SMA-BASED ACTIVE REINFORCEMENTS FOR BUILDING (BIM-31)
Reinforcement of compressed elements (confinement) in masonry or reinforced concrete allows to increase compressive strength and ductility. Reinforcements made of FRP (Fiber Reinforced Polymers) used in civil sector behave as passive systems intervening only for deformations subsequent to reinforcement installation.
Using know-how acquired on Shape Memory Alloys (SMA) CETMA has conceived a system that allows to put in tension the reinforcement during matrix polymerization, giving a beneficial radial compression layer to the reinforced element. It generates an increase of strength, ductility and, in case of masonry elements, also rigidity.
To achieve this result is exploited one of the properties of shape memory alloys, a metal alloy consisting mainly of nickel and titanium in equal parts, capable of "remembering its shape" even after the application of a plastic deformation to the overcoming of a characteristic temperature. If deformation recovery is prevented, a considerable force is generated within the alloy; such force, applied to the ends of a reinforcing fabric impregnated with resin, allows to put in traction such tissue until the complete matrix cross-linking.
Critical aspects of the system consist in selection of suitable materials (resin, alloy and type of reinforcement), implementation and curing of such system.< br />CETMA has know-how to identify the most effective solutions. This type of reinforcement can be given in particular situations, also of danger, because it can restore stiffness and strength of compressed elements cracked or damaged by seismic events.
CETMA is able to design and apply active structural reinforcements based on FRP and Shape Memory Alloys (SMA) for compressed masonry elements and reinforced concrete.