横风作用下大跨度人行悬索桥振动使用性研究

为了研究大跨人行悬索桥(LSSF)由横向风引起的振动舒适性问题，以主跨为460 m的柔性人行桥为对象，利用谱表示法生成不同湍流强度下的脉动风时程. 基于数值模拟方法识别的18个颤振导数，计算有理函数表达的自激力. 通过横风作用下的非线性抖振响应时域分析，比较自激力和结构阻尼对抖振响应的影响，分析湍流强度对抖振响应和舒适性的影响，讨论具有不同设计参数的中央扣和抗风缆对减轻桥梁抖振响应的效果. 结果表明，自激力对大跨度人行悬索桥的抖振响应有不可忽视的影响；在平均风速为15 m/s的横风作用下，湍流强度增加50%，桥梁的抖振响应增加30%~68%；中央扣能够明显减小1/4跨和3/4跨的竖向振动；增加抗风缆刚度能够有效减小竖向及跨中横向振动.

Investigation on vibration serviceability of long-span suspension footbridge under crosswind

A flexible footbridge with main span of 460 m was taken as an object in order to analyze the problem of vibration serviceability of long-span suspension footbridge (LSSF) induced by crosswind. Fluctuating wind time histories with different turbulence intensities were generated with spectral representation method. Rational-function-expressed self-excited force was calculated based on 18 flutter derivatives identified by numerical simulation method. The influence of self-excited force on buffeting response was compared with those of structural damping through nonlinear buffeting response analysis in time domain under crosswind. The influences of turbulence intensity on buffeting response and comfort were analyzed. The mitigation effects of central buckle and wind-resistant cable with different design parameters on the buffeting response of bridge were discussed. Results show that self-excited force has a non-negligible influence on buffeting response of LSSF. Turbulence intensity increases by 50% under the crosswind with a mean wind speed of 15 m/s, and the buffeting response of the bridge increases by 30%-68%. Central buckle can obviously reduce vertical vibration at 1/4 span and 3/4 span. Increasing the stiffness of wind-resistant cable can effectively reduce lateral vibration at mid-span and vertical vibration.