Tension Strand Release Apparatus for Prestressed Wind Towers

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Solution Overview

Problem

The existing methods for relieving tension strands in prestressed concrete towers, particularly in wind power plants, are unsafe and inefficient due to high tension forces and elongations, leading to risks for people and structures during release or severing.

Innovation Solution

An apparatus with two anchoring units and a lifting unit that temporarily receives and anchors tension strand sections, allowing for controlled reduction of spacing between the units to relieve tension strands safely, minimizing risks and increasing safety by reducing the length of tension strands subjected to residual tension during severing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tension strands are severed between anchorings to relieve them, then the tension strands can be removed, but uncontrolled movements and springing back occur due to high tension forces

Engineering Contradiction:

Improvesafety during tension strand releaseVSAvoiduncontrolled movements and springing back

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The tension strand is divided into multiple sections by introducing intermediate anchoring units between the end anchorings. Each section can be relieved and severed independently, preventing uncontrolled springing back of the entire strand. The segmentation allows controlled release of tension in manageable segments rather than dealing with the full tension force at once.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Intermediate anchoring units are installed and tension strands are relieved in a predetermined sequence before complete severing. The method involves preliminary anchoring of intermediate sections, gradual relief of tension, and controlled severing in stages. This preliminary action prevents sudden uncontrolled movements by preparing the system in advance for safe release.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If intermediate anchoring units are introduced to control tension relief, then safety is improved, but device complexity increases

Engineering Contradiction:

Improvecontrol over tension strand reliefVSAvoidnumber of anchoring units and lifting units

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The intermediate anchoring units are designed as multi-functional components that can serve multiple purposes: anchoring tension strands, providing attachment points for lifting units, and enabling sequential relief of different tension strands. This universality reduces the need for specialized equipment for each function, thereby managing complexity while maintaining control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system employs dynamic, movable anchoring units that can be positioned and adjusted along the tension strand as needed. The lifting units provide dynamic control over the spacing and positioning of anchoring units during the relief process. This dynamic capability allows the same equipment to handle various tension strand configurations and relief scenarios without requiring entirely different device setups.

Inventive Principle:

Principle #15Dynamics

3Reliability

If spacing between anchoring units is reduced to minimize residual tension, then safety during severing is improved, but the lifting unit must apply higher forces

Engineering Contradiction:

Improvesafety during severing by minimizing residual tensionVSAvoidforce required by lifting unit

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

By segmenting the tension strand into multiple sections with intermediate anchoring units, the total tension force is distributed across several smaller segments. Each lifting unit only needs to handle the tension of its local segment rather than the entire strand, making the force requirement manageable despite reduced spacing between units.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple lifting units work in combination, with each unit sharing the load of relieving tension in its respective section. The combined action of multiple lifting units distributes the total force requirement across several actuators, reducing the force burden on any single lifting unit while achieving the goal of minimizing residual tension through reduced spacing.

Inventive Principle:

Principle #5Merging (Combining)

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

Enables safe and controlled severing of tension strands, reducing risks and increasing safety by minimizing uncontrolled movements and allowing for the relief of all tension strands in a prestressed concrete tower, thereby reducing costs and enhancing process safety.

Implementation Method 1

a lifting unit which is configured to change a spacing between the first and second anchoring unit

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS20220010577A1Device and method for releasing a stressing strand

Publication Date: 2022.01.13 WOBBEN PROPERTIES GMBH

AI summary

An apparatus and a method for relieving a tension strand, in particular a tension strand of a prestressed tower, preferably a prestressed concrete tower of a wind power plant. Furthermore, the disclosure relates to a method for dismantling a prestressed tower and to the use of an apparatus. The apparatus comprises a first anchoring unit with a first tension strand receptacle for a first section of the tension strand, a second anchoring unit with a second tension strand receptacle for a second section of the tension strand, and a lifting unit which is configured to change a spacing between the first and second anchoring unit.