resource book

SpecifiersResource BookConcrete Anchoring Concrete Lifting

www.ramset.com.au

WELCOME TO THE RAMSETSPECIFIERS RESOURCE BOOKThis concise and systematically presented book contains the information most useful to Architects,Specifiers and Engineers when selecting the concrete anchoring solution that best suits their project.

Selection of a concrete anchoring product is made on the basis of the basic type of fixing (male or female, bolt or stud), macro environment, (e.g. coastal or inland), micro environment(particular chemicals) and of course the capacity that best meets the design load case.

Where the fixing is simple and does not warrant strength limit state calculations, selection on thebasis of load case is made simple and easy with working load limit tables for each concrete anchor.

Where more rigorous design and strength limit state calculation is required, the simplified step-by-step method presented in this booklet will allow rapid selection and verification of theappropriate concrete anchor.

The Brick and Block anchoring section gives design professionals guidance as to the behaviour of a number of fixings suitable for use in a variety of both solid and hollow pre-manufactured masonry units.

The capacity information presented considers the elemental nature of pre-manufactured masonryunits and advises designers as to suitable locations within the units accordingly.

With the continued growth of Precast Concrete as a construction medium, technical information ispresented here, sufficient to enable the selection of appropriate lifting hardware for precast concretecomponents subject to lifting, handling and erection.

In line with current practice, the information is presented in Working Load Limit format, consistant with capacity information presented for cranes, slings, chains, etc.

We know that you will find this book both useful and informative.

For additional information or any further enquiries, contact your local Ramset engineer at the following email addresses:

Western Australia [email protected]/Tasmania [email protected] Territory/South Australia [email protected] [email protected] South Wales/A.C.T. [email protected]

2

31 LEGEND OF SYMBOLS 5

2 NOTATION 6

3 DESIGN PROCESS 73.1 Simplified Design Approach 8-113.2 Worked Example 12-15

4 ANCHOR DESIGN SOFTWARE 16-18

5 SELECTING THE RIGHT ANCHOR5.1 Environmental Considerations 195.2 Anchor Feature Guide 20-215.3 Chemical Resistance 22-23

6 ANCHORING TECHNOLOGY6.1 Derivation of Capacity 246.2 Anchoring Principles 25-286.3 Base Materials 28-296.4 Design 306.5 Tension 31-346.6 Shear 35-366.7 Bending 376.8 Combined Loading 386.9 Anchor Groups 396.10 Assembly Torque and Preload 406.11 Long Term Preload Degradation 416.12 Slip Load and Cyclic Loading 426.13 Corrosion 436.14 Fire 43

MECHANICAL ANCHORING

7 SpaTec Safety Anchors7.1 General Information 45-467.2 Description and Part Numbers 467.3 Engineering Properties 467.4 Strength Limit State Design 47-52

8 HiShear 8.8 Structural Anchors8.1 General Information 53-548.2 Description and Part Numbers 548.3 Engineering Properties 548.4 Strength Limit State Design 55-60

9 Boa Coil Expansion Anchors9.1 General Information 61-629.2 Description and Part Numbers 629.3 Engineering Properties 629.4 Strength Limit State Design 63-68

10 TruBolt Stud Anchors10.1 General Information 69-7010.2 Description and Part Numbers 7010.3 Engineering Properties 7110.4 Strength Limit State Design 72-78

11 AnkaScrew Screw In Anchors11.1 General Information 79-8011.2 Description and Part Numbers 8011.3 Engineering Properties 8011.4 Strength Limit State Design 81-86

12 DynaBolt Sleeve Anchors12.1 General Information 87-8812.2 Description and Part Numbers 8812.3 Engineering Properties 8812.4 Strength Limit State Design 89-94

13 DynaSet Drop In Anchors13.1 General Information 95-9613.2 Description and Part Numbers 9613.3 Engineering Properties 9613.4 Strength Limit State Design 97-102

14 RediDrive Hammer In Anchors14.1 General Information 103-10414.2 Description and Part Numbers 10414.3 Engineering Properties 104

15 ShureDrive Anchors15.1 General Information 105-10615.2 Description and Part Numbers 106

16 RamPlug

16.1 General Information 107-10816.2 Description and Part Numbers 108

17 EasyDrive Nylon Anchors17.1 General Information 109-11017.2 Description and Part Numbers 110

CHEMICAL ANCHORING

18 ChemSet Anchor Studs & Injection RodChemSet Anchor Studs

18.1 General Information 11318.2 Description and Part Numbers 11318.3 Engineering Properties 113

ChemSet Injection Rod18.4 General Information 11418.5 Description and Part Numbers 11418.6 Engineering Properties 114

19 ChemSet Maxima Spin Capsules19.1 General Information 115-11619.2 Description and Part Numbers 11619.3 Engineering Properties 11619.4 Strength Limit State Design 117-122

20 ChemSet Injection 800 Series20.1 General Information 123-12420.2 Description and Part Numbers 12420.3 Engineering Properties 12420.4 Strength Limit State Design 125-130

TABLE OF CONTENTS

4TABLE OF CONTENTS cont.21 ChemSet Hammer Capsules21.1 General Information 131-13221.2 Description and Part Numbers 13221.3 Engineering Properties 13221.4 Strength Limit State Design 133-138

22 ChemSet Injection 10122.1 General Information 139-14022.2 Description and Part Numbers 14022.3 Engineering Properties 14022.4 Strength Limit State Design 141-146

BRICK AND BLOCK ANCHORING

23 TYPICAL PRE-MANUFACTURED MASONRY UNITS 149-151

24 ChemSet Injection 10124.1 General Information 152-15324.2 Description and Part Numbers 15324.3 Engineering Properties 153

25 AnkaScrew Screw In Anchors25.1 General Information 154-15525.2 Description and Part Numbers 15525.3 Engineering Properties 155

26 DynaBolt Anchor Hex Bolt26.1 General Information 156-15726.2 Description and Part Numbers 15726.3 Engineering Properties 157

27 RamPlug

27.1 General Information 158-15927.2 Description and Part Numbers 159

28 TYPICAL BOLT PERFORMANCE INFORMATION28.1 Strength Limit State Design Information 16128.2 Working Load Limit Design Information 161

CAST-IN ANCHORING

29 Elephants Feet Ferrules29.1 General Information 163-16429.2 Description and Part Numbers 16429.3 Engineering Properties 16429.4 Strength Limit State Design 165-170

30 Round Ferrules30.1 General Information 171-17230.2 Description and Part Numbers 17230.3 Engineering Properties 17230.4 Strength Limit State Design 173-178

31 TCM Ferrules31.1 General Information 179-18031.2 Description and Part Numbers 18031.3 Engineering Properties 18031.4 Strength Limit State Design 181-186

CAST-IN LIFTING

32 LIFTING TECHNOLOGY32.1 Important Notice 18932.2 Lifting Anchors 19032.3 Lifting Clutches 19032.4 Substrate Suitability 19132.5 References 19132.6 Load Case Determination 192-19332.7 Design Considerations 194-195

33 SYSTEMS FOR YARD CAST WALL PANELS33.1 Applications 19733.2 Installation 19833.3 Anchor Types 19833.4 Lifting Anchor Reinforcement Detail 19933.5 Capacity Information 20033.6 Description and Part Numbers 20133.7 Specification 201

34 SYSTEMS FOR SITE CAST WALL PANELS34.1 Applications 20334.2 Installation 20334.3 Anchor Types 20434.4 Capacity Information 20434.5 Description and Part Numbers 20534.6 Specification 205

35 SYSTEMS FOR COMPONENT PRECAST35.1 Applications 207-20835.2 Installation 20935.3 Anchor Types 21035.4 Lifting Anchor Reinforcement Detail 21135.5 Capacity Information 212-21735.6 Description and Part Numbers 21835.7 Specification 219

RESOURCE BOOK DESIGN WORKSHEET 220-221

Suitable for elevated temperate applications. Structural anchor components made from steel. Any plastic or non-ferrous parts make no contribution to holding power under elevated temperatures.

Suitable for use in seismic design.

Anchor has an effective pull-down feature,or is a stud anchor. It has the ability to clamp the fixture to the base material and provide high resistance to cyclic loading.

Has good resistance to cyclic and pulse loading. Resists loosening under vibration.

May be used close to edges (or another anchor) without risk of splitting the concrete.

Anchor is cast into substrate by either puddling, attaching to reinforcing or formwork.

AISI Grade 316 Stainless Steel, resistant to corrosive agents including chlorides and industrial pollutants.Recommended for internal or external applications in marine or corrosive environments.

Corrosion resistant. Impact resistant.Not recommended for direct exposure to sunlight.

Steel Zinc Plated to AS1791-1986.Minimum thickness 6 micron.Recommended for internal applications only.

Steel Hot Dipped Galvanised to AS1650-1989 and AS1214-1983.Minimum thickness 42 micron.For external applications.

Anchor can be through fixed into substrateusing fixture as template.

Temporary or removable anchor.

Suitable for wall applications.

Suitable for overhead applications.

Suitable for floor applications.

Suitable for hollow brick/block and hollow core concrete applications.

Suitable for use in drilled holes.

Suitable for use in cored holes.

Chemical anchors suitable for use in dry holes.

Chemical anchors suitable for use in damp holes.

Chemical anchors suitable for use in holesfilled with water.

PERFORMANCE RELATED SYMBOLSIndicates the suitability of product to specific types of performance related situations.

MATERIAL SPECIFICATION SYMBOLSIndicates the base material and surface finish to assist in selection in regard to corrosion or environmental issues.

INSTALLATION RELATED SYMBOLSIndicates the suitable positioning and other installation related requirements.

Suitable for AAC and lightweight concreteapplications.

1

5

We have developed this set of easily recognisable icons to assist with product selection.

