OVM250 Stay Cable System.ppt

OVM250 Stay Cable System
柳州欧维姆机械股份有限公司
Liuzhou OVM Machinery Co.,Ltd
Liuzhou City,Guangxi,P.R.China
May,2015

Contents
1. Foreword
2. OVM250 Structure
3. OVM250 Cable
4. OVM250 Anchorage
5. Corrosion Protection
6. Vibration Control of Cable
7. Individual Strand Installation
&Monitoring Method of cable force
8. Product Application

As the main structure of the bridge, stay cable system is one of the
most concerns of the Owner and designer in the following
considerations:
OVM250 stay cable system can meet these requirement and has been
applied in many projects successfully, OVM is ready to provide a reliable
stay cable system for your projects.
• Durability;
• Aerodynamic performance;
• Good anti-corrosion protection;
• High static and fatigue performance;
• Easy installation;
• Easy inspection & maintenance;
• etc.
1.Foreword

1） fib-2005：Acceptance of stay cable
systems using prestressing steels;
2） PTI-2007: Recommendations for stay cable
design, testing and installation;
3） CIP-2002: Recommendations of French
interministerial commission on
prestressing
4） JT/T771-2009: 无粘结钢绞线斜拉索技术条件
Technical conditions for unbonded steel strand
stay cable
Recommended specifications ：
1.Foreword

1）Anchorage zone：
Anchorage,Filling materials ,
Anchor cap,etc.
2）Transition zone：
Damper,collar,waterproof cap
and PE sheath connector,etc.
3）Free length：
Cable and outer HDPE sheath
2. OVM250 Structure

The cable consists of bundle of individually protected PE
sheathed low relaxation galvanized or epoxy coated strand.
Individual Strand with
anti-corrosion protection
HDPE sheath
3. OVM250 Cable

3.1 PE sheathed strand
Smooth.Galvanized or
epoxy-coated strand
PE sheath
Anti-corrosion
grease or wax
A series of experiments and equipments to ensure product quality
- - Numbers of inspections and tests:
1）Chemical resistant test
2）Chloride penetration test
3）Impact test
4）Abrasion test
5）Salt Spray Test
6）Water tightness test(Static &Dynamic)

1） Chemical resistant test
2） Chloride penetration test
说明：
1—放置115mL蒸馏水的隔间；
2—中心带24mm开口的两块玻璃板之间的PE；
3—放置175mL浓度为3mol/L的NaCl水溶液的隔间；
4—水平标记； 5—25mm的中心开口。
3） Impact test

4） Salt Spray Test 5） Abrasion test

6） Water tightness test(Static&Dynamic)
Water tightness test(Static) Water tightness test(Dynamic)

3.1.1.1 Strand types
In engineering applications, strands used to make cable mainly include:
3.1.1 Strand
B.Galvanized Strand
A.Bare Strand
C.Individual epoxy-
coated wire prestressing
steel strand
D.Epoxy-Coated Seven-
Wire Prestressing Steel
Strand
单丝涂覆型填充型涂覆型

Type Standard name Standard number
Bare 《Steel strand for prestressed concrete》
GB/T 5224
(ISO 6934-4).
（ASTMA416/A416M）
Galvanized
《High strength low relaxation hot-dip
galvanized steel strand for prestress》
YB/T 152
(NF35-035)
Epoxy-coated
《Individual epoxy-coated wire
prestressing steel strand》
GB/T 25823
JT/T 792
《Epoxy-Coated Seven-Wire Prestressing
Steel Strand1》
GB/T 21073
(ISO 14655)
（ASTMA882/A882M）
3.1.1.2 Common Standard for strand
3.1.1 Strand

Material
certification
3.1.1.3 Strand properties
● OVM sign the cooperation agreement strictly with steel strand material
suppliers, the test content contains the following items ：
1) Low relaxation, no welding;
2) Tensile strength, yield strength and elastic modulus；
3) Ductility (deflection) tensile properties-- One pin test
4）Fatigue and static strength
5）Anti-corrosion performance
3.1.1 Strand

