Hurricane Vulnerability Assessment: Latest Experience and ... #5/6_Pinelli.pdf · September, 2010...
Transcript of Hurricane Vulnerability Assessment: Latest Experience and ... #5/6_Pinelli.pdf · September, 2010...
September, 2010 IDRiM 2010
Hurricane Vulnerability Assessment: Latest Experience and Development in the Florida
Public Hurricane Loss Model
1st Annual Conference of the International Society for Integrated Disaster Risk Management
Kurt Gurley Kurt Gurley
JeanJean--Paul Pinelli, Gonzalo PitaPaul Pinelli, Gonzalo Pita
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Florida
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Agenda
• History• FPHLM: objectives, goals, and purpose• FPHLM engineering module overview• Conclusions
September, 2010 IDRiM 2010
Agenda
• History• FPHLM: objectives, goals, and purpose• FPHLM engineering module overview• Conclusions
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Turning Point
• Hurricane Andrew in 1992 was a wake up call
• $16 billion in insured losses and $26.5 billions in total losses expressed in 1992 dollars
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Pre-Andrew Building Codes
• Building codes adopted starting in the 1940’s
• South Florida Building Code in Miami area• Southern Building Code in rest of the state• Poor compliance and enforcement• Myriad of different jurisdictions
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Pre-Andrew Econometric Models
• Belief whole hurricane hazard situation lay exclusively within the actuarial field and could be managed with actuarial information alone
• relied up to the 1990’s solely on recent historical claim data
• Excess Wind Procedure• Model predicted $80 million for 1992 clearly less than the
$16 billion insured losses that Andrew caused (Musulin, 1997).
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Solution?
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Post Andrew State Response
• South Florida Building Code (1994) and Florida Building Code (2001)
• Citizens Property Insurance Corporation– State insurer of “last resort”
• Florida Commission on Hurricane Loss Methodology– established to mediate between the insurance industry
and the state of Florida, to set a method for the rate filing process and to review and certify the loss models
• Florida Public Hurricane Loss Model
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Agenda
• History• FPHLM: objectives, goals, and purpose• FPHLM engineering module overview• Conclusions
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Florida Public Hurricane Loss Model
• Funded by the Florida Office of Insurance Regulation.
• Administered through the International Hurricane Research Center at FIU - Project manager: Shahid Hamid http://www.cis.fiu.edu/hurricaneloss/index.html
• Multidisciplinary effort involving several institutions: FIT, FIU, FSU, NIST, NOAA, UF, UM
• Certified by the Florida Commission on Hurricane Loss Methodology in 2007, 2008, and 2009, http://www.sbafla.com/methodology/index.asp
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Objectives of the FPHLM
• “Develop a public model to determine hurricane risk and project losses to assure appropriate insurance rate regulation”
• Provide an alternative to commercial proprietary models which are NOT open to public scrutiny
From http://www.edf.org/article.cfm?contentid=5363
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Goals of the FPHLM
• To assess hurricane risk, and to predict annual expected insured residential losses for specific sites, zip codes, counties and regions in Florida (stochastic analyses).
• To predict insured losses for scenario analyses either user defined scenarios or historical events.
• To estimate insured losses for entire portfolios of residential / commercial-residential properties.
