

Insert Depth

The anchors should be installed so that the upper end of the stirrup does not project out of the end of the wall.

Anchor Arrangement

If using more than two double wall anchors, suspension will be structurally indeterminate unless a compensation equaliser or similar is used. This is due to possible uneven rope lengths or different heights of the installed double wall anchors. Without this aid it is impossible to calculate the load on each anchor.

Allowable Load Under Angle

In the load table our load values FVS is the vertical component of the load, no angled load reduction necessary.

Double wall anchor cover


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HOISTING, TRANSPORTATION AND RELOCATION

FLEXI-X LIFTERS

• Increase load capacity for tilting

• Easier to fix in the mould via the X cross bar

Rules for Flexi-X lifter positioning

1) Flexi-X must be positioned between two lattice girders

2) Only one Flexi-X may be located between two girders

3) Minimum spacing of adjacent Flexi-X’s = 500mm

Visual Check

A visual check on the anchors should be carried out for obvious damage before installation. Do not use damaged anchors.

Transport cases

Shear loading is not generally permitted during transport. A shear lift may only be used when lifting the slabs from horizontal to upright from the formwork platform or from the transport truck on site. Please refer to the engineer’s instructions for correct transportation position.

Modes of transport, hoisting and use of equalisers

There are different hoisting load factors to take into account in the calculations depending on the transport and lifting device. Each loadcase in the table covers a different lifting situation.

Pitching load adjustment for different shell 2 strengths

fcu > 20 MPa at time of lift, use pitching load x 1.15fcu > 25 MPa at time of lift, use pitching load x 1.30

Twinwall Thickness

Steel Cover Girder & Lifter Height

mm

200 25 120

250 25 170

300 25 220

300 25 220

300 35 200

350 35 250

400 35 300

Axial Load, T Pitching shear Load, T

Special Shell 2 requirements

≤ 3.3 ≤ 1.2 None

≤ 3.4 1.2 < PL < 1.5 2B12 bars @ 100crs

Instructions for installation and use of Schroeder double wall anchors

2.3 Minimum reinforcementMinimum reinforcement made of BST 500 Sis necessary in both concrete formwork of longi-tudinal ds = 8 mm and horizontal ds = 6 mmat interval s = 20 cm.

2.4 Inset depth of the compression memberTo ensure sufficient application of force theanchors should be installed so that the upperend of the stirrup does not project out of theend of the wall.

2.5 Anchor arrangement,influence on the structural system

The number and arrangement of transportanchors has a direct influence on the structuralsystem and the load of the individual anchors.

If the anchors are installed symmetrically withrespect to the centre of gravity and a compen-sating mechanism guarantees an equivalentcontact length, the anchor forces are equallylarge and the anchorage is optimally exploited.If the anchor and compensatory suspension arearranged asymmetrically the double wall willdistort initially after lifting.

If using more than two double wall anchors,suspension will be structurally indeterminate.Loading all double wall anchors will then requirethe use of a compensation equaliser or similar

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Fig. 8 Arrangement of double wall anchors

Axialzug

Querzug

Fig. 9 Hoisting the slab from the horizontal

due to possible uneven rope lengths or differentheights of the installed double wall anchors.Without this aid it is impossible to calculate theload on each anchor.

Inclined lifting increases the load on the doublewall anchor and the slinging and hoisting gearas compared to purely vertical lifting in accor-dance with the angle of inclination.

3. Hoisting, transportationand relocation

3.1 Component requirementsIf the required visual checks reveal damage tothe double wall this will jeopardise the payloadof the anchorage and this anchor can no longerbe used.

3.2 Transport situationsHorizontal tensile load is not generally permittedduring transport. It is permitted only when liftingthe slabs from horizontal to upright from theformwork platform or on the construction site.

Refer to the concrete element manufacturer’sinstructions for the correct transport position.

3.3 Modes of transport, hoisting loads,use of equalisers

There are different hoisting load factors to takeinto account in the calculations depending onthe transport- and lifting device.

Axial tensile

Tensileload

Construction Fixing Systems LimitedUnit 2, Westfield Estate, Henley Road, Medmenham, Marlow, Buckinghamshire SL7 2TA. UK

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Axialzug Schrägzug

Fig. 10 Axial tensile load with equaliser anddiagonal tensile load

Fig. 11 Structurally indeterminate suspensionwith compensation mounting

See section “4.1: Design loads” for hoistingload factors.

Depending on the number and location of thedouble wall anchors the use of an equaliser or acompensation sling may be necessary (see sec-tion “2.5: Anchor arrangement and influence onthe structural system”).

Use an equaliser when using horizontal tensileload to lift off the formwork table.

The slinging equipment must be used only asshown in fig. 9, 10 and 11 – never attach to com-pression member.

4. Calculations and proofThe loads on individual double wall anchors mustbe determined from an engineering perspectivein a structural calculation.

4.1 Design loadsThe following loads shall be generally appliedfor the dimensioning of double wall anchors.Application-specific features shall be taken intoaccount from an engineering perspective:the dead weight of the precast concrete elementshall be calculated based on the dimensions ofthe precast concrete element and the density ofthe concrete used.

G [kN] = V [m3] x g [kN/m3]V = Volume of concrete formworkg = concrete density – in the case of standard

concrete 25 kN/m3

Formwork adherence and -frictionThe formwork adherence when lifting the form-work depends on the surface quality of theformwork. The following guide values apply:

q adh [kN/m2]

Oiled steel formwork 1

Painted wood formwork 2

Unpainted wood formwork 3

Textured formwork should be taken into accountseparately.

The load is calculated as followsFs [kN] = q adh [kN/m2] x A [m2]

in which A = concrete contact surface to form-work [ m2].

Dynamic loadThere are different hoisting load factors to takeinto account in the calculations depending onthe transport- and lifting device.Following hoisting load factors shall be takeninto account:

Rotating tower crane,1.3 – 1.7gantry crane, mobile crane

Hoisting and transportation2 – 3on level terrain

Hoisting and transportation> 4on uneven terrain

Axialtensile load

Diagonaltensile load


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CFS Double Wall Anchor.indd 7 16/8/10 12:15:25








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concrete 25 kN/m3


q adh [kN/m2]











Axialtensile load



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Tilting up from horizontal

Statically determinate suspension with compensation mounting

Axial and angled loading

≤ 100 ≤ 200

≤ 100 ≤ 200

≤ 100 ≤ 200

‘X’ bars on Flexi-X lifter must lie in shell 1

Centres of lattice girders ≤ 500mm

In red zone lifters must be within 100mm of lattice. Axial and pitching capacity must be reduced by 50% If the pitching load is greater than

1.2T, but less than 1.5T, then the two edge bars on the mesh must be B12, spacing 100m

Note: Panel may be pitched in either direction, but if possible shell 1 should be uppermost

Axial Load

Pitching Load


GENERAL USAGE INSTRUCTIONS

1) Nominal lifter size to be same as nominal girder height.

2) Concrete strength of shell 2 at time of lifting ≥ 15 MPa

3) Minimum cover to lifter is 10mm. The ‘X’ bars in shell 1 should just be completely covered with concrete.

4) ‘X’ bars to be wired to mesh bars. Wire in 3 places only and avoid distortion of mesh through over-tightening.

5) Shell 1 thickness ≥ 65mm.

6) Combined thickness of shell 1 and shell 2 ≥ 145mm

7) Axial load may be inclined at 30 degrees to vertical without any down rating of capacity.

Documents

DOUBLE WALL LIFTING ANCHORS 07 - CFS Fixings