1.0 LEGEND OF SYMBOLS

62.0 NOTATION2

GENERAL NOTATION

a = actual anchor spacing (mm)

ac = critical anchor spacing (mm)

am = absolute minimum anchor spacing (mm)

As = stress area (mm2)

bm = minimum substrate thickness (mm)

db = bolt diameter (mm)

df = fixture hole diameter (mm)

dh = drilled hole diameter (mm)

e = actual edge distance (mm)

ec = critical edge distance (mm)

em = absolute minimum edge distance (mm)

fc = concrete cylinder compressive strength (MPa)

fcf = concrete flexural tensile strength (MPa)

fu = characteristic ultimate steel tensile strength (MPa)

fy = characteristic steel yield strength (MPa)

h = anchor effective depth (mm)

hn = nominal effective depth (mm)

g = gap or non-structural thickness (mm)

L = anchor length (mm)

Le = anchor effective length (mm)

Lt = thread length (mm)

n = number of fixings in a group

PL = long term, retained preload (kN)

PLi = initial preload (kN)

Pr = proof load (kN)

t = total thickness of fastened material(s) (mm)

Tr = assembly torque (Nm)

Xe = edge distance effect, tension

Xna = anchor spacing effect, tension

Xnae = anchor spacing effect, end of a row,tension

Xnai = anchor spacing effect, internal to a row,tension

Xnc = concrete compressive strength effect,tension

Xne = edge distance effect, tension

Xuc = characteristic ultimate capacity

Xva = anchor spacing effect, concrete edge shear

Xvc = concrete compressive strength effect, shear

Xvd = load direction effect, concrete edge shear

Xvn = multiple anchors effect, concrete edge shear

Xvs = corner edge shear effect, shear

Xvsc = concrete compressive strength effect, combined concrete/steel shear

Z = section modulus (mm3)

= concrete cube compressive strength (N/mm2)

T = torque co-efficient of sliding frictionx = mean ultimate capacity

STRENGTH LIMIT STATE NOTATION

M* = design bending action effect (Nmm)

Mu = characteristic ultimate moment capacity (Nm)

N* = design tensile action effect (kN)

Ntf = nominal ultimate bolt tensile capacity (kN)

Nu = characteristic ultimate tensile capacity (kN)

Nuc = characteristic ultimate concrete tensile capacity (kN)

Nucr = factored characteristic ultimate concrete tensile capacity (kN)

Nur = design ultimate tensile capacity (kN)

Nurc = design ultimate concrete tensile capacity (kN)

Nus = characteristic ultimate steel tensilecapacity (kN)

Nusr = factored characteristic ultimate steel tensile capacity (kN)

Ru = characteristic ultimate capacity

V* = design shear action effect (kN)

Vsf = nominal ultimate bolt shear capacity (kN)

Vu = ultimate shear capacity (kN)

Vuc = characteristic ultimate concrete edge shear capacity (kN)

Vur = design ultimate shear capacity (kN)

Vurc = design ultimate concrete edge shearcapacity (kN)

Vus = characteristic ultimate steel shearcapacity (kN)

Vusc = characteristic ultimate combined concrete/steel shear capacity (kN)

= capacity reduction factor

c = capacity reduction factor, concretetension recommended as 0.6

m = capacity reduction factor, steel bending recommended as 0.8

n = capacity reduction factor, steel tension recommended as 0.8

q = capacity reduction factor, concrete edgeshear recommended as 0.6

v = capacity reduction factor, steel shear recommended as 0.8

PERMISSIBLE STRESS NOTATION

fs = factor of safety

fsc = factor of safety for substrate = 3.0

fss = factor of safety for steel in tension and bending = 2.2

fsv = factor of safety for steel in shear = 2.5

M = applied moment (Nm)

Ma = working load limit moment capacity (Nm)

N = applied tensile load (kN)

Na = working load limit tensile capacity (kN)

Nac = working load limit concrete tensile capacity (kN)

Nar = factored working load limit tensile capacity (kN)

Nas = working load limit steel tensile capacity (kN)

Nasr = factored working load limit steel tensile capacity (kN)

Ra = working load limit capacity

V = applied shear load (kN)

Va = working load limit shear capacity (kN)

Var = factored working load limit shear capacity (kN)

Vas = working load limit steel shear capacity (kN)

73

This information is provided for the guidance of qualifiedstructural engineers or other suitably skilled persons in thedesign of anchors. It is the designers responsibility to ensurecompliance with the relevant standards, codes of practice,building regulations, workplace regulations and statutes as applicable.

This manual allows the designer to determine load carrying capacities based on actual application andinstallation conditions.

The designer must first select the anchor style/type to suitapplication and environmental conditions through the use of tables 5.1, 5.2 & 5.3 to identify the specific productfeatures, dimensional properties and environmentalcharacteristics required.

Then select an appropriate anchor size to meet the requiredload case through the use of either the working loadinformation provided or by use of the simplified designprocess described on the page opposite to arrive atrecommendations in line with strength limit state design principles.

Ramset has developed this Simplified Design Approachto achieve strength limit state design, and to allow for rapidselection of a suitable anchor and through systematicanalysis, establish that it will meet the required designcriteria under strength limit state principles.

The necessary diagrams, tables etc. for each specific productare included in this publication.

Ramset has also developed a software tool RamsetAnchor Design to enable engineers to quickly selectsuitable anchors for a specific set of design conditions andoutput the results for project file reference.

See section 4 of this publication for further details and an example of how to use the Ramset Anchor Designsoftware.

3.0 DESIGN PROCESS

8We have developed this design process to provide accurateanchor performance predictions and allow appropriate designsolutions in an efficient and time saving manner.

Our experience over many years of anchor design has enabledus to develop this process which enables accurate and quicksolutions without the need to work labourously from firstprinciples each time.

PRELIMINARY SELECTION

Establish the design action effects, N* and V* (Tension and Shear) acting on each anchor being examined using theappropriate load combinations detailed in the AS1170 series of Australian Standards.

Refer to charts 5.1, 5.2 and 5.3 in order to select an anchortype that best meets the needs of your application.

STRENGTH LIMIT STATE DESIGN

Refer to table 1a, Indicative combined loading interactiondiagram for the anchor type selected, looking up N* and V* to select the anchor size most likely to meet the designrequirements.

Note that the Interaction Diagram is for a specific concretecompressive strength and does not consider edge distance andanchor spacing effects, hence is a guide only and its useshould not replace a complete design process.

ACTION Note down the anchor size selected.

Having selected an anchor size, check that the design values for edge distance and anchor spacing comply with the absolute minima detailed in table 1b.If your design values do not comply, adjust the design layout.

Calculate the anchor effective depth as detailed in step 1c.

This is an important structural dimension that will be referred to in subsequent tables.

Typically, greater effective depths will result in greater tensile capacities.

ACTION Note down the anchor effective depth, h.Note also the product part no. referenced.

If the above questions are answered satisfactorily, proceed to step 2.

3.1 SIMPLIFIED DESIGN APPROACH

Select anchor to be evaluatedSTEP 1

Checkpoint 1

Anchor size selected ?

Absolute minima compliance achieved ?

Anchor effective depth calculated ?

3 Simplified Design Approach

93Simplified Design Approach

Referring to table 2a, determine the reduced characteristicultimate concrete tensile capacity (Nuc). This is the basiccapacity, uninfluenced by edge distance or anchor spacings andis for the specific concrete compressive strength(s) noted.

ACTION Note down the value for Nuc

Calculate the concrete compressive strength effect, tension, Xncby referring to table 2b. This multiplier considers the influenceof the actual concrete compressive strength compared to thatused in table 2a above.

ACTION Note down the value for Xnc

If the concrete edge distance is close enough to the anchorbeing evaluated, that anchors tensile performance may bereduced. Use table 2c, edge distance effect, tension, Xne todetermine if the design edge distance influences the anchorstensile capacity.

ACTION Note down the value for Xne

For designs involving more than one anchor, considerationmust be given to the influence of anchor spacing on tensilecapacity. Use either of tables 2d or 2e to establish the anchorspacing effect, tension, Xnae or Xnai.

ACTION Note down the value of Xnae or Xnai

This calculation takes into consideration the influences ofconcrete compressive strength, edge distance and anchorspacing to arrive at the design reduced concrete tensile capacity.

ACTION Note down the value of Nurc

Verify concrete tensile capacity - per anchorSTEP 2

Checkpoint 2

Design reduced concrete tensile capacity, Nurc

Nurc = Nuc * Xnc * Xne * ( Xnae or Xnai ) (kN)

Having calculated the concrete tensile capacity above (Nurc),consideration must now be given to other failure mechanisms.

Calculate the reduced characteristic ultimate steel tensilecapacity (Nus) from table(s) 3a.

ACTION Note down the value of Nus

For internally threaded anchoring products that utilise aseparate bolt such as the range of Cast-In Ferrules and theDynaSet anchor, make use of step 3b to verify the reducedcharacteristic ultimate bolt steel tensile capacity (Ntf).

Now that we have obtained capacity information for all tensile failure mechanisms, verify which one is controlling the design.

This completes the tensile design process, we now look toverify that adequate shear capacity is available.

Verify anchor tensile capacity - per anchorSTEP 3

Checkpoint 3

Design reduced ultimate tensile capacity, Nur

Nur = minimum of Nurc, Nus, Ntf

Check N* / Nur 1,

if not satisfied return to step 1

10

Referring to table 4a, determine the reduced characteristicultimate concrete edge shear capacity (Vuc). This is the basic capacity, uninfluenced by anchor spacings and is for the specific edge distance and concrete compressivestrength(s) noted.

ACTION Note down the value for Vuc

Calculate the concrete compressive strength effect, shear, Xvcby referring to table 4b. This multiplier considers the influenceof the actual concrete compressive strength compared to thatused in table 4a above.

ACTION Note down the value for Xvc

The angle of incidence of the shear load acting towards an edgeis considered by the factor Xvd, load direction effect, shear.

Use table 4c to establish its value.

