Behaviour of cold formed lipped angles in transmission line towers

The importance and use of equivalent radius of gyration method is discussed and necessary expressions are derived in this paper. The limiting values of slenderness ratio for the equivalent radius of gyration with the least radius of gyration are discussed to establish the buckling behaviour of lipped angles. Finite Element Analysis on the buckling behaviour of the mathematical models of individual lipped angle members and a full scale X-panel was carried out to compare the values predicted by equivalent radius of gyration. A series of compression tests were carried out on lipped angle sections and their behaviour is studied in the elastic and in the inelastic ranges of loading. These tests were broadly classified under two categories; concentrically loaded members and eccentrically loaded members. Experimental investigations on full scale tower panels with conventional patterns of leg and diagonals were also carried out. The results of the experiments were compared with analytical predictions using torsional flexural buckling equations, Finite Element Analysis and the equivalent radius of gyration approach.