Investigation on the behaviour of electric power transmission line supports with a special reference to 8-meter long pre-stressed concrete pole

摘要

For pre-stressed concrete power transmission line pole, load test is nothing but the load-deflection test. It is a must quality control check in order to ensure the strength of structural elements. In this paper, the strength of pre-stressed concrete poles used as transmission line supports for low tension supply lines has been investigated by conducting the load-deflection test. The test has been carried out on 8-meter long pre-stressed concrete poles made of M42 grade, which were selected in random from the lots. Further, the load-deflection study has been conducted on pole with glass fiber mat wrapping using isophthalic resin (GFRP) for a height of 0.23 m on either side of the ground line. The ground line for the above poles is at a height of 1.5 m from the butt end of the pole. In this study, it is found that the pole with GFRP wrapping improves marginally compared to the conventional pole in terms of strength and durability. The aim of this investigation was to improve the failure pattern of the pole. The sudden failure of the pole is avoided to some extent and the failure location moves away from the bottom of the pole. Further, an analytical model for the pole has been developed to predict the pole deformation at tip and found that it almost matches with the actual load test results when the value of moment of inertia of the pole is taken at a section where the centroid lies for the portion of the pole between load point and the fixed end.