MEASUREMENT, MODELING AND SIMULATION OF GROUND-LEVEL TROPICAL CYCLONE WINDS By FORREST JAMES MASTERS A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2004 Copyright 2004 by Forrest James Masters ACKNOWLEDGMENTS Kurtis Gurley, Luis Aponte, Gary Consolazio, Jennifer Jacobs, Perry Green, Lou Cattafesta, Tim Reinhold, Scott Robinette, Jon Lamb, Cos Gardener, Greg Kopp, Mark Powell, Eric Ho and Peter Vickery deeply deserve my gratitude. Only with their gracious support did this document make its way into your hands. iii TABLE OF CONTENTS Page ACKNOWLEDGMENTS ................................................................................................. iii LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii ABSTRACT..................................................................................................................... xiii CHAPTER 1 INTRODUCTION ........................................................................................................1 The Hurricane Wind to Damage Chain ........................................................................1 Research Underway......................................................................................................2 Florida Coastal Monitoring Program.....................................................................3 Hurricane Loss Reduction Project.........................................................................4 Scope of Research.........................................................................................................5 2 HURRICANE DAMAGE MITIGATION RESEARCH..............................................6 Sources of Wind Speed Data ........................................................................................6 Use of Permanent Instrumented Towers ...............................................................9 Use of Portable Instrumented Towers .................................................................10 Current Wind Load Design Provisions and Standards ...............................................18 American Society of Civil Engineer’s Minimum Design Loads for Buildings and Other Structures (ASCE 7-02) ..................................................................18 Applicability of the Current Standard .................................................................20 Reliability-Based Database-Assisted Design .............................................................22 Summary.....................................................................................................................25 3 ANALYSIS AND SIMULATION TECHNIQUES FOR WIND ..............................27 Characterization of Ground-Level Hurricane Winds .................................................27 Mean Velocity Profile .........................................................................................28 Turbulence Characteristics ..................................................................................32 Estimation of Roughness.....................................................................................37 Correlation and Spectral Relations......................................................................39 Stochastic Simulation Methods ..................................................................................42 Spectral Representation.......................................................................................43 iv Random Variable Transformation.......................................................................44 Existing Simulation Techniques.................................................................................46 Spectral Correction..............................................................................................53 Application of Simulation for the NIST Project: Interpolation of Existing Time Histories..................................................................................................58 Summary.....................................................................................................................58 4 FULL-SCALE MEASUREMENT OF TROPICAL CYLONE WINDS...................60 Deployment History, Organization and Logistics ......................................................60 Irene (1999) .........................................................................................................61 Gabrielle (2001)...................................................................................................62 Isidore (2002) ......................................................................................................62 Lili (2002)............................................................................................................63 Isabel (2003)........................................................................................................65 Satellite Tower System...............................................................................................68 Real-Time Data Acquisition.......................................................................................71 Internet Upload Capability ..................................................................................73 Continuous Data Acquisition ..............................................................................74 Automated Processing of Data ............................................................................74 Improved Graphical Interface..............................................................................75 Improved Flexibility............................................................................................77 Outcomes of Hurricane Isabel ....................................................................................77 Impact on Meteorology .......................................................................................77 Impact on Emergency Management....................................................................80 Summary.....................................................................................................................81 5 ANALYSES OF TROPICAL CYCLONE WIND DATA.........................................86 Experimental Assumptions.........................................................................................87 Concerning the Hurricane Boundary Layer ........................................................87 Concerning Experimental Rigor..........................................................................88 Concerning the Homogeneity and Flatness of Upwind Terrain..........................88 Data Reduction ...........................................................................................................91 Data Analyses .............................................................................................................92 Turbulence Intensities .........................................................................................93 Comparison to Known Gust Factor Curves.........................................................95 Formulation of Gust Factor Curves based on a 10-Minute Wind Speed for Varying Gust Durations and Roughness Lengths..........................................104 Integral Length Scales .......................................................................................109 Spectral Models.................................................................................................111 Summary...................................................................................................................113 6 MULTIVARIATE STOCHASTIC SIMULATION OF WIND PRESSURE OVER LOW-RISE STRUCTURES.........................................................................115 Methodology.............................................................................................................117 v Overview ...........................................................................................................117 Wind Tunnel Data Sets......................................................................................118 Cases Studied.....................................................................................................119 Interpolation Overview......................................................................................120 Interpolation of the Probability Targets ............................................................120 Validation of CDF Interpolation Concept .........................................................121 Interpolation of the Spectral Targets .................................................................124 Validation and Limitations of the Simulation Algorithm..................................126 Accuracy of the Simulation Algorithm .............................................................127 Results.......................................................................................................................129 Comparison of Peak Aggregate Uplift ..............................................................129 Summary...................................................................................................................136 7 CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE RESEARCH....137 Contributions to Full-Scale Measurement