[ ] Preliminary Results of Full-Scale Monitoring of Hurricane Wind Speeds and Wind Loads on...
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Transcript of [ ] Preliminary Results of Full-Scale Monitoring of Hurricane Wind Speeds and Wind Loads on...
[ ]Preliminary Results of Full-Scale Monitoring of Hurricane Wind Speeds and
Wind Loads on Residential Buildings
Peter L. DatinGraduate Research
Assistant
David O. PrevattDirector 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 hurricane’s 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 Websitewww.ce.ufl.edu/~fcmp
[ ]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
2
0
20
0
11
2
p
P P UC
UU
[ ]Example: FL-27 (GBB)
[ ]FL-27 Measured Wind Speeds
Tropical Storm Isidore (2002) Hurricane Ivan (2004)
[ ]FL-27 Sensor Layout and Model
Tropical StormIsidore Peak
Wind Direction
Hurricane Ivan Peak
Wind Direction
[ ]
Tropical StormIsidore Peak
Wind Direction
Hurricane Ivan Peak
Wind DirectionASCE 7-02GCp,min= -2.60
-1.09
-1.17
-3.01
-0.83
-0.71
-0.90
-3.00
-0.71
N/A
-0.57
-2.53
-0.55
-0.87
-1.39
-2.83
-1.10
-0.70
-0.55
-2.52
-0.48
-0.77
-0.52
-2.62
-0.85
-0.69
-0.58
-3.29
-0.59
-0.80
-0.63
-2.72
-0.50
-0.98
-0.52
-2.94
-0.57
-1.02
-0.80
-2.80
-2.63
-1.33
-2.00
-3.38
-2.24
-0.98
-0.64
-2.34
-1.15
-1.50
-2.00
-3.43
-1.46
-1.21
-0.81
-2.52
-0.62
-0.96
-0.71
-3.53
-0.71 -1.06
-1.08
-3.53
-1.21
-1.25
-1.16
-2.75
-1.32
-2.68
-1.64
-3.75
-1.44
-2.29
-1.66
-3.88
-1.39
-1.55
-0.80
-3.11
-1.32
Isidore FS
Isidore WT
Ivan FS
Ivan WT
Preliminary Results – Peak Minimum Cp Values
[ ]
y = 1.0542x
R2 = 0.2097
0.00
0.25
0 0.05 0.1 0.15 0.2 0.25
Model
Fu
ll-S
ca
le
y = x
(135 degrees)
Model
0.25
Ful
l-Sca
le
0.250.20.150.10.0500.00
y = 1.0542xR2 = 0.2097
y = x
RMS of Pressure Coefficients
Full-Scale vs. Wind Tunnel
-1.00
0.00
-1 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0
Model
Fu
ll-S
ca
le
y = x
(135 degrees)
y = x - 0.5
Model
Ful
l-Sca
le
-1 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0
1.0
y = x
y = x – 0.5
Mean Pressure Coefficient Values
RMS of Pressure Coefficients
y = 1.0542x
R2 = 0.2097
0.00
0.25
0 0.05 0.1 0.15 0.2 0.25
Model
Fu
ll-S
ca
le
y = x
(135 degrees)
Model
0.25
Ful
l-Sca
le
0.250.20.150.10.0500.00
y = 1.0542xR2 = 0.2097
y = x
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
-3 -2.5 -2 -1.5 -1 -0.5 0
Model
Fu
ll-S
cal
e
y = x
(135 degrees)
y = x - 1.0Ful
l-Sca
le
Model
0-1.5 -1.0 -0.5
-1.0
-2.0
-3.0
-4.0
-5.0
-6.0
y = x
y = x – 1.0
-3.0 -2.5 -2.0
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:
– 0.5Cp corresponds to 2 psf in full-scale
– 20% increase in model Cp based on a different estimate of terrain roughness
– By applying these changes there is close agreement between model and full-scale values
[ ]Adjusted Results
-3
-2
-1
0
1
0 5 10 15 20 25 Pressure Tap Location
Cp Values
Model Cp Mean Model Cp Min Model Cp Max FS Cp Mean FS Cp Min Average Cp Max:
Cp
Val
ues
Pressure Tap Location2520151050
-3
-2
-1
0
1
[ ]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