基于尾流振子模型的桥梁节段至实桥涡激共振振幅转换关系

CONVERSION OF THE VORTEX-INDUCED AMPLITUDES OF SECTIONAL MODELS TO FULL-SCALE BRIDGES BASED ON WAKE OSCILLATOR MODEL

该文基于一种用于涡振模拟的两自由度经验模型(尾流振子模型)推导了桥梁节段至实桥涡振振幅转换关系。首先介绍了尾流振子模型的形式及其特点,其次从展向全相关及展向不完全相关两方面推导了节段至实桥涡振振幅转换关系,最后结合实际桥梁对上述过程进行了算例验证,并与现场实测结果进行了比较。研究表明:当不考虑涡激力展向相关性影响时,节段至实桥涡振振幅只与结构振型函数有关,尾流振子模型得到的转换关系与传统经验非线性模型得到的转换关系相同;当考虑涡激力展向相关性时,计算得到的实桥涡振振幅可能小于节段模型结果,涡激力展向全相关条件下得到的计算结果与现场实测结果更接近。因此,当缺少精确的涡激力展向相干函数时,假定涡激力展向全相关计算得到的实桥涡振振幅可能更为可靠。

The approach for converting the VIV amplitudes of sectional models to full-scale bridges base on a two-degree-of-freedom empirical model （wake oscillator model） is established in this paper. The wake oscillator model to be used in this paper is firstly introduced. The conversion method by involving fully correlated and non-fully correlated cases are then derived based on this model. A real bridge is utilized as a case study, and the calculated results are compared with those of field measurements. Results indicate that once the span-wise correlation of VIV forces is ignored, the conversion of VIV amplitudes between sectional models and full-scale bridges, generated by wake oscillator model, equals to the result generated by the traditional nonlinear semi-empirical model. However, once the span-wise correlation of VIV forces is considered, the calculated VIV amplitudes of real bridges may be smaller than the results of sectional model tests. The calculated results by ignoring the span-wise correlation of VIV forces agree well with those of field measurements. Thus, the calculation of VIV amplitudes of a full-scale bridge by ignoring the span-wise correlation of VIV forces may be more reliable in the case of lacking an accurate spatial coherence function of VIV forces.