We investigate on the strength and ductility properties of recycled PET fiber-reinforced concretes (RPETFRCs) showing different mix-designs and PET filaments with variable mechanical and geometric properties. Available literature results of compression tests and four-point bending tests on such materials are reviewed comparing laboratory results in terms of compressive strength, first crack strength and ductility indices. The examined tests highlight that most relevant effects of the recycled PET fiber reinforcement are concerned with material toughness and ductility. In the case of low-strength concretes, significant compression and flexural strength enhancements due to the addition of recycled PET fibers are also observed.
We analyze the effects of multiaxial prestress on the limit behavior of I-shaped reinforced concrete elements subjected to combined axial load and bending. We provide a collection of design charts and moment – curvature diagrams for reinforced concrete I-beams with laterally and longitudinally prestressed flanges. The given results highlight the special ability of the active prestress technique in enhancing the strength and ductility properties of seismic resistant columns and shear walls.