ACTION Note down the value for Xvd

For a row of anchors located close to an edge, the influence ofthe anchor spacing on the concrete edge shear capacity isconsidered by the factor Xva, anchor spacing effect, concreteedge shear.

Note that this factor deals with a row of anchors parallel tothe edge and assumes that all anchors are loaded equally.

If designing for a single anchor, Xva = 1.0

ACTION Note down the value for Xva

In order to distribute the concrete edge shear evenly to allanchors within a row, calculate the multiple anchors effect,concrete edge shear, Xvn.

If designing for a single anchor, Xvn = 1.0

Examples

This calculation takes into consideration the influences ofconcrete compressive strength, edge distance and anchorspacing to arrive at the design reduced concrete shear capacity.

For a design involving two or more anchors in a row parallelto an edge, this value is the average capacity of each anchorassuming each is loaded equally.

ACTION Note down the value of Vurc

Note: Consider capacity of two anchors in row closest to edge only, ie. anchor load = V*TOTAL/2 to each anchor.

ACTION Note down the value for Xvn

Verify concrete shear capacity - per anchorSTEP 4

Checkpoint 4

Design reduced concrete shear capacity, Vurc

Vurc = Vuc * Xvc * Xvd * Xva * Xvn (kN)

n = 3

V*TOTAL

n = 2

V*TOTAL

n = 2

V*TOTAL

Assume slotted holes toprevent shear take up.

Simplified Design Approach3

11

Simplified Design Approach 3

Having calculated the concrete shear capacity above (Vurc),consideration must now be given to other failure mechanisms.

Calculate the reduced characteristic ultimate steel shearcapacity (Vus) from table(s) 5a.

ACTION Note down the value for Vus

For internally threaded anchoring products that utilise aseparate bolt such as the range of Cast-In Ferrules and theDynaSet anchor, make use of step 5b to verify the reducedcharacteristic ultimate bolt steel shear capacity (Vsf).

Verify anchor shear capacity - per anchorSTEP 5

Checkpoint 5

Now that we have obtained capacity information for all shear failure mechanisms, verify which one is controlling the design.

This completes the shear design process, we now look to verifythat adequate combined capacity is available for load caseshaving both shear and tensile components.

Design reduced shear capacity, Vur

Vur = minimum of Vurc, Vus, Vsf

Check V* / Vur 1,


For load cases having both tensile and shear components,verify that the relationship represented here is satisfied.

Combined loading and specificationSTEP 6

Checkpoint 6

Check

N*/Nur + V*/Vur 1.2,


Specify the product to be used as detailed.

12

3.2 WORKED EXAMPLEVerify capacity of the anchors detailed below:

Given data:

As the design process considers design action effects PER anchor, distribute the total load case to each anchor as is deemed appropriate.

In this case, equal load distribution is considered appropriate hence,

Given that each of the interior anchors is influenced by twoadjacent anchors, verify capacity for anchor B in this case.

From the information presented in tables 5.1 5.3, it is established that SpaTec anchors will be suitable for selection.

Having completed the preliminary selection component of thedesign process, commence the Strength Limit State Designprocess.

Concrete compressive strength fc 50 MPa

Design tensile action effect N*TOTAL 80 kN

Design shear action effect V*TOTAL 180 kN

Edge distance e 250 mm

Anchor spacing a 150 mm

Fixture plate + grout thickness t 42 mm

No. of anchors in shear n 4

Design tensile action effect (per anchor) N* 20 kN

Design shear action effect (per anchor) V* 45 kN

A B C D

V*TOTAL

= 30

250

150 150 150

Worked Example3

13

Worked Example 3

Refer to table 1a, Indicative combined loading interactiondiagram on page 45. Applying both the N* value and V* valueto the interaction, it can be seen that the intersection of thetwo values falls within the M16 band.

ACTION M16 anchor size selected.

Confirm that absolute minima requirements are met.

From table 1b (page 45) for SpaTec, it is required that edge distance, e > 170 mm. and that anchor spacing, a > 120 mm.

The design values of e = 250 mm and a = 150 mm complywith these minima, hence continue to step 1c.

The effective depth, h, is calculated by making reference to the Description and Part Numbers table on page 44 andcalculating effective depth, h = Le - t. Two options are availablefor the M16 SpaTec. Given that the fixture thickness value t is quite large, select the longer of the two M16 SpaTec

anchors available.

Hence, h = 150 - 42= 108 mm

ACTION h = 108Anchor selected is SA16167

Select anchor to be evaluatedSTEP 1

Checkpoint 1

Anchor size selected ? M16

Absolute minimaYescompliance achieved ?

Anchor effectiveh = 108 mm with SA16167depth calculated ?

Referring to table 2a, consider the value obtained for an M16 anchor at h = 110 mm (closest to our design value of h = 108 mm).

ACTION Nuc = 54.6 kN

Verify the concrete compressive strength effect, tension, Xncvalue from table 2b.

ACTION Xnc = 1.25

Verify the edge distanced effect, tension, Xne value from table 2c.

ACTION Xne = 1.00 (no effect)

As we are considering anchor B for this example, use table 2e on page 47 to verify the anchor spacing effect,internal to a row, tension, Xnai value. If we were inspectinganchors A or D we would use table 2d for anchors at the end of a row.

ACTION Xnai = 0.45

ACTION Nurc = 30.7 kN

Verify concrete tensile capacity - per anchorSTEP 2

Checkpoint 2

Design reduced concrete tensile capacity, Nurc

Nurc = Nuc * Xnc * Xne * Xnai (kN)

= 54.6 * 1.25 * 1.00 * 0.45

= 30.7 kN

14

From table 3a, verify the reduced characteristic ultimate steeltensile capacity, Nus.

For an M16 SpaTec, Nus = 100.5 kN.

ACTION Nus = 100.5 kN

Verify anchor tensile capacity - per anchorSTEP 3

Checkpoint 3

Nur = minimum of Nurc, Nus

In this case Nur = 30.7 kN(governed by concrete capacity).

Check N* / Nur 1,

20 / 30.7 = 0.65 1Tensile design criteria satisfied, proceed to Step 4.

Referring to table 4a, consider the value obtained for an M16anchor at e = 250 mm.

ACTION Vuc = 80.2 kN

Verify the concrete compressive strength effect, tension, Xvcvalue from table 4b.

ACTION Xvc = 1.25

Verify the load direction effect, concrete edge shear, Xvdvalue using table 4c.

ACTION Xvd = 1.32 for angle of 30 degrees to normal.

Verify the anchor spacing effect, concrete edge shear, Xvavalue using table 4d.

ACTION Xva = 0.62

In order to distribute the shear load evenly to all anchors in the group, the multiple anchors effect, concrete edge shear, Xvnvalue is retrieved from table 4e.

The ratio of (a / e) for this design case is 150 / 250 = 0.6.

ACTION Xvn = 0.69

ACTION Vurc = 56.6 kN

Verify concrete shear capacity - per anchorSTEP 4

Checkpoint 4

Design reduced concrete shear capacity, Vurc

Vurc = Vuc * Xvc * Xvd * Xva * Xvn (kN)

= 80.2 * 1.25 * 1.32 * 0.62 * 0.69

= 56.6 kN

From table 5a, verify the reduced characteristic ultimate steel shear capacity, Vus.

The shear capacity available from the SpaTec anchor is subject to its effective depth, h value. As was noted earlier h = 108 mm for this example, hence,

for an M16 SpaTec at h = 108 mm, Vus = 104.5 kN

ACTION Vus = 104.5 kN

Verify anchor shear capacity - per anchorSTEP 5

Checkpoint 5

Vur = minimum of Vurc, Vus

In this case Vur = 56.6 kN(governed by concrete capacity).

Check V* / Vur 1,

45 / 56.6 = 0.80 1Shear design criteria satisfied, proceed to Step 6.

Worked Example3

15

Worked Example 3

Check that the combined loading relationship is satisfied:

Reviewing the design process, examine the critical factorsinfluencing the overall anchor capacity.

For tension (governed by concrete failure),

Nuc = 54.6 kNXnc = 1.25Xne = 1.00Xnai = 0.45

It can be seen from the above values that whilst the concretecompressive strength effect, Xnc improves the design ultimatetensile capacity, the anchor spacing effect, Xnai significantlyreduces design ultimate tensile capacity.

Possible solution: Increase anchor spacing to raise the value of Xnai.

For shear (governed by concrete failure),

Vuc = 80.2 kNXvc = 1.25Xvd = 1.32Xva = 0.62Xvn = 0.69

Again, the concrete compressive strength effect, Xvc improvesthe design ultimate shear capacity. Anchor spacing effect, Xvareduces the design ultimate shear capacity.

Possible solution: Increase anchor spacing to raise the value of Xva.

Note that increasing the anchor spacing for this design willimprove Xnai, Xva and Xvn.

Re-consider the design using the adjusted values with anchorspacing, a set at 200 mm.

Nuc = 54.6 kNXnc = 1.25Xne = 1.00Xnai = 0.61

Hence Nurc = 41.6 kN (at a = 200 mm).

Vuc = 80.2 kNXvc = 1.25Xvd = 1.32Xva = 0.66Xvn = 0.74 (at a = 200 mm, hence a / e = 0.8)

Hence Vurc = 64.6 kN (at a = 200 mm).

Now,

Combined loading and specificationSTEP 6

Checkpoint 6


20 / 30.7 + 45 / 56.6 = 1.44 > 1.2

Combined loading criteria FAILED.


20 / 41.6 + 45 / 64.6 = 1.17 < 1.2

Combined loading criteria PASSES.

SpecifyRamset SpaTec Anchor,

M16 (SA16167).Maximum fixed thickness to be 42 mm.

To be installed in accordance withRamset Technical Data Sheet

16

4

4.1 ANCHOR DESIGN SOFTWARE4.1.1 RAMSET ANCHOR DESIGN

SOFTWARE v1.3

Ramset Anchor Design Software is provided to assist in thechoice of a suitable fastener which meets a specific set ofdesign inputs and is intended for use by suitably qualifieddesign professionals.

