Behaviour and design of FRP composite members subjected to axial compression or bending

Fibre reinforced polymers (FRP) represents a new class of construction materials. In the past two decades, their use has been spread from aerospace industry to civil infrastructure, which represents a new set of challenges. Applications of FRP are mainly concentrated in rehabilitation of structures, where corrosion is an important consideration. However, FRP structural members are a competitive construction material due to their high strength-to-weight ratio, corrosion resistance and, for certain applications, magnetic and electric properties. The present study aims at investigating the structural behaviour of FRP composite members. Fifteen specimens made of E-glass and either polyester or vinyl ester matrix are tested: (i) hollow square-section and rectangular-section members, as well as angle-section members are subjected to axial compression; (ii) l-section and W-section members are tested under bending. For the hollow square-section and rectangular-section members, the failure mode is the local buckling, while the angle-section members fail in a combination of local and global buckling. For the members under bending, local buckling of the loaded flange is the dominant failure for the W-section member, while the l-section members show lateral torsional buckling. Prediction models available in FRP design manuals, theory of plates and analytical methods are used to predict the critical buckling load of the members and compared to experimental results. Design equations taking into consideration the rotational stiffness of the plate connections are shown to be reasonably accurate.