POD Technique And Its Application To Wind Pressure Fields On Roof

The Proper Orthogonal Decomposition (POD) is an optimal decomposition of random fields in terms of an energy representation. The principle of POD is deduced by the Mercer theorem and the concept of Rayleigh quotient and its extreme property. A study of reconstruction and prediction of wind pressure field on roof using the proper orthogonal decomposition (POD) is presented. The wind tunnel tests of a pitched roof and dome-like roof are conducted by using the synchronous multi-pressure scanning system. Based on POD technique, the pressure field of the roof has been reconstructed by the first several proper modes. The pressure time series on locations of the roof where the pressure taps are not distributed have been predicted by two schemes. The interpolation technique is adopted to obtain the proper modes on locations without taps in the first scheme. In the second scheme two measurements are involved for a reference roof and a new roof which is to be predicted, respectively. The proper modes extracted from the measurement of the reference roof and the principal coordinates computed via pressure data from the measurement of the new roof are combined to obtain the pressure time series on the unknown regions of new roof. The statistics, such as the mean value, root mean square value, peak value, time-history curves and auto-spectra of the predicted pressures have been compared with those of the measured pressures. At last, the wind-induced responses of roof are calculated and compared by using the predicted pressure data and the measured pressure data. The effectiveness of the proposed prediction approach is examined by analyses of the wind-induced responses of the roof, obtained from the calculation with Load-response-correlation(LRC) method for pitched roof and Complete-Quadratic-Combination (CQC) method for dome-like roof.