Abstract: Through the analysis on three-equal-span continuous beam jump car test，it is found that the additional quality of test truck can affect the measured bridge natural frequencies． Ｒayleigh method is used to assume the shape function of bump test; correction coefficient λ is introduced and a modified formula for the measured natural vibration frequency of three-equal-span continuous beam． The case study shows that the error of field measuring frequency reduces by 27% after correction than that before correction．

Key words: bump test, additional mass, natural vibration frequency

摘要： 对三等跨连续梁跳车试验的分析发现，试验载重车附加质量会影响桥梁自振频率的测定结果。采用瑞利法假定跳车试验形函数，引入修正系数 λ，提出了三等跨连续梁实测自振频率的修正公式。实例验证表明: 实测频率误差值修正后比修正前减小 27%。

关键词: 跳车试验, 附加质量, 自振频率