Study On Reynolds Number Effects Of Streamlined Section Of Long Span Bridge

At present,the relevant design parameters of wind load in bridge wind resistant design are obtained through wind tunnel test.The three force coefficient is not only one of the important factors that affect the stability and safety of long-span bridges,but also an important parameter for other influencing factors.It has been considered that the Reynolds number effect of the three component coefficient with sharp edges is negligible.However,vortex induced resonance has occurred in the East approach bridge,and its starting wind speed is lower than that in low Reynolds number wind tunnel test.It can be seen that there are differences in the aerodynamic characteristics of the main girder under different Reynolds numbers.As a typical large span bridge section,streamlined bridge section is often used in long span bridges.It is very necessary to study the Reynolds number effect of the aerodynamic coefficient of the line type bridge section.In view of the above problems,the main works are listed as follows:Two kinds of streamlined bridge sections with the same width to height ratio but different local section are selected for low speed wind tunnel tests.The three component coefficient of the test model in a certain Reynolds number range is obtained by pressure integration,and the variation rule with the Reynolds number is studied.The distribution characteristics of the average pressure coefficient on the surface of a streamlined bridge section in the range of Reynolds number are described,and the influence of Reynolds number are explored.By reducing the length of pressure measuring pipeline,we get the real pressure information of the model surface,and study the fluctuating pressure distribution characteristics of the model surface and the variation rule of pressure gradient with Reynolds number.Through collecting and sorting out the existing streamlined bridge section test data,it is found that the difference of aerodynamic coefficients of streamlined bridge girder is larger under high and low Reynolds number,but the aerodynamic coefficient does not change after the critical Reynolds number.The aerodynamic coefficients of several similar streamlined box beams have the same rule as the change of Reynolds number.Using the characteristics of orthogonal decomposition method based on power spectral density matrix(SPT),the study of fluctuating wind pressure field on the typical streamlined box girder section is carried out carefully.The energy distribution in the form of wind pressure pulsation on model surface leading vortex frequency is found,and the effect of air flow in the mold surface is more intuitive.