Bridge Saddle with Flexible Polymeric Strand Protection

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Solution Overview

Problem

Conventional bridge saddle designs either fix strands in solidified cement mortar, making them irreplaceable but resistant to corrosion, or use individual tubes that are susceptible to corrosion and fretting fatigue.

Innovation Solution

A bridge saddle with non-hardening, solid, flexible, and elastic polymeric material is used to protect strands from corrosion, allowing them to be individually replaced and maintained, while sealing means prevent the material from escaping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solidified cement mortar is used to protect strands from corrosion, then corrosion resistance is improved, but strand replaceability deteriorates

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidstrand replaceability

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent changes the physical state parameter of the protective material from hardening (cement mortar) to non-hardening (flexible polymeric material). This allows the material to remain protective against corrosion while maintaining flexibility that enables strand removal and replacement without breaking the protective medium.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite system combining flexible polymeric material with sealing means (caps or plugs). The polymeric material provides corrosion protection similar to cement mortar, while the sealing means prevent material escape, together achieving both protection and maintainability.

Inventive Principle:

Principle #40Composite materials

2Ease of repair

If individual tubes are used to allow strand replacement, then ease of repair is improved, but corrosion resistance deteriorates

Engineering Contradiction:

Improvestrand replaceabilityVSAvoidcorrosion resistance

Core Design Contradiction:

Ease of repairVSReliability

Solution Approach 1:

The patent changes the material property from rigid tubes (prone to fretting fatigue) to flexible polymeric material. This flexibility eliminates the fretting fatigue issue while maintaining the ability to allow strand insertion and removal through the flexible medium.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The flexible polymeric material acts as a disposable protective medium that can be injected and sealed. Unlike durable tubes that suffer from fatigue, this material provides sufficient service life for corrosion protection while enabling maintenance through replacement capability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If cement mortar is used to fix strands, then protection from corrosion is improved, but strand mobility deteriorates

Engineering Contradiction:

Improvecorrosion protectionVSAvoidstrand mobility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the hardness parameter of the protective material from rigid (cement mortar) to flexible (polymeric material). This maintains corrosion protection while allowing strand movement, installation, and removal without the material breaking or cracking.

Inventive Principle:

Principle #35Parameter changes

4Ease of repair

If flexible polymeric material is used to protect strands, then strand replaceability is improved, but material stability deteriorates

Engineering Contradiction:

Improvestrand replaceabilityVSAvoidmaterial stability

Core Design Contradiction:

Ease of repairVSStability of the object's composition

Solution Approach 1:

The patent introduces sealing means (caps or plugs) as intermediary elements that confine the flexible polymeric material. These seals prevent the material from escaping while allowing strands to move freely within the contained flexible medium, thus achieving both stability and mobility.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution allows for the individual replacement of strands and reduces the risk of corrosion and fretting fatigue, while maintaining effective protection against chemical and electrolytic degradation.

Implementation Method 1

protective material arranged to protect the strand from corrosion

Methodology Applied

Scientific EffectCorrosion resistance:

Implementation Method 2

protection against chemical and electrolytic degradation

Methodology Applied

Scientific EffectChemical resistance:

Implementation Method 3

non-hardening, solid, flexible and elastic polymeric material

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 4

reduces the risk of corrosion and fretting fatigue

Methodology Applied

Scientific EffectFretting fatigue reduction:

Implementation Method 5

sealing means prevent the material from escaping

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentEP2550401B1Bridge saddle and method for protecting strands from corrosion in such bridge saddle

Publication Date: 2016.12.14 VSL INT AG

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AI summary

Strand guiding device that comprises a curved body (201 ) having a first end and a second end. The strand guiding device further comprises at least one channel extending from the first end to the second end inside the strand guiding device, the channel being arranged to be traversed longitudinally by a strand (301 ) of a cable, and further arranged to hold the strand (301 ) in place when under tension. The body (201 ) of the guiding device is filled with a protective material for protecting the strand (301 ) from corrosion and allowing later removal of the strand (301 ).