Italian design guidelines for the structural strengthening with FRP materials (ICEM13)

The strengthening or retrofitting of existing civil constructions to resist higher design loads, correct deterioration-related damage, or increase ductility has traditionally been accomplished by using conventional materials and construction techniques. Externally bonded steel plates, steel or concrete jackets, and external post-tensioning are just some of the many traditional techniques available. Nevertheless, the use of steel plates gives rise to many shortcomings, such as high installation costs and weight, visual intrusion and the possibility of corrosion which could adversely affect the bond strength. Nowadays, all of the above drawbacks can be easily overcome by applying advanced composite materials made of fibres in a polymeric resin (FRP). FRP materials are lightweight, non-corrosive, and exhibit high tensile strength. Additionally, these materials are readily available in several forms ranging from factory made laminates to dry fibre sheets that can be wrapped to conform to the geometry of a structure prior to adding the polymeric resin. The relatively thin profile is often desirable in applications where aesthetics or access are a concern. The growing interest in FRP systems for strengthening and retrofit can be attributed to many factors. Although the fibres and resins used in FRP systems are relatively expensive compared to traditional strengthening materials, like concrete and steel, labour and equipment costs to install FRP systems are often lower. Moreover, composite materials may have lower life cycle costs than conventional strengthening techniques because the FRP system is less prone to corrosion.