Study On Wind-induced Vibration Of Double Girder Gantry Crane

With the need of modern logistics,Gantry crane more and more to the direction of large-scale development.As the gantry cranes become more towering,the structure becomes more flexible,Its sensitivity to wind is more and more obvious,and it is easy to produce greater vibration and deformation under the action of wind.At present,the calculation of wind load for hoisting machinery is mainly based on considering the mean wind effect.However,the natural wind can be regarded as two parts: mean wind and fluctuating wind.Moreover,for the thin,long and flexible structures,the effect of fluctuating wind is more prominent than that of mean wind.Therefore,it is necessary to study the wind-induced vibration of large Gantry crane.Based on the basic theory of computational fluid dynamics and numerical simulation of wind speed field,using CFX-Workbench finite element analysis software,taking the double-beam gantry crane as the research object,simulation of two-way fluid-solid coupling numerical wind tunnel under different wind loads and the wind-induced vibration characteristics are analyzed.The main contents of this paper are as follows:(1)Based on the basic theory of the numerical simulation method of the fluctuating wind speed field and the actual wind field environment of Gantry crane,the time history curve of the fluctuating wind velocity is generated.Then the precision analysis and correlation analysis of the generated time history curves are also given.Through the analysis,it is found that the accuracy and correlation of the simulated multi point wind speed are the same as the theoretical ones.(2)Based on the theory of computational fluid dynamics,the appropriate turbulence model is chosen,then an aeroelastic model for Bidirectional fluid-solid coupling analysis is established;Based on the similarity theory of the model design,the method of modal fitting is used to determine the parameters of the simplified Gantry crane model.On the premise of determining the parameters,the simplified physical model and the actual Gantry crane have almost the same low order modal frequencies and the corresponding vibration modes,which have very similar vibration characteristics.(3)Wind tunnel simulation analysis of various special conditions of Gantry crane under the mean wind load is carried out.The results about the distribution of wind pressure and wind speed of the external flow field,and the distribution of wind pressure on the surface of the crane,and the wind force and the displacement of the structure under different working conditions were obtained.Then,the simulation results are compared with the theoretical calculation values and the results of static load method.At the same time,the variation rule of the wind reduction coefficient with the interval ratio is obtained by the simulation of several groups,and the results of the above analysis are further verified.The analysis shows that when only the average wind load is taken into account,the wind reduction coefficient determined by the crane design code(GB3811-2008)(hereinafter referred to as the "code")is larger.At the same time,it is feasible to calculate the theoretical wind load of the gantry crane according to the "standard",and have a greater safety margin.(4)Wind tunnel simulation analysis of various special conditions of Gantry crane under the dynamic wind load is carried out.The results about the distribution of wind pressure and wind speed of the external flow field,and the distribution of wind pressure on the surface of the crane,and the wind force and the displacement of the structure under different working conditions were obtained.Then,the simulation results are compared with the simulation results under the mean wind load and the theoretical values.The results show that the load of the crane under dynamic wind is very different from the "standard",and the fluctuating wind component in dynamic wind has a significant effect on the vibration of crane.