Vibration Analysis Of Steel Truss Pedestrian Bridge Excited By Crowd Load

With the development of cities in China,pedestrian bridges,as a very common structure,appear in every corner of the city for pedestrians to relieve traffic pressure.However,the vibration problem of pedestrian bridge not only affects the service life of the structure,but also affects the safety of pedestrians on the bridge.In the past,most of the researches on the vibration of pedestrian bridges were made of beam bridge structures.In this paper,a steel truss pedestrian bridge in Changsha is analyzed.With the help of the domestic and foreign scholars' research results and the analysis of Midas software,the general rules of the vibration of the steel truss pedestrian bridge are obtained,and the vibration comfort of the bridge is evaluated.The main research results are as follows:1.the pedestrian walking force model,the human bridge interaction theory and the human pedestrian bridge induced vibration analysis method are expounded.The pedestrian footstep load model used in this paper is determined.The vertical vibration of the steel truss pedestrian bridge is analyzed by the pedestrian walking force model based on Fourier trigonometric series,and the interaction of the human bridge is simplified as the model.The problem of forced vibration.2.the finite element model of the steel truss pedestrian bridge is built with Midas software,and the model is analyzed by the eigenvalue.The stiffness of the bridge structure is large and the first vertical fundamental frequency of the structure is far greater than the normal walking frequency of the pedestrian.3.Midas software is used to analyze the dynamic response of pedestrian bridge under the condition of normal walking,jogging and fast running,and the general response law of the bridge under the action of the crowd is obtained.4.the dynamic response of pedestrian bridge when multiple pedestrians cross the bridge are analyzed.Finally,it is concluded that there is little change in the speed response of pedestrians after batches crossing the bridge,while the acceleration response of the structure decreases significantly.5.from the three angles of deflection,axial force and bending moment,the impact of pedestrians on pedestrian bridges is analyzed.It is concluded that the impact effect of human load on the flyovers can not be ignored.The calculation of the pedestrian bridge can not be simply replaced by the static load effect of the pedestrian bridge with the effect of self weight on the pedestrian bridge.6.the dynamic response of footbridge under forced load and full load is discussed.The Matsumoto assumption is used to simplify the crowd load and to load the flyover.The structural dynamic response of footbridge under full load condition is obtained.7.according to the results of the dynamic response of the footbridge under full load condition,the vibration comfort degree of the pedestrian bridge is evaluated by 6 existing codes abroad.The results show that the response of the flyover can meet the requirements of various countries.