Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 1
The Trinidad and Tobago Institute of ArchitectsCPD Seminar
July 2018
Meteorological Hazards(wind, rain, surge, waves)
Tony Gibbs FREng HonTTIASecretary General of CCEO
• Historical development of the wind hazard for building design in the Caribbeano wind speeds
o topographic effects
o climate change
o the 2017 hurricane season
• Intensity-duration-frequency relationships and rational storm-water drainage design
• Regional maps of storm surge and waves
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 2
Historical developmentof the wind hazard
wind speeds
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 3
CP3 Chapter V:Part 2 – 1952
75 mph – 1-minute average(= 93 mph or 41 m/s 3-second
gust)
Rudimentary procedures
South Florida Building Code – 1960s
120 mph – fastest mile(= 137 mph or 61 m/s 3-second gust)
Rudimentary procedures
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 4
The Council of Caribbean Engineering Organisations
(CCEO)1969
gave a mandate to theBarbados Association of Professional Engineers
(BAPE)to prepare a wind load standard
Tony Gibbs, AR Matthews, HC Shellard“Wind Loads for Structural Design – 1970”
including
HC Shellard“Extreme Winds in the Commonwealth Caribbean”
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 5
Suggested Basic Wind Speeds (mph, 3s)for Some Commonwealth Caribbean Countries
1970
Jamaica 120 (= 54 m/s)BVI 120 (= 54 m/s)Leeward Islands 120 (= 54 m/s)St Lucia, St Vincent 120 (= 54 m/s)Barbados 120 (= 54 m/s)Grenada, Tobago 100 (= 45 m/s)Trinidad 90 (= 40 m/s)Guyana 50 (= 22 m/s)
1971 – Norris Helliwell
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 6
1981 Revision of“Wind Loads for Structural Design” (3s)CCEO – BAPE – NCST – OASTony Gibbs – HE Browne – BA Rocheford
Jamaica 56 m/s (= 125 mph)BVI 64 m/s (= 143 mph)Leeward Islands 64 m/s (= 143 mph)St Lucia, Dominica 58 m/s (= 130 mph)Barbados, St Vincent 58 m/s (= 130 mph)Grenada, Tobago 50 m/s (= 112 mph)Trinidad 45 m/s (= 101 mph)Guyana 22 m/s (= 49 mph)
BA Rocheford (Caribbean Meteorological Institute) 1984 Revision of Wind Speeds– 10-minute
Belize – Centre 29.0 m/s (= 65 mph) [= 93 mph 3s] Jamaica – N 37.0 m/s (= 83 mph) [= 119 mph 3s]Jamaica – S 41.0 m/s (= 92 mph) [= 132 mph 3s]St Kitts 44.5 m/s (= 100 mph) [= 143 mph 3s] Antigua 46.0 m/s (= 103 mph) [= 147 mph 3s] Dominica 41.0 m/s (= 92 mph) [= 132 mph 3s]St Lucia 43.0 m/s (= 96 mph) [= 137 mph 3s]Barbados 42.0 m/s (= 94 mph) [= 134 mph 3s]Tobago 31.5 m/s (= 70 mph) [= 100 mph 3s]Trinidad – Central 27.5 m/s (= 62 mph) [= 89 mph 3s]
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 7
Wind Speed Averaging Time A Point of Confusion
Peter Vickery
Durst-Deacon
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 8
The Caribbean Uniform Building Code (CUBiC:1985)The Boundary Layer Wind Tunnel Laboratory (University of Western Ontario)Davenport – Surry – Georgiou
Simulation of hurricane wind climate using:o drop in barometric pressure;o radius of the ring to maximum wind speeds;o translation speed;o angle of its track;o position of the point of interest relative to the
centre of the storm.
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 9
CU
BiC
Par
t 2
Sec
tio
n 2
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 10
Maximum Wind Speeds (50-year return)
CDMP
9 N
89
.5 W
23 N5
9 W
Wind Speeds
0 1 2 3 4 5knotsmph
kph
m/s
Storm Category
25 50 75 100 125
25 50 75 100 125 150
50 100 150 200 250
10 20 30 40 50 60 70
Ir P C van Staalduinenand
Dr Ir C P W GeurtsTNO
(Netherlands Organisation for Applied Scientific Research)
“Hurricane Hazard in the Netherlands Antilles ….”
