行人-结构竖向动力耦合效应试验研究

对于轻质大跨度钢桥结构，行人-结构之间的相互作用会使结构动力特性和行人荷载特性发生改变。为此，针对行人-结构竖向动力耦合效应对结构动力参数和行人荷载动载因子的影响进行试验研究。通过测试行人在8种不同步行频率下行走时结构的动力响应，得到60人次554组有效加速度响应时程，进行运行模态分析；利用无线六轴蓝牙加速度传感器，分别在刚性地面和柔性桥面上开展了3种不同步行频率下行走激励的动力特性试验，得到了60人次1200条有效加速度时程，并对其进行傅里叶变换。结果表明：考虑行人-结构竖向动力耦合效应，人行桥自振频率略有减小，阻尼比显著增加，且随着同步行走人数的增加，结构频率及阻尼比变化率逐渐减小。由于桥梁自振力的存在，行人荷载作用于刚性地面上的动载因子(dynamic load factor,DLF)大于柔性地面上的，试验结果表明，相较于刚性地面，行人在柔性桥面上行走时的第一阶动载因子减小14.7%。给出了刚性地面和柔性桥面前四阶行人荷载动载因子拟合公式，其可为柔性结构下考虑行人 结构相互作用的生物力模型的建立提供参考。

Experimental study on vertical dynamic coupling effect of pedestrian-structure

For light-weight long-span structures, the interaction between pedestrian and structure will change the dynamic characteristics of the structure and pedestrian load. In this paper, the influence of vertical dynamic coupling effect of pedestrian-structure on dynamic parameters of structure and dynamic load factor of pedestrian was experimentally studied. Firstly, by testing the dynamic response of the structure when pedestrians walk down at eight different walking frequencies, 554 groups of the effective acceleration response time histories of 60 person-times were obtained for operational modal analysis. Secondly, by using the wireless six-axis Bluetooth acceleration sensor, the dynamic characteristics experiments of walking excitation under three different walking frequencies were carried out on the rigid ground and flexible bridge deck respectively, and 1200 effective acceleration time-histories of 60 person-times were obtained for Fourier transform. The results show that, considering the vertical dynamic coupling effect of pedestrian-structure, the natural frequency of pedestrian bridge decreases slightly, the damping ratio increases significantly. With the increase of number of synchronous walking pedestrians, the change rate of structural frequency and damping ratio decreases gradually. Due to the existence of self vibration of the bridge, the dynamic load factor on the rigid ground is larger than that on the flexible bridge deck. The experimental results show that, compared with the rigid ground, the first order dynamic load factor of the pedestrian walking on the flexible bridge deck decreases by 14.7%.The dynamic load factor fitting formula of rigid ground and flexible bridge deck of the first four order pedestrian load was given in this paper. It can provide a reference for the establishment of the biological force model considering the pedestrian-structure interaction under the flexible structure.