Vibration Analysis Of Large Span Footbridge Based On Stochastic Pedestrian Flow

With the development of economy and technology,people’s living condition and tourism industry have a graet development,more and more large-span pedestrian bridges have been built,such as pedestrian suspension bridge.it has a slender girder and low rigidity,humaninduced vibration and human-structure interaction are prominent on suspension footbridge.Human-structure interaction may change the dynamic characteristics of the structure itself,so it is of great significance to conduct in-depth research on this.At the same time,the movement of the crowd is very complicated.Every pedestrian will judge and react to the surrounding environment.Based on the Monte-Carlo method,the study of crowd movement from the microscopic perspective will be closer to the actual situation.This article mainly carried out the following work:(1)Briefly compare the characteristics of the moving force model and the mass-springdamping model,and separately derive the matrix equations of the two models.For bridges with different dynamic characteristics(modal mass,frequency,damping ratio),the changes of frequency and damping ratio under the action of a single person are discussed.And study the effects of single person load(unsynchronized frequency,weight)and crowd load(human bridge mass ratio,crowd density)on dynamic characteristics changes and acceleration ratios of the two models.It was found that pedestrian step frequency and bridge mass ratio are the main influencing factors.(2)Combining the characteristics of pedestrian bridges,a random pedestrian flow simulation model is proposed,and the relationship between the crowd flow-crowd density and the average speed-crowd density curve obtained by simulation in this paper is compared with the views of different researchers.The comparison shows that it has a certain reliability.The crowd flow and average speed under different crowd densities and proportions in different directions were studied.At the same time,the influence of different bridge sizes on crowd flow and average speed was analyzed.(3)Relying on a long-span pedestrian suspension bridge and establishing a finite element model based on ANSYS to obtain the dynamic characteristics of the pedestrian suspension bridge.Combined with the random pedestrian flow proposed in this paper,the vibration response of pedestrian suspension bridges under different densities is analyzed,and the influence of different walking modes on the vibration response is studied.Combining the mobile force model and the MSD model to study the interaction between human and bridge。...