Overhead transmission lines

TEKNISK RIKTLINJE 2012-04-02 TR 05-02E utg 2

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Revision Ändringsnot Datum

1 (A) Revidering av standarder och ny mall 07 / 09 / 2010

2 New template. Clause 2.5.1.2.1-2.5.1.2.4 impregnation with creosote specified. Clause 2.5.4.1.2 Holding down bolt not to be in contact with the reinforcing bars. Clause 2.6.2.1 Tightening torque and locking of holding down bolt inserted. Appendices A, Control thread shall be installed at every tower. Clause 2.8.1 “All documentation shall be in Swedish or English” added. Clause 2.8.3 added.

02 / 04 /2012


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List of contents

2.1 References ................................................................................................................. 5

2.2 Scope ......................................................................................................................... 8

2.3 Definitions ................................................................................................................ 8

2.4 Description ................................................................................................................ 9

2.4.1 General ......................................................................................................... 9

2.4.2 Foundations for steel supports ................................................................... 9

2.4.3 Foundations for Concrete supports ............................................................ 9

2.4.4 Foundations for Wooden supports ............................................................. 9

2.5 Requirements .......................................................................................................... 10

2.5.1 Material ...................................................................................................... 10

2.5.1.1 Steel .............................................................................................. 10

2.5.1.2 Wood ............................................................................................ 10

2.5.1.3 Concrete ....................................................................................... 11

2.5.2 Design ......................................................................................................... 12

2.5.2.1 General ......................................................................................... 12

2.5.2.2 Grillage foundation ..................................................................... 14

2.5.2.3 Concrete foundation .................................................................... 14

2.5.2.4 Pile foundation ............................................................................ 14

2.5.2.5 Stay anchor .................................................................................. 15

2.5.3 Loading parameters .................................................................................. 15

2.5.4 Workmanship and material details.......................................................... 15

2.5.4.1 Steel .............................................................................................. 15

2.5.4.2 Concrete ....................................................................................... 16

2.5.5 Documentation ........................................................................................... 18

2.5.5.1 Drawings and calculations......................................................... 18

2.6 Construction ............................................................................................................ 19


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2.6.1 General ....................................................................................................... 19

2.6.2 Cast in-situ concrete foundations ............................................................. 19

2.6.2.1 General ......................................................................................... 19

2.6.2.2 Foundations in soil ...................................................................... 21

2.6.2.3 Anchored foundations on rock ................................................... 21

2.6.2.4 Foundations in loose soils–pile foundations .............................22

2.6.3 Pre-cast concrete foundations ..................................................................22

2.6.4 Grillage foundations ..................................................................................22

2.6.5 Tube foundations .......................................................................................23

2.6.6 Stay anchors ...............................................................................................23

2.7 Tests .........................................................................................................................23

2.7.1 General .......................................................................................................23

2.7.2 Concrete foundations .................................................................................23

2.7.3 Stay anchors .............................................................................................. 24

2.8 Delivery ................................................................................................................... 24

2.8.1 General ...................................................................................................... 24

2.8.2 Quality documentation ............................................................................. 24

2.8.2.1 Certificate.................................................................................... 24

2.8.2.2 Deviation report .......................................................................... 25

2.8.2.3 Separate reports and inspection companies ............................. 25

2.8.3 Transport and storing ................................................................ 25

Appendix A Control strand for testing of possible corrosion attack

on steel buried underground ..................................................... 26


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2.1 References

Note that standards, regulations etc. which are referred to in these guidelines are subject to continuous change and can be withdrawn, revised or replaced. The contractor shall immediately inform the client of such changes

SvK TR 05-03 Supports

Anläggnings AMA 98 Allmänna material- och arbetsbeskrivningar för anläggningsarbeten. (General material and work descriptions for civil construction works.)

BBK04 Boverkets handbok om betongkonstruktioner (National Board of Housing, Building and Planning, Concrete Design Manual)

BKR Boverkets Konstruktionsregler (National Board of Housing, Building and Planning, Design Regulations)

EBR handbook "Underhåll ledningar 0,4 – 420 kV" (Overhead line maintenance 0,4 - 420 kV)

Hus AMA 98 Allmänna material- och arbetsbeskrivningar för husbyggnadsarbeten. (General material and work descriptions for house building works)

NTR Dokument nr 1: 2011 Nordiska träskyddsklasser. Del 1: Furu och andra lättimpregnerbara barrträslag. (Wood durability classes: Part 1: Pine and other permeable softwoods.)

SGI handbook "Pålgrundläggning" (Pile foundations)

SS 13 70 03 Betong - Användning av EN 206-1 i Sverige (Concrete - Application of EN 206-1 in Sweden)

SS 21 18 45 Armeringsnät Ns 500 och Nps 500 (Steel fabric Ns 500 and Nps 500 concrete reinforcement)


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SS 81 20 01 Betongelement - Kantutformning (Precast concrete products - Edges on concrete elements - Dimensions)

SS 424 11 50 Material för luftledningar-Stagskruvar (Overhead line material - Stay tighteners)

SS-EN 10025-2 Hot rolled products of structural steels - Part 2: Technical delivery conditions for non-alloy structural steels– Steel S275JR

SS-EN 10025-3 Hot-rolled products of structural steels - Part 3: Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels – Steel S355N

SS-EN 50341 Overhead electrical lines exceeding 45 kV (AC)

EN 206-1 Concrete - Part 1: Specification, performance, production and conformity

EN ISO 4753 Fasteners - Ends of parts with external ISO metric screw thread (ISO 4753:1999)

EN ISO 9001 Quality management systems - Requirements.

