Research Of Stress Behavior And Human-induced Vibration Of Cable-stayed Pedestrian Suspension Bridge

In recent years,with the improvement of the aesthetic requirements of the bridge,a large number of flexible,large-span and beautiful pedestrian bridges have appeared,and the number of cable-supported pedestrian suspension bridges directly supported on the main cable has gradually increased.The cable-supported footbridge is flexible and has low natural vibration frequency.It is easy to fall into the range of pedestrian walking frequency and cause human-bridge resonance,which affects the comfort of pedestrians.However,there are few studies on this type of bridge.In this thesis,a cablesupported pedestrian suspension bridge in a scenic area was taken as the background,and the finite element model was established by using Midas / Civil finite element analysis software.The static and dynamic characteristics,bending and torsion coupling characteristics and human-induced vibration response of the cable-supported pedestrian bridges with different structural parameters were analyzed,and the vibration reduction control was studied.The main research contents and conclusions of this thesis are as follows:(1)The influence of the rise-span ratio of the main cable,the rise-span ratio of the wind-resistant cable and the inclination angle of the wind-resistant cable on the static performance of the cable-supported pedestrian suspension bridge was analyzed.It is found that the internal forces of the main cable and the wind-resistant cable are inversely proportional to their respective rise-span ratios;(2)The natural vibration characteristics of the cable-supported pedestrian suspension bridge were analyzed.It is found that the vertical bending mode is not coupled with other modes,but the transverse bending mode is coupled with the torsional mode.With the increase of the vibration order,the vibration mode gradually changes from the transverse bending mode to the torsional mode.The vertical bending frequency increases with the decrease of the rise-span ratio of the main cable and the wind-resistant cable and the increase of the inclination angle of the wind-resistant cable;(3)The human-induced vibration analysis and comfort evaluation of the cablesupported pedestrian suspension bridge were carried out according to the loading method of the German EN03 specification.It is found that the maximum acceleration of the main girder mainly depends on the reduction coefficient of the pedestrian load,the loading method based on different modes and the position of the main girder node that produces the maximum acceleration;(4)The influence of pedestrian load on the maximum acceleration of the structure was analyzed.In the evaluation of pedestrian comfort,the maximum vertical acceleration of the main beam can be calculated by the most unfavorable vertical loading with the same frequency in the center of the bridge deck according to the vertical bending mode.However,for the lateral acceleration,the influence of the eccentric vertical force needs to be considered;(5)According to the comfort evaluation results,the vibration control of the original bridge model was carried out.Through the preliminary setting of the multiple tuned mass damper system(MTMD)and the optimization of the relevant parameters of the vibration reduction system,the pedestrian is arranged in a medium comfort range when passing through the bridge.