Effect of cross-sectional geometry on the cyclic bending behaviour of hollow box pulwound FRP Profiles

The use of pultruded fibre-reinforced polymer (FRP) profiles as structural elements in building and construction has been facilitated by the development of pulwinding technology. Nevertheless, a lack of understanding and associated design guidelines for profiles subjected to cyclic loads are limiting their application to structures subject to repetitive loading and seismic events. This paper reports a numerical investigation using finite element (FE) modelling on the cyclic bending behaviour of box pulwound FRP (PFRP) profiles. The FE model, which is validated with experimental data, investigates the influence of key cross-sectional geometric parameters, namely the flange thickness (tf), web thickness (tw), corner radii ratio (r/R), and cross sectional aspect ratio (h/b). It also concludes three optimised design configurations for applications of serviceability, strength, and energy absorption. The effect of these design parameters on the failure mode, moment capacity, secant stiffness, and energy absorption capacity was quantified and the related interactions were determined by a full-factorial experimental matrix. The tf, r/R, and h/b controlled the design of the profile for energy absorption, bending moment, and secant stiffness by 42.2%, 47.6%, and 49.3%, respectively. Considering the related interactions in the design will maximise the bending strength, secant stiffness, and energy absorption capacity up to 1.66, 1.42, and 1.50 with an increase in the material cost of only up to 10.2%, 7.9%, and 16.8%, respectively, compared to the control profile.