kích thước của cáp dự ứng lực bản chất cáp dự ứng lực

A number of features are incorporated as a result of many years of experience in the field:  Stressing carried out in any number of stages;  Accurate control of prestress force;  No n

VSL Australia

Post-Tensioning

Systems

INTRODUCTION 5

VSL CAPABILITIES 6

MULTISTRAND POST-TENSIONING 9

STRAND PROPERTIES – TO AS 4672 10

TENDON PROPERTIES 10

SELECTED DESIGN CONSIDERATIONS 11

VSL STRESSING ANCHORAGE TYPE SC LIVE END 12

VSL COUPLING ANCHORAGE TYPE KAS - FOR USE WITH SC ANCHORAGE 13

INTERMEDIATE ANCHORAGE TYPE Z 14

VSL DEAD END ANCHORAGE 15

SHEATHING & CORROSION PROTECTION 16

DIMENSIONS OF PT-PLUS® DUCTS 16

ECCENTRICITY OF TENDONS 16

STRESSING SEQUENCE 17

STRESSING 17

GROUTING 17

JACK CLEARANCE REQUIREMENTS 18

STRESSING JACK DETAILS 18

SLAB POST-TENSIONING 21

STRAND PROPERTIES – TO AS 4672 22

TENDON PROPERTIES 22

SELECTED DESIGN CONSIDERATIONS 23

VSL STRESSING ANCHORAGE TYPE S5 – S6 LIVE END 24

VSL DEAD END ANCHORAGES TYPE H – TYPE P 25

VSL SLAB COUPLING ANCHORAGE TYPE S 26

JACK CLEARANCE REQUIREMENTS 27

STRESSING JACK DETAILS 27

INTERNAL STRESSING POCKET 27

ANCHORAGE REINFORCEMENT – S5-3, S5-4, S5-5, S6-3, S6-4 ANCHORS 28

ANCHORAGE REINFORCEMENT – S6-5 ANCHORS 28

ANCHORAGE REINFORCEMENT - TIES 29

STRESSING JACK DETAILS 29

GROUND ANCHORS 32

VSL PERMANENT ANCHOR FULLY ENCAPSULATED 33

VSL TEMPORARY ANCHOR 33

VSL PERMANENT GROUND ANCHORS - 15.2mm STRAND 34

VSL CT STRESSBAR GROUND ANCHORS 34

VSL TEMPORARY GROUND ANCHORS 34

VSL PERMANENT GROUND ANCHORS BEARING PLATE AND ANCHORHEAD 35

STRESSING 36

FLAT JACKS 39

CONTACT US 40

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Post-tensioning is, even so being a mature technology, still a fantastic tool for the design engineer to actively define the internal load path in concrete structures by superposing a favorable internal stress state This permits to minimize deformations, helps to increase slenderness of members, reduces reinforcement congestion, enables segmental construction without need for wet joints and allows the use of high strength steel

This brochure gives an overview of the available post-tensioning systems and their fields of application It provides guidance to

practising engineers in the design of post-tensioned structures using VSL post-tensioning systems

VSL is a recognised leader in the field of special construction systems Well proven technical systems and sound in-house engineering are the basis of the group’s acknowledged reputation for innovative conceptual structural solutions VSL has developed, manufactured and installed durable, state-of-the-art post-tensioning systems for over 60 years The VSL post-tensioning systems comply with

international standards and approval guidelines for use on both new and existing structures

VSL does not only select and offer the best suited post-tensioning hardware and layout for a given project but proposes also innovative detailing of the permanent work and construction techniques with the aim to improve durability, increase site safety and reduce construction time and costs

VSL likes to work in partnership with owners and clients right from the conceptual stage VSL’s engineers can work closely with the design engineer during the design development stage and with the contractor's estimating team during the tender stage What

differentiates VSL from other players in the market, is its holistic approach, which is fundamental in arriving at well balanced technical solutions respecting equally permanent work and construction aspects VSL’s biggest asset however is the quality of its highly

experienced, multicultural staff

VSL’s capabilities can be categorised into four different services:

/// SYSTEMS & TECHNOLOGIES

We ensure the development and constant improvement of our

portfolio of in-house technologies

Our Services:

Bridge Construction Containment Structures Heavy lifting

Engineered Precast Structures Offshore Structures

/// GROUND ENGINEERING

/// REPAIRS & STRENGTHENING

We offer tailored services to ensure the stability of your structure’s

life cycle, from inspections and assessment through to repair works

and upgrading

Our Services

Structural Diagnostics & Monitoring

Repairs & Strengthening

Infrastructure Protection

High Strength Concrete Solutions & Products

We are specialists in ground engineering and special foundations thanks to our long history of proven design and build capabilities gained on the most complex and varied projects

Our Services

Diaphragm walls Micro Compaction Subsurface grouting Micro Piling & Ground Anchors High Directional drilling & Coring Ground Freezing

