2/16/2017 1 by Tim Marshall P.E. Meteorologist In the Eye of the Storm: Perspective From an Engineer, Meteorologist and Storm Chaser Presented at 2017 Tornado Summit Oklahoma City, OK February 14, 2017 1957 Began to position chase vehicles April 21, 1967 Oak Lawn, IL Tornado 1967 -Oak Lawn, IL news
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In the Eye of the Storm - Tornado Summit...2/16/2017 2 Oak Lawn Tornado Damage Destroyed mobile home park April 21, 1967 Oak Lawn Tornado Track Rated F4 Traveled 16.2 miles @ 60 mph
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2/16/2017
1
by Tim Marshall P.E.
Meteorologist
In the Eye of the Storm: Perspective From an Engineer, Meteorologist and Storm Chaser
Presented at 2017 Tornado Summit Oklahoma City, OK February 14, 2017
1957 Began to position chase vehicles
April 21, 1967Oak Lawn, IL Tornado
1967 -Oak Lawn, IL news
2/16/2017
2
Oak Lawn Tornado Damage Destroyed mobile home park
� Over 30,000 slide images of Over 30,000 slide images of Over 30,000 slide images of Over 30,000 slide images of tornadoes, chasing, and damage.tornadoes, chasing, and damage.tornadoes, chasing, and damage.tornadoes, chasing, and damage.
� Thousands of hours of video and Thousands of hours of video and Thousands of hours of video and Thousands of hours of video and tape recordings of chases in tape recordings of chases in tape recordings of chases in tape recordings of chases in formats from Super8, VHS, SVHS, formats from Super8, VHS, SVHS, formats from Super8, VHS, SVHS, formats from Super8, VHS, SVHS, HiHiHiHi----8, MiniDV, and SD.8, MiniDV, and SD.8, MiniDV, and SD.8, MiniDV, and SD.
� Thousands of papers, books, and Thousands of papers, books, and Thousands of papers, books, and Thousands of papers, books, and newspaper articles on tornadoes.newspaper articles on tornadoes.newspaper articles on tornadoes.newspaper articles on tornadoes.
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Books, videos
and files
– oh my!
Chase logs and hand drawn maps are
kept in notebooks
Slides are labeled and sleeved
Tornado Room “Ring of Honor”
THE 2016TWIRL PROJECT
http://www.cswr.org
Tornadic Winds: In-situ and Radar measurements at Low levels (TWIRL)
5 pods in
SCOUT 3
Team: Brandon Molyneaux, Jacob DeFlitch, and Katie Griffith
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The instrumented pod cost 6K each
2016 TWIRL PROJECT
Dr. Josh Wurman Dr. Karen Kosiba3 SCOUTS
3 DOWS
Dr. Josh Wurman inside DOW-72016 TWIRL PROJECT
2016 TWIRL PROJECT
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SULPHUR, OKCHASE
MAY 9, 2016
4:05pI-35
WYNNEWOOD
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
SM
4:05pI-35
WYNNEWOOD
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
4:07 PM Multi-vortex
tornado SW
4:07PM – POD L deployed4:11pI-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
1m
WYNNEWOOD
2/16/2017
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4:11pI-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
1m
WYNNEWOOD
4:15 PM Pod M deployed
4:18pI-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
WYNNEWOOD
4:18pI-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
WYNNEWOOD
4:17 PM POD N deployed4:19 PM Tornado crossed Meridian Rd.
The tornado went south of all 3 pods
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4:25 PM Tornado lifts and destroys house4:44 PM – Multi-vortex
tornado forms south
4:50p
I-35
HWY
177
DAVIS Rt. 7
SCOUT 3
WYNNEWOOD
SULPHUR
4:50p
I-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
WYNNEWOOD
4:52 PM – Wedge just south 4:55 PM – Wedge just south
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Quickly deployed pod in front of wedge tornado
Thanks to Scott Peake
SCOUT 3
Reality duplicates HollywoodV O R T E X 2 S P E C I A L E D I T I O N
V
4:57p
I-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
WYNNEWOOD
4:57p
I-35
SULPHUR
HWY
177
DAVIS Rt. 7
SCOUT 3
WYNNEWOOD
5:00 PM Tornado
approaching us. Pod hit.
1 m/s = 2.237 mph
89 mph
Courtesy of CSWR
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1 km
Courtesy of CSWR
1 km
Courtesy of CSWR
1 km
Courtesy of CSWR
1 km
Courtesy of CSWR
1 km
Courtesy of CSWR
1 km
78mph
Courtesy of CSWR
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1 km
Courtesy of CSWR
1 km
Courtesy of CSWR
1 km
Courtesy of CSWR
FIRST POD HIT FOR
CSWR
TORNADO TRACKS by
NWS
KATIE
TORNADO
9 MILES
LONG
21 MINUTES
RATED EF-4
SULPHUR
TORNADO
17 MILES
LONG
43 MINUTES
RATED EF-3
I-
3
5
OKC AreaDamage Surveys
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1999, 2003 and 2013 PATHS
1 SQ. MILE
May 3, 1999 – Moore, OK
Still images from video by Tim Marshall
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Variation of damage: F0 to F5
118
F-scales overlaid on aerial photo
CRITICAL
CONNECTIONS
Problems with foundation attachment
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Typical connection of wall to slab
F indicates likely failure areas
Types of connections to slab
Straight-nailed studs pulled away from bottom plate (May 1999)
Studs pulled out from strapped bottom plate (May 1999)
Bottom plate had been secured with shot pins (May 1999)
Scrape in slab where cut nail moved (May 1999)
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Cut nails were all that was left of this house (May 1999)
I returned to Moore in August 1999 and examined 40 homes under construction…
� Five homes were bolted to their foundations (12.5%).
� Six homes were strapped to their foundations (15%).
� 29 homes were nailed or pinned to their foundations (72.5%).
Building Code Requirements
� Wood bottom plates on exterior walls shall be bolted to the foundations a maximum of 6 feet apart.
� A nut with washer must be tightened on each bolt.
� There shall be a minimum of TWO bolts per plate section.
130
Anchor Bolt Placement
12.5% foundations had bolts ( Aug. 1999) Properly bolted wall plates (Aug. 1999)
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15% of foundations had straps (Aug. 1999) Oops. Strap outside wall insulation board (Aug. 1999)
Oops #2 – Straps outside of insulation board (Aug. 1999)
72.5% of walls were to be nailed or pinned to their foundations (Aug. 1999)
Shot pinned wall plate to slab (Aug. 1999)Use of cut nails on perimeter walls was a code violation (Aug. 1999)
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How deep does a cut nail extend into the slab?
About a half inch if it doesn’t spall the concrete!
Problems with wall attachment
Let-in brace helps stiffen wall (Aug. 1999) Oops. What you don’t see WILL hurt you.
(Aug. 1999)
Solid sheathing help stiffens wall corner in lieu of let-in brace. But what about the pink stuff? (August 1999)
Problems with the attachment of roof framing
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Typical rafter-top plate connection that performs poorly when it is uplifted
New house built after it was destroyed by tornado. Note nails through corner of top plate (Aug. 1999)
One house had clips between rafters and top plate (Aug. 1999)