Methodology for collapse fragility development for hurricane events: Electrical transmission towers

Abstract

This paper introduces a methodology for developing collapse fragility curves for windstorms, with a focus on assessing collapse of electrical transmission towers for hurricane events. Incremental dynamic analysis (IDA) that incorporates the entire hurricane duration is adopted for collapse modeling. Fragility curves are cumulative distribution functions of a structural limit state such as collapse capacity, which is designated in this work as the intensity measure associated with the onset of collapse. A suite of selected hurricane wind records are used with IDA to propagate uncertainties from wind speeds, directions, and durations to collapse capacities. Compared with earthquake engineering methodologies, this work proposes appropriate approaches for scaling of wind records, fitting of IDA curves from simulation data, and parameter estimation of hurricane fragility curves. Fragility curves are appropriate for use both to quantify uncertainty in the context of performance-based wind design and for regional loss assessments. As inelastic deformations are allowed in performance-based wind design, it is useful to develop fragility curves based on nonlinear time history analysis for the entire windstorm duration, which has not been addressed in prior work.