Analysis Of Wind-induced Response Of Large-span Annular Open-web Cable-truss Structures

The large-span annular open-web cable-truss structure has the advantages of light weight,large span,and convenient construction.It is particularly suitable for large stadium buildings.Due to its large flexibility,it is easy to generate large vibrations and deformations under wind excitation.Wind load is an important control load in the design of this kind of structure.If wind load is handled improperly,this kind of structure will be damaged and destructed,leading to significant losses.However,there is currently only a wind-vibration formula for the vertical cantilever type structure in our country's specification,and large-span structure is not involved.At present,there are few research results related to the wind-induced vibration response of annular open-web cable-truss structures.In this paper,a series of studies have been carried out on the wind-induced vibration response characteristics of annular open-web cable-truss structures,and the equivalent static response expression of the structure has been established,which provides a reference for the wind-resistant design of the structure.The main research contents and achievements of this article are as follows:Using Singular Value Decomposition(SVD)technology,the initial force distribution of the annular open-web cable-truss structure was obtained,in order to fix its initial configuration.The balance matrix of the framed structure is established.Based on its rank,whether the structure can bear prestress can be determined.The feasible prestress of the annular open-web cable-truss structure was derived.After obtaining the initial force distribution,the finite element model of this structure was obtained.By calculating its displacement under static load,the applicability of the finite element model of the structure is verified.The distribution of wind pressure on the surface of the structure was simulated by using Fluent,for the sake of obtaining the shape coefficient of the annular open-web cable-truss structure.Based on the AR model in the linear filter method,fluctuation wind speed time series with spatial correlation is simulated in MATLAB.The simulated wind speed spectrum was obtained by using the Fourier transform,and compared with the target spectrum to verify the simulation result.Finally,the numerical simulation of wind pressure was attained by using Fluent,then the shape coefficients of on the upper surface of the structure were obtained,so the conversion from the wind speed time series to the wind load time series was achieved.The wind vibration coefficient was given based on the response of annular open-web cable-truss structure.The dynamic characteristics of the structure such as natural frequency,mode shape and damping was analyzed in ANSYS.The wind-induced response is solved in the time domain,including the displacement time history of each node and the internal force time history of each element.The theoretical formula of the peak factor is introduced.Combined with the fundamental frequency of the annular open-web cable-truss structure,the recommended peak factor is 4.1.The concept of the response wind vibration coefficient was applied to the design of annular open-web cable-truss structure.Based on the mean value and standard deviation of the time-history results,the overall displacement wind vibration coefficient of the CC-type structure(the inner and the outer rings are all circular)is calculated as 2.05,and the overall force wind vibration coefficient is calculated as 1.48.The expression of the equivalent static wind response of the annular open-web cable-truss structure was established.The concept of nonlinear adjustment coefficient was introduced to establish the relationship between the mean value of wind-induced vibration and the static response under average wind load.Considering the difference in basic wind pressure,initial force level,mast height,and structural shape of different structures,the influence of the above-mentioned parameter changes on the overall wind vibration coefficient is discussed.The parametric analysis shows that increasing the basic wind pressure and the initial force level will reduce the overall wind vibration coefficient of the structure,and reducing the mast height has a similar effect;compared to the CC type cable truss structure,the EE type(the inner and the outer rings are all elliptical)cable truss structure has a slightly larger overall wind vibration coefficient.The software simulation results of the wind vibration coefficient well agree with the conclusion of the actual structure wind tunnel test.The displacement and force increments obtained by the equivalent static method well envelope the extreme values of the corresponding results of the time-history method,illustrating the applicability of the equivalent static method.