The program attempts to acquire the minimum data needed tofully specify the anchoring problem,

~ substrate details

~ adverse environments

~ interfering edges and anchors

~ load case information

and to offer a range of anchors which meet the requirement.

Additional information prompts with defaults, ensuring it hasbeen considered. Once a selection has been made all inputs,calculated values and installation details are available as output.

The Ramset Anchor Design Software is ideal for consideringcomplex anchor layouts and grouped anchor configurations.Note that the calculations being performed relate to the singlefastener currently at the reference location. The softwareprovides a calculation of the viability of THAT anchor andassumes that all other anchors:

~ are the same type

~ have the same installation conditions,

~ are subject to the same force.

For multiple anchor connections, the design professional musttherefore distribute the applied load case(s) to each anchor inthe group and evaluate each anchor separately.

This approach allows the designer flexibility in distributingloads to anchors so as to optimise the connection detailwithout the constraints of a software imposed distributionmethod.

The software will check that the substrate thickness isadequate for allowing anchor capacity to be generated. TheStructural Engineer should check the substrates sectionalcapacity for resisting the applied load.

By default the software will select from a wide range offasteners types that suit the design parameters of the specificanchor.

4.1.2 USE OF THE RAMSET DESIGNSOFTWARE

Having installed and run the program proceed to the toolbar atthe top of the screen and select the "New" button, this willbring you to the first of four input screens.

Project/Customer Details

On the first screen (Fig. 1) enter Project/Customer Details. These are simply details that will help identify the project youare designing and will form part of the printed output that canbe stored as part of the project documentation.

Fig. 1

On completion of these details, the "Next" button located onthe bottom of the screen will move you onto the second inputscreen.

Material Details

On the second screen (Fig. 2) enter the Material Details.These refer directly to the substrate properties of the projectyou are designing.

Fields which must be completed are;

~ Fixture and Non Structural Space ThicknessThis refers to the thickness of the fixture and the nonstructural gap which is any non structural material (e.g. plaster, grout, packer, foam) in between the substrateand the fixture.

~ Structural Depth and Compressive StrengthThis refers to the substrate thickness and its compressivestrength. Note that the program assumes the substrate is asolid homogeneous material with a particular compressivestrength. Therefore it cannot design hollow block fixings,however core-filled blockwork can be analysed using anequivalent compressive strength value.

Anchor Design Software 4

17

Fields which may be completed to help define the anchorselection criteria are:

(Note if these fields are left blank then the program willconsider all possible anchors in the range that would besuitable for the design conditions you impose.)

~ Fastener EnvironmentThese boxes can be "ticked" if there is a particular attributethe anchor must exhibit. e.g. Selecting the "Corrosive"attribute will ensure only galvanised and stainless steelfixings are considered and eliminate zinc plated anchors.

~ Anchor for ConsiderationYou can individually select specific anchor types to beconsidered in the design, and eliminate any that you do notwish to be evaluated.

The screen should then be similar to the following.

On completion of the details, the "Next" button will move youonto the third input screen, or alternatively hit "Previous" tomake any changes to the first input screen.

Layout of Dimensional Considerations.

On the third screen (Fig. 3) enter the layout of edges andother fasteners which may affect the design.

These are details on the anchor layout, which enable any lossin capacity due to being close to an edge or a neighbouringfastener, of the particular connection you are designing to betaken into account.

Select the "Layout" button.

Select your anchor group configuration, e.g. for a 2 x 2 anchorlayout select the "four" line. Now fill out all the applicable edgedistances and spacings. Note that you do not have to enter inall the edges if the anchors are located internally within a slabor panel. Once you are satisfied with the layout, select the"Finish" button.

Fig. 2

You will notice from the above diagram the fastener in thecross hairs is the reference fastener location upon which allcalculations are made. You are able to change the fastener toone of the other anchors - details on how to do this can befound by selecting the "Help" button.

The "Concrete Compaction Factor" represents the quality ofthe concrete. For well vibrated and compacted concrete, thisvalue should be set at 1.0. For poorly finished or unsupervisededge concrete, set the value at 1.5.

On Completion of all details, the "Next" button moves youonto the final input screen, or alternatively select "Previous"to make any changes to the second input screen.

Limit State or Working Load Design

The fourth screen (Fig. 4) requires you to enter either the Limit State or Working Load Design Loads - applied loadon the single anchor position selected. This refers to theloads applied on the anchor in question, and can either beentered in as a Limit State Load or a Working Load.

To design in Limit State, select the "Change to Limit StateDesign" button. You can then adjust the reduction factors as required.

Finally input the applied loads on the anchor you are designing,remembering that this load is applied to the single anchorposition only.

You will note that the Shear force is split into "Y" and "Z" axiscomponents. Entering a +ve load in the "Y" box will mean itwill be directed toward the top of the screen, if you wish todirect the load in the opposite direction simply input the valueas a -ve load. Likewise for the "Z" axis.

Fig. 3

Anchor Design Software4

18

You will notice on the above screen that the anchors are listedin order of capacity utilised and also display a relative cost,which is an index cost allowing you to compare theapproximate installed cost of the various types of suitableanchors.

Select your preferred anchor via the "Select" button and thescreen will then show the design output screen. This screenshows you the Design Inputs, parameters which you haveentered and computed Design Outputs which includescapacities, governing factors and installation dimensions. If youwould like to see the detailed calculations, then select therelevant tabs, i.e. Design, Layout, Cross Section and Installation.

On completion, the "Finish" button will commence thecomputation of all the possible solutions for the parametersyou have entered. The possible solutions will be displayed inthe "Possible Acceptable Anchors" dialogue box.

It is important to note that if the input design parameterswere incomplete or no possible solutions could be found,the program will advise as to the reasons why, (e.g. anchors too close to edge). You are then able toadjust the design as detailed, using the design input iconson the summary output screen (Fig. 6).

Fig. 4

Fig. 5

The icons in the top right hand corner of the screen enable youto navigate through the completed design.

The first four from the left are actually the four design inputscreens you have just completed.

The fifth icon (calculator icon) allows you to recalculate forpossible solutions in case you make any amendments or wouldlike to select a different anchor.

The next icon (printer icon) allows you to print a summary ofthe design, which will show the project description, anchorlayout, design inputs and outputs. More detailed printouts areavailable if you go to "File" then "Print..." then select theprintout you would like.

The next icon (disk icon) allows you to save the design forfuture reference and can be retrieved at a later date.

For a copy of our latest Design Software, contact your localspecialist Ramset Sales Engineer (details on inside frontcover) for a demonstration.

Fig. 6

19

5.1 ENVIRONMENTAL CONSIDERATIONS5

Coastal EnvironmentExternal

Coastal EnvironmentInternal

Inland EnvironmentExternal

Alpine EnvironmentExternal

Alpine EnvironmentInternal

Industrial Enviro.External

Industrial Enviro.Internal

Submerged HoleAfter Set

Hollow Block(Web)

Hollow Block(Cavity)

Inland EnvironmentInternal

Tropical EnvironmentExternal

Tropical EnvironmentInternal

Internal Wet Areas

Dry Hole

Damp Hole

Water Filled Hole

Fire Resistant

Solid Concrete

Solid Clay Brick

Wire Cut Clay Brick

SpaTec Boa Coil AnkaScrewTruBolt DynaBolt DynaSet RediDrive ShureDrive RamPlugHiShear8.8EasyDrive

NylonChemSet

SpinChemSet

800 SeriesChemSetHammer

ChemSet101

ANCHOR

(SS)

(SS) (SS) (SS) (SS) (SS) (SS) (SS) (SS) (SS)(SS)

(SS) (SS) (SS) (SS) (SS) (SS)(SS) (SS) (SS) (SS) (SS) (SS) (SS) (SS) (SS)

(SS) (SS)

(SS)

(SS)(SS) (SS)

(SS) (SS) (SS) (SS) (SS)

(Zn) (Zn) (Zn) (Zn) (Zn) (Zn) (Zn) (Zn) (Zn)

(Zn) (Zn) (Zn) (Zn)

(Zn) (Zn) (Zn) (Zn) (Zn)

(Zn) (Zn) (Zn) (Zn)

(Zn) (Zn) (Zn) (Zn)

(Zn)

(Zn) (Zn) (Zn) (Zn)(Zn)

(Zn) (Zn) (Zn) (Zn)

(Zn) (Zn) (Zn) (Zn) (Zn)(Zn) (Zn) (Zn) (Zn) (Zn)



(Gal)

(Gal)

(Gal)

(Gal)

(Gal) (Gal)

(Gal) (Gal)

(Gal) (Gal)

(Gal) (Gal)

(Gal) (Gal) (Gal) (Gal) (Gal) (Gal)

(Gal) (Gal) (Gal) (Gal)



(SS) (SS) (SS)(SS)

(SS)

(SS) (SS)

(SS)

(SS)(SS)

(SS) (SS) (SS) (SS)

*

*

LEGEND = Recommended = Possible* With accessories.

520

5.2 ANCHOR FEATURE GUIDEThe following chart provides a quick guide for selecting theappropriate Ramset Concrete Anchor to suit your needs. Please refer to page 5 for the Legend of Symbols for a detailedexplanation of the symbols used.

