CAREER: Quantifying Wind Hazards on Buildings in Urban Environments

Stanford University, Stanford CA

Investigators

Abstract

Two-thirds of the weather and climate disasters that have occurred in the United States over the past ten years were extreme wind events. Wind-resistant design of buildings plays an important role in securing the nation's welfare and prosperity through reduced building damage, fatalities, societal disruptions, and business discontinuities during these extreme events. Considerable challenges arise as an increasingly large portion of the nation's building inventory is located in urban environments with exposure to extreme wind events. Interference effects, caused by interactions between different building geometries, can increase the local wind speed on buildings by 50% or more compared to the undisturbed atmospheric boundary layer wind speed. Routine calculations for design wind loads do not account for these interference effects and, therefore, significantly can underestimate the wind loading on buildings and result in inadequate building design. The goal of this Faculty Early Career Development Program (CAREER) award is to advance fundamental understanding of wind flow phenomena for the design of resilient and sustainable buildings and urban environments through establishment of computational frameworks that can quantify and, where possible, reduce the uncertainty in computational predictions of these phenomena. The capability to make well-informed decisions based on computational predictions and uncertainty quantification will lead to optimized designs for more wind-resilient and, thus, safer buildings and cities. High school, undergraduate, and graduate students and high school teachers will participate in the research program. The experimental and numerical data sets resulting from this research will be leveraged to establish active learning modules for wind engineering for high school, undergraduate, and graduate students. Workshops held during years two and five of the award will support the education of a diverse community of engineers to understand the complexity of urban flow and wind loading phenomena and the strengths and weaknesses of computational models, wind tunnel tests, and field experiments. The research will use the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Wall of Wind facility at Florida International University and archive project data in the NHERI Data Depot (https://www.DesignSafe-ci.org). This research will establish computational models to quantify the influence of the surrounding built environment on the local wind speed and turbulence and the resulting interference effects on the wind loads on buildings in urban environments. The research plan will involve a comprehensive program of field measurements, wind tunnel tests, and computational fluid dynamics (CFD) simulations with uncertainty quantification and data assimilation. The Engineering Quad on Stanford's campus, which is representative of an urban environment, will serve as a test bed for implementing the research plan. Rather than pursuing a traditional deterministic investigation, novel stochastic methods will be explored to enable comparison of experimental and numerical results with confidence intervals. Specific focus of the research will be on: (1) using data assimilation algorithms to reduce uncertainty related to the inflow boundary conditions, (2) systematic quantification of the effect of geometrical simplifications, and (3) using multi-fidelity algorithms to reduce turbulence model form uncertainties. The research results will provide essential new information on the fitness-for-purpose and integration of models with different levels of fidelity and will indicate the potential of leveraging urban sensor networks to improve the accuracy of the predictions. The research program will result in a fundamentally improved understanding of interference effects and enable considerable advances in CFD modeling for urban flow and wind loading. More broadly, the novel computational strategies resulting from this research will benefit other sustainable urban design problems influenced by wind, such as street canyon and building ventilation, outdoor and indoor air quality, harvesting renewable energy resources, and urban planning for heat island mitigation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.