Research On Static And Dynamic Characteristics And Comfort Of Pedestrian Suspension Bridge

Pedestrian suspension bridges are favored by many scenic spots in China because of their unique shape and easy integration with the environment,and many pedestrian suspension bridges have been built in recent years.However,there is no specification for pedestrian suspension bridges in China,so this paper takes a domestic scenic spot pedestrian suspension bridge as the research object,and studies the static and dynamic characteristics and comfort of pedestrian suspension bridges,to derive the influence of structural parameters on the mechanical characteristics and comfort of pedestrian suspension bridges,and give structural selection suggestions for the reference of similar bridges.The details are as follows:(1)By collecting domestic and international data,the history of the development of suspension bridges,the development of calculation theory,and the current research status of pedestrian suspension bridges are outlined,and the research significance and research content of this paper are described.(2)The effects of different stiffening beam arrangements,different main cable spacing,and different wind cable layout mode on the static and dynam ic characteristics of the structure are investigated respectively.For the static characteristics,the effects of the parameter changes on the stress of the main cable,the span displacement of the stiffened beam,and the internal force of the main tower are mainly studied,which are used to optimize the structural parameters of the pedestrian suspension bridge;for the dynamic characteristics,the effects of the parameter changes on the self-oscillation frequency and key vibration pattern of the structure are mainly studied,which are used to adjust and correct the structural parameters under the static analysis results.The results show that in the structural selection,the stiffened girders can be selected as "two longitudinal girders + all diagonal braces",the spacing between the cables can be increased appropriately under the premise of the structural load-bearing capacity,and the wind-resistant cable layout mode can be selected as " inclination angle of 30° + cross diagonal wind resistance cable" or " inclination angle of 30° + cross diagonal wind resistance cable".(3)The existing pedestrian load models were compared,and according to the walking characteristics of pedestrians in China,the single pedestrian force load model in the form o f the Fourier series is adopted,and the crowd loads were converted into synchronic pedestrian load models according to different crowd densities and walking step frequencies,and forty different pedestrian load models were established,and then the synchronic pedestr ian loads were separately applied to the structure in the form of concentrated forces using the influence line principle the maximum vibration response is obtained by applying the synchronous pedestrian load to the most unfavorable position of the structur e individually.After obtaining the maximum vibration response,the comfort of the structure was evaluated according to the EU Euro code.It was found that the comfort level of the structure deteriorates with the increase of the number of pedestrians or st ep frequency on the bridge,so the number of pedestrians and step frequency on the bridge should be strictly controlled to ensure the comfort level of the structure.(4)The effects of changing the spacing of the main cable,the layout mode of the stiffening beams,and the angle of the wind-resistant cables on the comfort of the pedestrian suspension bridge were investigated.The results show that for the background project if comfort is the selection criterion,the sling spacing should be3.0m or 6.0m,the stiffening beam should be "three longitudinal beams + all diagonal braces",and the wind-resistant cable inclination angle should be within 30°～60°.