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SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES TOPOMACHINES

SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

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Page 1: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

TOPOMACHINES

Page 2: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

“Scraper Mesh System”: Schematic view & working principle

Traction Cable

Actuator

Scraper Ring

Actuator

Back & forth motion

Page 3: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Scraper Mesh System for Stay Cables: General layout

Scraper Mesh Termination

Scraper Mesh

Command Control System

Electric winch

Electric winch

Page 4: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Need Analysis: Snow removal

Snow Removal

Snow has low mechanical strength, but could have big accumulation.

In wet snow weather, slush bombs could form.

If not removed quickly, snow can freeze and generate ice.

Snow has to be removed from the entire surface of the stay pipe quickly

and frequently

Ice Removal

Ice adhesion strength is high.

During freezing rain, an ice layer can appear.

If not removed quickly, thick ice could form.

The more quickly ice is removed, the less energy is required.

o Scraper Mesh System removes snow mechanically.

o While it looks relatively easy to remove snow from a stay pipe, few solutions have been proposed.

o Mechanical solutions are the most appropriate, as thermal solutions require considerably more energy.

Page 5: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Need Analysis: Ice removal

Snow Removal

Snow has low mechanical strength, but could have big accumulation.

In wet snow weather, slush bombs could form.

If not removed quickly, snow can freeze and generate ice.

Snow has to be removed from the entire surface of the stay pipe quickly

and frequently

Ice Removal

Ice adhesion strength is high.

During freezing rain, an ice layer can appear.

If not removed quickly, thick ice could form.

The more quickly ice is removed, the less energy is required.

o Few systems are able to remove ice from a stay pipe.

o Important: a de-icing system is not necessarily able to remove snow from the stay pipe.

o An example for that is the Pulse Electro-Thermal De-icing System (PETD).

Page 6: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

De-icing is difficult due to ice adhesion strength

o Ice is a brittle material.

o But its adhesion strength to underlying surfaces could be very high.

o For a stay pipe made of HDPE, breaking shear stress of ice could be of the order of 1 Mpa or even more.

More powerful design of the Scraper Mesh System is not the solution.

Stay pipes would have to resist unacceptable large forces.

Page 7: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Complementary Action - Thermal

o A Heating Skin melts the ice at the stay pipe interface.

o This action effectively cancels ice adhesion strength.

o As a result, the Scraper Mesh can remove very thick ice easily.

Dual strategy to remove ice

Principal Action - Mechanical:

o Adjusting Scraper Mesh motion frequency.

o As a result, the Scraper Mesh removes any ice accretion and prevents ice layer formation.

Page 8: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Overall Snow & Ice Removal System

Our Snow & Ice Removal System is composed of two sub-systems:

o Scraper Mesh;

o Heating Skin.

Snow & Ice Removal System

Scraper Mesh

Main Sub-System

Removes Snow & Thin ice

Heating Skin

Auxiliary Sub-System

Melts the ice at stay pipe interface.

Page 9: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Snow & Ice Removal System action

Melts the ice interface

Moves back & forth

Removes Snow & Ice

Heating Skin

Scraper Mesh

Scraper Mesh

(if necessary)

Page 10: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Fully Automatic Snow & Ice Removal System

• Snow removal: – Mechanical sweeping; – Regular iterative motion (e.g., @5-minute intervals); – Prevents snow accumulation.

• Ice removal: – Interface heating (if necessary) + Mechanical scraping; – Regular iterative motion (e.g., @5-minute intervals) – Prevents ice layer formation, removes ice accretion of any thickness.

• Fully automatic, high performance system: – Robust, modular design – Service life = 50 years – Reliable, Available, Maintainable, Safe – Low Operation & Maintenance Costs

Today, our system is the only available Fully Automatic Snow & Ice Removal System for Stay Cables.

Page 11: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES
Page 12: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Heating skin activated

Page 13: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES
Page 14: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Heating skin activated

Page 15: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES
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Page 17: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES
Page 18: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Aerodynamics & aesthetics

Aerodynamics

Negligible additional drag due to Scraper Rings and Traction Cables.

No expected aerodynamics effect, as air is allowed to flow freely around Traction Cables.

Helical ribs can be included in the design of the Scraper Mesh in order to prevent galoping.

Aestethics

The Scraper Mesh would be barely visible, particularly if it is of the same color as the stay pipe.

Page 19: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Proposed prototype test bench

Page 20: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

Scraper Mesh System: Advantages

• Off-the-shelf technology

• Automatic, push-button system

• Robust, high performance, cost-effective

• Ultra-lightweight

• Can be made almost invisible or otherwise decorative

• Architectural Mesh option available (polygonal or biological design)

Page 21: SCRAPER MESH SYSTEM FOR BRIDGE STAY CABLES

www.topomachines.com

[email protected]