随机荷载下索梁结构拉索参数振动分析
Analysis of cable parametric vibration for cable-beam structure subjected to random excitation

采用拉索参数振动和索-梁-塔相互振动的有限元方法，以1993年Fujino进行的索梁结构试验模型为对象，进行随机荷载下拉索参数振动计算和分析. 结果表明，当随机荷载强度达到一定水平时拉索发生参数振动，横向振动位移远高于主梁位移；三自由度的理论解析法只适用于主梁竖向一阶频率与拉索横向一阶频率之比为2∶1的索梁结构，对于主梁竖向二阶频率与拉索横向一阶频率之比为2∶1的索梁结构，该方法求得的主梁竖向位移偏小.
An experimental model of cable-beam structure，conducted by Fujino in 1993，was calculated and analyzed about the cable parametric vibration subjected to random excitation，by finite element (FE) method，which can take the cable parametric vibration and the coupled vibration between cable and beam-tower into account. The result shows that the cable parametric vibration is excited when the random load increases to a certain value，and the horizontal displacement of cable is much larger than that of beam. The theoretical analysis method，considering three degree of freedoms，is merely appropriate for the cable-beam structure，with the ratio of the first vertical frequency of beam to the first horizontal frequency of cable is close to 2∶1. When the ratio of the second vertical frequency of beam to the first horizontal frequency of cable is close to 2∶1，the vertical displacement of beam obtained by the theoretical analysis method is much smaller