大跨度倒虹吸管桥结构抗震性能

Seismic Performance of Large-span Inverted Siphon Pipe Bridge Structure

建立了考虑支座、伸缩节等细部构件的大跨度倒虹吸管桥有限元模型,采用有限单元法对管桥结构的抗震性能进行了研究,分析了支座、伸缩节、管内水体质量对结构动力响应的影响。计算结果表明:大跨度拱桥结构对地震波有明显放大作用,放大系数约为2~5;钢管采用单向滑动支座,约束了钢管横向位移,伸缩节变形和支座滑移量均在10 mm以内,对结构抗震有利,但支座在横向将承受较大的反力,给支座设计带来困难;由于伸缩节和滑动支座的设置,钢管在地震作用下近似刚体运动,钢管应力增幅较小,但支承环将产生较明显的弯曲应力,是抗震中的一个薄弱环节;大直径输水钢管管内水体质量巨大,会增大结构的动力响应,计算中应予以考虑。

The finite element model of a pipe bridge structure with large span inverted siphon including support and expansion joint is established.The structural seismic performance of the pipe bridge is investigated using finit element method by examining the influence of supports,expansion joint and water mass in steel penstock on structural seismic response.The large span arch bridge has a significant amplification effect on seismic wave,and the amplification coefficient is within 2-5.Unidirectional sliding supports constrain the lateral displacement of the steel penstock and keep the deformations of the expansion joints and the sliding distance of the supports both within 10 mm,which are beneficial to the seismic resistance of the structure.However,the supports bear large reaction force in lateral direction,which is unfavorable to the design of the supports.Due to the sliding supports and expansion joints,the steel penstock moves like a rigid body under earthquake.The stress of steel penstock is not much affected;but the supporting ring becomes a weakness as it is subjected to notable bending stress.In addition,the huge water mass in the large-diameter steel penstock should also be considered in calculation as it intensifies the structural dynamic response.