Comfort Evaluation For Footbridge Vibration

With the development of modern footbridge trending to be the light, large span, delicate and exquisite, the pedestrian-induced vibration of the structure is becoming more and more obvious. This phenomenon may be not enough to cause the safety issues of the structure, but it brings discomfort to the pedestrian on the bridge, causing anxiety even panic, so the analysis of the bridge vibration amplitude and the evaluation of pedestrian comfort on the design of footbridge and maintenance of completion stages are of great necessity to take damping measures on the footbridge which owns the problems of vibration comfort. Therefore this paper takes typical footbridges of Wuhan as the background, and researches the footbridge problems of vibration comfort.First of all, this paper introduces the pedestrian bridge on the problems of vibration comfort situation and existing problems in and aboard, including three aspects. The first is the load of the pedestrian, focusing on the pedestrian load testing, modeling and simplified problems;The second is the research about the interaction of pedestrian and bridge dynamics, including people "lock" and the impact of vibration on the walking force;The third is the evaluation methods of comfort and the research of standards, specializing on four widely used international standard specifications, analyzing and comparing methods of the current national norms in the evaluation of the vibration comfort of the pedestrian bridge, usage of the pedestrian excitation load model and comfort evaluation, and on this basis,the assessment method used in this research is determined.Secondly, the current research in and abroad about vibration comfort of footbridge mainly concerns the theoretical calculations, but the theoretical and experimental results have differences to some extent, and the experimental results are mostly for single bridge, lacking comparing research on a large number, different crosses and variable structural forms of pedestrian bridges. Since there are not any relevant standards of vibration comfort for footbridge, although reports about comfort issues of city footbridge sometimes appeared, there is few assessment for it, and the current situation of domestic cities footbridge is not clear. Therefore, it is necessary to understand the present situation of city footbridge in our country through experiment. This article takes 13 typical pedestrian bridges of Wuhan as the research objects, and conducts experimental research on the natural frequency and the maximum acceleration, handles and analyzes experimental results to compare the theoretical value of the presumption in different specification, providing experimental testing basis for further study on vibration comfort of footbridge.Finally, the vibration characteristics of the Li gong yi qiao footbridge is analyzed by using general finite element software ANSYS and three-dimensional dynamic finite element method, combined with the measured mode to verify validity of the model. This analysis offers reference for grasping the basic vibration characteristics of the pedestrian bridge with the complex structure from the theory and evaluating its vibration comfort.