Computational framework for mimicking prototype failure testing of transmission line towers

• Method to estimate deflection contributions from bolt slip in transmission towers.
• Concept of rotation planes proposed.
• Bolt slip deflections integrated with results of nonlinear analysis.
• Comparison of results with real world transmission towers tested in test beds.

Traditional analysis of transmission line tower structures gives good estimate of ultimate strength but deflection estimates are much less than actual deflections measured from tests. This is caused by additional deflections due to joint properties like bolt slip in splices and splice plate deformations. These two displacement contributing factors are difficult to include in analysis. Prototype tower testing in test beds, which provides design strength evaluation and actual deflections is expensive. This paper presents a simple analytical procedure which captures not only the ultimate load and associated deflections but also the additional deflections because of bolt slip in leg splices. The formulation incorporates a corotational updated Lagrangian procedure in finite element analysis framework. The additional deflections are integrated into a nonlinear analysis formulation used for reticulated structures which also considers member buckling and yielding. To demonstrate the applicability of the formulation, towers which were experimentally tested in test beds are studied and the results are compared with strength and deflection measurements. The formulation has been demonstrated to be a reasonable alternative to expensive proto type testing.