Abstract Current design practices for transmission tower structures are based on 3D linear elastic truss analyses and on full-scale testing experience. This paper reviews current practices and presents a nonlinear analytical technique for accurate simulation and prediction of the ultimate strength and behaviour of transmission towers under static load conditions. Both geometric and material nonlinearities are accounted for in the analysis. A formex formulation is used for the automatic generation of data that is necessary for the analysis. The behaviour of four different full-scale towers is described and the predicted results are compared with tests.