ENV 10080 Steel for the reinforcement of concrete - Weldable ribbed reinforcing steel B500 - Technical delivery conditions for bars, coils and welded fabric.

EN 10204 Metallic products - Types of inspection documents

EN ISO 10684 Fasteners - Hot dip galvanized coatings

EN 12794 Precast concrete products - Foundation piles

ISO 216 Writing paper and certain classes of printed matter - Trimmed sizes - A and B series

ISO 724 ISO general-purpose metric screw threads - Basic dimensions

ISO 965-4 ISO general purpose metric screw threads - Tolerances - Part 4: Limits of sizes for hot-dip galvanized external screw threads to mate with


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internal screw threads tapped with tolerance position H or G after galvanizing


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2.2 Scope

These guidelines are applicable to foundations for wood, steel and concrete structures. The term "foundations" shall be taken to include stay anchors. The relevant sections of SvK TR 05-03 are applicable for design, manufacture and documentation of steel foundations.

2.3 Definitions

Technical terms and definitions used in these guidelines: Grillage foundation Foundation consisting of sleepers and a steel framework or sleepers and steel beams to transfer loads from the support to the ground. The sleepers can be made of concrete or wood. Foundation framework Framework comprising steel angle sections, designed for the purpose of transferring loads from the support to the ground, installed on sleepers, or anchored in rock by anchor bolts. Rock anchor Anchor bolts drilled and secured into rock designed for the purpose of transferring loads from the foundation. Holding down bolt Bolt between the structure footing and the foundation designed for the purpose of anchoring the structure to the foundation Moment foundation Foundation principally subjected to bending moments. Uplift foundation Foundation principally subjected to uplift loads. Compression foundation Foundation principally subjected to compression loads. Cast in-situ foundation Foundations cast in-situ at the structure location. Pre-cast foundation Foundation produced in a factory approved for the manufacture of concrete elements and transported to the structure location. Stay anchor Anchor in soil or rock designed for the purpose of transferring stay loads.


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Pile foundation Foundation in soft soil designed for the purpose of transferring loads to the ground by means of piles. Pile s to firm bottom End bearing piles

Piles to firm bottom. End bearing piles Piles to certain depth for load to be transferred by friction Friction piles Piles to certain depth for load to be transferred by cohesion. Cohesion piles Sheet foundation Foundation in soft soil where the load is transferred to the ground by timbered sheet walls. Tube foundation Foundation in soft soil where the load is transferred to the ground by concrete tubes. The concrete tube can either be cast in one piece or be made of jointed rings.

2.4 Description

2.4.1 General Foundations and stay anchors with exposed steelwork buried underground shall be fitted with corrosion control wire in accordance with appendix A.

2.4.2 Foundations for steel supports Steel supports shall be located on steel foundation frameworks attached to sleepers or on to rock, on steel beams attached to sleepers, or on pre-cast / cast in-situ concrete foundations. Only steel or concrete piles may be used, timbered sheet foundations are not permitted.

2.4.3 Foundations for Concrete supports Concrete poles can be founded by embedding a part of the pole in the soil. Concrete poles can also be founded in pipes or on concrete foundations. In soft soil concrete structures shall be founded on concrete foundations with piles anchored in the foundation pad.

2.4.4 Foundations for Wooden supports Wooden poles shall be founded according to Swedish Standard SS-EN 50341:8.5.3/SE.1.1. In soft soil wooden poles shall be founded in tubes, on piles or alternatively timbered sheet foundations.


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2.5 Requirements

2.5.1 Material Unless otherwise specified, all material delivered shall correspond to the latest available edition of the appropriate Swedish standard and Code of Practice or alternatively foreign standards that the client deems to be equivalent or superior. If no standard is applicable, all materials and workmanship shall be of the best quality and detailed information shall be submitted to the client for approval.

If the standard to be followed is not written in Swedish or English the supplier shall submit a translated copy in Swedish or English to the client. The supplier shall inform the client timeously regarding the applicable standards for the materials to be supplied. The materials shall be inspected and tested to verify compliance with the applicable specifications or standards.

2.5.1.1 Steel

2.5.1.1.1 Reinforcing steel Reinforcing steel for concrete foundations shall comply with the requirements of the relevant Swedish standard with only steel of weldable quality being allowed.

2.5.1.1.2. Holding down bolts, including nut and washer Holding down bolts shall be made of grade S355N or B500 steel. For hot-dip galvanising refer to 2.5.4.1.2. Washers for holding down bolts shall be made of grade S275JR steel galvanised to give

a zinc coating of 650 g/m2 (95 m). Nuts for holding down bolts shall be hot-dip galvanised and made of grade 8.8 steel.

