Evaluation Of Vibration Comfort Of Footbridge Under Wind Load And Pedestrian Load

In recent years,the prosperity of the national economy provides institutional and material guarantee for the rise of tourism.More and more people choose to go out in the golden week.In a short period of time,a large number of tourists swarmed into the scenic spot,and the number of tourists increased sharply.In the short period of time,the scenic spot even fell into a state of paralysis.In order to alleviate the problem,the scenic area will choose to build a large number of pedestrian bridges.However,footbridge has the characteristics of light weight and slender,and it is easy to produce excessive vibration and comfort problems under wind load and pedestrian load,so it is necessary to evaluate its vibration comfort.Up to now,test and measurement or finite element time history analysis are often used to evaluate the comfort of pedestrian suspension bridge.These two methods are often time-consuming,labor-consuming and even consume a lot of resources.Therefore,it is urgent to find a method to quickly evaluate the comfort of pedestrian suspension bridge.Through consulting a large number of literature,it is found that there are few research results considering wind-pedestrain-bridge system when evaluating the vibration serviceability of pedestrian suspension bridge under the combined action of wind load and pedestrian-induced forces.Yet,pedestrians are highly sensitive to structural vibration,and they can adjust their walking movements autonomously according to the vibration of the structure,resulting in the walking f orce being large or small,so as to keep the body balanced and maintain the stability of the walking process.Therefore,when evaluating the vibration comfort of pedestrian suspension bridge under the combined action of wind load and pedestrian-induced forces,wind-pedestrain-bridge system should be considered.In view of this,this paper has done the following work and research:(1)This paper introduces the research status of pedestrian walking structural vibration and structural vibration under wind load systematically,as well as the evaluation criteria of vibration comfort in various countries.After comparing the comfort standards of various countries,I decided to use the comfort limit value formulated in EN03-2007 to evaluate the vibration comfort of footbridges under different working conditions.(2)After a lot of research,I proposed an efficient evaluation method(FRF)to evalute the vibration comfort of human-induced vibration of footbridge.Taking a simple supported bridge as an example,the vibration comfort of pedestrian bridge in the middle of span is collected through the experiment when eight groups of pedestrians walk tests with different numbers of pedestrians are conducted,establishing the ANSYS model of simple supported beam br idge,then calculate the vibration comfort of the model in the middle of span under the same working conditions.Analyzing the results to verify the accuracy of FRF method in calculating the vibration comfort of footbridge.Taking a pedestrian suspension bridge as an example,by comparing the time history analysis results and FRF prediction values,it is verified that FRF method has higher accuracy in vibration comfort evaluation of pedestrian suspension bridge,and has higher calculation efficiency and saves computer memory compared with time history analysis.(3)Introducing the simulation theory of fluctuating wind in detail,and introducing the simulation process of fluctuating wind.The fluctuating wind field is simulated by MATLAB software,and the power spectr um and coherence function are tested to ensure the accuracy of wind field.Then,basing on finite element,a 3D buffeting time domain analysis program considering instantaneous wind attack angle is developed,which lays a solid foundation for the establish ment of wind man bridge coupling model.Then the wind pedestrian bridge coupling model and wind bridge coupling model are established,and the mid span peak acceleration and comfort evaluation results of the two models under different working conditions ar e compared.The results show that considering the wind pedestrian bridge coupling has a significant impact on the vibration comfort of pedestrian suspension bridge under complex working conditions.