Analysis Of Mechanical Characteristics And Buffeting Response Of Stiffened Beam Narrow Suspension Bridge

The long-span narrow suspension bridge structure is often built in an environment with complex terrain and harsh conditions due to its superior terrain capability,uniform internal force distribution,and economical and beautiful structure.The stiffening beam width is generally set between 2m and 5m,and as the span continues to increase,the high span ratio and the wide span ratio of the overall structure are drastically reduced,so that the vertical and lateral stiffness of the narrow suspension bridge is reduced.Therefore,the dynamic stability of the overall structure of the bridge is poor.It is easy to generate large amplitude under external load excitation,which reduces the comfort of pedestrian vehicles.In summary,the wind-resistant design is extremely important for the large-span stiffened beam narrow suspension bridge.However,the domestic special specifications and norms for the design of such bridge structures are not sufficient enough.The wind-induced vibration characteristics of deep-span long-span suspension bridges are also studied.Lack of it.This paper takes the Gouertan bridge of Xingshan County in Xingshan County,Hubei Province as the engineering background.The hook-up bridge of the Goering Beach is located in Gudongkou Reservoir,Xingshan County,Hubei Province.The total length of the bridge is 185.4m and the bridge span is(15.5+150+15.5)m.The main bridge is a 150 m ground anchored single-span double-hinged suspension bridge.The bridge span loss ratio is 1/15,the bridge full width is 4.0m,the road width is3.5m,and the width to span ratio is 1/37.5.Firstly,the theoretical analysis and numerical modeling of the wind field of the large-span narrow suspension bridge are carried out,then the refined finite element calculation model of the narrow suspension bridge is established,and the static and dynamic characteristics analysis,static wind stability analysis and buffeting response analysis of the narrow suspension bridge of the Gouertan beach are carried out.Finally,considering the parameters of main cable stiffness,anti-wind cable,main cable vertical span ratio,stiffening beam width and center buckle,the effects of various structural parameters on static and dynamic characteristics,static wind stability and buffeting response are studied.Combined with the above engineering background,the main research contents of this paper are:1)The pulsating wind speed function is simulated by harmonic synthesis method and accelerated by FFT conversion technology.Based on the MATLAB mathprogramming software,the wind field of the long-span narrow suspension bridge is numerically modeled,and the simulated pulsating wind speed and pulsating wind power spectrum are tested.Wind loads include static wind loads,buffeting forces and pneumatic self-excitation.The static wind load is obtained from the design reference wind speed.The buffeting force is obtained from the downwind to the pulsating wind speed and the vertical wind to the pulsating wind speed.The aerodynamic self-excitation mainly considers the aerodynamic stiffness and aerodynamic damping of the stiffened beam structure,and is simulated by the MATRIX27 matrix unit in ANSYS..2)Using the finite element calculation and analysis software ANSYS,based on the mechanical analysis theory of the suspension bridge,the finite element calculation model of the large-span narrow suspension bridge with different wind-resistant cables,vertical span ratio,stiffening beam width and central buckle is established.3)The finite element model of different structural parameters(main cable span ratio,presence or absence of wind-resistant cable,stiffening beam width,central buckle)is used to analyze the static and dynamic characteristics of the finite element model,and the static and dynamic characteristics of the large-span narrow suspension bridge are compared and analyzed.Impact,static analysis includes: main cable,stiffening beam stress,and axial force at the bottom of the pylon.The dynamic characteristics calculation includes: the natural vibration frequency and vibration mode of the narrow suspension bridge structure,and analyzes the natural vibration frequency corresponding to several typical vibration modes.The calculation results are analyzed,and the force characteristics and vibration mode types of some long-span narrow suspension bridges are summarized.4)Static wind stability The critical wind speed and the torsional divergence critical wind speed are used as the discriminant indicators to evaluate the effects of anti-wind cable,span ratio,stiffening beam span and central buckle on the static wind stability of the structure,and analyze the large span stiffening.Instability development path and instability mechanism of beam narrow suspension bridge.5)Based on the APDL language programming function in ANSYS,the three-dimensional buffeting time domain analysis program of the long-span suspension bridge is compiled.The buffeting response of the long-span narrow suspension bridge is analyzed,and the sagittal ratio,the anti-wind cable,the stiffeningbeam width and the central buckle are compared.The effect of wind-induced vibration response across a narrow suspension bridge.The research content of this paper is a useful supplement to the research and development of the wind-induced vibration characteristics of the long-span stiffened beam narrow suspension bridge,which is of great significance to the practical engineering application,especially for the environment of rivers,lakes and mountains and valleys with poor wind conditions.The wind-resistant design and construction of the large-span stiffened beam narrow suspension bridge has important reference significance.