Design Wind Speeds for the Caribbean Design Wind Speeds for the Caribbean for use with the for use with the
Wind Load Provisions of ASCE 7Wind Load Provisions of ASCE 7Prepared by
Peter J Vickery and Dhiraj WadheraApplied Research Associates
8540 Colonnade Center Drive, Suite 307Raleigh, NC 27615
Under a special grant from the Office of Foreign Disaster Assistance of
the United States Agency for International Development (OFDA/USAID).
OverviewOverviewSimulation Methodology
B and RMW modelsSea Surface Drag Coefficient ModelHurricane Boundary Layer Model
Model ValidationDesign Wind SpeedsSummary
Simulation Approach and Flow ChartSimulation Approach and Flow Chart
0
50
100
150
200
250
1 10 100 1000 10000
Return Period (years)
Peak
gus
t Win
d Sp
eed
(mph
)
Holland B ParameterHolland B Parametery = -2.237x + 1.732
R2 = 0.336
0.00
0.50
1.00
1.50
2.00
2.50
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
SQRT(A)
Hol
land
B P
aram
eter
B estimates derived from upper level flight data and H*Wind snapshots of hurricane wind fields.B modeled as a function of A where
Rd is the gas constant for dry air, pc
is the central pressure, Ts is the sea surface temperature (˚C), Δp is central pressure difference, RMW is radius to
maximum winds
⎟⎟⎠
⎞⎜⎜⎝
⎛⋅
Δ+⋅
⋅=
eppTR
fRMWA
csd
c
1ln2
Vickery and Wadhera (2008), “Statistical Models of Holland Pressure Profile Parameter and Radius to Maximum Winds of Hurricanes from
Flight Level Pressure and H*Wind data”
In Press JAMC0
10
20
30
40
50
60
0 1 2 3 4 5 6 7 8 9 10
Distance from Storm Center (r/RMW)
Gra
dien
t Bal
ance
Win
d Sp
eed
(ms-1
)
B = 0.75B = 1B = 1.3B = 1.5
RMW ModelsRMW ModelsAtlantic Region
Δp is central pressure difference, Ψ
is the latitude and ε
is the random error term. The error, σlnRMW , is modeled in the form:σlnRMW = 0.448
Δp ≤
87 hPaσlnRMW = 1.137 –
0.00792Δp 87 hPa ≤ Δp ≤
120 hPaσlnRMW = 0.186
Δp >120 hPa
ε+Ψ+Δ×−= − 0337.010291.6015.3)ln( 25 pRMW r2=0.297,σlnRMW=0.441
0
25
50
75
100
125
150
30 40 50 60 70 80 90 100 110 120 130
Central Pressure Difference (hPa)
Rad
ius
to M
axim
um W
inds
(km
) DataModel Median+/- 2 Standard Deviations
Hurricane Boundary Layer ModelHurricane Boundary Layer ModelBoundary Layer Model developed using Dropwindsonde data.
Includes the radial variation of BL heightMarine Boundary Layer Model given by:
Boundary layer Height given by:
⎥⎦
⎤⎢⎣
⎡−= n
o Hza
zz
kuzU )()ln()( *
*
mrIH e 99,75.0/260.07.343 2* ==+= σ
Vickery et al (2008), “A Hurricane Boundary Layer and Wind Field Model for Use in Engineering Applications”, In Press JAMC
RMW 0-30 km
0
100
200
300
400
500
600
700
800
900
1000
10 20 30 40 50 60 70 80Mean Wind Speed (m/sec)
Hei
ght (
m)
Drag Coefficient over the OceanDrag Coefficient over the Ocean
Powell, 1980 Powell, et al, 2003
Cd
open terrain = 0.00471
Sea Surface Drag Coefficient ModelSea Surface Drag Coefficient Model
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0 10 20 30 40 50 60
Mean Wind Speed at 10m (m/sec)
Dra
g C
oeffi
cien
t
RMW 10 - 30 km, LSF over 20 m - 100 mRMW 10 - 30 km, LSF over 20 m - 150 mRMW 10 - 30 km, LSF over 20 m - 200 mLarge and Pond (1981) with 0.0019 maximum
0.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0 10 20 30 40 50 60
Mean Wind Speed at 10m (m/sec)
Dra
g C
oeffi
cien
t
RMW 30 - 60 km, LSF over 20 m - 100 mRMW 30 - 60 km, LSF over 20 m - 150 mRMW 30 - 60 km, LSF over 20 m - 200 mLarge and Pond (1981) with 0.0022 maximum
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0 10 20 30 40 50 60
Mean Wind Speed at 10m (m/sec)
Dra
g C
oeffi
cien
t
RMW 60 - 100 km, LSF over 20 m - 100 mRMW 60 - 100 km, LSF over 20 m - 150 mRMW 60 - 100 km, LSF over 20 m - 200 mLarge and Pond (1981) with 0.0025 maximum
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0 10 20 30 40 50 60
Mean Wind Speed at 10m (m/sec)
Dra
g C
oeffi
cien
t
All RMW - LSF over 20 m - 200 mAll RMW - LSF over 20 m - 150 mAll RMW - LSF over 20 m - 100 mLarge and Pond (1981) with blended maximum
Wind Field Model ValidationWind Field Model Validation All Hurricanes - Marine
y = 0.994x
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
Observed Peak Gust Wind Speed (mph)
Mod
eled
Pea
k G
ust W
ind
Spee
d (m
ph)
All Hurricanes - Land
y = 0.991x
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140Observed Peak Gust Wind Speed (mph)
Mod
eled
Pea
k G
ust W
ind
Spee
d (m
ph)
All Hurricane - Land and Marine
y=0.993x
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140Observed Peak Gust Wind Speed (mph)
Mod
eled
Pea
k G
ust W
ind
Spe
ed
(mph
)
Modeled and Observed Heading, Modeled and Observed Heading, Translation Speed and Central PressureTranslation Speed and Central Pressure
