考虑SSI效应的输电塔-线体系风振响应简化分析

输电塔的分析设计通常按基础固支来处理，然而多数情况下地基并不是刚性的. 为了考虑弹性地基对输电塔风振响应的影响，建立了考虑土与结构相互作用（soil-structure interaction，SSI）的输电塔-线体系简化计算模型，并推导了风振响应动力方程. 基于提出的简化计算模型，选取工程中某特高压输电塔-线体系，编写MATLAB程序进行了结构系统的动力特性分析和风振响应时程分析，并选取了3种不同参数的地基土对输电塔的风振响应进行了对比分析. 研究结果表明:考虑SSI效应后，单塔的位移均方根值增大约20%，加速度均方根值减小约14%，基底剪力及基底弯矩最大值分别减小约7%、12%；考虑塔线耦联和SSI效应后，与仅考虑SSI效应的单塔相比，输电塔的位移响应有所增大，但加速度响应变化很小；随着地基土刚度减小，SSI效应的影响越明显，表明软土地基下输电塔的风振响应分析不能忽略SSI效应. 

Simplified Analysis of Wind-Induced Response of Transmission Tower-Line System Considering SSI Effect

Analysis and design of transmission tower is normally performed considering fixed base, however, in most cases, the foundations are not rigid. In this study, a simplified calculation model of transmission tower-line system was developed with consideration of the soil-structure interaction （SSI）, and the dynamic equation of wind vibration response was derived. Based on the proposed simplified calculation model and MATLAB program, a transmission tower-line system from an actual project was selected to conduct the analysis of the dynamic characteristics and the time domain analysis of wind vibration of transmission tower. The model was tested and analysed with three different types of soil. The results show that the RMS displacement of transmission tower increases by about 20%, the RMS acceleration is reduced by about 14% and the maximum base shear and the base bending moment decrease by about 7% and 12%, respectively, when considering the SSI effect. The displacement response of transmission tower increases, but the acceleration changes are small if the tower line coupling effect and SSI effect are considered. As the soil hardness decreases, the SSI effect is more obvious; hence, the SSI effect should not be ignored when the transmission tower is built on soft soil.