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VSL Multistrand

Post-Tensioning

8 ///

The VSL Multistrand system comprises from three to fifty-five strands (either 12.7 or 15.2mm diameter), round duct and anchorages Prestressing force is applied to the tendons after the casting and curing of surrounding concrete All strands are stressed simultaneously using a hydraulic jack and are fastened at the live end by wedge grips The free space inside the duct is then pressure-filled with cement grout

A number of features are incorporated as a result of many years of experience in the field:

 Stressing carried out in any number of stages;

 Accurate control of prestress force;

 No need to determine tendon length in advance;

 Simultaneous stressing of all strands in a tendon, with individual locking of each strand at the anchorage point; VSL stressing equipment is easily operated to ensure a safe and rapid stressing procedures Special emphasis has been placed on rationalised manufacturing of equipment and anchorage parts as well as efficient work site practice

Ballina Bypass, Australia

PT Strands, Australia

Westlink M7, Sydney, Australia

Nominal Mass (kg/m)

Minimum Breaking Load (kN)

Minimum Proof Load (0.2% Offset) (kN)

Min Elong To Fracture in 500mm (%)

Relaxation After 1,000 Hrs at 0.8 Breaking Load (%)

Modulus of Elasticity (GPa)

Tendon Unit No of Strands Minimum Breaking Load

(kN)

Steel Duct Internal Diameter (mm)

2 Duct diameters are for corrugated steel duct

3 Duct external dia = inside dia + 6mm nominal

4 Corrugated PT-Plus duct is also available, refer to page 16

5 For special applications, other strand and tendon capacities are available

6 Anchorage size up to 6-91 available on special order from overseas

7 12.9mm, 15.2mm and 15.7mm minimum breaking 300kN breaking load strand available as special order from overseas

 Tendon in conventional steel duct: µ = 0.20

 Tendon in PT-PLUS® duct: µ = 0.12

Irrespective jack or tendon jack, a loss due to wedge draw-in of nominally 6mm occurs at lock-off If necessary

compensation can be provided by appropriate procedures

Spiral and/or rectangular stirrup reinforcement is required for all anchorages to control local zone stresses The design of this reinforcement is the responsibility of the Consulting Engineer For assistance, please contact your local VSL office

12 ///

Note: Antiburst reinforcement to Engineers details not shown

Strand Type 12.7mm Tendon Unit

1 Dimension R does not allow for Lift off force check Small recesses can be provided for special cases Please check with your local office for details

2 *Plate type anchorages (Type P) Also available for other tendon units

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Tendon Unit A Dimensions (mm) B C Tendon Unit A Dimensions (mm) B C

14 ///

Centre-stressing anchorages are used for ring tendons in circular structures, or for those tendons where the ends cannot be fitted with normal stressing anchorages

Tendon Unit

Dimensions (mm)

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Tendon Unit A Type H B C D Type P E F Tendon Unit A Type H B C D Type P E F

16 ///

For conventional applications, corrugated galvanised steel ducts are used.For diameters of steel ducts refer to page 10 For applications requiring enhanced corrosion protection and improved fatigue resistance of the tendons, the use of the VSL PT- PLUS® System with corrugated plastic duct can provide a number of important advantages This fully encapsulated, watertight system offers outstanding corrosion protection, and the plastic duct eliminates fretting fatigue between the strand and duct It also provides reduced duct friction The PT-PLUS™ System may be configured with special details and

installation techniques to provide Electrically Isolated Tendons (refer to GC system in VSL International Technical Catalogue) These tendons may be electrically monitored at any time throughout the life of the structure

All ducts are manufactured in a variety of standard lengths and are coupled on site

Strand Type

12.7mm Strand Type 15.2mm Duct Dimensions (mm)

Tendon Unit Tendon Unit d D thickness

e (mm)

Tendon Unit Steel Duct e

(mm)

Plastic Duct

e (mm)

on-18 ///

Dimensions

(mm)

VSL Jack Type VSL50 VSLB7 VSL190 VSL290 VSL460 VSL670 VSL750 VSL1000 VSL1250 VSL1650 VSL1700

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VSL Slab

Post-Tensioning

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VSL post-tensioning offers economies over other systems, especially when construction cycles are considered There is less material handling on site, reducing site labour force which reduces site activity congestion

Most importantly, there is the quality and service of VSL specialised high-performance site teams and unequalled back-up The VSL post-tensioning slab system has been used in many thousands of buildings and other structures throughout

Australia The system uses up to five strands in flat-shaped ducting and anchorages

Strands are stressed individually and then gripped by wedge action The entire duct is subsequently fully filled with cement grout injected under pressure so that the strands are fully bonded to the surrounding concrete

Coles National Distribution Centre, Melbourne, Australia

Austrak Industrial Park, Melbourne, Australia

Nominal Mass (kg/m)

Minimum Breaking Load (kN)

Minimum Proof Load (0.2% Offset) (kN)

Min Elong To Fracture in 500mm (%)

Relaxation After 1,000 Hrs at 0.8 Breaking Load (%)

Modulus of Elasticity (GPa)