2.5.1.1.3 Adjustable anchor clamps Adjustable anchor clamps shall be manufactured in accordance with Swedish Standard SS 424 11 50. However they may deviate from SS 424 11 50 in two respects. Firstly they may be of the straight wedge design and secondly they may be designed for staywires larger than specified in Swedish Standard SS 424 11 50. However the relevant requirements of Swedish Standard SS 424 11 50 shall still apply in these cases.

2.5.1.1.4 Steel piles A certificate of compliance shall be submitted if requested by the client.

2.5.1.2 Wood

2.5.1.2.1 Grillage foundation Sleepers for foundations shall be made of pine and impregnated with MT-creosote oil Wood protection class A in accordance with NTR Dokument nr 1:2011. Wood for sleepers shall be fresh, firm and in good condition and shall not contain typical compression wood or cross grain. Spiral grain shall not exceed a slope of 1:7. Furthermore the wood shall be free from log blue, storage blue, decay, insect holes, rotten knot, water-wood or harmful weakening defects such as big star and ring shakes. Minor superficial blue stain and water stain which do not have a detrimental effect on the serviceability of the sleeper are however permitted. The maximum diameter of knots shall be less than 40 % of the sleeper width.


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The sleepers shall be thoroughly cleaned of bark and phloem. They shall also be accurately sawn with smooth parallel surfaces and the ends cut square to the longitudinal axis of the sleeper.

2.5.1.2.2 Timbered sheet foundations Pine planks, strength class T30, are to be used for timbered sheet foundations and shall be made of pine and impregnated with MT-creosote oil Wood protection class A in accordance with NTR Dokument nr 1:2011.

2.5.1.2.3 Wooden piles Pine piles are to be used and shall be impregnated with MT-creosote oil Wood protection class A in accordance with NTR Dokument nr 1:2011. Material shall conform to the requirements of BKR “Boverkets konstruktionsregler” 4:4.

2.5.1.2.4 Environmental consideration The use of impregnated wood is to be avoided in tower sites with special environmental or nature conservation considerations. The contractor shall obtain clarity in this respect from the Client prior to finalising the material to be used.

2.5.1.3 Concrete The publication BBK04, "Boverkets handbok om betong konstruktioner", is to be followed for concrete works unless stated otherwise.

2.5.1.3.1 Cast in-situ foundations Concrete shall be of a minimum standard equivalent to K30, waterproof, air content in accordance with BBK 94 table 7.3.2.1a, quality class I and moderate aggressive environment according to BBK 94 clause 7.3.2. Concrete shall be manufactured by factories associated to KRB. Concrete shall: Be of minimum compression strength class C25/30. Be composed in accordance with Swedish Standard SS 13 70 03:5.3.3 to resist water ingress. Possess air content in accordance with table 5.3.2.b of Swedish Standard SS 13 70 03 to withstand frost erosion. Be of execution class 1 in accordance with BBK 04 Fulfil the requirements of exposure class XF 3 in accordance with EN 206-1.

2.5.1.3.2 Pre-cast factory manufactured foundations Concrete shall: Be of minimum compression strength class C25/30. Be composed in accordance with Swedish Standard SS 13 70 03:5.3.3 to resist water ingress. Possess air content in accordance with table 5.3.2.b of Swedish Standard SS 13 70 03 to withstand frost erosion. Be of execution class 1 in accordance with BBK 04 Fulfil the requirements of exposure class XF 3 in accordance with EN 206-1. Concrete shall be manufactured by factories associated to KRB.


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2.5.1.3.3 Concrete piles Concrete piles shall conform to the requirements of classes "1" and "AD1" in accordance with EN 12794.

2.5.1.3.4 For rock anchoring For grouting a cement/water mixture shall be used with a water cement ratio of 0.27 - 0.28. If an alternative grout is to be used it shall be approved by the client.

2.5.1.3.5 Base plates Grouting of base plates is to be performed with expanding grout with a minimum thickness of 20 mm. The grout shall have a standard certificate of approval issued by the National Housing Board (Boverket).

2.5.1.3.6 Concrete sleepers Concrete sleepers shall conform to the requirements of clause 2.5.1.3.2.

2.5.1.3.7 Concrete tubes Concrete tubes shall be reinforced and manufactured in a factory that is approved by the Kontrollrådet för Betongvaror (KRB) (Control council for concrete products)

2.5.2 Design

2.5.2.1 General Design shall be performed in accordance with Swedish Standard SS-EN 50341:8. Foundations shall be designed to withstand all the load cases which occur on the supports. A soil investigation shall be carried out on which the design of the foundation shall be based. The soil investigation shall be presented in accordance with the standard forms of SGF. Density values of the backfill in accordance with SS-EN 50341:8.3/SE.1 can be used for the design of the foundation. The density of backfill for foundations in peat soils can be assumed to be a minimum of 2 kN/m3, unless sub-soil investigations indicate another value. Foundations shall be founded at a minimum depth in accordance with Swedish Standard SS-EN 50341:8.2/SE.1.1 "Frost proof depth". The foundation depth may be reduced if ground insulation is used under the pad and if so this shall be stated on the drawings. The amount of depth reduction shall be verified by calculations which are to be approved by the client. The required resistance for overturning is given in Swedish Standard SS-EN 50341:8.5.2/SE.4. Moment foundations are to be designed in accordance with a method accepted in Sweden where lateral earth pressure, substratum, overturning and horizontal movement are considered. The supplier is obliged to present the method to be used. The required resistance for uplift is given in Swedish Standard SS-EN 50341:8.5.2/SE.4. Foundations that are subject to uplift loads shall be designed for the weight of the soil and the concrete. Uplift load x safety to uprooting = Weight of soil + weight of concrete.


