Ribbed Polymeric Deviator Duct for Post-Tension Concrete

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Solution Overview

Problem

In post-tension segmental construction, existing systems face challenges with point-of-contact forces damaging post-tension tendons and ducts due to abrupt bends, and require improved tendon routing and bonding with concrete, while also needing to minimize material costs and enhance corrosion resistance.

Innovation Solution

A polymeric duct with a unique diameter profile and ribbed exterior for superior bonding, allowing for arcuate tendon routing with reduced contact forces and preventing concrete spalling, made from high-density polyethylene for lightness and corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If abrupt bends are used in tendon routing, then tendon routing is simplified, but point-of-contact forces damage tendons and ducts

Engineering Contradiction:

Improvetendon routingVSAvoidpoint-of-contact forces damaging tendons and ducts

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent employs arcuate (curved) tendon ducts instead of abrupt bends to route tendons through concrete segments. The curved geometry allows tendons to follow a smooth arc, distributing contact forces along the curve rather than concentrating them at sharp corners, thereby preventing damage while achieving the desired routing direction.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The duct features a varying diameter profile with enlarged end portions and a reduced central portion. This local variation in geometry allows the duct to accommodate tendon routing requirements while distributing contact forces to the enlarged sections, preventing stress concentration at any single location.

Inventive Principle:

Principle #3Local quality

2Reliability

If conventional ducts are used, then material costs are reduced, but bonding with concrete is insufficient

Engineering Contradiction:

Improvebonding with concreteVSAvoidmaterial costs

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The duct incorporates external ribs or corrugations on its outer surface that protrude into the concrete matrix. These localized surface features increase the bonding interface area and mechanical interlocking between the duct and concrete, enhancing anchorage without requiring expensive materials or complex manufacturing processes.

Inventive Principle:

Principle #3Local quality

3Reliability

If metallic materials are used for ducts, then strength is improved, but corrosion resistance deteriorates

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidduct strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent employs a polymeric duct material that combines adequate tensile strength with inherent corrosion resistance. The polymer duct maintains sufficient structural integrity to withstand construction and tensioning forces while being immune to the corrosion that plagues metallic ducts in concrete environments, eliminating the need for protective coatings or cathodic protection.

Inventive Principle:

Principle #40Composite materials

4Adaptability or versatility

If duct diameter is uniform, then manufacturing is simplified, but tendon routing flexibility is reduced

Engineering Contradiction:

Improvetendon routing flexibilityVSAvoidduct manufacturing

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The duct features a varying diameter profile with enlarged end portions and a reduced central portion. This parameter variation in the cross-sectional dimension allows the duct to accommodate tendon routing requirements while distributing contact forces to the enlarged sections, preventing stress concentration at any single location.

Inventive Principle:

Principle #35Parameter changes

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 effectively reduces material costs, prevents tendon damage, and enhances bonding with concrete, allowing for efficient 50% internal and 50% external post-tensioning while preventing corrosion-related deterioration.

Implementation Method 1

made from high-density polyethylene for lightness and corrosion resistance

Methodology Applied

Scientific EffectCorrosion resistance:

Implementation Method 2

A polymeric duct with a unique diameter profile and ribbed exterior for superior bonding

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8640292B1Deviator system for use in post-tension segmental concrete construction

Publication Date: 2014.02.04 SORKIN FELIX L

AI summary

A deviator apparatus for use in segmental concrete construction has a duct and a pipe extending through an interior of the duct. The duct has a first end and a second end and a central portion. The first end has a diameter substantially greater than a diameter of the central portion. The pipe has a diameter substantially less than a diameter of a duct at the first end. The pipe has a length substantially greater than a length of the duct. A plurality of tendons extend through the pipe. The duct increases constantly in diameter from the central portion to the first end. The duct has ribs formed on an exterior surface thereof.