基于土弹簧的桩-土-输电塔抗震性能研究

在传统输电塔抗震分析中,通常假设输电塔固定在地面上,而不考虑土G结构相互作用(SoilG Structure Interaction,SSI)对结构的影响,从而可能导致输电塔抗震性能评估不准确.依托某 1000kV输电铁塔实际工程,对地震动激励下考虑SSI的输电塔进行综合的地震响应、倒塌破坏和倒塌易损性分析.在 ABAQUS中,通过沿桩体设置依据 API规范确定的零长度弹簧模拟土体与桩体间的相互作用,建立考虑SSI的输电塔有限元模型.基于数值模型,开展输电塔动力特性和结构动力响应分析.采用增量动力分析(Incremental Dynamic Analysis,IDA)方法,研究SSI对输电塔倒塌机理和易损性的影响.结果表明:考虑和未考虑SSI的输电塔振型相似,但自振频率相差较大;忽略SSI会低估输电塔的地震响应,同时高估输电塔的抗倒塌能力.因此考虑SSI可以提高输电塔抗震能力,进而确保输电线路的安全性.

Seismic response of pile-soil-transmission tower based on soil springs

In traditional seismic analysis studies, transmission towers are usually assumed to be fixed on the ground, neglecting the soil-structure interaction (SSI) that may lead to inaccurate seismic performance evaluation of transmission towers. A comprehensive analysis of the seismic response, collapse damage, and collapse vulnerability of an actual 1000- kV transmission tower was carried out, considering SSI under seismic excitations. In ABAQUS, the interaction between soil and pile was simulated by setting zero-length springs along piles. A finite-element model of the transmission tower considering SSI was also established. Based on the numerical model, the dynamic characteristics and structural dynamic response of the transmission tower were analyzed. The impact of SSI on the collapse mechanism and vulnerability of the transmission tower was studied using the incremental dynamic analysis method. Results show that the vibration modes of the transmission tower with and without considering SSI are similar, but the natural frequencies differ greatly. Ignoring SSI will lead to underestimating the seismic response of the transmission tower and overestimating its collapse resistance. Therefore, studies considering SSI can improve the seismic capacity of the transmission tower, thereby ensuring the safety of the transmission line.