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The weight of soil is to be calculated using the volume that is defined in Swedish Standard SS-EN 50341:8.5.2/SE.2. Steel anchor bars for uplift foundations or stay anchors on rock are to be designed such that the embedded length in rock is equivalent to the weight of the frustum of a pyramid with a 45° frustum angle in solid rock or 30° in soft rock. Uplift load x safety to uprooting = Weight of rock.

The density for solid rock shall be assumed as 26 kN/m3 If a shorter embedded length is achieved as a result of the adoption of an alternative design philosophy, which does not conform to the above, the anchor shall be tested in accordance with clause 2.7.3. Compression foundations in cohesive soils are to be designed in accordance with the formula below.

DCVHLBBDQ utill 8.0)3.11)(2.01)(2.01(5.

Limit condition:

5.20 BD and

0.10 LB

For 5.2BD

is 5.1)2.01( BD

where Qtill = Allowable average vertical earth pressure (kN/m2). D = The depth from the lowest ground surface to the bottom of the foundation (m). B = Width of pad (m). L = Length of pad (m). H = Horizontal load (kN). V = Vertical load (kN). Cu = Undrained shear strength of the soil (kPa).

= Density of soil over the pad (kN/m3). Compression foundations in frictional soils are to be designed in accordance with the formula below.

VHLBBDDN

VHLBBN

q

till5,112,011,01

5,113,012

1

2

2

Q

where Qtill= Allowable average vertical earth pressure (kN/m2).

N = Bearing capacity factor for the soil under the bottom the foundation Nq = Bearing capacity factor for the soil above the bottom the foundation

Values for N and Nq are given in the graph on page 14. D = The depth from the lowest ground surface to the bottom of the foundation (m). B = Width of pad (m). L = Length of pad (m). H = Horizontal load (kN). V = Vertical load (kN).

1 = Density of soil over the pad (kN/m3).

2 = Density of soil under the pad to the depth of 2B (kN/m3).


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0º 5º 10º 15º 20º 25º 30º 35º 40º 45º

1

2

5

10

20

50

100

200

300

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0

d

tan d

Bearing capacity factor Nq

and N

N q

N

where k= characteristic value of the angle of internal friction for the soil

material

1,11,1

''' tantan

tan

k

nm

kd

m = Partial factor in accordance with BKR 4:31 (Boverkets konstruktionsregler).

n = In accordance with Swedish Standard SS-EN 50341:8.2/SE.1.2 (1.1 for safety class 2)

2.5.2.2 Grillage foundation The stability of grillage foundations is to be checked in accordance with clause 2.5.2.1. Sleepers shall be made from wood, steel or concrete. Grillage foundations for stay attachments shall be installed with a sleeper support which transfers the horizontal component of the load to every sleeper. The sleeper support shall be rigidly fixed to the foundation beams.

2.5.2.3 Concrete foundation Stability is to be checked in accordance with clause 2.5.2.1. Concrete and reinforcing are to be designed in accordance with “Boverkets handbok om betongkonstruktioner” – BBK04 and safety class 2 according to clause 1.1.1.4. Strength is to be designed in the ultimate limit state and crack width in the serviceability limit state. See BBK04 chapter 1.

2.5.2.4 Pile foundation Pile foundations are to be designed in accordance with BKR “Boverkets konstruktionsregler” chapter 4:313 and the Swedish Geotechnical Institute handbook "Pålgrundläggning" (Pile foundations). The design of pile groups is to be in accordance with "Handboken Bygg" chapter K11:22.


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2.5.2.5 Stay anchor Stay anchors are to be designed taking into account the weight of the overlying soil and the weight of the anchor with a minimum safety in accordance with Swedish Standard SS-EN 50341:8.5.2/SE.2. Tensile load (anchoring) x safety to uprooting = weight of soil + anchor. Stay anchors in rock are to be designed on the basis of utilising as an anchor either reinforcing steel bar B500 or fully threaded bar. Anchors are to be embedded in accordance with clause 2.6.2.3.

2.5.3 Loading parameters Foundations shall be designed to withstand all load cases for the supports with safety in accordance with Swedish Standard SS-EN 50341:8 and clause 2.5.2.

2.5.4 Workmanship and material details

2.5.4.1 Steel

2.5.4.1.1 Corrosion protection steel foundations Steel buried in soil shall be hot-dip galvanised in accordance with Swedish Standard SS-EN 50341:7.9/SE.1. The application of vinyl tar paint shall be used to improve the corrosion protection when steel foundations are located in particularly corrosive soils. This shall be applied in two coatings with the first layer being dry before the second

layer is applied. Total film thickness is to be 100-150 m. The hot-dip galvanised steel is to be washed before painting with ammonia water. Mix proportions shall be 1 part of 25 % ammonia water to 10 parts of water.

