In the railway bridge analysis and design method, dynamic train loads are regarded as static loads enhanced by an impact factor (IF). The IF coefficients for various railway bridges have been reported as a function of span length or frequency of the bridges in Eurocode (2003). However, these IF coefficient values neglect the effects of very high speeds (>200 km/h) and soil-structure interaction (SSI). In this work, a comprehensive study to assess the impact factor coefficients of mid-span vertical displacements for continuous and integral railway bridges subjected to high-speed moving loads is reported. Three different configurations, each for the three-dimensional (3D) continuous and integral bridge, are considered. Also, single-track (1-T) and two-track (2-T) “real train” loading cases for both these bridge types are considered. Subsequently, finite element analysis of the full-scale 3D bridge models, to identify their IF values, considering the effects of SSI for three different soil conditions, is conducted. The IF values obtained from the study for both bridge types are comparable and are greater than the values recommended by Eurocode (2003). The results reveal that with a loss of soil stiffness, the IF value reduces; thus, it confirms the importance of SSI analysis.

在铁路桥梁分析和设计方法中，列车动态载荷被视为通过冲击因子（IF）增强的静态载荷。在Eurocode（2003）中，已经报道了各种铁路桥梁的IF系数与桥梁的跨度或频率的关系。但是，这些IF系数值忽略了极高速度（> 200 km / h）和土壤-结构相互作用（SSI）的影响。在这项工作中，报告了一项综合研究，以评估承受高速移动载荷的连续和整体铁路桥梁中跨竖向位移的影响系数。考虑了三种不同的配置，每种配置用于三维（3D）连续桥和整体桥。同样，考虑了这两种桥梁类型的单轨（1-T）和两轨（2-T）“实际列车”装载工况。随后，考虑到SSI在三种不同土壤条件下的影响，对3D桥梁的全尺寸模型进行了有限元分析，以确定它们的IF值。从研究中获得的两种桥梁的IF值是可比的，并且大于Eurocode（2003）推荐的值。结果表明，随着土壤刚度的降低，IF值降低；反之，则降低。因此，它证实了SSI分析的重要性。