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Influencing factors in numerical simulation of wind load on buildings
Abstract
Data from full-scale building tests conducted in Texas Tech University are used to quantify the uncertainties associated with the use of computational fluid dynamics to obtain wind load predictions for full-scale structures. It is demonstrated that the effects of computational domain is relatively small, and the effects of grid arrangement, turbulence model and inlet boundary condition are relatively obvious. Finally, guidelines are suggested for reasonable design and suitable choice of turbulence model.
A roof of gable-roofed low-rise building model with body type ratio 1.5: 1: 1 was devided into several regions and numerical simulation of local wind pressure on the roof was carried out. Comparison between the simulation results and wind trnnel test varifies the effectiveness of the numerical method for analysis of wind pressure of low-rise building. Based on the numerical simulation, the influence of relative location change of interference-causing building model on area shape coefficient of wind pressure in local roof region of interference-affected building was analyzed. The results show that in the case of tandem arrangement, the areas shape coefficients of the interfered building decrease obviously because of the occlusion effect of upper reaches' interference-causing building. Under the side-by-side arrangement, the areas shape coefficients of the interfered building increase overall. Under the staggered arrangement, the areas shape coefficients of the interfered building show some regularity, which depends on the influence between gap flow and wake flow.
In this paper, a sort of modeling and meshing method based on the characteristic size of antennas is put forward, which can be used to numerically compute the wind loads. Based on the Reynolds-averaged N-S equations and Renormalization Group k-ε turbulence model (RNG k-ε), the wind loads on antenna are computed in considering of some modeling parameters, such as the sizes of computational domain, grid size. Through the comparison between the results obtained by numerical computation and the ideal value derived by wind tunnel tests, the method of modeling and meshing the computational domain has proved to be effective, and the fitted curves of the drag coefficients show that the computational results for wind loads on antennas will be more accurate if the large sizes of the computational domain and little sizes of the grid are adopted.
This report describes the use of some computer programs written by one of the authors (DP) in predicting mean and peak wind pressures on arched-roof buildings. The research was carried out because there is a lack of good wind-tunnel and full-scale data on arched-roof buildings. The programs have been validated by comparing the results with wind-tunnel and full-scale data associated with the Texas Tech building.
Velocity and pressure fields around a low-rise experimental building located at Texas Tech University are predicted using Large Eddy Simulation ( LES ). The distributions of mean and rms surface pressure coefficients predicted by LES are compared with those of field and wind tunnel measurements. The results of LES correspond very well with the measured data.
A research team led by Mehta at Texas Tech University is carrying put wind-pressure measurements on a low-rise building [1]. These measurements made on the full-scale test building are expected to provide high-quality data for comparison with and verification of scale-model tests performed in wind tunnels. The objects of comparison were wind tunnel tests on models of the building, which were carried out at the Building Research Institute in Japan in order to verify techniques for wind tunnel testing for low-rise buildings. Three scale models, 1:65, 1:100 and 1:150, were used in the tests. The results showed good agreement of wind tunnel tests with tests on the full-scale test building in terms of mean wind-pressure coefficients. But the differences in the coefficients of rms and peak wind-pressure were found to be rather large. The frequency-response characteristics of the pressure-measurement system were one of the most important factors in producing the differences on these coefficients. The effect of size-reduction ratio on the mean and rms wind-pressure coefficients were found to be negligible within the range tested.
The full-scale test building at Texas Tech University represents one of the best instrumented full-scale installations for determining wind loads on low buildings. In particular, it is intended to provide data of the highest quality for comparison with and verification of model scale experiments. In advance of full-scale data from the test building, a model scale experiment was undertaken to define the characteristics of the local pressures, partly to aid in the definition of the full-scale experiment and partly to provide an “unbiased” set of pressures for comparison. This paper describes the model and documents the test procedures in which results were determined for two simulated terrain roughnesses. Representative wind tunnel results are presented, and some comparisons are included with the first reliable data available from the full-scale experiment.