Structural reinforcement

By "structural consolidation" we mean the set of techniques, practices and operations aimed at reinforcing a structure, whether it is damaged or simply in need of restoration. What are consolidation interventions? The structural consolidation intervention consists in securing a building that has suffered evident damage to the load-bearing structure. It is not an operation necessarily foreseen only in emergencies, such as following seismic damage or earthquakes. The structural consolidation of buildings for civil use is increasingly required, especially in seismic risk areas. The consolidation intervention consists in carrying out one or more works involving the individual structural elements of the building to obtain a greater degree of safety, without substantially modifying its overall behaviour. Structural consolidation also finds great application in the restoration of historic buildings, in these cases the intervention is particularly delicate and requires specific specific skills. Consolidation can be carried out through: – the use of FRCM reinforcement systems, i.e. fiber-reinforced composite materials with an inorganic matrix, called FRCM (Fabric Reinforced Cementitious Matrix). The use of FRCMs in Italy is regulated by the Superior Council of LL.PP. – the use of FRP reinforcement systems Fiber Reinforced Polymers (or FRP or polymeric matrix fiber-reinforced materials or simply fiber-reinforced materials) constitute a wide range of composite materials, consisting of a polymeric matrix of an organic nature with which a reinforcement is impregnated in continuous fiber with high mechanical properties. They differ from inorganic matrix fiber-reinforced composites (FRCM), in which the inorganic matrix, based on cement or lime, is reinforced with networks made with continuous fibers. FRPs can be of two types:
– Preformed systems, mainly consisting of elements in the form of thin plates (sheets or strips) prepared in the factory by pultrusion, or other production processes with proven technological validity, and subsequently glued on site to the member to be reinforced with adhesives supplied by the same Producer;
– Systems impregnated in situ (for example wet lay-up systems), consisting of sheets or fabrics of single or multi-directional fibers, impregnated directly on site with polymeric resin, which can also act as an adhesive to the substrate affected by the reinforcement intervention . The fibers used for the production of FRP must have high mechanical strength or high elastic modulus, depending on the problem to be addressed. The most common are: carbon, glass and aramid; less used are boron and ceramic fibers. The Italian technical standards provide for the use of these systems in accordance with what is indicated in point 11 part c) of the same standards, i.e. that these systems must be in possession of a specific certification obtained by pursuing one of these two paths: the Certificate of Technical Assessment (CVT) issued by the Superior Council of Public Works, or obtaining a CE marking pursued following the release of an ETA (European Technical Assessment) requested by the manufacturer for a given system. The use of FRP in Italy is regulated by the Superior Council of LL.PP.

– the use of reinforcement systems in composite materials (CRM) Composite Reinforced Mortar: When we speak of CRM we mean the Composite Reinforced Mortar technique (Reinforced Mortar with Composite material), a technique attributable to that of the traditional reinforced plaster on existing masonry, which involves the use of a reinforcing frame made up of meshes and preformed angles in glass fibers (GFRP) or carbon (CFRP) embedded in a lime or cement-based structural mortar. The technique provides that meshes and corner pieces must be connected through preformed or even semi-impregnated composite connectors and joined to the masonry elements through chemical anchors. The Italian technical standards provide for the use of these systems in accordance with what is indicated in point 11 part c) of the same standards, i.e. that these systems must be in possession of a specific certification obtained by pursuing one of these two paths: the Certificate of Technical Assessment (CVT) issued by the Superior Council of Public Works, or obtaining a CE marking pursued following the release of an ETA (European Technical Assessment) requested by the manufacturer for a given system. The use of CRMs in Italy is regulated by the Superior Council of LL.PP.
– the use of reinforcement systems in composite materials (FRC) Fiber Reinforced Concrete: FRC (fiber reinforced concrete) systems are fiber-reinforced composites with a cement matrix and reinforcing fibers (organic or metallic fibers) which give ductility to the concrete, giving a plastic behavior (hardening or degrading). They are known as high ductility concretes because the FRC system is able to resist tensile strength after cracking in the concrete. They are used for the reinforcement of structural elements in reinforced concrete (jacket of beams and pillars) and for the extradossal reinforcement of floors, being able to create even non-reinforced floors with FRC. The Italian technical standards provide for the use of these systems in accordance with what is indicated in point 11 part c) of the same standards, i.e. that these systems must be in possession of a specific certification obtained by pursuing one of these two paths: the Certificate of Technical Assessment (CVT) issued by the Superior Council of Public Works, or obtaining a CE marking pursued following the release of an ETA (European Technical Assessment) requested by the manufacturer for a given system.
– the use of reinforcement systems with the CAM® System (Active Stitching of Manufactured Products): The main element of the CAM® System is the high-performance metal strip which, closed on itself through the joining elements, creates hoops in tension which, suitably arranged on the structures, induce an active three-dimensional confinement which tends to bring the tensional state of the material back to a hydrostatic type configuration. On masonry structures these hoops are always connected to each other through specific elements of the CAM® System (the drawn plates), therefore, in addition to the confinement action, they create particularly effective connections between the structural elements of the building thanks to the high mechanical performance of the tape and the diffuse effect of the CAM® mesh.

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