Modeled and Observed Heading, Modeled and Observed Heading, Translation Speed and Central PressureTranslation Speed and Central Pressure
Location - 20N & 85W
0
5
10
15
1900 1915 1930 1945 1960 1975 1990 2005Year
Num
ber o
f hur
rican
es w
ithin
25
0 km
of t
he s
ite
Location - 12N & 61W
0
5
10
15
1900 1915 1930 1945 1960 1975 1990 2005
Year
Num
ber o
f hur
rican
es w
ithin
25
0 km
of t
he s
ite
N (All hurricanes)
Np (Hurricanes with CentralPressure values)
Location - 16N & 65W
0
5
10
15
1900 1915 1930 1945 1960 1975 1990 2005Year
Num
ber o
f hur
rican
es w
ithin
25
0 km
of t
he s
ite
Location - 18N & 75W
0
5
10
15
1900 1915 1930 1945 1960 1975 1990 2005Year
Num
ber o
f hur
rican
es w
ithin
25
0 km
of t
he s
iteNumber of Hurricanes with central Number of Hurricanes with central pressure valuespressure values
Comparison of observed and Modeled Central Comparison of observed and Modeled Central PressuresPressures
Observed minimum central pressure within 250 km of a location
Minimum 50 year modeled central pressure within 250 km of a location
Comparison of 100 Year Modeled Wind Comparison of 100 Year Modeled Wind Speeds with Values from Georgiou (1986)Speeds with Values from Georgiou (1986)
Wind Speeds are representative of 10-30 minute mean values over marine exposure
Comparison of 100 Year Modeled Wind Comparison of 100 Year Modeled Wind Speeds with CUBiCSpeeds with CUBiC
Location This Study (ms-1) CUBiC (ms-1)
Trinidad (S) 14.3 29.6
Trinidad (N) 38.0 38.0
Grenada 47.8 47.1
Barbados 50.1 51.2
Saint Vincent 49.6 52.4
Saint Lucia 53.2 53.2
Antigua and Barbuda 59.9 55.5
Montserrat 60.3 55.8
St. Kitts and Nevis 61.7 55.8
Dominica 55.4 56.2
Wind Speeds are representative of 2-3 sec gusts
Basic NonBasic Non--Wind Speed Definition from Wind Speed Definition from ASCE 7ASCE 7
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1 10 100 1000 10000
Return Period (years)
VR
P/V 5
0
263.16.1 ==LFW
352.115.16.1 =×=× IWLF
50 700 1700
Basic Wind Speed Definition from ASCE7Basic Wind Speed Definition from ASCE7Jamaica
0
0.5
1
1.5
2
2.5
1 10 100 1000 10000
Return Period (years)
V RP/
V 50
50 700 1700
1.58
1.73
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1 10 100 1000 10000
Return Period (years)
VR
P/V 5
0
263.16.1 ==LFW
352.115.16.1 =×=× IWLF
50 700 1700
50 Year Wind Speeds for Caribbean50 Year Wind Speeds for Caribbean
130
120
110
100908070
6050
40
30
130
120120
130
120 110
120 130
100
90
120
110100
90
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
700 Year Wind Speeds for Caribbean700 Year Wind Speeds for Caribbean
180180
170170
15014013012011010090
80
70
160
190
160
170
160
150140130120
170
160150140130
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
100 Year Wind Speeds for Caribbean100 Year Wind Speeds for Caribbean
140
130
1201101009080
7060
50
40
30
140
140
150
130
130
140130
120
110
100
30
130
120110
100
150 140
120
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
1700 Year Wind Speeds for Caribbean1700 Year Wind Speeds for Caribbean
190180
170
160150140130120110100
9080
190 180
170
170
180
200
190
160150140
170
170160150
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Cubafor Cuba
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Jamaicafor Jamaica
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Hispaniolafor Hispaniola
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Puerto Ricofor Puerto Rico
Wind speeds are 3 sec gusts at a height of 10m in flat open terrain
Load Factor (Load Factor (VV700700 //VV5050 ))2 2
3
2
4
2.5
5
2.752.25
3.25
3.54.5 3.75 4.256
4.755.25
1.75
75.5 85.75
6.56.25 9
2
4
2
5.75
3.75
3.25 2.75
5.25
2
66.52.25
2
4.75
6
1.75
1.75
5.5
2.752.25
53.5
4.25
6
2
5
3.25
5.25
4.5
1.75
2.5
SummarySummaryA hurricane simulation method is used to estimate design wind speeds for the Caribbean region. Wind speed maps for return periods of 50, 100, 700 and 1700 year have been developed.The model has been validated through comparisons to the historical observations of central pressure difference, storm heading, translation speed and minimum distance of approach.700 year and 1700 year return period wind speeds are given as design wind speeds for category 2 and Category 3 & 4 structures respectively (with wind load factor=1)Provides design wind speeds for the Caribbean that can be used with ASCE 7 wind provisions
This presentation has been made possible through the financial support of the Division of Humanitarian
Assistance, Peace and Security of the Canadian International Development Agency (HAPS/CIDA)
and the Office of Foreign Disaster Assistance of the United States Agency for International
Development (OFDA/USAID).
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