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针对非规则梁桥的振型重要性指标进行研究。首先,通过理论分析,确定在判断振型重要性方面,传统的振型质量参与系数存在缺点,并定义了振型位移贡献、振型位移贡献系数、振型位移贡献比例等新指标。然后,针对一座典型的非规则梁桥,通过振型质量参与系数分析和振型位移贡献系数分析的对比研究,确定采用振型位移贡献比例判断振型重要性,更加合理。最后,通过多座桥梁的参数分析,验证了振型位移贡献比例比质量参与系数更加优越。研究结果表明:振型质量参与系数仅能反映振型对于结构总体动力反应的重要性,而不能明确反映振型对于结构局部动力反应的重要性;振型位移贡献比例能弥补这一缺陷,可以作为振型重要性的指标;当前n阶振型位移贡献比例之和超过80%时,以前n阶振型为基础得到的结构位移可以满足非规则梁桥计算精度的需要。
Research on the importance of vibration mode of irregular beam bridge. First of all, through theoretical analysis, it is determined that there are some shortcomings of the traditional modal mass participation coefficients in judging the importance of the modal shape, and the new indexes such as the displacement contribution of the modal shape, the contribution coefficient of the modal displacement and the contribution ratio of the modal displacement are defined. Then, for a typical irregular beam bridge, it is more reasonable to determine the mode shape importance by using the ratio of the displacement of vibration mode to determine the mode shape through the comparative analysis of modal mass participation coefficient analysis and vibration mode displacement contribution coefficient analysis. Finally, through the parametric analysis of multiple bridges, it is verified that the contribution ratio of mode displacement is more superior than the mass participation coefficient. The results show that the participation coefficient of mode shape quality can only reflect the importance of mode shape to the overall dynamic response of the structure, but can not clearly reflect the importance of the mode shape to the local dynamic response of the structure. The proportion of the mode displacement contribution can make up for this defect. As an indicator of the importance of the modal shape. When the sum of the contributions of the n-th modal displacement exceeds 80%, the structural displacement based on the previous n-order modal can satisfy the calculation accuracy of the irregular beam bridge.