Strengthening of Gulfport 230 kV Wooden Transmission Structures with Glass-Fiber-Reinforced Polymer Wrap

Abstract

This paper presents a statistically designed experimental program to present and analyze an effective and practical strengthening system for deteriorated crossarms of the Gulfport timber structures using glass-fiber-reinforced polymer (GFRP) wrap. In this research, a total of 14 strengthened and six control specimens with a length of approximately 3.1 m were tested to failure. The experimental program was conducted in two phases: feasibility study and parameter optimization designed by using the Taguchi method and analysis of variation (ANOVA). The feasibility study concluded that the proposed strengthening system was sufficient for increasing the strength of the deteriorated crossarms of the Gulfport structures well above the critical end-of-life (EOL) design threshold value of the crossarms. The parametric optimization of the strengthening system identified the critical variables to be the crack-repair material, the width of the wrap, and sanding the surface. Using statistical advantages of the Taguchi method of experimental design, the mean strength of the strengthened specimens was estimated, and a 95% confidence interval for that mean was calculated. This estimated mean was 70% higher than the EOL threshold of the crossarms.