To date the use of FRP (Fiber Reinforced Polymers) for structural reinforcement and seismic retrofit of the building stock is largely spread both at national and international level.
On the contrary, the importance of fibers used for structural profiles hasn’t been completely realized in the field of design so far, although it appears to be highly promising. There are several possible applications and range in the field of engineering:
∙ building constructions (bridge deck, walkways);
∙ transports (coverage for trains, buses, trams, sideboard trucks, etc.);
∙ chemical industry (corrosive environments);
∙ insulators for high voltage, transformers, etc.;
∙ sports equipment (hockey sticks, arrows, prows, tents).
Therefore, compositematerials represent one of the latest technological innovations in the product industrialization field with confirmation also in the mechanical, electric, electrotechnical field and more. The peculiarity of these products lies in the combination of two components apparently very different from each other, not only from the material, but also from the ‘character’ point of view; however, they are able to simulate the mechanical response to the external stresses. Therefore, they are characterized by lightness, strength, elasticity and durability and in this regard the current major applications are represented by pedestrian bridges and driveways, removable or permanent light structures, but also by structural elements of small dimensions.
By virtue of this winning combination ( fiber and resin ), the material brings significant quality of transmittance which give it the power to act as a thermal break.
In particular, in this section we’ll speak about a Pultruded Profile, a composite generated by the same production, defined pultrusion process, process that combines resins and fibers of different types. There are different typesof Pultruded Profiles, differentiated from the resin or fiber used: the production process is able to process thermosetting moulds (epoxy resin, polyester, vinyl ester, acrylic, etc.) or thermoplastic moulds in combination with fibers of different types, such as glass fibers, carbon or Kevlar (aramid fiber). However, the most currently used combination is the one with isopolyester and glass fiber (GFRP)..
The regulations that currently govern and direct the designers’ activities in the field of structural engineering with fiberglass reinforced pultruded profiles are, as follows:
∙ UNI EN 13706, ‘Reinforced plastics composites – Specifications for pultruded profiles – Testing methods and general requirements’;
∙ CNR-DT 205/2007, ‘Designing, Execution and Control Instructions’.
Next week we’ll discuss on Production techniques within the context of FRP composites.