谐波激励下斜拉桥面内非线性振动试验研究

斜拉桥拉索的振动问题一直是桥梁工程领域的研究热点。为揭示拉索大幅振动的力学机理，课题组建立了斜拉桥的全桥精细化模型，本文测试和研究了单频激励下的斜拉桥可能的非线性振动行为。首先，通过自由振动试验测试了模型的模态参数，并与两类有限元模型（OECS模型和MECS模型）进行对比，结果吻合良好。其次，试验研究了在单个竖向简谐激励下斜拉桥模型的非线性响应。研究发现：当激励频率与斜拉桥某阶全局模态频率接近时，主梁产生主共振，并引起多根长索产生大幅的参强振动；当激励频率与某根斜拉索面内一阶频率之比为1：2或者2：1时，可以观测到索中产生超谐波和亚谐波共振现象。

Experimental study on in-plane nonlinear vibration of a cable-stayed bridge subjected to a hamonic excitation

The vibration problem of cable-stayed bridge cables has always been a research hotspot in the field of bridge engineering. In order to reveal mechanical mechanism of the large vibration of cables, our group established a full-bridge refined model of cable-stayed bridge. The possible nonlinear vibration behaviors of cable-stayed bridges under single-frequency excitation are studied in the paper. Firstly, modal parameters of this model are examined by free vibration test, which is compared with two types of finite element models (OECS model and MECS model). The results are in good agreement with each other. Secondly, the non-linear response of cable-stayed bridge model under a single vertical harmonic excitation is studied. The research shows that when the excitation frequency is close to the global modal frequency of the cable-stayed bridge, the phenomenon of primary resonance is observed on the beam, which causes great amplitude parametric and forced vibrations of some long cables; when the ratio of excitation frequency to the first-order in-plane frequency of the cable is 1:2 or 2:1, the Superharmonic resonance or Subharmonic resonance phenomenon have also been observed in the cable.