悬挂系统的动力耦合作用对1000kV出线构架地震响应和极限承载力的影响研究

Effect of dynamic interaction between the suspended system and 1000kV outgoing line frame on its seismic responses and ultimate bearing capacity

1000kV出线构架是特高压变电站内重要的下部支承结构,为了研究悬挂系统的动力耦合作用对其地震响应和极限承载力的影响,选取输电导线的6种垂跨比和5种档距作为分析工况,采用7组真实远场记录作为地震激励。首先比较各工况在多遇、设防、罕遇和极罕遇地震下的构架地震响应,然后讨论构架的全过程曲线、强震失效模式和极限承载力,最后提出考虑悬挂系统动力耦合作用的构架结构响应和极限承载力的预测模型。研究表明:悬挂系统的动力耦合作用是输电导线的初始水平张力作用、地震激励下的弹性约束作用和耗能减震作用的三者叠加;构架的变形路径、塑性发展规律、失效模式和极限承载力对垂跨比和档距都非常敏感;输电导线初始水平张力影响构架在强震作用下的破坏属性;构架结构响应和极限承载力的预测模型可为其抗震设计提供理论支持。

The 1000 kV outgoing line frame(OLF1000) is an important supporting structure in ultra-high voltage substation. To investigate the influence of dynamic interaction between the suspended system and OL1000 on its seismic responses and ultimate bearing capacity, six sag-to-span ratios and five spans of transmission lines were selected as the analysis cases, and seven real and far-field ground motions were used as excitations. Firstly, the seismic responses of OLF1000 in different analysis cases were compared under excitations with frequent, fortification, rare, and very rare intensities. Furthermore, the whole process curves, failure modes under strong earthquakes, and ultimate bearing capacities of OLF1000 were discussed. Eventually, the prediction models for structural responses and ultimate bearing capacity of OLF1000 were proposed by considering the dynamic interaction. The research results disclose that the dynamic interaction between the suspended system and OLF1000 consists of the initial horizontal tension effect, elastic constraint effect and energy dissipation effect under earthquakes. The deformation path, development law of plasticity, failure mode, and ultimate bearing capacity of OLF1000 are very sensitive to the sag-to-span ratio and span. Additionally, the initial horizontal tension of transmission lines may affect the failure characteristics of OLF1000 under strong earthquakes. Finally, the prediction models can provide the theoretical supports for the seismic design of OLF1000.