SpaTec Safety Anchor

Boa Coil Anchor

TruBolt Anchor

HiShear 8.8 Anchor

DynaBolt Anchor Hex Bolt

DynaBolt Anchor

AnkaScrew Screw In Anchor

RamPlug Nylon Anchor

ChemSet Hammer Capsule & Stud

ChemSet Maxima Capsule & Stud

ChemSet Injection 101 Series Mortar & Stud

ChemSet Injection 800 Series Mortar & Stud

DynaSet Drop In Anchor

RediDrive Anchor

ShureDrive Anchor

EasyDrive Nylon Anchor

Ferrules Elephants Feet

Ferrules Round

Ferrules TCM Stainless Steel

PRODUCT PERFORMANCE RELATED MATERIAL SPECIFICATION

521

SpaTec Safety Anchor

Boa Coil Anchor

TruBolt Anchor

HiShear 8.8 Anchor

DynaBolt Anchor Hex Bolt

DynaBolt Anchor

AnkaScrew Screw In Anchor

RamPlug Nylon Anchor

ChemSet Hammer Capsule & Stud

ChemSet Maxima Capsule & Stud

ChemSet Inj. 101 Series Mortar & Stud

ChemSet Inj. 800 Series Mortar & Stud

DynaSet Drop In Anchor

RediDrive Anchor

ShureDrive Anchor

EasyDrive Nylon Anchor

Ferrules Elephants Feet

Ferrules Round

Ferrules TCM Stainless Steel

INSTALLATION RELATED

PRODUCT

LEGEND = Recommended

22

ENVIRONMENT Concentrate % Hammer Caps Spin Capsule 100 Series 800 Series SS Fixings Gal ZincAcetic Acid 10 Acetic Acid 30 Acetic Acid Concentrate Acetone 25 Acetone 100 Ammonia (aq) Concentrate Ammonia Gas Aniline 100 Battery (Accumulator) Acid Beer Benzene Benzol Boric Acid (aq) Bromine Any Butanol 100 Calcium Carbonate All Calcium Chloride (aq) Any Calcium Hydroxide (aq) Carbon Dioxide 100 Carbon Monoxide 100 Carbon Tetrachloride 10 Carbon Tetrachloride Concentrate Cement Suspension Saturated Citric Acid 15 Citric Acid Any Common Salt Solution Any Copper Nitrate Any Copper Sulphate Any Diesel Fuel 100 Distilled Water Engine Oil 100 Ethanol 10 Ethanol 40 Ethanol 50 Ethyl Acetate 100 Formaldehyde (aq) 30 Formic Acid 10 Formic Acid 40 Formic Acid 100 Fuel Oil Freon Gasoline Glycerine Ethylene Glycol 100 Heptane 100 Hydrochloric Acid 1 Hydrochloric Acid 10 Hydrochloric Acid 20 Hydrochloric Acid Concentrate Hydrogen Fluoride 20 Hydrogen Peroxide 10 Hydrogen Peroxide 30 Iodine 100 Isopropyl Alcohol 100 Lactic Acid 10 Lactic Acid Any

aq = aqueous solution (diluted)% = % by weight

LEGEND = Resistant = Not Resistant

5.3 CHEMICAL RESISTANCEResistance of anchors exposed to:

5

23

ENVIRONMENT Concentrate % Hammer Caps Spin Capsule 100 Series 800 Series SS Fixings Gal ZincLaitance Linseed Oil 100 Machine Oil 100 Magnesium Chloride All Methanol 10 Methanol 100 Motor Oil 100 Nitric Acid 10 Nitric Acid 20 Nitric Acid 30 Nitric Acid 50 Nitric Acid Concentrate Oleic Acid 100 Perchlorethylene 100 Petrol 100 Petroleum 100 Phenol 1 Phenol 100 Phosphoric Acid 10 Phosphoric Acid 20 Phosphoric Acid 30 Phosphoric Acid Concentrate Potassium Carbonate Any Potassium Chloride All Potassium Hydroxide 10 Potassium Hydroxide 40 Potassium Nitrate Any Rain Water 100 River Water Sea Water Sewerage Soap Water Any Sodium Carbonate (aq) Any Sodium Chloride (aq) Any Sodium Hydroxide 10 Sodium Hydroxide 20 Sodium Hydroxide 40 Sodium Hydroxide 50 Sodium Phosphate Any Sodium Silicate Any Sulphuric Acid 1 Sulphuric Acid 10 Sulphuric Acid 20 Sulphuric Acid 30 Sulphuric Acid Concentrate Swimming Pool Water Any Tannic Acid 10 Tap Water Tataric Acid Any Tetrochloroethylene 100 Toluene 100 Trichloroethylene 100 Turpentine Washing Powder 100 Xylene 100

LEGEND = Resistant = Not Resistantaq = aqueous solution (diluted)% = % by weight

5

24

ANCHORINGTECHNOLOGY

Internationally, design standards are becoming moreprobabilistic in nature and require sound Engineeringassessment of both load case information and componentcapacity data to ensure safety as well as economy.

Published capacity data for Ramset Fasteners anchoringproducts are derived from Characteristic UltimateCapacities.

From a series of controlled performance tests, under test conditions Ultimate Failure Loads are established for a product.

Obviously, the value obtained in each test will varyslightly, and after obtaining a sufficient quantity of testsamples, the Ultimate Failure Loads are able to be plottedon a chart.

Test values will typically centre about a mean value.

Once the mean Failure Load is established, a statisticallysound derivation is carried out to establish theCharacteristic Ultimate Capacity which allows for thevariance in results as well as mean values.

The Characteristic Value chosen is that which ensuresthat a 90% confidence is obtained that 95% of all testresults will fall above this value.

From this value, and dependent on local design requirements,the design professional may then undertake either a strengthlimit state or working load design assessment of theapplication at hand, confident that they are working with state of the art capacity information.

6.1 DERIVATION OF CAPACITY

x = Mean Ultimate CapacityXuc = Characteristic Ultimate Capacity

Tested ultimate load

Quan

tity

of te

st re

sults

xXuc

6

625

6.2.1 GENERAL

Ramset anchors are high quality, precision made fasteningssecured with either a torque induced setting action, adisplacement induced setting action, a chemical bonding action,or are cast into the plastic concrete.

Resistance to tensile loads is provided by mechanisms whichdepend upon the type of anchor, and its method of setting.Information on the elements that comprise the resistancemechanisms is given separately for each type of anchor.

Generally, shear load resistance mechanisms are more uniformamongst anchors, and comprise these elements:

~ the bolt or stud, and in some cases, the steel spacer of the anchor.

~ the ability of the anchor to resist the bending momentinduced by the shear force.

~ the compressive strength of the concrete.

~ the shear and tensile strength of the concrete at the surfaceof the potential concrete failure wedge.

When loaded to failure in concrete shear, an anchor located near an edge breaks a triangular wedge away from the concrete.

6.2 ANCHORING PRINCIPLES

e

Load

Anchor

Concrete Wedge

Drilled hole

CONCRETE WEDGE FAILURE MODE

6.2.2 TORQUE SETTING ANCHORS

SpaTec, TruBolt, and DynaBolt anchors are insertedthrough the hole in the fixture, into a hole drilled into theconcrete, and are set by the application of assembly torque tothe nut or bolt head.

The diameter of the drilled hole is slightly larger than the outerdiameter of the anchor. When torque is applied to the bolt heador nut of the anchor, the cone is drawn up into the sleeve toexpand its effective diameter. The wedge action of the cone nutin the sleeve increases with increasing torque. The reaction ofthe concrete against the expanded sleeve of the anchor createsa high friction force between the anchor and the wall of thedrilled hole. The body of the concrete contains and restricts theexpansion forces. The application of assembly torque producesa preload between the fixture and the concrete.

If increasing load were to be applied to the fixture, preloadwould reduce and finally be removed. At this point, the steelcone would begin to be drawn further into the expansionsleeve. When loaded to failure in concrete tension, the failuremode of a correctly installed anchor is characterised by theformation of a concrete cone, the apex of which is located atthe effective depth of the anchor.

Alternatively, if the tensile capacity of the steel is exceeded,the anchor will break.

TORQUE SETTING ACTIONSpaTec, TruBolt & DynaBolt Anchors

continued over

Anchoring Technology

626

6.2.2 TORQUE SETTING ANCHORS cont.

Effective depth is the effective length, Le of the anchor less thefixture thickness, t.

h = Le - t

Note that for the purpose of calculating h, the fixturethickness t should include the thickness of non structuralgrout, packing, etc.

Applied tensile loads are resisted by these elements:

~ the anchor bolt or stud.

~ the wedge action of the steel cone in the sleeve.

~ friction between the expanded sleeve and the drilled hole.

~ shear and tension at the surface of the potential concrete cone.

6.2.3 ROTATION SETTING ANCHORS

The Boa Coil anchor is set by driving the anchor into the holewith a hammer up to the depth set mark and then, using aspanner or wrench, rotating the bolt through the coil, therebysetting the anchor.

The diameter of the drilled hole is a similar size to that of the anchor.

Resistance to tensile load is provided by the two (2)components which make up the Boa Coil anchor, the boltand the coil.

The reaction of the concrete against the expanded anchorcreates a high friction force and an undercut forms betweenthe anchor and the hole wall. The body of the concretecontains and restricts the expansion forces. The action oftightening the anchor bolt against the fixture produces apreload between the fixture and the concrete.

As the applied tensile load increases, a commensuratedecrease in preload occurs, until at some point after all preloadhas been removed, first slip occurs.

Concrete is locally crushed around the coil as it beds in further,accompanied by an increase in load capacity.

When failure occurs in the concrete the mode of failure is abroaching effect whereby load is still being held until theapplied load is equivalent to the shear and tensile capacity ofthe concrete, at this point a cone of failure occurs. There islittle or no damage done to the anchor bolt, but the Boa Coilis destroyed, and must be replaced if the anchor bolt is to bere-used.

hLe

t

Applied tensile load

Anchor

CONCRETE CONE FAILURE MODE


627

6.2.4 DISPLACEMENT SETTING ANCHORS

DynaSet anchors are inserted into a drilled hole, and set by the displacement of the expander plug.

The diameter of the drilled hole is slightly larger than the outerdiameter of the anchor. When the expander plug is fully drivenhome (displaced), it expands the lower portion of the anchorbody, to increase its effective diameter. Because the anchor isexpanded by a series of blows to a setting punch, a certainamount of shock loading is imparted to the concreteimmediately adjacent. The reaction of the concrete against the expanded body of the anchor creates a high friction forcebetween the anchor and the wall of the drilled hole. The bodyof the concrete contains and restricts the expansion forces. A bolt is subsequently screwed into the anchor.