2.5.4.1.2 Holding down bolts inclusive of nuts and washers Fully threaded bars or alternatively deformed reinforcing bars B500 are to be used as holding down bolts. The load is transferred by bond between the steel and the concrete. U-bolts can be used as holding down bolts. The use of other types of holding down bolts is subject to the approval of the client. Holding down bolts shall have undersized metric threads with the ends chamfered such that satisfactory starting of the threads is achieved in accordance with EN ISO 4753. Before hot-dip galvanising the diameter of the threads shall conform to the requirements of ISO 965-4. Holding down bolt shall not be in contact with the reinforcing bars. Hot-dip galvanising The basic dimensions of the threads in accordance with ISO 724 are not to be exceeded after the specified length has been hot-dip galvanised. The minimum zinc coating on holding down bolts shall conform to the requirements of EN ISO 10684 clauses 6.2.3 and 8.3. Acid cleaning is only to be carried out on that part of the holding down bolt that is to be hot-dip galvanised. Tests Holding down bolts are to be visually inspected before and after hot-dip galvanising. Sample testing shall include hot-dip galvanised length, bolt length and thread dimensions. Certificate The supplier shall submit a test report in accordance with clause 2.2 of EN 10204.


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2.5.4.2 Concrete

2.5.4.2.1 Pre-cast foundations Foundations are to be manufactured in accordance with “Boverkets handbok för betongkonstruktioner” BBK04 and execution class I. Testing is to be performed in accordance with BBK04 9.3. It is the responsibility of the contractor to ensure that the supplier carries out the manufacturing under adequate production supervision. All visible corners are to be chamfered with an F20 three edge fillet in accordance with SIS 81 20 01 with a width of approximately 27 mm. Foundations are to be manufactured to meet the tolerances given in the table below.


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Dimension Basis of

measurement (mm)

Tolerance (mm) Definition of dimension b)

Bolt group a) Length, width, height ±20 3 Location in the horizontal plane

±25 1

Location in height ±20 2 Crookedness and inclination

Height (H) H/600, min. ±10, max. ±25 4, 16

a)Tolerances for bolt groups shall be stated on drawings or an instruction referred to on a drawing. b) In accordance with “HusAMA 98” The requirements of surface roughness as below shall be fulfilled. Permitted number of local peaks per m2

Height (mm)

Number

1 2 3

10 5 2

A maximum of 20 cavities (pores) per m2, with diameters of 5-10 mm and a maximum depth of 5 mm, are allowed. A certificate containing the following information shall be included in the as-built documentation.

Supplier

The clients order number

Quantity of foundations included in the consignment

Drawing number

Information regarding tests performed and test results.

Date and signature of quality manager

Further manufacturing documents:

Method of manufacture

Lifting points

Storage location prior to transport to site.

Required concrete strength before lifting and transport from manufacturing site.

Marking of foundations shall include:

Manufacturer

Date of manufacture

Type (i.e. drawing number)

Weight

The manufacturer shall be responsible for the repair of any damages incurred during transport.


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Prefabricated concrete units shall be protected during transport so that damages do not occur. Units with transport damages are not accepted.

2.5.5 Documentation All text shall be written in Swedish or English. SI units shall be used in all documents, calculations and drawings. A summary of documentation requirements is contained in chapter 14.

2.5.5.1 Drawings and calculations The contractor shall prepare all drawings required for the work. The contractor shall present the drawings in such a way that they unambiguously specify how all details are to be made. The contractor shall furnish the client with workshop drawings, working drawings and calculations for review as called for in this specification or which are required to verify compliance with the contract, or for any other reasons as requested by the client. Drawings and calculations are subject to the client’s review and approval. The contractor shall furnish the client with copies of drawings and calculations which the latter shall review. In this respect the contractor shall ensure that the drawings are produced timeously to allow time for review and amendments to be made before they are used for manufacturing or construction purposes. Drawings prepared by the contractor, which are subject to review by the client, may not be used for manufacturing or construction purposes before they have been approved by the client. The review of drawings by the client does not release the contractor from any of his obligations in accordance with these guidelines, or from his responsibility of ensuring that the design and drawings are correct. All designs shall be in accordance with these guidelines and take due cognisance of the requirements regarding manufacturing and installation etc. The contractor shall be responsible for all designs prepared by him. Design calculations are to be approved by the client. The contractor’s obligations shall be deemed to include any additional measures, such as more detailed inspections etc., if revealed as a necessity by the client’s review On the drawings the following shall be given, if appropriate:

On every foundation type drawing excavation depth and dimensions of the pad and chimney.

Diameter, type and length of holding down bolts.

Waterproofing, air content, together with quality, strength and environmental classes of concrete.

Diameters, quantity, lengths, centre to centre distances, bending radii and concrete cover for reinforcing.

Dimensions, lengths, types and positions of piles.

Diameters, embedded length and positions of rock anchor steel.

Type of concrete tubes.

Type of ground insulation.

Type, cross-section and lengths of sleepers.

Steel foundation frameworks are to be presented in accordance with the requirements given in Chapter 3, - Supports.

Requirements for excavation, backfilling and grouting.

Applicable regulations and security class shall be stated for concrete foundations. Drawings for concrete foundations shall also conform to the requirements of BBK04 clause 1.4.2.


