Description
Strengthening an existing structure by introducing active prestressing: this is the key advantage of shape memory steel.
TES TECHNIFOR uses this innovative technology to strengthen reinforced concrete structures, particularly as part of rehabilitation, alteration and strengthening projects on existing structures.
Activated directly on the structure, shape memory steel generates a prestressing force without the need for conventional tensioning systems using hydraulic jacks. This solution is particularly well suited to projects where restricted access, limited space or the need to preserve the existing structure make conventional techniques difficult to implement.
From engineering to installation, TES TECHNIFOR manages the entire process: structural assessment, design, surface preparation, installation, activation and inspection.
How does shape memory steel work?
The principle is based on the specific properties of an iron-based shape memory alloy.
The steel is pre-strained during manufacturing. Once installed and anchored to the structure to be strengthened, it is activated by heating.
The material then tends to recover its original shape. As its contraction is restrained by its connection to the structure, this reaction generates a prestressing force.
The existing structure therefore benefits from active strengthening: unlike passive strengthening, which is mainly mobilised when the structure undergoes further deformation, shape memory steel introduces a prestressing force as soon as it is activated.
This technology can therefore improve both the load-bearing capacity of the structure and its serviceability performance, particularly by controlling deformation and cracking.
Main Stages of Implementation
1. Structural Assessment
The process begins with an assessment of the existing structure, including its geometry, reinforcement layout, material properties and the identification of any structural deficiencies.
2. Strengthening Design
The strengthening solution is designed according to the structural behaviour, the loads and forces to be carried, and the required performance.
This engineering phase determines the quantity, arrangement and characteristics of the strengthening elements.
3. Preparation and Installation of the Strengthening System
The substrates are prepared and the shape memory steel elements are positioned and securely connected to the structure in accordance with the selected system.
4. Thermal Activation
The steel is heated in a controlled manner. The shape memory effect of the material then generates the required prestressing force within the structure.
5. Protection and Finishing
Depending on the configuration of the structure and the selected solution, the strengthening system can then be protected and integrated into the structure, particularly using suitable mortars or sprayed concrete.
When Should Shape Memory Steel Be Used?
This technology is particularly suitable for the rehabilitation, alteration and strengthening of existing structures.
It can address a range of structural requirements, including increased loads, changes in structural behaviour, structural deficiencies, repairs following damage, or the need for improved control of deformation and cracking.
Flexural Strengthening
The system can be used to increase the load-bearing capacity of structural elements such as:
- reinforced concrete slabs;
- beams;
- floors;
- bridge decks and other civil engineering structures.
The introduction of prestressing can also improve the serviceability performance of the strengthened element, particularly by limiting deformation and crack opening.
Shear Strengthening
Shape memory steel elements can also be used to provide additional shear strengthening to an existing structure.
This solution may be particularly useful where a beam or another structural element is required to withstand loads greater than those originally considered in its design.
Punching Shear Strengthening
In certain configurations, shape memory steel can be used to provide additional strengthening to a slab around its supports and increase its punching shear resistance.
This requirement may arise, for example, following an increase in loading or a change in the use of a building.
Repair Following Damage or Accidental Cutting of Reinforcement
Core drilling, the creation of openings or alteration works carried out on an existing structure may result in the accidental cutting of reinforcement bars or prestressing elements.
Following structural assessment and engineering analysis, shape memory steel may provide a solution for restoring or supplementing the structural capacity of the damaged element.
Why Choose Shape Memory Steel Strengthening?
Prestressing without hydraulic jacks! Tensioning is achieved through the thermal activation of the material. The system therefore makes it possible to introduce a prestressing force into the structure without conventional mechanical tensioning using hydraulic jacks.
This is particularly advantageous in existing buildings, where restricted access and limited working space can make conventional prestressing techniques difficult to implement.
Active Structural Strengthening
Once activated, shape memory steel applies a force to the structure.
This prestressing force can help to:
- increase the load-bearing capacity of the structure;
- relieve existing reinforcement;
- reduce cracking;
- limit deformation;
- improve the serviceability performance of the structure.
A Solution Suited to Rehabilitation Projects
Work on existing structures often involves significant constraints: limited working space, difficult access, maintaining building operations, preserving the existing structure or dealing with complex geometries.
Shape memory steel therefore provides a particularly attractive solution for introducing prestressing directly into the structure to be strengthened.
A Ductile Steel Strengthening Solution
Shape memory steel combines the properties required for prestressing with the ductility of steel reinforcement.
It therefore provides a complementary solution to the other structural strengthening techniques implemented by TES TECHNIFOR.
Shape Memory Steel, Carbon Fibre or Steel Strengthening?
There is no single strengthening solution suitable for every structure. The choice of system depends in particular on the type and condition of the structure, the forces to be carried, the required performance and the constraints associated with the works.
TES TECHNIFOR has expertise in a range of strengthening solutions:
- shape memory steel;
- carbon-fibre plates and fabrics;
- prestressed carbon-fibre strengthening;
- steel section strengthening;
- sprayed concrete and mortars.
These techniques can be used independently or combined as part of a comprehensive strengthening solution.
The objective is therefore not to impose a particular system, but to determine the solution best suited to the actual behaviour of the existing structure.
Comprehensive Expertise in Structural Strengthening
Strengthening an existing structure begins with understanding how it behaves. TES TECHNIFOR combines the expertise of its engineering department and site teams to support structural assessment, alteration and strengthening projects.
Depending on the project requirements, our services may include:
assessment of the existing structure → reinforcement detection → investigations and core drilling → engineering and structural design → substrate preparation → installation of the strengthening system → protection and inspection.
The complementary nature of our specialist activities also enables structural strengthening to be combined with concrete sawing, core drilling, creation of structural openings, sprayed concrete and other specialist works required for the alteration of existing structures.
Shape Memory Steel Strengthening in Grand Est and Paris
Based in Gondreville, near Nancy, TES TECHNIFOR provides engineering and structural strengthening services throughout Grand Est and the Paris region, including Nancy, Metz, Reims, Strasbourg and Paris.
Our teams work on existing buildings, industrial facilities, car parks, civil engineering structures and other structures requiring increased load-bearing capacity, structural alterations or strengthening.
Our expertise in a range of structural strengthening techniques enables us to assess each project according to the specific characteristics of the structure and the technical and operational constraints involved.
Do You Have a Structural Strengthening Project?
Increased loading • strengthening of a slab or beam • building alteration • insufficient reinforcement • damaged reinforcement • cracking • deformation • strengthening of an existing structure
Contact TES TECHNIFOR to discuss your project and determine the most appropriate strengthening solution for your structure.