The mode of failure in concrete tension is characterised by theformation of a shear cone, the apex of which is located at theeffective depth of the anchor.

Applied tensile loads are resisted by the following elements:

~ the bolt.

~ the steel annulus of the anchor.

~ friction between the expanded anchor and the drilled hole.


6.2.5 CHEMICAL ANCHORS

ChemSet Maxima Spin Capsules, ChemSet HammerCapsules, ChemSet Injection Systems anchors are set in adrilled hole by the hardening of the chemical mortar.

The mortar penetrates the pores and irregularities of the basematerial and forms a key around the threads of the stud. Thecured mortar becomes a hard, strong material that transfersload to the base material via mechanical and adhesive bondswith the surface of the drilled hole.

When tested to failure, a shallow concrete cone may form atthe top of the anchor. This cone does not necessarily contributeto the tensile strength of the anchor, but simply registers thedepth at which the concrete cone strength happens to equateto the cumulative bond strength of the adhesive to the sides ofthe hole. For a given concrete strength, the stronger theadhesive bond, the deeper the cone.

Applied tensile loads are resisted by:

~ the stud.

~ bond between the stud and the mortar shear in the mortarbond between the mortar and the concrete.

~ shear and tension in the concrete.

Setting tool

DISPLACEMENT SETTING DYNASET ANCHORS

CHEMICAL ANCHORING

Adhesive covered stud

Applied tensile loadAnchor

Concrete cone

CONCRETE BOND FAILURE MODE


628

6.2.6 CAST-IN ANCHORS

Prior to pouring the concrete, Ramset Ferrules are placed in theform and typically fixed to it or to the reinforcement mesh. Theyare retained in the hardened concrete by either the enlargementon the base of the anchor, or by a bar located in the cross-hole.

The mode of failure in concrete tension, is characterised by theformation of a concrete cone, the apex of which is located at theeffective depth of the anchor.

Applied tensile loads are resisted by:

~ the bolt screwed into the insert.

~ the steel annulus of the insert.

~ steel capacity at the reduced section (cross-hole).

~ shear strength in the base enlargement, or the cross-bar.


6.3.1 SUITABILITY

Ramset anchors can be used in plain or in reinforced concrete. It is recommended that the cutting of reinforcement be avoided.The specified characteristic compressive strength "fc" will notautomatically be appropriate at the particular location of theanchor. The designer should assess the strength of the concreteat the location of the anchor making due allowance for degree ofcompaction, age of the concrete, and curing conditions. Particular care should be taken in assessing strength near edgesand corners, because of the increased risk of poor compactionand curing. Where the anchor is to be placed effectively in thecover zone of closely spaced reinforcement, the designer shouldtake account of the risk of separation under load of the coverconcrete from the reinforcement.

Concrete strength "fc" determined by standard cylinders, isused directly in the equations. Where strength is expressed inconcrete cubes, a conversion is given in the following table:

Where structural base materials are covered with a non-structural material such as plaster or render, anchorsshould be embedded to the design depth in the structural basematerial. Allowance must be made for the thickness of the non-structural material when considering the application ofshear loads, and in determining the moment arm of appliedbending moments.

In hollow block masonry, where the cores are filled withconcrete grout, Ramset anchors may be designed and specifiedsimilarly as in concrete, provided the designer assesses theeffective strength of the masonry including the joints.

However, it is not advisable to use certain heavy duty anchorsin unfilled hollow masonry units (either bricks or blocks). These heavy duty anchors include all SpaTec, TruBolt andChemSet capsule anchors, and DynaBolt, Boa Coil anchor,DynaSet, and Chemical Injection anchors greater than M12 indiameter. In any case the designer should assess the effectivestrength of the masonry including the joints, and determinehow the loading is to be transferred to the masonry structure.Load tests should be conducted on site to assist in assessingmasonry strength.

Ramset heavy and medium duty anchors are not recommended for low strength base materials such asautoclaved aerated concrete, except for ChemSet InjectionSystem studs up to M12.

ELEPHANTS' FEET, ROUND & TCM FERRULES

6.3 BASE MATERIALS

Cube Strength (N/mm2) 20 30 40 50 60Cylinder Strength fc (MPa) 15 24 33 42 51

The design engineer is responsible for theoverall design and dimensioning of thestructural element to resist the service loadsapplied to it by the anchor.


629

Concrete Edge

am

Prohibited zone

Free zone

em

Prohibitedzone

PROHIBITED ZONES FOR SPACINGS AND EDGESMinimumconcretethickness

'bm'

Edge distance "e"

2em

1.5h2.0h

em

CONCRETE THICKNESS

Concrete Edge

2*em

Prohibited zone

Free zone

emProhibited

zone

PROHIBITED ZONES AT CORNER FOREXPANSION ANCHORS

Spacings, edge distances, and concrete thicknesses are limitedto absolute minima, in order to avoid risks of splitting orspalling of the concrete during the setting of Ramset torqueand displacement setting expansion anchors. Absolute minimafor stress-free anchorages such as chemical and cast-in anchorsare defined on the basis of notional limits, which take accountof the practicalities of anchor placement.

Absolute minimum spacing "am" and absolute minimum edgedistance "em", define prohibited zones where no anchor shouldbe placed. The prohibited spacing zone around an anchor has aradius equal to the absolute minimum spacing. The prohibitedzone at an edge has a width equal to the absolute minimumedge distance.

6.3.2 ABSOLUTE MINIMUM DIMENSIONS

Where an expansion anchor is placed at a corner, there is less resistance to splitting, because of the smaller bulk ofconcrete around the anchor. In order to protect the concrete,the minimum distance from one of the edges is increased totwice the absolute minimum.

The concrete thickness minima given below, does not includeconcrete cover requirements, and are not a guide to thestructural dimensions of the element. It is the responsibility of the design engineer to proportion and reinforce the structural element to carry the loads and moments applied to it by the anchorage, and to ensure that the appropriate cover is obtained.

In order to avoid breakthrough during drilling of the hole intowhich anchors will be installed, maintain a cover value to thebase of the hole equal to 2x the drilled hole diameter, dh. ie. fora hole of 20 mm diameter allow 40 mm cover to the rear faceof the substrate component.

In certain circumstances, it may be possible to install anchorsin thinner concrete elements. If cover to the anchor is notrequired, and a degree of spalling can be tolerated between the end of the expansion sleeve and the far surface of theconcrete, embedment close to the far surface may be feasible.More information on the conditions for reduced concretethickness may be obtained from Ramset Engineers.

Where an anchor is installed at the absolute minimum edgedistance "em", concrete thickness is at a maximum of 2 * h.(Effective depth "h", is measured from the concrete surface tothe end of the anchor expansion sleeve unless otherwisestated.)


630

6.4.1 WORKING LOAD DESIGN

Using the permissible stress method which is still valid in many design situations:

L (applied load) Ra (working load limit capacity)

Working load limits are derived from characteristic ultimatecapacities and factor of safety:

Ra = Ru / Fs

Factors of safety are related to the mode of failure, andmaterial type, and the following are considered appropriate for structural anchoring designs:

fss = factor of safety for steel in tension and bending= 2.2

fsv = factor of safety for steel in shear= 2.5

fsc = factor of safety for concrete= 3.0

6.4.2 STRENGTH LIMIT STATE DESIGN

Designers are advised to adopt the limit state design approachwhich takes account of stability, strength, serviceability,durability, fire resistance, and any other requirements, indetermining the suitability of the fixing. Explanations of thisapproach are found in the design standards for structural steeland concrete. When designing for strength the anchor is tocomply with the following:

Ru S*

where:


Ru = characteristic ultimate load carrying capacity

S* = design action effect

Ru = design strength

Design action effects are the forces, moments, and othereffects, produced by agents such as loads, which act on astructure. They include axial forces (N*), shear forces (V*), and moments (M*), which are established from the appropriate combinations of factored loads as detailed in theAS1170 Minimum Design Load on Structures series ofAustralian Standards.

Capacity reduction factors are given below, these typicallycomply with those detailed in AS4100 - Steel Structures andAS3600 - Concrete Structures. The following capacityreduction factors are considered typical:

c = capacity reduction factor, concrete tension= 0.6

q = capacity reduction factor, concrete shear= 0.6

n = capacity reduction factor, steel tension= 0.8

v = capacity reduction factor, steel shear= 0.8

m = capacity reduction factor, steel bending= 0.8

Whilst these values are used throughout this document, other values may be used by making the adjustment for as required.

6.4 DESIGNAnchoring Technology

631

6.5.1 STEEL TENSION

The characteristic ultimate tensile capacity for the steel of ananchor is obtained from:

Nus = As fu

where:

Nus = characteristic ultimate steel tensile capacity (N)

As = tensile area (mm2)= stress area for threaded sections (mm2)

fu = characteristic ultimate tensile strength (MPa)

fy = characteristic yield strength (MPa)

The tensile working load limit (permissible stress method) forthe steel of a Ramset anchor is obtained from:

Nas = Nus / 2.2

The appropriate concrete compressive strength "fc" is the actualstrength at the location of the anchor, making due allowance forsite conditions, such as degree of compaction, age of concrete,and curing method.

Concrete tensile working load limits (permissible stressmethod) for anchors are obtained from:

Nac = Nuc / 3.0

6.5 TENSION

hh

air gap

h

EFFECTIVE DEPTH FOR ANCHORS

6.5.2 CONCRETE CONE

Characteristic ultimate tensile capacities for mechanicalanchors vary in a predictable manner with the relationshipbetween: - hole diameter (dh)

- effective depth (h), and- concrete compressive strength (fc)

within a limited range of effective depths, h.

