Rehabilitation of Wooden Utility Poles with Sprayed-GFRP Composites

Abstract

Different rehabilitation techniques have been utilized to extend the service life of wooden utility poles, which are mainly affected by degradation and decay. This paper presents an evaluation of the performance of wooden utility poles rehabilitated using sprayed glass fiber–reinforced polymer (GFRP) composites and near-surface-mounted (NSM)-GFRP bars. Seven full-size (305-mm diameter) new wooden poles and five full-size old wooden poles, taken out of service, were tested under monotonically increasing lateral load. The test parameters included the thickness (4, 6, and 8 mm) and length (1.0 and 2.0 m) of the sprayed-GFRP coating, and rehabilitation methods (sprayed-GFRP composites, NSM-GFRP bars). The results showed that the sprayed-GFRP coating can restore the load-carrying capacity and enhance the stiffness of both old and damaged poles. In addition, the load-carrying capacity of the wooden poles was not affected by the increase in GFRP thickness after the thickness reached 6 mm. It was also concluded that using the NSM-GFRP bars is not cost-effective compared to the sprayed-GFRP composites. A simple analytical procedure was introduced to estimate the load-carrying capacity of retrofitted poles and to calculate the required thickness of the sprayed-FRP layer, which yielded reasonably conservative results.