Analysis and design procedures for the flexural behavior of glass fiber-reinforced polymer composite poles

Abstract

Earlier research progress on using fiber-reinforced polymer (FRP) composite poles for transmission lines revealed that the use of these poles is economically viable and industrially reliable. While this promising alternative technique is coming to be widely accepted in practice and evolving to become the future of the construction in transmission lines, the development of appropriate design guidelines that deal with detailed analysis of such poles has lagged behind. Design approaches for conventional steel/wood poles were influential in providing safety and robustness to these poles. However, little advanced approaches focused on the design of fiber-reinforced polymer poles. This is the focus of the present paper. The available design procedures of fiber-reinforced polymer poles are based on the allowable stress design theory of composite material under various states of stress. However, various experimental results show that cracking and early failure of fiber-reinforced polymer poles are normally controlled by the relative location of the opening from the base of the pole. Most of the design guidelines ignore such effect and accounts only for the effect of these holes by considering their influence on the abrupt reduction in the cross-sectional area of the poles. These guidelines do not give a specific attention to the impact of the opening on the generated stress concentrations in their vicinity. Furthermore, local buckling at a nearby area of the opening generally dominates the mode of failure of such poles that requires more attention to the relative locations of the openings. A new design approach is introduced to accurately evaluate the design equations for the flexural behavior of fiber-reinforced polymer -composite poles. The accuracy of both the developed design procedures and that of existing design approaches are verified by comparison with documented test results of an early experimental program of the authors.