正常交通流下斜拉桥的振动模态测试

Vibration Mode Measurement for Cable-Stayed Bridge Under Normal Traffic Condition

通常斜拉桥的振动检测在限制过桥车辆情况下进行,无法真实反映桥梁实际状态下固有的自振特性,同时也影响当地交通.文中提出利用过桥车辆作为激振源,选择对低阶模态敏感的测点作为参考点,把参考点的测试数据作为输入信号,其它测点的测试结果作为输出信号.通过判定参考点与其它测点相应信号的相干性来识别斜拉桥的固有频率与振型,共识别出天津永和斜拉桥前12阶固有频率和振型,各阶模态频率分阶清楚,振型曲线光滑,与未通车时的测试结果基本吻合.

The vibration measurement of cable-stayed bridge is often made under restrictive vehicles traffic. It cannot actually reflect the eigen characteristics of bridge under normal traffic, and it affects local traffic inevitably.In this paper a new method of measurement vibration mode of the cable-stayed bridge has been worked out.It uses the passing vehicles as the source of the vibration and selects the spot which is sensitive to the lower-order mode as the reference point.The reference point′s testing results are made as the input signal and the other points′ testing results as the output signal.By means of estimation of coherence between the reference point and the other points,we can identify the cable-stayed bridge′s natural frequency and mode shape.Tianjin Yonghe cable-stayed bridge′ preceding 12 steps natural frequency and mode shape have been identified as an example.Every frequency is distinct,and the mode shape′s curve is slick.It is also consistent with the testing result which is got when the bridge is not open to traffic.