人－桥竖向耦合振动计算方法

摘要

In order to investigate the human-bridge vertically coupled vibration of lightweight footbridges,a human-bridge vertically coupled vibration equitation based on a bipedal pedestrian model was developed.A comparison between the simulated foot force on rigid ground and the foot force time history curve presented in reference showed that the human body bipedal walking model provided here can simulate the features of ground reaction force properly.Reasonable ranges of the parameters of this bipedal model were discussed.A 22.8m-span aluminum alloy footbridge (with the 1st vertical bending vibration natural frequency of 7.23 Hz)was taken as an example to calculate the structural dynamic responses under vertical crowd-bridge interaction.Stochastic crowd walking parameters were generated by Monte-Carlo method to simulate the random crowd conditions of different densities,and the direct integral method was used to compute the dynamic response of the foot bridge considering crowd-bridge vertically coupled vibration.The results indicated that as the crowd density rises,the predominant frequencies of the human-bridge coupled vibration tend to dispersing,the vibration responses are much smaller than those not considering the coupling effect.%为了分析轻质人行桥的人－桥竖向耦合振动，建立了基于双脚支撑人体计算模型的人－桥耦合振动方程。根据行人在刚性地面行走时的步伐荷载计算结果与文献给出的步伐荷载时程曲线对比，验证了双脚支撑人体计算模型能较好地模拟行人的脚步力特性并讨论了合理的人体参数取值范围。以一座跨度22．8 m、第一阶竖弯自振频率7．23 Hz 的铝合金人行桥为例，运用 Monte Carlo 法模拟人群的步行参数，形成不同密度人群过桥的随机工况，并用直接积分法计算了考虑人群－桥竖向耦合振动的铝合金人行桥动力响应。计算结果表明，当人群密度较大时，考虑人桥耦合的人致振动卓越频率趋于分散，其振动响应明显小于不考虑耦合影响的计算结果。