 Minimum tangent length behind the anchorage: 0.5m

The friction losses in the anchorage due to curvature of the strand and friction of the strand in the wedges usually amount to:

 Edge stressing: 3% average

 Internal pocket stressing: 5% average

Frictional losses along the tendon can vary fairly widely and depend upon several factors, including the nature and surface condition of the prestressing steel; the type, diameter and surface conditions of the duct and the installation method The following values may be assumed for design:

 Tendon in conventional steel ducts: µ = 0.20

 Tendon in PT-PLUS® duct: µ = 0.12

A loss due to wedge draw-in of nominally 6mm occurs at lock-off

Duct Type Bi Ba Dimensions (mm) Hi Ha

26 ///

Strand Type Tendon Unit

Dimensions (mm)

12.7mm Strand 5-4 5-5 95 95 190 235 110 110 240 240 215 215 15.2mm

Strand 6-4 6-5 95 95 190 235 110 110 240 265 215 238

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Plan and sections of stressing pocket Details shown are typical and may vary for particular applications

Plan and Stressing pocket

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Anchorage at slab edge and anchorage at slab beam

Detailing at the slab edge and beam

Strand Type Tendon Unit No of Ties each side

Dimensions (mm)

30 ///

Ground Anchors

/// 31

Corrosion protection is provided by the cement grout in temporary anchors and by full encapsulation of the entire anchor in a thick walled polyethylene sheath for permanent anchors

VSL Rock Anchors range in ultimate capacities up to 23,750kN Tendons are constructed from either a number of 12.7mm or 15.2mm diameter, high tensile steel strands or single VSL stressbars

VSL Soil Anchors are used in alluvial soils, stiff clays or highly weathered rock The ultimate capacity of these anchors is determined by the capability of the ground in the bond zone to transfer the load from the anchor Anchor details are similar

to rock anchors

VSL Soil Nails are used to reinforce soil in an excavation or embankment They are formed by inserting VSL Bar into a drilled hole which is filled with cement grout Corrosion protection similar to ground anchors can be provided depending on the application Soil nails have no or only nominal initial applied force

VSL Rock Bolts are used to strengthen and stabilise jointed rock, and to stabilise defined blocks of rock They are formed by inserting VSL Bar into a drilled hole and anchoring it in place with either a mechanical anchorage, a chemical anchorage or cement grout The bar is stressed to apply an initial force

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Sheath Diameters (mm)

1 Where block outs, voids or drill hole casing are required, drill hole diameters and bearing plate dimensions should

be confirmed with your local VSL office

2 Drill hole sizes are based on 10mm external cover

(mm)

Temporary Drill Hole Dia

(mm) Jack Type Required

Drill Hole Dia

(mm)

Corrugated Sheath (mm)

15.2mm

Super (kN)

Minimum Drill Hole Dia (mm) Jack Type Required

Ultimate Capacity 15.2mm Super (kN)

Minimum Drill Hole Dia (mm) Jack Type Required

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No of Strand Tendon Unit

Dimensions (mm)

1 * Denotes non preferred bar size Please check with your local VSL office regarding availability

2 ** Denotes hole dimension to be site specific

3 Details given may be varied for particular applications

4 For strand anchors the maximum configuration size is shown Lesser number of strands may be specified

5 Additional capacities available on request

6 Drill hole sizes are based on 10mm external cover

7 Anchors can be monitorable and restressable

8 Removable ground anchors are available

9 Electrically isolated ground anchors are available

10 Bearing plate dimensions are suitable for 15.2mm super and 15.2mm EHT strands

36 ///

 Jack sizes are the same as for multistrand or stressbar systems

 Additional special purpose jacking chairs are provided to permit test loading

 Load cells can be provided that screw onto the anchor head to permit load measurement at any time, or permanently attached to enable continuous load monitoring

 Both hydraulic and electrical load cells are available

Northwest Transitway, Sydney, Australia

Landsboroug Maleny Road, Australia

Lake Narracan Dam, Victoria, Australia

Lapstone Hill, Australia

Lake Narracan Dam, Victoria, Australia

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Flat Jacks

38 ///

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Flat jacks are widely used for a multitude of civil engineering and construction applications such as:

 Underpinning

 Prestressing of columns

 Counteracting sinking coundations

 Prestressing of road woks or airport runways

 Prestressing concrete in confined spacing

 Lifting and lowering of bridge superstructures for bridge bearing adjustments

 Counteracting loads applied during backfilling

 Lifting heavy weights

 Pile testing

The VSL flat jack is constructed of two moulded steel sections welded together to form a containment vessel Hydraulic fluid

or grout is injected all pressures of up to 13.5 Mpa into a peripheral ring, moving the lifting plates apart, so that a force is applied with a maximum lifting stroke of 25mm per jack

Effective Area at Zero Extensions

103 (mm)

Thickness T**

(mm)

Maximum Travel

E (mm)

Installation Gap (mm)

1 *1150c Flat Jacks are specially produced to order and could be subject to a delay

2 **Flat Jack thickness may vary +-3mm