Buffeting Fatigue Analysis Of Bridge Girder Considering Uncertainty Of Turbulence Parameters

With the advancement of science and construction technology,as well as the increasing travel needs of people,the bridge structure is rapidly developing in the direction of large spans and flexibility,which in turn makes the bridge’s sensitivity to wind loads continuously increase.On the one hand,wind load may cause excessive deformation or vibration of the structure,which seriously affects the safety and comfort of the structure.On the other hand,when the wind load acts on the structure for a long period of time,fatigue damage or even fatigue failure may occur inside the structure.At present,for the analysis of fatigue damage,most of the structural parameters including the relevant parameters of atmospheric turbulence are regarded as definite values,and then the corresponding calculations are made.However,in actual engineering,fatigue failure of a structure is a complicated process affected by many uncertain factors.If these factors are ignored,it may cause a larger error between the calculation result and the actual situation.Therefore,this paper considers the uncertainty of turbulence parameters in the calculation of structural wind-induced response and combines the Nataf transform to deal with the correlation between the parameters and the improved frequency domain T-B spectrum method to analyze the buffeting fatigue damage of long-span bridges.The specific content includes:1.Briefly introduce the domestic and international research status of structural fatigue damage analysis methods,bridge buffeting fatigue research and sources of uncertainty.2.Briefly introduce the basic concept of fatigue and the calculation method of structural fatigue damage in time and frequency domain,including improved frequency domain T-B spectrum method.3.Introduced the definition of atmospheric turbulence and turbulence parameters,and analyzed the uncertainty of different turbulence parameters which correlation were dealt with by Nataf transform.Then,based on the improved TB spectrum method,the alongwind fatigue damage analysis of a structure was carried out.It shows that considering the uncertainty of the turbulence parameters makes the average fatigue damage of the structure increase,and the increase is related to the wind speed,damping ratio and material parameters,of which the exponential decay coefficient has the most obvious effect.4.Taking a long-span bridge as example to analyze the buffeting fatigue of the bridge girder considering the uncertainty of turbulence parameters.The study found that considering the uncertainty of the turbulence parameters increased the calculated average fatigue damage value of the long-span bridge,and has strong fluctuation,may even make the calculated nominal fatigue life greatly reduced.Therefore,in the analysis of structural fatigue damage,it is necessary to consider the uncertainty of turbulence parameters and selecting the appropriate turbulence parameters is very important for practical engineering.