مدل سازی تونل باد و تجزیه و تحلیل اثرات باد در کم افزایش ساختمان
Abstract: Wind tunnel modeling is a robust technique which allows determination of wind effects on buildings and other structures. Due to complexity of flows and induced wind loads, other techniques can not be reliably used in practical analyses of such effects. Information deduced from wind tunnel testing has been successfully employed in development of design guidelines and in direct applications in wind-resistant design of variety of structures, including low-rise buildings. Although wind tunnel modeling of wind loading has been generally accepted as a viable tool, over the years a number of questions regarding accuracy and limitations of this technique have been raised. Some of the questions related to modeling of wind loading on low-rise buildings were addressed in the research described in this dissertation. Investigation of reported discrepancies in the laboratory-field and inter-laboratory comparisons was one of main focuses of this study. To identify the origins of the discrepancies, careful studies of reported wind tunnel set-ups, modeling of field/target approach wind conditions, measurement techniques and quality of obtained data and data analyses were carried out. Series of experiments were performed in boundary-layer wind tunnels at the Wind Engineering and Fluids Laboratory, at Colorado State University, to aid these analyses. It was found that precise matching of characteristics of approach field wind and flows modeled in wind tunnels was essential to ensure compatibility of the simulated building wind loads. The issue of the accuracy of predictions of the extreme wind-induced loading based on the results of wind tunnel modeling was addressed. In this investigation, the peak wind-induced pressures on low-rise buildings were analyzed using two advanced techniques: the extreme value distribution theory (GEV) and the peak-over-threshold approach. The extreme roof suction pressures predicted from these two approaches were compared with field observations. The degree of convergence of the EVD fits was discussed for Type I and Type III EVDs. The advanced experimental tool, electronically-scanned 1024-channel pressure measurement system, was developed and employed in wind tunnel modeling of wind loads on low-rise building. The wind-induced pressures were simultaneously acquired at 990 locations uniformly distributed over the surfaces of a model of a generic low-rise building. The Proper Orthogonal Decomposition (POD) analysis was performed to capture the spatio-temporal characteristics of the acquired pressure field. It was found from POD analysis that the pressure data sets can be substantially reduced, while preserving the main spatio-temporal features of the building wind loading.