Partial turbulence simulation method for predicting peak wind loads on small structures and building appurtenances

Large-scale wind tunnel testing is preferred for small structures and building appurtenances for maintaining modeling accuracy and minimizing Reynolds number effects. In these circumstances the ability to obtain a large enough turbulence integral scale is usually compromised by the limited dimensions of the wind tunnel. So, it is not normally possible to fully simulate the low frequency end of the turbulence spectrum. In this paper the approach is taken of dividing the turbulence into two distinct statistical processes, one at high frequencies which can be simulated in the wind tunnel, and one at low frequencies which can be treated in post-test analysis using the assumptions of quasi-steady theory. In this Partial Turbulence Simulation (PTS) method the contribution of both the high and low frequency turbulence on the wind loads on structures is included by using the probability of load from each of the two processes, with one part coming from the wind tunnel data representing the high frequency component and the remainder from the assumed probability distribution (taken in this paper as Gaussian for generic boundary layer flow) of the missing low frequency component. The two processes are approximated as independent of each other. The efficacy and validity of the method and its various assumptions are assessed by comparing predicted local peak pressure coefficients from tests on large scale models of the Silsoe cube and Texas Tech University (TTU) building in the Wall of Wind facility at Florida International University (FIU) with the corresponding full-scale data. Generally good agreement was found between the model results and full scale, particularly when comparing the highest overall peak pressure coefficients. These results, although limited to peak local pressures on the two test buildings for which good full scale data are available, are encouraging and invite further experiments to explore the range of applicability of the PTS method. This method, although developed in the Wall of Wind facility at FIU, can be equally used in conventional boundary layer wind tunnels and has the potential to enhance the ability of existing boundary layer wind tunnel facilities to predict full scale wind loads.