This is typically expressed by a formula such as:

Nuc = factor * dbfactor * h1.5 * fc

Anchors may have constraints that apply to the effective depth of the anchor or the maximum or minimum concretestrength applicable.

Effective anchor depth is taken from the surface of thestructural concrete to the point where the concrete cone isgenerated. In establishing the effective depth for anchors, thedesigner should allow for any gap expected to exist betweenthe fixture and the concrete prior to clamping down.


632

6.5.3 PULL-THROUGH

This mode of failure occurs in expansion anchors under tensileloading, where the applied load exceeds the frictionalresistance between either the cone and the expansion sleeve,or the sleeve and the sides of the drilled hole in the concrete.Failures of this type are often associated with anchors that areimproperly set, or used in larger diameter holes drilled into theconcrete with over-sized drill bits.

The load carrying capacities of anchors with thick-walledexpansion sleeves such as SpaTec and properly-set DynaSet

anchors, are not sensitive to this mode of failure. The recommended limits on concrete strength "fc" in thedetermination of concrete cone strength for DynaBolt andTruBolt anchors, act as a precaution against this mode of failure.

6.5.4 CONCRETE BOND

Chemical Anchors

Characteristic ultimate tensile load carrying capacities forconcrete bond failure in the compression zone varies with holedepth, effective depth and concrete strength in a similarmanner to concrete cone failure in mechanical anchors.

Effective anchor depth "h" is taken from the start of theadhesive, (usually the surface of the concrete) to the bottom of the stud. For chemical capsule anchors, it is not usual todeviate from the depths given in the Section Properties andData. Whilst it is essential to provide sufficient resin to fill thespace between the stud and the concrete, the installer mustavoid excessive overspill. Hole depths for capsule anchors maybe increased in increments related to the volume of capsulesavailable. It is recommended to seek advice from Ramset

Technical Staff before deviating from the recommended holedepths or hole diameters.

The appropriate concrete strength "fc" to be used in theseequations, is the actual strength at the location of the anchor,making due allowance for site conditions, such as degree ofcompaction, age of concrete, and curing method.

Concrete tensile working load limits (permissible stressmethod) for Ramset chemical anchors are obtained from:

Nac = Nuc / 3.0

h

EFFECTIVE DEPTH FOR CHEMICAL ANCHORS


633

6.5.5 CRITICAL SPACING

In a group of mechanical anchors loaded in tension, the spacingat which the cone shaped zones of concrete failure just beginto overlap at the surface of the concrete, is termed the criticalspacing, ac.

For chemical anchors the critical spacing is determined byinterference between the cylindrically shaped zones of stresssurrounding the anchors.

At the critical spacing, the capacity of one anchor is on thepoint of being reduced by the zone of influence of the otheranchor. Ramset anchors placed at or greater than criticalspacings are able to develop their full tensile loads, as limitedby concrete cone or concrete bond capacity. Anchors atspacings less than critical are subject to reduction in allowableconcrete tensile loads.

Both ultimate and working loads on anchors spaced betweenthe critical and the absolute minimum, are subject to areduction factor "Xna", the value of which depends upon theposition of the anchor within the row:

Nucr = Xna * Nuc

for strength limit state design.

And, for permissible stress method analysis:

Nar = Xna * Nac

For anchors influenced by the cones of two other anchors, as aresult for example, of location internal to a row:

Xna = a / ac 1

Unequal distances ("a1" and "a2", both < ac) from twoadjacent anchors, are averaged for an anchor internal to a row:

Xna = 0.5 (a1 + a2) / ac

If the anchors are at the ends of a row, each influenced by the cone of only one other anchor:

Xna = 0.5 (1 + a/ac) 1

The cone of anchor A is influenced by the cones of anchors B and C, but not additionally by the cone of anchor D. "Xna" isthe appropriate reduction factor as a conservative solution.

Critical spacing defines a critical zone around a given anchor,for the placement of further anchors. The critical spacing zonehas a radius equal to the critical spacing. The concrete tensilestrengths of anchors falling within the critical zone arereduced. For clarity, the figure includes the prohibited zone as well as the critical zone.

ac

Cone of Failure Anchors

a

aacBond cylinders

Anchors

a a aCone of Failure Anchors

ANCHORS IN A ROW

A B

C D

ANCHOR GROUP INTERACTION

CRITICAL

No influence. Interactionoccurs betweenfailure cones.

Capacity reductionnecessary.

Risk of cracking.

REDUCTION PROHIBITED

a ac a < amac > a > am


634

6.5.6 CRITICAL EDGE DISTANCE

At the critical edge distance for anchors loaded in tension,reduction in tensile loads just commences, due to interferenceof the edge with the zone of influence of the anchor.

Cast-In and Expansion Anchors

The critical edge distance (ec) for expansion and cast-inanchors is taken as one and a half times effective depth:

ec = 1.5 * h

Chemical Anchors

For chemical anchors the critical edge distance is determinedby interference between the edge and the cylindrically shapedzones of stress surrounding the anchors.

ec = 4 * db

If the edge lies between the critical and the absolute minimumdistance from the anchor, the concrete tensile load reductionco-efficient "Xe", is obtained from the following formula:

Xe = 0.3 + 0.7 * e / ec 1

where:

Xe = edge reduction factor tension

Critical edge distances define critical zones for the placement of anchors with respect to an edge. The critical edge zone hasa width equal to the critical edge distance. The concrete tensile strengths of anchors falling within the critical zone arereduced. For clarity, the figure includes the prohibited zone aswell as the critical zone.

Rotation Set Anchors

The critical edge distance for Boa Coil anchor is taken as:

ec = 6 * db

e

ec

Cone of Failure

Anchor

INTERFERENCE OF EDGE WITH CONCRETE CONES

ec

Bond cylinder

Anchor

INTERFERENCE OF EDGE WITH BOND CYLINDER

Concrete Edgeemec

Prohibited zone

Free zone Critical zone

CRITICAL EDGE ZONE


635

4 * dhMinimum for bolt shear

1.25 * dbMinimum for bolt and spacer shear

d h

MINIMUM INSERTION FOR BOLT SHEARe

Load

Anchor

Concrete Wedge

Drilled hole

CONCRETE WEDGE FAILURE MODE

3 * dbMinimum for bolt shear

d h

MINIMUM INSERTION FOR BOLT SHEAR

5.6.1 ANCHOR STEEL SHEAR

For an anchor not located close to another anchor nor to a freeconcrete edge, the ultimate shear load will be determined bythe steel shear strength of the anchor, provided the effectivedepth of the anchor is compliant with the following:

SpaTec

h 4 * dh

For SpaTec it is required that the bottom end of the spacer is inserted at least one and a quarter times hole diameter (1.25 * dh) in order for the shear strength of the spacer to beallowed as contributing to the shear strength of the anchor.

Boa Coil

For full bolt shear,

h 6 * db

A reduced shear capacity is applicable down to a minimumvalue of 3 * db.

TruBolt

h 4 * dh

DynaBolt

h 3.5 * dh

DynaSet anchors are not normally embedded to four times thediameter of the drilled hole, and their characteristic shearcapacities relate to the bending strength of the anchor or shearof the inserted bolt.

The designer should also take into account any conditions thatmay cause bending moments and unbalanced forces to beapplied simultaneously. Any tendency of the fixture to lift awayfrom the surface under load will generate moments and tensionforces.

The characteristic ultimate shear capacity (Vus) for the steel ofan anchor is obtained from:

Vus = 0.62 * As * fu (N)

6.6.2 CONCRETE EDGE SHEAR

Where load is directed either towards or parallel to an edge,and the anchor is located in the proximity of the edge, failuremay occur in the concrete.

6.6 SHEARAnchoring Technology

636

6.6.3 SPACING UNDER CONCRETE SHEAR

At a spacing of at least 2.5 times edge distance, there is nointerference between adjacent failure wedges. Where anchorspacing is less than 2.5 times edge distance, the shear loadcapacities in the concrete are subject to a reduction factor "Xva".

Xva = 0.5 ( 1 + a / (2.5 * e)) 1

The direction of the shear load towards an edge will influencethe concrete edge shear capacity. This is accounted for withthe factor Xvd.

When a row of anchors is subject to a shear load actingtowards an edge, the distribution of each anchors capacity in the anchor group is derived by using the factor Xvn.

V*A = V*B = V*C

Vur V*A, V*B, V*C

Two anchors installed on a line normal to the edge, and loadedin shear towards the edge, are treated as a special case.Where the anchors are loaded simultaneously by the samefixture, the ultimate or the concrete edge shear capacity foreach anchor will be influenced by the other anchor. Where thespacing "a" between anchors A and B is less than or equal to"eB" the edge distance of anchor B, the ultimate edge shear foranchor A is equal to anchor B, despite the longer edge distanceof anchor A:

a a

e

Failure wedge

Concrete edge

INTERFERENCE BETWEEN SHEAR WEDGES

Failure wedge

Shear force

Concrete edge

A

B

eB

a

ANCHORS IN LINE TOWARDS AN EDGE

e1

e2

Failure wedge

Concrete edges

Shear Force

ANCHOR AT A CORNER

For an anchor located at a corner and where the second edgeis parallel to the applied shear, interference by the second edgeupon the shear wedge is taken into account by the followingreduction factor:

Xvs = 0.30 + 0.56 * e1 / e2 1

V*

n = 3

V*TOTAL

V*A V*B V*C


637

Applied load

Moment arm

Fixture

Non-structuralmaterial or gapOne hole diameter

DESIGN BENDING MOMENT

6.7 BENDINGThe designer's calculation of the design bending moment (M*)should include an allowance in the moment arm of one holediameter inwards from the face of the concrete:

M* = V* * ( dh + g + t / 2)

where:

V* = shear design action effect (N)

g = gap between fixture and concrete surface (mm)

t = fixture thickness (mm)

Anchor moments need only be considered if there is a non structural material or gap between the fixture andsubstrate that results in application of a moment to the anchor itself.

