考虑非稳态风荷载斜拉索风雨激振响应分析

Analysis of wind-rain-induced vibration responses of stay cables considering unsteady wind loads

为研究自然风荷载对斜拉桥拉索风雨激振的影响,将数值模拟的非稳态风荷载作用到拉索振动微分方程中,对拉索振动响应进行了详细分析。首先,针对水线初始位置,使用最小二乘法拟合得到水线初始位置方程;接着,采用四阶Runge-Kutta法求解拉索振动响应。通过比较在非稳态风和稳态平均风作用下的拉索响应,发现在非稳态风荷载下拉索最大振幅的变化趋势并没有发生较大改变,皆是随着风速的增大先增大后减小;但拉索的整个振动过程发生了变化,伴随着节拍改变,其最大振幅也出现在不同振动周期内。此外,从风速-振幅曲线知,对频率为1Hz,2Hz和3Hz的拉索,在一定风速范围内,考虑非稳态风荷载的拉索振幅反而更大,而且此时的风速范围也更大。

In order to study the influence of natural winds on the wind-rain-induced vibrations of cable stayed bridges,the vibration responses of cables are scrutinized by applying unsteady winds to the differential equations of cable vibration.Firstly,the rivulet initial position equation is obtained by means of the least-squares method.Then,the fourth-order Runge-Kutta method is used to determine the responses of wind-rain-induced vibrations of cables.Through comparing the oscillate responses of cables under the unsteady and steady mean winds,it is found that the maximum amplitudes of the cables don’t change much under unsteady winds.The maximum amplitudes firstly increase and then decrease with the increase of wind speed.However,the whole vibration process of the cables has been changed along with the beat;simultaneously,the maximum amplitudes of cable vibrations will also appear in different periods.Moreover,according to the wind velocity-amplitude relationships,within a certain wind speed range,the peak amplitudes of the cables with the frequencies being 1Hz,2Hz,and 3Hz are instead larger in the case of taking into unsteady wind loads account and likewise,the wind speed range is wider.