1997
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 11
Wind Hazard Maps for the Caribbean Basin
(3-second mph at 33ft) Overall region and individual islands
April 2008
Principal researcher – Applied Research Associates (Peter Vickery)Regional coordinator – Tony Gibbs (CEP International Ltd)
Executing agency – Pan American Health Organisation (Dana van Alphen)Funding agency – United States Agency for International Development
(Tim Callaghan and Julie Leonard)
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 12
Caribbean Basin Wind Hazard Maps:
a series of overall, regional, wind-hazard maps using uniform, state-of-the-art approaches covering all of the Caribbean islands and the Caribbean coastal areas of South and Central America
Contour plots of modelled minimum central pressures (mbar) 50 year return period. Contours represent the minimum pressure anywhere within 250 km of a point
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 13
130
120
110
100
9080
70
60
50
40
30
130
120120
130
120 110
120 130
100
90
120
110100
90
50 Year Wind Speeds for Caribbean
140
130
120
110
100
9080
70
60
50
40
30
140
140
150
130
130
140130
120
110
100
30
130
120110
100
150140
120
100 Year Wind Speeds for Caribbean
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 14
180180
170
170
150
140130120110
100
90
80
70
160
190
160
170
160
150140130120
170
160150140130
700 Year Wind Speeds for Caribbean
190
180
170
160150140130120110
100
90
80
190180
170
170
180
200
190
160150140
170
170160150
1700 Year Wind Speeds for Caribbean
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 15
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 16
Peak gust wind speeds (mph) in flat open terrain as a function of return period for selected locations in the Caribbean
Return Period (years)Location
1700700
11087Trinidad (S)147128Trinidad (N)
152133Isla Margarita168154Grenada165149Curacao156149Bonaire162146Aruba169152Barbados171155Saint Vincent172155Saint Lucia171159Martinique172159Dominica168157Guadeloupe172161Montserrat161150Belize170163St. Kitts and Nevis168160Antigua and Barbuda175167Saint Martin/Sint Maarten176165Anguilla176167US Virgin Islands180169British Virgin Islands198187Grand Cayman197178Little Cayman/Cayman Brac162150Turks & Caicos (Grand Turk)170155Turks & Caicos (Providenciales)180162Andros180165Eleuthera180163New Providence (Nassau)178162Great Abaco175161Grand Bahama (Freeport)
Wind load factor (VT/V50)2
for Hurricane and Non-Hurricane Wind Speedsplotted vs return period
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1 10 100 1000 10000
Return Period (Years)
Win
d L
oad
Fac
tor
Non-Hurricane
Hurricane
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 17
Contour plots of (V700/V50)2
Contour plots of importance factorfor ASCE category III and IV structures
defined by I=(V1700/V700)2
1.2
1.3
1.41.51.6 1.7 1.8 2 1.9
1.1
1.11.2
1.2
1.2
1.2
1.2
1.5
1.1
1.2
1.3
1.3 1.2
1.2
1.3
1.7
1.2
1.2
1.3
1.2
1.3
1.4
1.2
1.5
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 18
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1 10 100 1000 10000
Return Period (Years)
Win
d L
oa
d F
ac
tor
Non-Hurricane
Hurricane
(Vrare/Vfrequent) increases with closeness to the equator
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 19
The 1933 Hurricane
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 20
Trinidad HurricaneWilmoth Houdini and his Humming BirdsNew York 19 October 1933
The Catholic priest, Reverend Father John,Told the story how the storm began,He said it was about ten o’clock,When Cedros got the fatal shock,A man, a woman and three children cried,The woman was hit by a flying galvanise,My sympathies extended to the land of Iëre,Sans d’humanite
topographic effects
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 21
o Topographic effects are very important in most Caribbean countries.
o This issue receives attention in most modern wind-loading standards. Wind speed-up is recognised over hills, ridges, and escarpments.
o Valleys are sometimes missing.
