Modified procedure for assessing the bending strength of composite GFRP poles

Abstract

Fibreglass lighting poles have gained a considerable amount of popularity in the market due to their advantages, and interest in them continues to grow. Consequently, the challenge of ensuring their safe design is becoming increasingly important. However, the current standard design procedure is not sufficient, because it does not consider one of the most common failure modes of composite poles, namely local buckling in the vicinity of the inspection opening. A verification of the standard’s calculated values has been done with the use of experimental testing. The calculated design bending strength was three times higher than the actual bending strength for 3.0 m high poles and twice higher for 9.0 m high poles. This paper proposes an improved method for estimating the bending resistance of composite poles with inspection openings. The method was developed using results from tests on full-scale poles, material sample tests, and experiments in a FEM environment. The proposed method provides more accurate results than the procedure for assessing the bending strength of these poles as presented in the EN 40–3–3 standard. The bending resistance value obtained using the modified calculation method is higher than the experimental value by an average of 6.6 %.