A numerical investigation into the response of free end tubular composite poles subjected to axial and lateral loads

This paper presents a numerical investigation of cantilevered glass fiber-reinforced polymer (GFRP) tubular poles subjected to lateral and axial loads. A 3D finite element analysis was conducted to establish the lateral load–deflection responses under different axial loads and the axial load–bending moment interaction curves at ultimate. The model accounts for geometric nonlinearities and the composite laminate structure. Failure modes were established based on either material failure according to the Tsai-Wu failure criterion, or stability failure. The model was validated by using experimental results. A parametric study was then carried out on poles with various angle-ply and cross-ply laminates as well as different diameter-to-thickness (D/t) and length-to-diameter (L/D) ratios. The study showed that the reduction in axial strength as (L/D) ratio increases becomes more severe as (D/t) ratio is reduced. The GFRP laminate structure has a considerable effect on axial and flexural strengths of the poles for certain (D/t) ratios. It was also shown that axial load–moment interaction curves are generally linear. Increasing the fraction of longitudinal fibers in cross-ply laminates or reducing the fiber angle with the longitudinal direction in angle-ply laminates results in a larger interaction curve. A simplified design approach for the poles has been proposed.