土-结构相互作用下输电塔-线耦合系统整体可靠度分析

To investigate the influence of soil-structure interaction and tower-line coupling effect on global reliability of transmission towers, a simplified mechanical model of a transmission tower–line coupling system considering soil-structure interaction under stochastic wind excitation was established. A multi-mass mechanical model was adopted to simulate the transmission tower, insulator, conductor, and foundation. The effect of the subsoil on the dynamic response of the coupling system was modeled using the swing-rocking (S-R) model, and the stochastic wind field was generated using the spectrum representation–dimension reduction method. The simplified mechanical model and the probability density evolution method (PDEM) were employed to develop a global reliability analysis method for transmission tower–line coupling systems considering soil-structure interaction. Finally, a suspension-type tower from an ultra-high voltage alternating current transmission line was used as an example. The probability density function (PDF), mean, and standard deviation of the tower-top displacement were calculated, and the global reliability was evaluated with the tower-top displacement extremum as the control variable. The results show that after considering tower-line coupling effect, the cumulative distribution function (CDF) of tower-top displacement extremum shifts noticeably to the right, and the failure probability increases from 1.605 × 10⁻³⁸ to 0.932. After soil-structure interaction is taken into account, the CDF of tower-top displacement extremum shows a slight rightward shift, and the failure probability increases. Compared with the fixed-base condition, the increase ratios of failure probability under medium-hard soil, medium-soft soil, and weak soil conditions are 4.44%, 5.22%, and 11.76%, respectively. Compared with the Monte Carlo method, the proposed method efficiently obtains the probabilistic information of the tower-top displacement. The computational time is only 1/33 of that of the Monte Carlo method, while the two-norm relative errors of the mean and standard deviation are within 3%.