1）Mechanical Properties：
 Breaking strength - 1860MPa
 Good fatigue resistance
performance
• Stressing range=300MPa
• Upper stress=0.45fs
 Ductility - one-pin test
 Stability Elastic modulus,low
relaxation
● Test content：
Tensile test
3.1.1 Strand

Natural rise detection method
Deflection tensile test
1—张拉端； 2—固定端；
3—芯轴中心； 4—夹具。
尺寸要求：
L1:(700±50)mm; L2:≥750mm
;
α：20°±0.5°
Relaxation rate test
3.1.1 Strand

Salt spray test
2） Strand Coating performance （Galvanized or epoxy-coated ）
Chemical resistance test
3.1.1 Strand

Impact resistance test
湿海绵
Indicator
alarm
Coating
Continuity
test
Method: In the process of coating, use a 67.5 V dc
pinhole detector with wet sponge or equal meth
od for continuous pinhole test of coating.
Thickness test
With magnetic thickness gauge or
other appropriate method，measuring
the thickness of the coating along the
curved surface
Adhesion test
3.1.1 Strand

3.1.2.1 Grease specification (fib)
3.1.2 Anti-corrosion grease or wax

3.1.2.2 Wax specification (fib)
3.1.2 Anti-corrosion grease or wax

The thickness of hot-press PE sheath is uniform, smooth without crack,
without hole, without obvious fold and mechanical damage.
3.1.3 PE sheath
HDPE specification (fib)

3.2.1 Two options for outer HDPE sheath
3.2 Outer HDPE sheath
Weld Outer HDPE sheath together

3.2.2 The function of outer HDPE sheath
Outer HDPE sheath is mainly used as a corrosion barrier, in addition, they may
provide the following functions：
1） Aesthetics by use of stabilised coloured pipes
2） Reduction of wind drag through the formation of a circular stay cable surface
3） thermal insulation
4） Protection against vibrations induced by rain and wind with appropriate surface
corrugations.
3.2.3 The Diameter and thickness of outer HDPE sheath
The ratio of outer diameter and wall thickness (SDR) should meet the following
requirements:
(1)The SDR shall not be less than 17 when HDPE sheath pipes are injected with fillers.
(2) The SDR shall not be less than 32 when HDPE sheath pipes are not injected with
fillers but the thickness of outer HDPE sheath should not be lower than 6mm.

3.2.4 HDPE test
 Outer layer: white and ultraviolet
resistant;
 Inner layer: carbon black and provide
necessary mechanical performance;
 Surface treatment: double helical rib
ensure safe drag coefficient of complete
stay cable under wind & rain;
 At tower end a stretching device is set
up to allow the pipe move freely when
temperature changes.
Stretching device

Ultraviolet resistant
 HDPE Antioxident Formula
 Accelerated aging test
The Durability of black PE
is 3-5 times comparing
with other colors.
 Calculate durability according
to the local UV intensity
3.2.4 HDPE test

Anti-aging performance
 GB/T 16422.2-1999 (idt ISO 4892-2:1994)
Plastic –Methods of exposure to laboratory light sources
Part 2 Xenon-arc sources
3.2.4 HDPE test

● The stability of the color
According to colour stability study, the stability of
all kinds of color as follows：
Stability is enhanced Stability is reduced

4.OVM250 Anchorages
4.1 OVM250 Structure
4.1.1 Adjustable-end
Anchor head Socket Nut Sealing device PE Sheathed
Strand
•Strand anchored individually by wedge and the entire cable anchored by nut-thread
assembly. This design makes possibility of de-stressing, removal and replacement for
both single strand and entire cable without any modification to the permanent structure.
•The length of socket can be designed to meet the requirement in case adjustment of
cable is needed for uncertainties.
Wedge

4.1.2 Fixed-end
•Dead end can also be designed adjustable;
•The anchorage will not fail before the main tension element fails;
•Surface of metal component(nut, thread etc.) is zinc coated protected, this protection for where are
not accessible will still effected even after installation of stay cable;
•The inner space of anchorage will be filled with grease after cable adjustment to provide anti-
corrosion protection;
•Sealing device ensure the entrance of strand into anchorage is watertight. This has been proven by
CIP & PTI test.
Wedge
Anchor head Sealing device
PE sheathed strand
4.OVM250 Anchorages

