斜拉桥塔-索-桥面连续耦合振动模型及其影响因素分析

针对端部激励下大跨度斜拉桥主塔、拉索与桥面梁协同振动问题,考虑拉索的初始垂度、倾角、阻尼及拉索重力弦向分力影响,引入拉索的高精度抛物线形,建立桥塔-拉索-桥面连续耦合非线性振动精细化模型,推导结构系统在桥面和索塔激励作用下的非线性振动方程,研究塔-索-桥面梁结构系统面内振动特性,并编制程序分析桥面与拉索频率比、桥面激励幅值、索力、拉索阻尼及拉索倾角对拉索振动特性的影响规律。结果表明:桥面梁与拉索频率比是系统发生大幅振动的直接诱因,其频率比为有理数时,系统将发生大幅振动,频率比接近2时将激发大幅主参数共振;桥面激励幅值和索力对拉索振动特性影响较大,拉索振幅随桥面激励幅值的增加呈非线性增加,随索力的增加呈先急剧减小,后趋于稳定;索的振幅随拉索阻尼增加而减小,但是减小幅度有限;实际工程中,拉索倾角对斜拉索振动影响较小。

Study on Coupling Vibration Model and Influence Factors of Tower- Cable-Deck in Cable-stayed

In order to study coupling vibration of tower-cable-deck under end excitation. Considering sag, angle, damping and gravity of the tangential component of cable, and introducing the high precision parabola, the refined model of tower-cable-beam was established. The nonlinear vibration differential equation of tower-cable-beam under end excitation was deduced. The effect of the frequency ratio of cable and beam, deck excitation amplitude, cable force, damping and angle were analyzed. The results show that: The frequency ratio of deck beam and cable is the large incentive for system vibration. The vibration between deck and cable has "beat" feature. The system occur a large vibration, when frequency ratio is integer times. The frequency ratio close to 2 will inspire the principal parametric resonance. The deck excitation amplitude and the cable force have larger influence. The vibration amplitude nonlinearly increases with deck excitation increasing, first decrease and then tends to be stable with cable increasing. The vibration amplitude decrease with damping rising, but reduced amplitude is limited. Cable angle has little effect on the vibration of stay cable.