SMA Anchor Rods for Thermal Deformation in Construction

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Solution Overview

Problem

Conventional anchoring systems in construction, particularly in concrete structures, face issues with force transmission and thermal deformation, where the anchoring adhesive becomes rigid and prevents linear prestressing of anchors after hardening, and existing end anchoring systems only transmit force through the end area of the anchor rod, not utilizing the full length effectively.

Innovation Solution

The anchoring system employs shape memory alloy (SMA) steel rods with a heat-resistant polymer compound, where the SMA rods revert to their original shape and prestress the anchor upon heating, ensuring even force distribution along the entire length after the filling compound hardens, allowing for linear prestressing and high adhesive strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional adhesive bonding is used to anchor steel rods, then adhesion strength is improved, but thermal deformation resistance deteriorates and post-curing prestressing becomes impossible

Engineering Contradiction:

Improveadhesion strengthVSAvoidthermal deformation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the adhesive bonding function from the anchoring system, replacing it with a mechanical friction-based anchoring mechanism. The steel rod is anchored through friction contact with the borehole wall rather than chemical adhesion, eliminating the harmful thermal deformation effects while maintaining anchoring strength.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the chemical adhesive bonding system with a mechanical friction-based system. The steel rod is secured through friction contact with the borehole wall, substituting the chemical bonding mechanism with a purely mechanical one that is insensitive to thermal effects.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If end anchoring systems are used, then force transmission is simplified, but the full length of the anchor rod is not utilized effectively

Engineering Contradiction:

Improveanchoring system complexityVSAvoideffective anchor rod length

Core Design Contradiction:

Device complexityVSLength of moving object

Solution Approach 1:

The patent ensures continuous force transmission along the entire length of the steel rod through distributed friction contact with the borehole wall. This allows the full length of the anchor rod to be utilized effectively, unlike end-anchoring systems where only a portion contributes to force transmission.

Inventive Principle:

Principle #20Continuity of useful action

3Stability of the object's composition

If adhesive bonding is used, then anchor stability is improved, but post-curing tensioning capability is lost

Engineering Contradiction:

Improveanchor stabilityVSAvoidpost-curing tensioning

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent creates a dynamic anchoring system where the steel rod can be tensioned after curing by rotating it, which generates friction forces that secure the anchor in place. This allows post-curing tensioning operations while maintaining anchor stability during service.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent prepares the borehole with a specific geometry and surface characteristics that will generate sufficient friction forces during the subsequent tensioning operation. The borehole is designed in advance to facilitate the friction-based anchoring mechanism and post-curing tensioning capability.

Inventive Principle:

Principle #10Preliminary action

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

This solution enables the anchor rods to maintain permanent prestress over their entire length, enhancing the structural integrity and preventing thermal deformation-related stress cracks, while allowing for post-tensioning without shearing forces, thus improving the load-bearing capacity and stability of the structure.

Implementation Method 1

The anchoring system employs shape memory alloy (SMA) steel rods with a heat-resistant polymer compound, where the SMA rods revert to their original shape and prestress the anchor upon heating

Methodology Applied

Scientific EffectShape memory alloy effect: Shape Memory Alloy

Implementation Method 2

heat-resistant polymer compound

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Data Source

PatentEP2885439B1Anchoring system for a support in construction, and method for using same

Publication Date: 2020.01.15 S & P CLEVER REINFORCEMENT

Figure 1~4

AI summary

The anchoring system is suitable for rock and concrete (2) and any solid support. The anchor rod (4), which is made, for example, of a threaded rod made of a shape memory alloy (SMA), is held in the anchor bore (3) by means of a filling compound (5) as the anchoring medium. In order to fill the anchor bore (3) between the anchor rod (4) and the wall of the anchor bore (3), a heat-resistant filling compound (5) is used which consists of a two-component polymer compound or of polymer compound on a cementitious basis. The anchor rod (4) is then heated to its austenite phase by applying heat externally via its stub that protrudes from the filling compound, thus pre-stressing the anchor rod (4). The anchor rod (4) is subsequently cooled to the external temperature after the filling compound has cooled (5). An abutment plate (10) lies on the external wall (1) around the opening of the anchor bore (3), and is clamped with the anchor rod (4).