Hurricane Wind Hazards and Design Risks in the United States

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The Phase 1 of the project investigated basic assumptions used in hurricane risk assessment, with emphasis on developing and evaluating hurricane windfield models. A new windfield model, based on the results of a numerical hurricane boundary layer model, was developed with gust factor information derived exclusively for hurricanes. The model includes the effect of storm translation in a more realistic fashion than does the windfield model used to develop ASCE 7-88 design windspeeds. Using the new model and analyses, site- specific numerical simulations of hurricane windspeeds at Miami and New York City have been performed. These simulations indicate that the selection of the subregion used to derive statistical distributions of key parameters is critical. In addition, the new windfield model was found to have a pronounced effect on the predicted windspeeds, particularly in the New York area, where the asymmetries in fast- moving storms are significant. The Phase II of the project centers on research leading to fundamental improvements in hurricane risk analysis and the reduction of the biases and uncertainties associated with the prediction of hurricane windspeeds. Particular emphasis will have nationwide significance and, if successful, influence future wind load design criteria in the United States and other countries where hurricanes are important contributors to extreme wind frequencies. Some potential application of results from this research will be: wind loading recommendations by region; specialized structural loading and analysis products for specific categories of structures, such as transmission towers; risk analyses for offshore facilities; site-specific analysis and design recommendations.