4.2 Anchorage Design
•Except anchored by wedges, there is no steel to steel contact of all strand
to avoid fretting corrosion and fatigue;
•Circular arc is designed at any position of deflecting to avoid localized
stress of strand.
4.OVM250 Anchorages

Carburized layer of wedge teeth
(50 times zoom-in)
)
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3
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The following measures ensure the high performance of anchorage:
• Anchorage system is designed by reliability-method and finite element analysis;
• carburization technique applied to ensure the requirement for wedge of both
hardness of teeth and toughness inside;
• Numerous static and fatigue tests prove the high performance of OVM anchorage.
4.OVM250 Anchorages

 Static performance and periodic
load performance: Comply with
fib specification;
Co-efficiency :ηa≥95%fs
Elongation: єapu≥2%
 Fatigue performance comply with
PTI , CIP and fib specifications.
4.OVM250 Anchorages
4.3 Mechanical properties

4.3.1 Static test
4.OVM250 Anchorages

The specification for fatigue test requirement
Specificatio
n
Test requirement
PTI
•Upper stress=0.45GUTS, Stressing range=159MPa
•Angular deviation=10mrad
•2 million cycles and failed area less than 2%
•Static performance after fatigue test: Co-efficiency ≥95%GUST or
≥92%AUST
fib
≥92%AUST
CIP
4.3.2 Fatigue test

Test Lab:
EMPA,Swiss
OVM250-31
OVM250-43
1)PTI requirement：
 Stress range=200MPa
 Upper stress=0.45GUTS
 2 million cycles and failed area less than 2%．
4.3.2 Fatigue test

PTI
Static performance after fatigue test:
Co-efficiency ≥95%
4.3.2 Fatigue test

Test lab:
CTL, US
2)CIP requirement：
• Stressing range=200MPa
• Upper stress=0.45GUTS
• Angular deviation=10mrad
• 2 million cycles and failed area less than 2%
• Static performance after fatigue test:
Co-efficiency ≥95%GUST or ≥92%AUST
OVM250-31/55
4.3.2 Fatigue test

OVM250-31 ／ OVM250-55
CIP
4.3.2 Fatigue test

3)Fatigue test according to fib
specifications
OVM250-109
Test lab:
CTL,USA
4.3.2 Fatigue test

4)OVM250-139 Fatigue test
CTL,USA
. Stressing range=250MPa
• Upper stress=0.45GUTS
• Angular deviation=10mrad
• 2 million cycles and failed area less than 2%
• Static performance after fatigue test:
Co-efficiency ≥95%GUTS
4.3.2 Fatigue test

OVM250 Fatigue Test:
No. Type Specification Upper stress
Stressing
range
(MPa)
Lab Test time
1 OVM250-31 PTI 0.45GUTS 159 EMPA,Swiss 2006
2 OVM250-31 PTI 0.45GUTS 200 CTL,USA 2006
3 OVM250-42 PTI 0.45GUTS 159 EMPA,Swiss 2007
5 OVM250-43 CIP 0.55GUTS 140 CTL,USA 2010
6 OVM250-55 CIP 0.55GUTS 140 CTL,USA 2010
8 OVM250-109 fib 0.45GUTS 200 CTL,USA 2011
9 OVM250-139 CIP/fib 0.45GUTS 250 CTL,USA 2012
4.3.2 Fatigue test

5.1 Cable Muti-layer
Anti-corrosion structure Outer HDPE sheath
（single-layer or double-layer）
PE sheathed strand
Strand
Grease or wax
PE sheath
Epoxy-coated
or Galvanied
5.Corrosion Protection

5.2 Anti-corrosion structure
of Transition zone
HDPE Outer sheath
Waterproof cap
Collar
Internal
Damper

5.3 Anti-corrosion structure of anchorage
 Surface handling of anchorage: galvanized
- Effective seal structure and sealing socket
- fill anticorrosive material on site
 Pass water tightness test according to
CIP&PTI