In the case of working load limit design, applied moments (M)are calculated as follows:

M = V * ( dh + g + t / 2)

V = applied shear force (N)

Characteristic ultimate bending capacities (Mu), are obtainedfrom the following formula:

Mu = fy * Z

where:

fy = characteristic yield strength (MPa)

Z = section modulus of the anchor (mm3)

and for working load limit bending moment (Ma):

Ma = Mu / fss= Mu / 2.2


638

6.8.2 SHEAR AND BENDING

There is no reduction in shear capacity in the case of combinedbending and shear. Shear capacity and bending capacity arechecked independently.

6.8.3 TENSION AND SHEAR

Design for combined tension and shear, requires firstly thedetermination of anchor capacities. Strength limit state designcapacities are taken as:

Nur = cNurc nNus

Vur = qVur vVus

where:


Nur = design reduced ultimate tensile capacity

Vur = design reduced ultimate shear capacity

c = capacity reduction factor concrete tension

q = edge capacity reduction factor concrete shear,recommended as 0.6

n = capacity reduction factor, steel tension,recommended as 0.8

v = capacity reduction factor, steel shear, recommended as 0.8

Working load capacities are determined as follows:

Na = Nar Nsr

Va = Var Vas

where:

Na = working load limit tensile capacity

Va = working load limit shear capacity

Strength limit state combination of tension and shear complieswith the following:

N* / Nur 1

V* / Vur 1

N* / Nur + V* / Vur 1.2

The following formulae are used for working load combination:

N / Na 1

V / Va 1

N / Na + V / Va 1.2

where:

N = applied tensile load

V = applied shear load

Applied shear

Moment arm

COMBINED TENSION AND SHEAR

Applied moment

Moment arm

Appliedtension

COMBINED TENSION, SHEAR AND BENDING

6.8 COMBINED LOADING6.8.1 TENSION AND BENDING

Where an anchor is subjected to combined tension andbending, ultimate tensile capacity for the steel is determined as follows:

Nusr = Nus * (1 - (M* / mMu))

where:

m = capacity reduction factor, steel bending,recommended as 0.8

Factored working load limit steel tensile capacities, to allow for the effects of bending moments are given by:

Nasr = Nas * (1 - M / Ma)

where:

Nasr = factored working load limit steel tensile capacity (N)


639

This information deals specifically with the design of individualanchors, loaded either as a single anchor or as a member of a group. Under the relevant loading condition, as a generalprinciple, all load reduction factors applicable to an individualanchor in the group should be multiplied together to accountfor the combined effects on the anchor of multiple loads, grouplayout, and base material geometry. In the application of loads,due allowance should be made for eccentricities in the lines ofaction of loads relative to the centroid of the group, and forany other conditions likely to cause a magnification of load to an anchor, i.e. prying forces.

In a group loaded in shear there is a risk of uneven loading,particularly where more than two anchors are arranged onebehind the other in the direction of the load. The designershould assess and make appropriate allowance for the abilityof the fixture to distribute the load to anchors in the group.

The simplified strength limit state design process detailed in this document is intended to cover a wide range of applications.

It is suitable for verifying capacity of single anchors or groups ofanchors, however it must be remembered that the capacity datagiven is PER ANCHOR and load cases must be distributed to allanchors in a group and each anchor verified as being suitable.

The simplified design process allows verification of:

Single anchors subject to shear and/or tension.

For a row of anchors subject to a shear force componenttowards an edge, the design tables assume that the designload case is evenly distributed to all anchors in the group andcalculates the averaged shear capacity for each anchor.

V*A = V*B = V*C

n = 3

Vur = per anchorcapacity

It is unable to verify capacity for anchors in the followingconfigurations:

Location at a corner with shear load component towards the edge(s).

An anchor is considered to be at a corner if the ratio of theedge distance parallel to the direction of shear to the edgedistance in the direction of shear is less than 1.25.

Anchors subject to a moment.

Anchors in a line towards an edge with a shear loadcomponent acting towards that edge, unless it is assumedthat the anchor closest to the edge takes all of the shear load, V*TOTAL.

Groups of anchors (row, rectangular array etc.) subject totensile loading and/or shear loading not towards an edge.

Groups of anchors subject to tensile and/or shear loadingwhere the line of anchors parallel to (and closest to) the edge are considered to take the total shear load.

For these cases, please refer to the Ramset Anchor Designsoftware or contact your local Ramset Technical SalesEngineer for advice.

6.9 ANCHOR GROUPS

V*

N*

V*

e1

e2

V*TOTAL

N*TOTAL

V*TOTAL

V*TOTAL

V*A V*B V*C

N*TOTAL

V*A + V*B + V*C = V*TOTAL

These anchors assumed to be in slotted holes

V*TOTAL

A B C

e1 > 1.25 acceptablee2


640

Clamped materialPreload or clamping load Applied load

PRELOADING OF FIXTURE TO CONCRETE

SpaTec and DynaBolt AnchorsPULL DOWN MECHANISMS

6.10 ASSEMBLY TORQUE AND PRELOADThe application of assembly torque to a well designed anchor,results in the generation of a preload or clamping forcebetween the fixture and the concrete. Because the fixturesupports the concrete and suppresses cone failure, preload mayexceed concrete cone failure load. The concrete experiences anelastic compression beneath the fixture. Under external loadingof the fixture, the surfaces of the joint will not separate untilthe applied load exceeds the preload. Although the magnitudeof the preload influences the deformation of the fixing underload, it does not in general, affect the ultimate static loadcapacity of the fixing.

Heavy and medium duty sleeve anchors with a fully functioning pull-down mechanism such as Ramset SpaTec

and DynaBolt anchors, ensure that loss of preload to thespacer or sleeve is negligible, even where a substantial gapmay have existed between the concrete and the fixture, due to unevennesses in the mating surfaces. After the expansionsleeve has enlarged to grip the sides of the hole, the pull-downmechanism allows the gap to be closed and the fixture to beclamped against the concrete.

Boa Coil anchors and stud anchors such as TruBolt anchorsand chemical anchors also have the capability to clamp thefixture to the concrete.

Torque controlled expansion anchors without an adequate pull-down capability, suffer from loss of preload to the spacer orsleeve, whenever there is a gap between the mating surfaces.This results in a reduction in the preload available forcompression of the concrete. Such anchors may perform undercyclic loads as if there were an inadequate preload, eventhough the specified assembly torque may have been carefullyapplied. In some instances it is possible for the fixture to beloose against the concrete surface from the time of initialassembly of the fixing.

Initial preload (PLi) which is developed immediately after the application of assembly torque, is calculated for Ramset

anchors as:

PLi = * Pr

where:

= proportion of proof load as initial preload65% for mechanical anchors25% for chemical anchors

Pr = bolt or anchor proof load (kN)= As * fy

Assembly torques required (Tr) to develop initial preloads aregiven by the following formula:

Tr = T * db * PLi

where:

T = torque co-efficient of sliding friction 0.14 for SpaTec anchors0.32 for cold-formed anchors and stainless steel anchors0.37 for machined anchors


641

6.11 LONG TERM PRELOAD DEGRADATIONIn considering the long term performance in concrete ofexpansion and cast-in anchors under cyclic loading, accountmust be taken of concrete creep which causes a degradation ofpreload over time. Immediately after the application of assemblytorque and the establishment of initial preload, there is a rapidinitial reduction in preload, followed by a continued gradualreduction over time, towards a long term limiting value of "PL",at "" % of initial preload. As a guide, "" may be taken astypically 70% for SpaTec anchors, and as 40% for DynaBolt

and TruBolt anchors.

In a particular application, the proportion of preloadpermanently retained will depend upon concrete strength,concrete quality including curing, level and direction ofconcrete stress, applied load level, timing of applied loads, andthe value of the total spring rate for the anchor/fixture/basematerial system.

1.0

0 3 6 9 12

PL/PLi

Time (Months)

PRELOAD DEGRADATION


642

6.12 SLIP LOAD AND CYCLIC LOADINGProvided the applied load is less than the remaining preload,slip virtually does not occur, and the fixing experiences theapplied load as a reduction in elastic compression of theconcrete. When the applied load exceeds the preload, theclamped material can separate from the concrete and slippageof the joint can commence. If the design requirement is fornegligible slip (say 0.1mm), the assembly torque should be bothcarefully specified and applied. It is recommended that anchorcapacity be limited to a percentage of the expected preloadafter allowing for long term degradation.

The Boa Coil anchor performs more like a slight undercutanchor where the first slip measured at 0.1mm is close to theultimate load of the anchor in concrete. The Boa Coil anchorsability to sustain cyclic loads depends primarily upon theinteraction of the Boa Coil and the concrete sides of the hole. It is this unique interaction that enables the Boa Coil anchorto achieve high first slip loads. To ensure long life of thefastener under cyclic loading the designer should ensure (as forslip loads), that the applied load does not exceed 65% of thefirst slip load, called the reduced characteristic ultimate slipload. When the applied load is less than the reducedcharacteristic ultimate slip load the Boa Coil anchor has theability to withstand an infinite number of repetitions of theapplied load.

The ability of an anchor to sustain cyclic loads depends (as for slip loads) primarily upon the relationship between the applied load and the effective preload in the anchor. Where the applied load is less than both the preload and thestatic working load, the fastening has the ability to withstandan infinite number of repetitions of the applied load. The cyclicloading is experienced as changes in pressure at the interfaceof the fixture and the concrete, and the stress range in theanchor should never approach the endurance limit. To ensurelong life of the fastening under cyclic loading, the designershould ensure (as for slip loads), that the applied load is lessthan "h" % of the expected long term preload after allowing for degradation.

Ultimate load

Displacement

65% of slip load

Appliedload

Long term preload= slip load

SLIP LOAD AND PRELOAD

Ultimate load

Displacement

65% of slip loadAppliedload

SLIP LOAD

Long term preload= slip load

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