时速400 km/h铁路常用跨度预应力混凝土简支梁竖向基频限值研究

建立有限元模型，计算常用跨度预应力混凝土简支箱梁的竖向基频，以设计荷载对桥梁的动力效应不小于运营列车对桥梁的动力效应为准则，确定梁体容许动力系数；基于移动荷载模型，得到常用跨度简支箱梁在列车作用下的动力系数；在综合分析桥梁动力响应与列车类型、运营速度、桥梁竖向基频关系的基础上，提出了时速400 km/h常用跨度预应力混凝土简支箱梁的竖向基频限值。研究表明:通过调整车长与桥梁跨度之比可避开基阶振型的共振，有利于行车安全；在车长25 m左右的列车作用下，跨度24 m、32 m和40 m的预应力混凝土简支箱梁竖向自振基频限值取125/L、155/L和90/L时，可以有效地降低梁体动力响应。

RESEARCH ON THE BASIC FREQUENCY LIMIT OF RAILWAY COMMON SPAN PRESTRESSED CONCRETE SIMPLY SUPPORTED BEAM WITH 400 km/h

Finite element model is established to calculate the vertical basic frequency of PC (prestressed concrete) simply supported box-girder with common span. The allowable impact factor of girder is determined according to the principle of the bridge dynamic effect under the action of running train not greater than that of design value. Based on the moving load model, the impact factor of the simply supported box-girder with common span is determined under moving train. The lower vertical basic frequency limit of PC simply supported box-girder with common span is recommended as 400 km/h, through comprehensively analyzing the relationship between the dynamic response of the girder and the type of train, the operation speed and the girder vertical basic frequency. The research shows that adjusting the ratio of the vehicle length to the bridge span could avoid the resonance of the fundamental vibration mode, which is beneficial to vehicle running safety. The lower vertical basic frequency limit of PC simply supported box-girder with span of 24 m, 32 m and 40 m are recommended, which are 125/L, 155/L and 90/L, respectively, which could effectively reduce the dynamic response of girder caused by vehicle with 25 m length.