Towards nonlinear analysis of transmission tower structures

Abstract

The main purpose of the research presented in this thesis is the development of a compact and practical nonlinear analytical tool for modelling the nonlinear global structural response of large scale steel structures with particular application to transmission towers. Two different nonlinear analytical procedures are presented. The first procedure is suitable for analysing single members or small subassemblies. In this procedure fine discretization of the structural member into several elements and fine discretization of the element cross-section into a finite number of elementary areas is mandatory. The second procedure is suitable for analysing large scale steel structures. In this procedure, the nonlinear response of the structural member is simulated accurately without the need to resort to fine discretization. In addition, an efficient force-space model where the constitutive relationships are described in terms of stress-resultants and generalized nodal displacements is employed. This procedure provides a compact and practical nonlinear analytical tool for predicting the nonlinear global structural response of large scale steel structures. Full-scale transmission tower structures are analysed using the proposed nonlinear analytical procedure. The results obtained from the analyses are compared with reported full-scale test results. The proposed nonlinear analytical procedure is not only capable of predicting accurately the ultimate load of the tower structure but also the failure modes of the tower which closely resemble the failure modes obtained from full-scale tests. A formex formulation for the automatic configuration processing of transmission tower structures is also presented. Finally, the effect of the semi-rigid nature of steel structural joints is investigated.