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The type of foundation for each support is to be stated on the respective support drawing or on a separate assembly drawing. Where required a separate foundation plan is to be made for supports to show details of excavation and backfill. With every drawing submission a drawing list shall be included. The list shall include all foundation drawings together with notes indicating changes. The size of drawings shall conform to ISO 216:

A1 (594x841 mm)

A2 (420x594 mm)

A3 (297x420 mm)

A4 (210x297 mm)

Sizes larger than A1 should be avoided. All dimensions given on the drawings shall be in mm. Every drawing shall have a provision in the lower right-hand corner for the client’s title and drawing number if the client so wishes. A panel for indicating the revision status shall be included on every drawing. The following applies for calculations: The design calculations shall be submitted together with the factors of safety and/or partial factors used. The output data from computer programs shall be presented in such a way that the client can check input data and results. SvK TR 05-03 applies for foundation frameworks.

2.6 Construction

2.6.1 General It is not permitted for any support to have its foundations in soils with significantly different characteristics. Thus one foundation may not be placed on firm soil, such as rock, moraine or gravel, while another is placed on loose soil. In such cases the loose soil has to be replaced or alternatively the rock blasted. Concrete foundations are to be installed with a minimum dimension of 30 cm from ground level to the top of the foundation. Steel foundations and all stay anchors with steel components buried below ground level, whether adjustable or not, are to be equipped with an inspection strand to enable corrosion to be checked. The installation is to be done in accordance with appendix A.

2.6.2 Cast in-situ concrete foundations

2.6.2.1 General Concrete works shall conform to quality class I in accordance with BBK 04 8.4. Prior to dismantling formwork the concrete strength shall be a minimum of 6 MPa At an individual support location the same type of formwork material shall be used for all foundation parts situated above ground level. All visible corners are to be chamfered with an F20 three edge fillet in accordance with SIS 81 20 01 with a width of approximately 27 mm. All other requirements regarding concrete quality and testing shall conform to BBK04.


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Foundations are to be manufactured to meet the tolerances given in the table below. Dimension Basis of

measurement (mm)

Tolerance (mm) Definition of dimension b)

Bolt group a) Length, width, height ±20 3 Location in the horizontal plane

±25 1

Location in height ±20 2 Crookedness and inclination

Height (H) H/600, min. ±10, max. ±25 4, 16

a) Tolerances for bolt groups shall be stated on drawings or an instruction referred to on a drawing.

b) In accordance with “HusAMA 98”

The distances between the foundations of an individual support shall have such tolerances that the support can be easily assembled and will not be subjected to stresses for which it was not designed. The requirements of surface roughness as below shall be fulfilled. Permitted number of local peaks per m2

Height (mm)

Number

1 2 3

10 5 2

A maximum of 20 cavities (pores) per m2, with diameters of 5-10 mm and a maximum depth of 5 mm, are allowed. Backfilling shall be carried out with materials that do not include topsoil, remnants of timber or frozen soil. Within 0.5 metres from the foundation the maximum stone size shall be 200 mm care being taken so that any such stones do not fall down and damage the foundation. After completion of installation and backfilling it shall be verified that the foundation is in the correct position. Acceptable deviations in height, plane, inclination and rotation within the same support location shall be given on drawings or on accompanying instructions. Grouting is to be done to the required extent. Grouting of baseplates for supports is to be completed as soon as possible after the support has been erected. The steel construction is to be aligned vertically by means of adjustable bolts, or wooden wedges, which are to be removed in sequence with the grouting work. Pressure distributing steel plates must be used to prevent damage of the foundations upper edge when adjustable bolts are used. The thickness of the grout shall be a minimum of 20 mm. Grouting is not to be carried out when the air or the top of the foundation have a temperature lower than +5 °C. The top of the foundation concrete shall be thoroughly moistened before the grouting is carried out. However, free water shall not exist. It is essential that all interstices between the base plate and the concrete are completely filled such that total contact between the plate and the grout is achieved. Spaces in baseplates around holding down bolts shall be filled with grout. Reinforcing bars or mesh is to be placed in the grout for thickness exceeding 50 mm or when the grout is subject to accelerated drying.


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For tightening torque for holding down bolt see SvK TR 05-03 Supports. Nuts for holding down bolt shall be locked with two punches.

2.6.2.2 Foundations in soil Foundations shall if possible be installed against original undisturbed soil. Machine excavation may be made to a depth of 10 cm above the final foundation depth. The remaining excavation is to be carried out by hand to ensure that the foundation will rest on undisturbed soil. As an alternative machine excavation can be made to a depth 10 cm below the final foundation depth and a layer of gravel or crushed stone then applied. This layer is to be compacted in accordance with “Anläggnings AMA98” Table CE/4 Material type 2. A suitable synthetic fibre membrane is to be laid on the bottom of the excavation for loose soils or soils liable to flotation. The synthetic fibre membrane installed shall conform to the usage classification of “Anläggnings AMA98” appendix 4 and to the table below.

