Study On Wind Load Characteristics Of Long-span Gable Roof And Prediction Of Wind Pressure

The large-span roof structure has been widely used in stadiums,airport terminals,exhibition centers and other buildings because it can provide a large area of column-free space.These roof structures have the characteristics of large span,light weight,small damping and low natural frequency;And they are located in the area of high turbulence near the ground,where the phenomenon of air flow around and aerodynamic effects are quite complex;Wind load has become one of the control loads for such structural design.This structure’s area is large,and the number of wind pressure measurement points in the rigid model pressure test often cannot meet the actual engineering finite element nodes,which is inconvenient for the refined large-span structure wind resistance design.It is necessary to predict wind pressure for unknown areas based on limited wind pressure data.In this paper,based on the orthogonal decomposition method(POD)method,different interpolation functions are used to predict the wind pressure field,and the applicability of these methods to the wind pressure prediction of large-span structures is studied.Thus,a POD-GRNN method,a wind load prediction method for long-span structures,is proposed.The main research results of this article are as follows:(1)In this paper,a wind tunnel test of a large-span gable roof model under different wind fields was carried out to study the wind pressure distribution characteristics of the roof.It is found that the mean wind pressure coefficients at different wind directions in different wind fields are all negative,that is,the entire roof is subjected to wind suction.Affected by surface roughness and incoming turbulence,the mean wind pressure coefficient under the effect of uniform flow is larger than that of terrain category A and C.The increased turbulent components in the incoming flow increase the fluctuating energy,and the value of the fluctuating wind pressure coefficient is inverse.(2)The POD decomposition on the fluctuating wind pressure field was carried out.The fluctuating wind pressure field was rebuilt,and the effect of the reconstructed modal number,the location of the measuring point and different turbulence fields on the reconstruction result was analyzed.Different interpolation functions are used to predict the mean wind pressure coefficient and fluctuating wind pressure coefficient,and combine with the POD method to predict the fluctuating pressure time series.The time domain and frequency domain characteristics of the predicted fluctuating pressure are analyzed,and the applicability of different interpolation functions in predicting the wind pressure field of large-span roofs is discussed.(3)The generalized regression neural network(GRNN)and POD method are used to predict the of the large-span gable roof’s mean wind pressure coefficient,fluctuating wind pressure coefficient,and the time series of fluctuating pressure.A high-precision prediction method for wind pressure on large-span structures-POD-GRNN method is proposed.The research shows that,compared with the ordinary interpolation function,in the prediction of wind pressure coefficient,the result predicted by the GRNN in the area within the range of the cylindrical vortex is closer to the test value.And the time and frequency domains of the wind pressure field predicted by POD-GRNN are more consistent with the test values.The proposed POD-GRNN method is also used to predict the wind load of a square large-span roof,and it also obtains good prediction accuracy,indicating the superiority of this method.