SMA Wire Plate for Localized Concrete Prestressing
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Solution Overview
Problem
Existing concrete prestressing techniques face challenges in applying local prestressing, especially in small regions like the end of a girder or plastic hinge region, due to practical constraints on reinforcement position and orientation.
Innovation Solution
A method utilizing a plate with a shape memory alloy (SMA) wire embedded in a localized region of a structure, where the SMA wire is deformed and self-anchored, generating compressive force upon heating, allowing for localized prestressing without the need for mechanical anchorage systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional mechanical anchorage and jacking methods are used for prestressing, then prestressing can be applied to concrete structures, but the position and orientation of reinforcement are constrained especially in small regions
Solution Approach 1:
The patent extracts the anchorage function from the reinforcement itself by embedding the prestressing reinforcement directly into the concrete structure without external anchorage devices. The reinforcement is embedded at an angle and relies on bond strength and concrete compression to develop prestress, eliminating the need for separate anchorage systems and making the method adaptable to localized regions with complex geometries.
Solution Approach 2:
The patent replaces the traditional mechanical anchorage and jacking system with a bond-based system. Instead of using mechanical devices to transfer and maintain prestress forces, the reinforcement develops prestress through bond with the concrete and compression in the concrete, substituting a simpler chemical/physical bond mechanism for complex mechanical systems.
2Ease of operation
If prestressing reinforcement is anchored and jack mechanically, then prestress can be applied, but practical constraints are imposed on position and orientation especially in small regions
Solution Approach 1:
The patent removes the anchorage and jacking equipment from the prestressing process, embedding the reinforcement directly into the concrete. This extraction of mechanical devices simplifies the operation in localized regions, as the reinforcement can be placed and embedded without requiring space for anchorage devices or jacking equipment.
Solution Approach 2:
The reinforcement serves its own anchorage function by being embedded in the concrete and developing bond strength with the surrounding material. The system is self-anchoring through the bond between the reinforcement surface and concrete, eliminating the need for separate anchorage services or devices.
3Strength
If local prestressing is applied in small regions using traditional methods, then prestress can be achieved, but it becomes problematic and in some cases unfeasible
Solution Approach 1:
The patent applies prestressing reinforcement locally at specific regions of the structure where flexural and shear capacity is needed. The reinforcement is embedded at strategic locations and angles to provide targeted strengthening without requiring full-structure prestressing, making local application feasible and effective.
Solution Approach 2:
The patent segments the prestressing application into discrete localized regions rather than applying it uniformly across the entire structure. This segmentation allows prestress to be applied independently to specific areas needing strengthening, making the process more feasible and manageable for local repairs and modifications.
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 method effectively transfers compressive prestress to the structure, enhancing its flexural and shear capacity, with achievable prestress values ranging from 2 MPa to 25 MPa, facilitating structural strengthening and repair.
Implementation Method 1
heating the SMA wire to a temperature above an austenite finish temperature of the SMA wire, thereby generating a compressive prestress force in the SMA wire
Data Source
AI summary
A method to strengthen or repair concrete and other structures comprises securing a plate having a shape memory alloy (SMA) wire embedded therein to a localized region of a structure. The SMA wire has a deformed shape configured for self-anchorage within the plate. The SMA wire is heated at or above an austenite transformation temperature, and the SMA wire resists shape recovery and remains self-anchored within the plate. Accordingly, a compressive force is generated within the SMA wire and transferred to the plate. At an interface between the plate and the localized region of the structure, the compressive force is transmitted from the plate to the structure, thereby providing localized prestressing of the structure.