Development of a novel pole using spun-cast concrete inside glass-fiber-reinforced polymer tubes

This paper introduces a novel pole consisting of spun-cast concrete inside glass-fiber-reinforced polymer (GFRP) tubes (SCFTs). The GFRP tube is intended to replace all or part of the steel reinforcement. It confines and protects the thin concrete wall and any steel reinforcement used. This novel concept emerged after studying two types of poles, namely a hollow GFRP tube that failed prematurely by local buckling and a completely filled GFRP tube (CFFT) that was higher in strength but much heavier than the hollow tube. The feasibility of fabrication in a conventional spin-casting facility is demonstrated. Push-off tests on segments cut from an SCFT pole were tested to examine the bond strength. Flexural testing showed that the strength of a 13-in.-diameter (330 mm) SCFT pole with a 0.15-in.-thick (5.3 mm) GFRP tube and a 2.4 in. (60 mm) concrete wall is equivalent to that of a conventional pole of the same size, reinforced with twelve no. 6 (19M) reinforcing bars or prestressed with twelve 1/2-in.-diameter (13 mm) 7-wire strands. SCFT poles also behave fairly elastically. Practical considerations that need to be addressed to encourage wide acceptance of this concept are identified.