Flexural Behavior of Composite FRP-Concrete-Steel Poles

A new composite pole is being developed. The pole consists of an outer fiber reinforced polymer (FRP) shell, inside steel tube, and concrete filled between the two tubes (The composite FRP-concrete-steel pole is hereafter referred to as CFCSP). The FRP tube used in this research is produced using a centrifugal casting technique with glass-fibers oriented in the longitudinal and hoop direction. The longitudinal fibers provide flexural resistance to the section, whereas the hoop fibers confine the concrete and give shear resistance to the pole. The steel tube acts as longitudinal reinforcement, and the concrete is confined by the two tubes. Steel and concrete are two materials that have been considered economical in construction for several decades. Steel provides a ductile behavior in tension, whereas concrete is brittle with high compressive strength but low tensile strength. The greatest advantage of the composite poles is their excellent corrosion resistance because the FRP is highly resistant to corrosion while the inside steel tube is protected by the FRP tube and the concrete core. The ends of the steel tube can be sealed with welded steel plates to protect the hollow steel core. Another advantage of the composite FRP-concrete-steel pole is the light weight because the inner void reduces the redundant weight, and the hollow core provides space for cabling and electricity. Therefore, it would be promising to combine these materials in an optimal manner to produce the most economical and beneficial composite pole.

This research work presents the investigation on the flexural behavior of composite FRP-concrete-steel poles (CFCSPs). The flexural behavior of these poles was evaluated in terms of load-deflection curves, ultimate moment capacities, and load-strain response. The previously mentioned terms were evaluated at 1^st service load (25% of predicted ultimate load), 2^nd service load (50% of predicted ultimate load), and ultimate load. An analytical model was developed to accurately predict the behavior of composite FRP-concrete-steel poles. Prototype specimens were manufactured and tested to better understand the flexural behavior of the composite poles and verify the analytical model.