人-桥动力相互作用下侧向振动的动力放大系数分析

Analysis of the dynamic amplification factor of latetral structural vibration induced by crowd-bridge interaction

从社会力模型和人桥相互作用的机理出发研究了柔性人行桥在人桥相互作用下侧向振动的动力放大系数。首先将人行激励分解为固有侧向力和附加侧向力,分别采用傅里叶级数模型和社会力模型表示上述侧向力,从而建立考虑负阻尼的强迫振动模型。结合该模型推导出动力放大系数的表达式,在此基础上给出了基于动力放大系数的结构动力响应的简化计算方法。最后,结合某人行桥结构,对比分析了采用建议的估算方法与时程模拟结果的差异,证实了简化计算方法的有效性。

Depending on the social force model and the mechanism of crowd-bridge interaction,the lateral dynamic amplification factor of flexible footbridges was studied.The lateral step force induced by pedestrian was divided into two parts,namely the intrinsic lateral force and additional lateral force.Representing the two parts of forces by Fourier series and social force respectively,the motion equation of footbridge was set up with the consideration of negative damping.The expression of dynamic amplification factor was derived from the structural motion equation.Then a simplified method for estimating structural responses was proposed according to the relationship between structural responses and the dynamic amplification factor.The peak displacement and acceleration of a concrete footbridge were calculated by using the simplified method and the conventional time history analysis respectively.The results of the two methods were compared with each other,and the effectiveness of the simplified method was validated.