Numerical characterisation of FRP curved reinforcement produced by filament winding

Abstract

Previous studies have demonstrated that an automated filament winding process can conveniently produce shear reinforcement for concrete structures. The method allows the creation of geometrically complex elements suitable for materials optimisation. This is in addition to the advantages of non-metallic reinforcement. On the contrary, the biggest drawback is the anisotropy properties of fibrous materials. Concentrations of stresses and material defects characterise the reinforcement’s curved portions; thus, material efficiency reduction is expected. Generally, the strength of pultruded FRP stirrups is estimated at about 30-40% of the tensile strength in the direction of the fibres. Still, experimental studies have shown that efficiency can be increased due to the manufacturing process and cross-section aspect ratio. This study aims to identify a mechanical model for predicting the bent strength of FRP stirrups fabricated by the filament winding technique. This is here formalised as a non-linear equilibrium problem of a curved Timoshenko beam on an elastic foundation. Numerical results agree with the experimental data available from previous studies, assessing the model’s suitability.