Study On Pedestrian Comfort And Wind-induced Buffeting Of Special-Shaped Cable-stayed Bridge

Bridge is one of the important ways to improve the beauty of the city.Each big city also strives for ’one bridge and one scene’ when designing urban bridges.Therefore,the shaped cable-stayed bridge with a beautiful shape has been widely used in urban bridge construction.The tower of special-shaped cable-stayed bridge is inclined or curved,and the section is complex.The force of the tower structure is complex,and the aerodynamic coupling between the tower and the main beam is obvious.At the same time,the modern bridge gradually tends to be long and thin,which leads to the decrease of the overall damping and stiffness of the bridge structure,and the main beam section tends to choose streamlined section,which makes the aerodynamic performance of the bridge more complex.The superposition of the above factors will lead to the increasingly prominent problem of the dynamic coupling between the bridge structure and the natural wind field.Therefore,the buffeting response law originally applicable to the ordinary cable-stayed bridge is not necessarily applicable to the specialshaped cable-stayed bridge.The research on special-shaped cable-stayed bridge started late.In the current domestic specifications,the wind resistance design of cable-stayed bridges is ordinary multi-tower cable-stayed bridges.The wind resistance design of special-shaped cable-stayed bridges is not involved,so the research on wind-induced vibration of specialshaped cable-stayed bridges has high engineering significance.Based on a special-shaped cable-stayed bridge in Xiamen,the finite element model of the special-shaped cable-stayed bridge is established in this paper.Firstly,the dynamic characteristics and static response of the bridge are analyzed,and the correctness of the finite element model is verified.Secondly,the human-induced vibration comfort of the bridge is briefly evaluated based on the current specification,and the influence of walking mode,pedestrian number,pedestrian step frequency and other factors on pedestrian comfort is studied.The influence of crowd load on the dynamic characteristics of the bridge is analyzed,which lays the foundation for the production of wind tunnel experimental model.Then the wind tunnel test and numerical simulation method are used to analyze the three-component coefficients of the main girder and the pylon section of the special-shaped cable-stayed bridge,and the fluctuating wind speed time history of the main girder and the pylon.Based on the quasi-steady theory,the time domain model of the aerodynamic self-excitation is obtained,and the fluctuating wind speed time history of the main girder and the wind effect of the pylon of the two calculation models are calculated.On this basis,the effects of self-excited force and tower wind effect on the buffeting response of the bridge were studied and compared with the wind tunnel test results.The study shows that the vertical displacement of the main girder is less affected by the tower wind effect,but the lateral displacement response of the tower and the lateral and torsional displacement responses of the main girder are greatly affected by the tower wind effect,and the increase in the lateral displacement response of the tower is obvious.At the same time,the self-excited force will make the displacement response of the main beam of the bridge slightly reduced,but the influence is small.The wind effect of bridge tower calculated by standard method is safe.