. Sealing components are made
of special material to achieve
waterproof performance;
. Long sealing length ensures
complete sealing;
. Durable material applied
5.4 Sealing device

Fill anticorrosive material into the
anchorage after cable is installed :
1)grease ;
2)wax;
3)soft resins.
Wax is a kind of anticorrosive material
based on mineral oil . It has good adhesion,
resistance to environmental climate erosion
and corrosion protection performance.
5.5 Filling materials

5.6 Water tightness test
1）CIP requirement
CIP
Test period is 6 weeks

CIP Water tightness test

∠30°
3m
CIP
Water
tightness
test

CIP
Water tightness test

No dyed water leaking observed on
both strand and anchorage.
CIP

After 2 million cycles
fatigue test, stay cable was
put into red-dyed water
with 3m water head.
2）PTI watertightness test

No dyed water leaking observed on both strand and anchorage.
PTI

 The cause of vibration ：
- Rain-wind induced vibration
- wind induced vibration（whirlpool＼wake current＼flutter＼
galloping etc.）
- Parametric excitation （car＼structure）
 Methods of controlling Vibration：
- increase damping devices
- avoid the resonance frequency
- Change the surface shape
6.Vibration control of cable

Measures of Vibration prevention :
 Single strand contains grease and PE layer, the damping coefficient is
bigger, is advantageous to the energy dissipation damping
 Due to the internal steel strand cable is independent with each other,
it is difficult to form a resonance
 Install high-performance internal damper in the guide pipe or install
the external damper on cable , for vibration damping energy consumption
 Double helical rib effectively prevent water flow on pipe
surface;Effectively mitigate oscillations induced by wind & rain.

Measures of
Vibration prevention

●Internal damper
. Dampers are adjustable, replaceable and
interchangeable, easy for inspection and
maintenance.
. After fatigue test, OVM dampers are
proven to be long life service.
Cable Guide tube Damper

. Material performance test
. Damper-cable assembly test
● Test on damper

● External damper
Through theoretical analysis and numerical simulation, verify the cable
chattering, vortex under vibration and wind up with the maximum amplitude of
whether meet the requirements. According to the analysis results, choose
external damper and design connector of cable and damper.
Connector

 Adopt isotonic force method for individual strand to ensure strength
evenly of every strand.
 Install sensors in the anchorage or cable to realize the cable force in the
construction and operation process.
7.Individual Strand Installation

Single strand tensioning isotonic method and equipment

magnetic flux sensor（CCT20）
Purposes: construction monitoring and
long-term measuring
- Anchor is provided with magnetic flux sensor
integration
protective tube
clip
signal line
Anchorage
on pylon
CCT20 sensor
concrete

1st largest cable-stayed bridge of its type by 2012
Tongling Highway-railway Bridge over Yangtze River, China
Span 630 m, height of pylon 220m, stay cable 5,632 tons
6-lane expressway on the upper deck, 4-lane railway below
OVM supplied multi-strand stay cable system and steel girder erector,
undertaking the installation of stay cable
8.Product application

8th largest cable-stayed bridge of MS type by 2012
Queshi Bridge, China
Span 518 m
OVM supplied multi-strand stay cable system
& undertook the installation

9th largest cable-
stayed bridge of
MS type by 2012
Anqing Bridge over Yangtze River, China
Span 510 m
OVM supplied multi-strand stay cable system
& undertook the installation

Lali Bridge, Iran
Span 100m+256m+100m
OVM supplied multi-strand stay cable systems,
equipments and construction service

Avahz 8th Bridge, Iran
Span 212m
OVM supplied multi-strand
stay cable systems,
equipments and
construction service

Kum-Kang 1st Bridge, Republic of Korea
Span 100m+180m+180m+180m+100m
OVM supplied multi-strand stay cable system and equipments

Kum-Kang 4th Bridge, Republic of Korea
Span 370m
OVM supplied multi-strand stay cable system, equipments and construction service

OVM250 Stay Cable System.ppt

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