考虑SSI效应的输电塔-线耦合系统抗震可靠度分析

Seismic Reliability Analysis of Transmission Tower-line Coupling System Considering SSI Effect

为研究输电塔在土结相互作用(Soil Structure Interactions,SSI)和塔-线耦合作用影响下的抗震可靠度,提出了考虑SSI效应的输电塔-线耦合系统抗震可靠度分析方法.建立考虑SSI效应的输电塔-线耦合系统简化力学模型,推导其在随机地震作用下的运动方程.基于随机函数-谱表示方法模拟随机地震动加速度时程,对耦合系统进行随机地震动力响应分析.以基于GF-偏差点集的样本分数矩最大熵法估计随机地震响应极值分布,并求解耦合系统抗震可靠度.选取工程中某特高压输电塔-线体系作为研究对象,对本文方法的有效性进行验证.结果表明,当塔底地基土为软弱土时,考虑SSI效应后,塔顶位移响应极值增大约46.59%,加速度响应极值增大约17.43%,结构失效概率增加约70.32%.考虑塔-线耦合作用后,塔顶位移响应极值减小约0.51%,加速度响应极值增大约1.74%,结构失效概率减小约15.71%.对于考虑SSI效应的输电塔-线耦合系统,塔底地基土越软,塔顶位移与加速度响应极值越大.与蒙特卡洛法相比,本文方法求解的结构失效概率最大误差仅为9.97%,具有较高的精度和计算效率.

To investigate the seismic reliability of transmission towers under the influence of Soil Structure Interactions(SSI)and tower-line coupling effect,a seismic reliability analysis method of transmission tower-line coupling system considering the SSI effect was proposed.Firstly,a simplified mechanical model of the transmission tower-line coupling system considering the SSI effect was developed,and the dynamic equation under stochastic seismic excitation was derived.Secondly,the random function-spectrum representation model was used to generate random seismic acceleration time-history samples,and the seismic dynamic response of the coupling system was analyzed.Thirdly,the maximum entropy and fractional moments based on GF-discrepancy points were used to predict the distribution function of the extreme-value variable of random seismic response,and the coupling system’s seismic reliability was solved.Finally,the effectiveness of the proposed method was verified through a transmission tower-line system from an actual project.The results show that:When the foundation soil category is typeⅣ,after considering the SSI effect,the maximum vertex displacement and acceleration increase by 46.59%and 17.43%,respectively,and the failure probability increases by 70.32%.When considering the tower-line coupling effect,the maximum vertex displacement is reduced by 0.51%,the maximum vertex acceleration increases by 1.74%,and the failure probability is reduced by 15.71%;For the transmission tower-line coupling system considering the SSI effect,the foundation soil becomes softer,and the maximum vertex displacement and acceleration become larger.Compared with results using Monte Carlo Simulation(MCS),the maximum relative error of the proposed method is 9.97%.The proposed method has high accuracy and efficiency.