Design Wind Speeds for the Caribbean for use with …...Design Wind Speeds for the Caribbean for use with the Wind Load Provisions of ASCE 7 Prepared by Peter J Vickery and Dhiraj

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


Dra

g C

oeffi

cien

t


0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0 10 20 30 40 50 60


Dra

g C

oeffi

cien

t


0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0 10 20 30 40 50 60


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


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)


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


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


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


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


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


180180

170170

15014013012011010090

80

70

160

190

160

170

160

150140130120

170

160150140130



140

130

1201101009080

7060

50

40

30

140

140

150

130

130

140130

120

110

100

30

130

120110

100

150 140

120



190180

170

160150140130120110100

9080

190 180

170

170

180

200

190

160150140

170

170160150


50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Cubafor Cuba


50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Jamaicafor Jamaica


50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Hispaniolafor Hispaniola


50, 100, 700 and 1700 Year Wind Speeds 50, 100, 700 and 1700 Year Wind Speeds for Puerto Ricofor Puerto Rico


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).

Documents

Design Wind Speeds for the Caribbean for use with …...Design Wind Speeds for the Caribbean for use with the Wind Load Provisions of ASCE 7 Prepared by Peter J Vickery and Dhiraj