竖向行人-结构相互作用中的行人MD及SMD模型参数识别

MD and SMD model parameters of pedestrians for vertical human-structure interaction

大跨轻柔结构易出现行人荷载下的振动舒适度问题,行人与结构的相互作用是准确预测人致结构振动的关键难题之一。通过一低频人行桥的小组行人试验,研究了两种竖向人-结相互作用模型的参数及其适用性问题。首先由试验获得空桥和有行人时的系统频响函数。随后,将行人的质量-阻尼器(Mass-Damper,MD)模型和本文建议的弹簧-质量-阻尼器(Spring-Mass-Damper,SMD)模型,分别与结构耦合并推导耦合系统的频响函数理论表达式,再拟合实测值识别MD和SMD模型的参数。结果表明:试验条件下行人对结构质量贡献约为体重的40%,阻尼贡献为1400kg/s。行人SMD模型的自振频率约为1.9Hz,阻尼比约30%。行人SMD模型参数尚无其他文献报道,与不同姿态静止人体的SMD参数的对比说明了结果的合理性。最后,利用数值模拟解释了MD模型的局限性,建议采用SMD模型模拟竖向行人-结构相互作用。

Light and slender structures are prone to vibration serviceability problems due to pedestrians. The interaction between pedestrians and structures is one of the challenging issues in accurately predicting structural vibrations. Based on the test data from a low-frequency footbridge under pedestrians＇ loading, mass-damper （MD） model and spring-mass-damper （SMD） model are used to model pedestrians on the footbridge and their model parameters are extracted. First, the frequency response functions （FRF） of the empty footbridge and occupied footbridge are obtained from the test data. Second, MD model and SMD model are used to model pedestrians and to build coupled models of the pedestrians and the footbridge. Third, MD and SMD model parameters of a single pedestrian are extracted by fitting the theoretical FRF for the measured FRF. Results show that a single pedestrian contributed 40~ of his/her real mass and 1400 kg/s to the footbridge in our case. The SMD model of a single pedestrian has a natural frequency of 1.9 Hz and a damping ratio of 30~.~. To the best of the authors＇ knowledge, no SMD parameters of pedestrians have been reported elsewhere. However, a comparison between SMD parameters obtained in our paper and those in the literature from static humans with different gestures is done, justifying the application of SMD model to pedestrians. In the end, numerical simulation is done to unveil the limitation of MD model and SMD model is recommended as a proper model of pedestrians for application in human-structure interaction （HSI）.