Photo: UWO-BLWTL
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 22
Sketch showing effects of topography
on wind velocity on a hilly island
10 m80Vs
100Vg
60
gV100
g
120sV
Vs
V
100gV
40
100
Open sea Winward Speed up over Sheltered leewardcoast
Speed up
Coast hill crest
Probability 1% / year, 100-Year Return Time
Wind Speeds
0 1 2 3 4 5knotsmph
m/s
Storm Category
25 50 75 100 125
25 50 75 100 125 150
50 100 150 200 250
10 20 30 40 50 60 70
Winds
Antigua
Wind
Wave
Surge
10yr 25yr 50yr 100yr
Min Max
5
AR
C-M
INU
TE
S
0
5
KIL
OM
ET
ER
S
0
10
MIL
ES
0
5
Ross Wagenseilfor PGDMApril 2001
PGDMMay200116.98 N
61.9
25 W
17.20 N
61. 65 W
1
3
4
2
N
3. English and Falmouth HarboursNelson’s Dockyard 48 m/s Falmouth SE 41 m/sFalmouth NW 52 m/s
2. ParhamDesalinization plant 50 m/sWaterfront by town 47 m/sHill above town 53 m/s
1. St. John’sDowntown 47 m/sEast side of town 51 m/s
4. Jolly HarbourChannel entrance 45 m/sInner boat basin 44 m/sBeach front 45 m/s
Directory Topo. Map
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 23
N
100-Year Return Time
Wind Speeds
0 1 2 3 4 5knotsmph
kph
m/s
Storm Category
25 50 75 100 125
25 50 75 100 125 150
50 100 150 200 250
10 20 30 40 50 60 70
DominicanRepublic
Winds
0
0.5
1
0
50
100
DE
GR
EE
S
KIL
OM
ET
ER
S
MIL
ES
0
25
50
100
Ross Wagenseilfor CDMPJanuary 2000
17.5 N
72 W
20.17 N
68 W
CDMP
West Basin Mid-
BasinEastBasin
Caribbean
Wind
Wave
Surge
10yr 25yr 50yr 100yr
Return to Directory
Risk Management Solutions
Hurricane Georges in Puerto Rico – 1998
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 24
Topographic effect
showing wind velocity increase
ASCE 7
Hill
mL
x
z
H
H/2
H/2
x
z
z
x
H/2
H/2
Escarpment
mL
x
H
z
speed up
(leeward)
V(z)
(windward)V(z)
(windward)V(z)
speed up
(leeward)
V(z)
Tortola, British Virgin Islands
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 25
Pre-Ivan photograph by Brooks La TouchePre-Ivan photograph by Brooks La Touche
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 26
The Grenada National Stadium
Photo: Tony Gibbs
Climate ChangeFake Science?
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 27
Hurricane Catarina as it approached the Brazilian shore at midday on 27 March 2004.
(Illustration courtesy Greg Holland; satellite data courtesy NOAA/University of Wisconsin.)
Hurricane Ivanjust before striking Grenada
Central Pressure 956 mbarPeak Gust Wind ~135 mph
“The most intense hurricane ever recorded so close to the equator in the North Atlantic” – NHC
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 28
A new World SurfaceWind Gust Recordwas registered at
the Paso Real de San Diegometeorological station (78317)
in Pinar del Rio, Cuba,during hurricane Gustav.
The Dinespressure tube anemometer
recorded a gust of340 km/h (=211mph).
Hurricane Gustav 2008
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 29
AMO = Atlantic multi-decadal oscillations
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 30
Percentage Increase in Basic Wind Speed in Eastern Caribbean vsPercentage Increase in Annual Rates of Cat 4 and 5 Hurricanes
0%
5%
10%
15%
0% 50% 100% 150% 200% 250% 300% 350%
Increase in Basic Wind Speed
Increase in Annual Frequency of Category 4 and 5 Hurricanes
Category II Buildings
Category III and IV Buildings
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 31
the 2017 hurricane season
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 32
164‐181 mph gust ove
r land
= Categ
ory 4‐5 Hurrican
e16
4‐181 mph gust ove
r land
= Categ
ory 4‐5 Hurrican
e
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 33
164‐181 mph gust ove
r land
= Categ
ory 4‐5 Hurrican
e16
4‐181 mph gust ove
r land
= Categ
ory 4‐5 Hurrican
e
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 34
Cat 3‐4 HurricaneCat 3 Hurricane
Cat 5 Hurricane > 173 mph gust over land
165-182 mph gust over land= Category 4-5 Hurricane
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 35
rainfallintensity-duration-frequency
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 36
72
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 37
Title of the Presentation73
mapsstorm surge and waves
Meteorological HazardsTTIA CPD Seminar
23 July 2018
Tony Gibbs FREng 38
Maximum Storm Surge (50-year return)
Surge Heights
1 2 3 4 5 6
5 10 15 20
Meters
Feet
Maximum Wave Heights (50-year return)
CDMP
9 N
89
.5 W
23 N
59
W
Wave Heights
Meters
Feet
1 2 3 4 5 6 7
5 10 15 20 25
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