[ ] Preliminary Results of Full-Scale Monitoring of Hurricane Wind Speeds and Wind Loads on Residential Buildings Peter L. Datin Graduate Research Assistant David O. Prevatt Director and Assistant Professor Wind Load Test Facility Department of Civil Engineering Clemson University

[ ] Outline Introduction The Florida Coastal Monitoring Program (FCMP) Goals of the FCMP In-field experimental methods –Mobile tower system –Instrumented houses –Public access to collected data Wind tunnel testing Preliminary results – comparison of full-scale to wind tunnel Summary and preliminary observations Future work

[ ] Introduction Hurricanes continue to cause severe damage to residential structures Historically, these tests derived from frontal weather systems Need to validate wind tunnel results for extreme wind events Wind tunnel tests can only provide limited knowledge of wind loads on full-scale structures Necessary to improve our understanding of the wind-structure interaction during extreme wind events

[ ] The Florida Coastal Monitoring Program was started in 1998 Research venture between –Clemson University –University of Florida –Florida International University –Institute for Business and Home Safety Sponsored by: –Florida Department of Community Affairs –SC and FL Sea Grant Consortia Objectives –In-field measurement of hurricane wind velocities and wind-induced pressures on residential buildings –Wind tunnel studies to compare with full-scale data FCMP mobilizes before a hurricane makes landfall placing instrumentation in the path of the storm

[ ] Portable Hurricane Instrumentation 32 homes in Florida and 6 in the Carolinas are pre-wired to be instrumented Absolute pressure transducers record pressures at critical locations on the roof Establish a reference pressure to measure atmospheric pressure that must be subtracted from the absolute pressure to obtain actual wind pressures Stiff 10-meter towers placed in hurricanes path Measure wind velocities, temperature, barometric pressure, etc. Pressure Sensors Computer Box

[ ] Public Access to Collected Data High resolution wind speed data available –10 Hz sampling rate –15-minute mean wind speed –3-second gust wind speed Available in near real-time on the FCMP website Used in official NOAA tropical cyclone reports FCMP Website

[ ] Measured Hurricane Ivan Wind Speeds Measured wind speeds during Hurricane Ivan (2004) converted to 3-second gust at 10-meters

[ ] Atmospheric Boundary Layer Wind Tunnel Atmospheric boundary layer wind tunnel Open circuit wind tunnel 3-meters wide by 2- meters high Total length – 100 feet Can simulate various terrains Model sizes from 1:50 to 1:500

[ ] Pressure Coefficients Non-dimensional quantification of wind pressures Can derive pressure coefficients from full-scale and wind tunnel Derive pressure coefficients based on 3-sec gust wind speed Allows direct comparison between full-scale and wind tunnel values Allows direct comparison with building code provisions

[ ] Example: FL-27 (GBB)

[ ] FL-27 Measured Wind Speeds Tropical Storm Isidore (2002)Hurricane Ivan (2004)

[ ] FL-27 Sensor Layout and Model Tropical Storm Isidore Peak Wind Direction Hurricane Ivan Peak Wind Direction

[ ] Preliminary Results – Peak Minimum Cp Values

[ ] Model 0.25 Full-Scale y = x R 2 = y = x RMS of Pressure Coefficients Full-Scale vs. Wind Tunnel Model Full-Scale y = x y = x – 0.5 Mean Pressure Coefficient Values RMS of Pressure Coefficients Model 0.25 Full-Scale y = x R 2 = y = x Full-Scale Model y = x y = x – Peak Minimum Pressure Coefficients Continuing research to determine sources of error Possible sources of error: –Inaccurate regression analysis –Wind tunnel models do not accurately simulate turbulence and wind speed for suburban terrain –Limitations of instrumentation accuracy Adjustments to data: –0.5C p corresponds to 2 psf in full-scale –20% increase in model C p based on a different estimate of terrain roughness –By applying these changes there is close agreement between model and full-scale values

[ ] Adjusted Results Cp Values Pressure Tap Location

[ ] Summary and Preliminary Observations Meteorological data used in civil engineering applications to provide greater understanding of wind characteristics and interaction with structures Unique data set on common residential building shapes subjected to hurricane force winds Linear regression shows agreement between full- scale and model scale, but this may not accurately represent the data distribution Loads measured at full-scale may not represent the worst wind loading condition since it is only from one wind direction First step in addressing continuing failures in components and cladding of residential buildings

[ ] Future Work Development of a reliability model of the data to provide a statistical basis for estimating the wind loads Further analysis of collected data from 5 additional houses in 2004 and another 5 in 2005 Distribution of wind loads through the structure Continuing importance in collecting and making meteorological data available to the research community Future research results will be posted at: davidoprevatt.com