高速铁路大跨度混凝土简支箱梁动力特性分析

Dynamic Analysis of Long-span Concrete Simply Supported Box Girder in High-speed Railway

研究目的:我国高速铁路桥梁以跨度32 m预应力混凝土简支箱梁桥为主,对于下部基础费用占比大的桥梁区段,采用大跨度简支梁可以显著降低工程费用,高速铁路大跨度简支梁是一个重要的研究方向,其在列车作用下的动力特性是设计需要考虑的关键因素。本文利用移动荷载列计算方法,分析车桥共振条件,提出不同跨度混凝土简支梁的方案设计,分析列车作用下大跨度简支梁的动力特性,为确定高速铁路大跨度简支梁的合理跨度提供支撑。研究结论:(1)共振速度与简支梁自振频率和车长相关;车长d与跨度L的比值是简支梁桥车桥共振的关键影响因素;(2)大跨度简支梁设计中,静活载作用下的梁端转角限值决定了简支梁的最小梁高;(3)当跨度逐渐接近动车组车长的2倍时,简支梁的动力系数和跨中加速度也逐渐增加;有限元分析的车桥共振现象与公式分析的结论基本一致;(4)本研究成果可指导高速铁路大跨度简支梁的工程设计。

Research purposes: The high-speed railway bridges in China are mainly prestressed concrete simple supported box girder bridges with a span of 32 m. When the bridge foundation cost more,the use of long-span simply supported girders can significantly reduce the engineering cost. It is an important research direction to increase the span of high-speed railway simply supported girders. The dynamic characteristics of the girder under train action are the key factors to be considered. The paper analyzed the resonance condition of vehicle-bridge by using the moving load series method,completed the design of concrete girder with different span,and completed the dynamic characteristic analysis of long-span simply supported girder under train action,to provide support for determining the reasonable span of large-span simply supported girder.Research conclusions:(1) The resonance velocity was related to the natural frequency and vehicle length. The ratio of vehicle length d to span L was the key influencing factor of vehicle-bridge resonance.(2) The minimum section height of large-span simply supported girder was determined by the angle limit of girder end under static design load.(3) When the span was approaching to 2 times the length of the vehicle,the deformation dynamic coefficient and acceleration of the simply supported girder increased gradually. The results of finite element analysis were consistent with those of formula analysis.(4) The research results could be used to guide the design of high-speed railway long-span simply supported girders.