Type of refill Minimum synthetic fibre membrane usage class

Soil 2 Crushed materials with granular size<250 mm

3

Crushed materials with granular size>250 mm

4

The synthetic fibre membrane installed shall be placed in accordance with “Anläggnings AMA98 DBB”. It shall be stated on the drawings for foundations placed on fill how the fill is to be composed and made. Fill shall conform to the requirements of “Anläggnings AMA98” clause CEB.2. The top surface of blasted stone fill is to be sealed with well graded materials comprising maximum granular size of 65 mm and particles with sizes between 0.06 mm and 20 mm being less than 10 % by weight. Compaction is to be performed by vibration in accordance with “Anläggnings AMA98” Table CE/4 Material type 2 The dimensions of backfill and berms for uplift and moment foundations are always to be checked to ensure that they conform to the stated dimensions.

2.6.2.3 Anchored foundations on rock Loose materials are to be removed where foundations are located on rock with anchor rods. The top surface is to be cleaned to rock cleaning class 1 in accordance with “Anläggnings AMA98” clause CBC. The rock surface is to be bench blasted if the inclination of the bed rock is more than 1:2. Embedment lengths for anchor rods shall be stated on each respective type drawing. Drilled hole diameters shall be 20 mm greater than the anchor rod diameter. Rock in which joints and fissures occur is to be reinforced by means of B500 type reinforcing bars. The reinforcing bars are to be drilled and embedded in the rock to a length such that the rock is effectively monolithic. Alternatively the embedded length of the anchor rods can be increased. If there is a risk that the grout for anchoring will dissipate into joints and cracks, or there is a continuous water flow, the hole is to be injected with grout. When the grout has hardened the hole is to be re-drilled.


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Grouting shall not take place if the temperature of the rock is lower than +2 C. The drilled hole is to be carefully cleaned of water, drill cuttings and all contaminations. The mixing of grout for anchor rods shall take place in a Rojo-mixer, or equivalent, and continue until the grout is thoroughly mixed and has obtained a plastic consistency. The grout is to be inserted by means of a pump and a tremi-pipe to the bottom of the hole. The tremi-pipe is to be gradually withdrawn during the placing procedure. The pumping of grout is to be done with a pump working normally. The rock anchor grout shall conform to the requirements given in clause 2.5.1.3.4. Anchor rods shall conform to the requirements given in clause 2.5.1.1.1 or 2.5.1.1.2.

2.6.2.4 Foundations in loose soils–pile foundations Piles shall be manufactured from concrete or steel in accordance with Swedish standards. Piling works are to be performed in accordance with “Boverkets konstruktionsregler” BKR. Piles shall be fitted with rock shoes when a sloping rock surface forms the bearing stratum. Piles are to protrude a minimum of 100 mm into the foundation pad. Concrete covering reinforcing steel of concrete piles, subject to uplift loads, within the foundation pad is to be broken out and the reinforcing steel anchored in the foundation pad.

2.6.3 Pre-cast concrete foundations Excavation and backfilling shall conform to clause 2.6.2.2.

2.6.4 Grillage foundations Foundations shall be installed at a frost proof depth unless special precautions are taken. The foundation depth shall therefore, with the exception of peat soil, be a minimum of 1.5 m in soils liable to frost heave and 1.35 m in soils not liable to frost heave (refer to Swedish Standard SS-EN 50341:8). Notwithstanding this requirement the foundation depth shall be the minimum that is required for stability. The foundation depth is defined as the distance from the final ground surface to the lower edge of the sleepers. In soils extremely liable to frost heave (Gr. III according to the National Road institute grading) the backfill shall comprise dense material which is not liable to frost heave. Backfilling around foundations shall be performed with due care. Stones larger than fist size shall not come closer than 10 cm to foundation frameworks or the steelwork of the support. The density value of the backfill shall be a minimum of what have been used in the design of the foundation. To compensate for the initial imperfect degree of compaction the backfill is to be made to a correspondingly higher level than the original ground level. The following applies to supports with more than one foundation:

Foundations located in peat soils are to be situated on soil with identical properties.

The distance from the lower edge of the sleeper to the firm bearing stratum may not be less than 0.5 m for foundations in loose soils with different depths to the firm bearing stratum

The differential height between foundations from the lower edge of the sleeper to the bearing stratum may not exceed 1.5 m.


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The distance from the lower edge of the sleeper to the firm bearing stratum may not be less than 0.4 m for foundations in loose soils with equal depths to the firm bearing stratum.

To avoid differential settlement the bottoms of the individual foundation excavations shall be accurately levelled and the soil type be similar over the entire bottom surface. Excavation and backfilling shall further conform to clause 2.6.2.

2.6.5 Tube foundations For tube foundations the following applies:

a) The tube backfilling is to be made to a level 100 mm below the lower edge of the concrete or wooden pad with frictional material compacted in accordance with “Anläggnings AMA98” Table CE/4 Material type 2. Grading shall be completed to the level of the lower edge of the pad with backfill that contains no stones.

b) Concrete legs of any support are to be appropriately secured to the foundation pad after which the foundations are to be filled with concrete, with a minimum quality in accordance with C20/25, consistency class S2 in accordance with EN 206:4.2.1 and a maximum aggregate size of 16 mm, or with other material approved by the client.

c) Wooden legs of supports are to be secured to the concrete or wooden pad. Thereafter the space between the leg and the inside of the tube is to be filled with crushed stones. These shall have a diameter between 18 and 32 mm and be compacted in layers of 300 mm thickness. Each layer shall be compacted with a minimum of 4 passages using a 15 kg hand-ram or equivalent.

