Study On Dynamic Response And Vibration Control Of Footbridge Under Pedestrian Loads

With the rapid development of our society and economy,the process of urbanization is accelerating.With the application of modern high-strength building materials and the requirements of urban aesthetics,urban footbridges are developing towards the direction of light weight,large span and low damping,resulting in the low first-order vertical natural vibration frequency of many footbridges,and even falling into the sensitive range of pedestrian walking frequency,resulting in excessive vibration of footbridges.The excessive vibration of the structure will cause the pedestrian walking discomfort and even affect the safety of the structure,so it is very important and practical to study the vibration and vibration control of the footbridge under the pedestrian loads.In this paper,a wireless acceleration sensor was used to test the walking load.Derived the formula for calculating the number of equivalent rows of people walking randomly,and using the combination of test and numerical simulation,taking the concrete steel truss pedestrian bridge as the carrier,the vertical response of the pedestrian bridge under the pedestrian load was analyzed,and TMD(Tuned Mass Damper)is used for vibration control analysis.The major researches which have been done are shown as follows:(1)The three-axis wireless acceleration sensor was used to test the walking force of multiple testers under different walking frequency,and considered multiple working conditions such as pedestrian fixed walking frequency,free walking,running and synchronization of multiple pedestrians.By comparing the walking force under different working conditions,the influence of different characteristic parameters of human body on walking force was analyzed,and the regularity was found out.(2)Based on the theory of forced vibration,the vertical vibration response of the footbridge under single and multi-person moving loads was deduced,and a method for calculating the equivalent number of pedestrians when a crowd walks randomly was given in combination with Latin hypercube sampling.Taking two footbridges with different fundamental frequencies as examples,the vertical vibration response of the footbridge when single-pass resonance and multiple people cross the bridge randomly is analyzed.(3)The method of field test and finite element simulation was used to study the human induced vertical response of a steel truss pedestrian bridge.The finite element software ABAQUS was used to establish a solid model of the full bridge to analyze its dynamic characteristics.At the same time,Fortran was used to program the pedestrian load,and it is associated with the finite element software to calculate the vibration response of the pedestrian bridge under the pedestrian load.The obtained data are compared to verify the correctness and accuracy of the finite element simulation.(4)The TMD vibration control technology was introduced to reduce the vibration of two footbridges with different fundamental frequencies in this paper.The vertical vibration response of the pedestrian bridge with TMD system under different pedestrian conditions was calculated theoretically.The performance of TMD system was evaluated and the effect of vibration reduction was verified.