Reliability of Tower and Tower-Line Systems under Spatiotemporally Varying Wind or Earthquake Loads

Towers or tower-line systems within a power network can experience damages under rare earthquakes or strong winds. The estimation of the failure probability of a tower-line system is rarely addressed for scenario wind or earthquake events. One of the difficulties to evaluate the reliability of a tower or tower-line system is associated with the computationally demanding task of assessing the nonlinear inelastic dynamic responses or capacity curves of the towers under spatiotemporally varying wind or earthquake loads. An assessment of the capacity curve of a tower within the tower-line system (i.e., considering tower-wire interaction) under the spatiotemporally varying wind or earthquake loads is presented based on the incremental dynamic analysis. The estimated capacity curves are compared with those obtained using the nonlinear static pushover analysis for a single tower. The comparison indicates that the use of the nonlinear static pushover analysis could lead to useful results, although in such a case the uncertainty in the capacity curve caused by the record-to-record variability of the spatiotemporally varying loads cannot be captured. Moreover, a simple procedure to evaluate the reliability of a tower-line system for scenario wind or earthquake events is proposed by considering the spatial correlation of winds or ground motion measures. The results emphasize that the consideration of the spatial correlation of natural hazards could be important to estimate the failure probability of a tower-line system.