2.6.6 Stay anchors For stay anchors founded in soil the density of the backfill shall be a minimum of 18 kN/m3 above the ground water table, at a normal degree of compaction. In water logged soil the submerged density of the backfill shall be a minimum of 11 kN/m3 (silt and mud have in many cases a lower density). Excavation and backfilling shall further conform to clauses 2.6.2 and 2.6.4 respectively. Clause 2.6.2.3 is applicable for stays anchored in rock.

2.7 Tests

2.7.1 General Tests are to be performed in accordance with the standards that are approved by the client. Where no standard exists all details regarding testing are to be submitted to the client for approval. The contractor shall keep the client informed of the testing programme to enable planned inspections to be performed and attended by the client.

2.7.2 Concrete foundations Concrete for concrete foundations is to be tested at an official testing institute in accordance with existing concrete regulations.


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2.7.3 Stay anchors Requirements for tensile tests are contained in clause 2.5.2.1. A minimum quantity of 10 % of stay anchors in rock shall be tensile tested. In particular tensile testing shall be performed at locations with poor rock quality and where Betokem or an equivalent has been used for grouting. A minimum tensile load of 60 % of the breaking load shall be applied to anchors subject to tensile testing and records made during testing. Tensile tests are not to be made within 28 days after

grouting nor are they to be made at temperatures lower than +5 C where Betokem or an equivalent has been used. The contractor shall draw up a schedule for the testing of stay anchors in rock which is to be approved by the client. The testing of tensile loads, are to be applied in line with the anchor. If the anchor under test should pull out then, a new anchor shall be installed and tensile tested.

2.8 Delivery

2.8.1 General The contractor shall undertake to prepare a quality assurance programme, in accordance with EN ISO 9001, which is to be reviewed and approved by the client before commencement of work. All quality documentation related to the work being performed shall be available for inspection by the client’s representative until finalisation of the work. All documentation shall be in Swedish or English.

2.8.2 Quality documentation Prior to delivery from the manufacturer the contractor shall present quality documentation to the client. The quality documentation shall include documents in accordance with clauses 2.8.2.1 – 2.8.2.3.

2.8.2.1 Certificate A certificate, duly signed by the contractor’s representative who is authorised to sign such QA. documents, which includes:

sufficient information for the part to be identified references to those standards and requirements which have been applied for

the manufacturing and inspection

records confirming that the inspections specified have been performed and the required results attained

Testing is to be in accordance with clause 2.7 and the client shall be given the opportunity to participate in tests and inspections. A certificate of delivery will be issued by the client if the works inspections and tests have been found to conform to the requirements of these guidelines in all respects. Goods forming part of foundations and stay anchors may not be delivered to site before they have been inspected and tested in accordance with clause 2.7.


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2.8.2.2 Deviation report Deviation reports together with every report related to major remedial works.

2.8.2.3 Separate reports and inspection companies Certificates for investigations which require separate reports, i.e. material tests, design and test assembly reports. Certificates from an independent inspection company, if such a company has been employed.

2.8.3 Transport and storing The foundations and foundation material shall be packed up in that way that they will not be damaged or fouled at transport, construction and storing.


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APPENDICES

Appendix A Control strand for testing of possible corrosion attack on steel buried underground Control strands shall, for new lines, be installed on every support location to estimate the corrosiveness of the soil at each individual support location in a line and to keep possible corrosion attacks under control. The control strand is to be installed on every stay anchor of stayed steel supports and on the foundation of self-supporting steel supports. For stayed wooden supports the control strand is to be installed at the adjustable anchor bolts. The distance between installed control strands is in no case required to be less than 5 metres. Tensile testing of the control strand shall be accordance with EBR handbook "Underhåll ledningar 0,4 - 420 kV" and should be performed during the regular maintenance inspection of the line.

Wooden

support

Placement of control strand for different types of supports. The control wire is only required to be installed on one stay anchor in the case of stay anchors having a distance of less than 5 metres between each other.

Soft hot-dip galvanised steel strand Fe 60 wire 4,5 mm diameter.


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INSTALLATION OF

CONTROL STRANDMinimum 5

turns

The strand is to be

tied loosely to thestay rod or the main

member. It shall not

be wrapped aroundthe stay rod or the

main member.

Anchoring to be achieved

by installing the controlstrand around an

immovable part of the

foundationa.


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TENSILE TESTING OF

THE INSTALLED

CONTROL STRAND

Place sling round the support leg, or a come-along

clamp on the stay, at an appropriate height in

accordance with figure 1, 2 and 3.

Release the lock on the winch of the tensioning

device and pull out the bond.

Attach the hooks to the eye of the control strand and

the come–along clamp on the sling round the main

member or the stay.

Lock the winch and wind in the bond until the

control strand breaks or the dynamometer shows that

a load of 2.0 kN has been achieved.

Unload the tensioning device by releasing the winch.

On small staywires for wooden poles an

appropriate wedge type come–along

clamp can be used.

Fig. 1 Fig. 2

Fig. 3

Documents

Overhead transmission lines