考虑行波效应的大跨度倒虹吸明钢管地震反应分析

Influence of travelling wave on seismic response of exposed steel penstock for inverted siphon

近年来调水工程大规模建设,地震灾害频发,使长距离输水明钢管的抗震性能这一问题愈发受到重视,与此同时,地震动行波效应对平面投影尺度较大的空间结构的影响已逐渐被认识和接受。本文采用非线性时程动力分析的方法研究考虑行波效应的大跨度明钢管的地震响应。结果表明:行波效应会增大明钢管主要构件如波纹管伸缩节、支座和钢管在地震作用下的变形或应力响应量,其影响程度与波速有关,波速越小,影响越明显,当波速大于1000m/s后,地震反应与不考虑行波效应时的结果相近;此外结构自身的特性也会影响地震响应。因此当校核明钢管的抗震安全性时,应准确建立整体分析模型,并在低波速区段(小于1000m/s)考虑行波效应。研究结论可以为类似结构的抗震设计和分析提供补充分析和参考。

Earthquake occurs more frequently in recent years. With a large number of water conveying engineering under construction, aseismic performance of long-distance exposed steel penstock becomes significant. The fact that travelling wave effect has an influence on seismic response of spatial structures with a large plane scale, has been known and accepted widely. The effect of travelling wave on an exposed long steel penstock for inverted siphon is computed by a nonlinear time history method in this study. The results show that travelling wave effect can enlarge seismic deformation and stress responses in the main components of penstock, such as bellow expansion joints, supports, and steel pipe. Its extent much depends on wave speed： the smaller the wave speed, the more significant such an effect. When wave speed exceeds 1000 m/s, the seismic responses are approaching to the ones without this effect. The responses also depend on the structural characteristics of penstock. Thus, in checking aseismic safety of an exposed steel penstock, an accurate model must be adopted and travelling wave effect should be considered for the pipe of low celerity （i.e. below 1000m/s）. These results can be useful to aseismic design and analysis of similar structures.