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Agenda
• History• FPHLM: objectives, goals, and purpose• FPHLM engineering module overview• Conclusions
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Public Model Overview
ProgrammingModel
MeteorologyModel
Provides probabilistic or scenario wind field info
EngineeringModel
Given wind, predicts damage
ActuarialModel
Filters damages into insured losses
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Engineering Research Team
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Research Objectives
Determine types Quantify wind resistanceTranslate wind speed into loads
Monte Carlo Simulation
% Quantify damages
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FLORIDA EXPOSURE
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3 major residential building categories
• 1. Single Family Homes• 2. Manufactured (Mobile) Homes• 3. Condominium and apartment buildings
– Low-rise (1-3 stories)– Mid-rise (4+ stories)
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Typical Single Family Home Distribution in Florida
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Manufactured Homes
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Low-rise residential
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Variety of mid/high-rise buildings
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Wind DamageLow-rise vs. mid/high-rise
• Low-rise buildings including single-family-homes– Can be categorized in a few typical generic buildings– Can suffer substantial external structural damage (in addition to envelope
and interior damage) including complete collapse– Modeling approach : the building is modeled as a whole
• Mid-rise buildings– They are highly variable in shape, height, material, etc– Cannot be categorized in a few generic building types– Engineered structures that suffer little external structural damage and are
unlikely to collapse– Can suffer extensive cladding and opening damage leading to water
penetration and interior damage– FPHLM adopts a modular approach : the building is treated as a
collection of apartment units
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Closed Building Open Building
Mid-high risebuildings characterization
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Mid-high rise building characterization for Modular Approach
Opening Type Unit Type Quantity Dimensions
[ft] Corner / Closed 5 5 x 4 Corner / Open 8 5 x 4
Middle / Closed 2 5 x 4 Windows
Middle / Open 5 5 x 4 Entry Door All 1 8 x 4
Sliding Door All 1 8 x 8
Apartment types according to location
Number of openings per apartment type
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Different modules based on:
• Building layout (open/closed)• Position of the apartment (Corner/middle)• Base area
• Story height (debris hazard)
• Opening type
• Exterior wall type
Possible cases: ~2048
Mid-high riseApartment modules definition
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Research Objectives
Determine types Quantify wind resistanceTranslate wind speed into loads
Monte Carlo Simulation
% Quantify damages
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Wind Speed External Wind Load
• Translate wind speed into pressures and forces on the exterior of the whole building (low-rise) or on the façade of the apartment modules (mid/high-rise)
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Component Wind Loads
InputDiscrete 3 sec
wind speed(e.g.V = 110 mph)
OutputComponent
loads/pressures(e.g. one sheathing panel)
• Data Sources:– Wind load provisions in code
(ASCE-7-05)– Directional modifications– Wind tunnel corrections– Full scale measurement
• Influences:– Building shape– Wind direction
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• Probability of window breakage due to debris modeled by exponential cumulative distribution function
– A =Fraction of potential missile objects in the air– NA = Total # of available missile objects – B= Fraction of airborne missiles that hit the house – C= Fraction of the impact wall that is glass – D= Probability of momentum above damage threshold
• Parameters calibration based in large part on post storm field studies of residential damage
• Applied to each window on model house
]****exp[1)( DCBNAVp AD −−=
Wind-borne Missiles
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Model Components
Determine types Quantify wind resistanceTranslate wind speed into loads
Monte Carlo Simulation
% Quantify damages
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Component Resistance to Wind
• For each structural type or apartment unit type– Identify major
components– Model the capacity of
each component– Determine Load Paths
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Low-Rise Buildings Components
• Type: e.g., Concrete Block, Gable Roof
• Selected components– Roof cover– Roof sheathing– Overhang– Gable end trusses– Roof to wall connections– Wall covering– Wall sheathing– Openings: windows, sliding
doors, entry doors
Openings
Roof SheathingRoof Cover
Roof to Wall Connections
WallsOpenings
Roof SheathingRoof Cover
Roof to Wall Connections
Walls
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Mid/High-Rise BuildingsModular Unit Components
• Type: e.g., Closed building, Corner Unit, No shutters, 16 windows
• Selected components– Pressure Windows– Impact Windows– Pressure Entry Door– Impact Entry Door – Pressure Sliding Door – Impact Sliding Door
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Model Components
Determine types Quantify wind resistanceTranslate wind speed into loads
Monte Carlo Simulation
% Quantify damages
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Research Goal
Create a probability-based system response model to:
1. Simulate the performance and interaction of the components of typical Florida buildings
2. Evaluate their vulnerability during interaction with hurricane winds
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Example Damage Matrix
Partial output file : each row corresponds to 1simulation; eachcolumn to a component; there are 32 columns for low-rise matrices
Building Concrete block, gable roof, no shutters Wind 150 mph 3-sec gust, 45º to axis
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Damage matrix sample result
Exte
rior D
amag
e
Wind Speed [3sg – mph]
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Model Components
Determine types Quantify wind resistanceTranslate wind speed into loads
Monte Carlo Simulation
% Quantify damages
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Vulnerability Model %
• From the Damage Matrices– Convert modeled physical damages into damage
ratios = repair cost/(home or unit value)– Define the vulnerability of different building or
unit types = P(damage|wind speed)– Provide a logical method for prediction of damage
to other coverages– Validate the damage predictions
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Damage Modeling
Exterior
Damage
Stage 1
Building Damage
Leaks
Water penetration propagation
Interior & Utilities Damage
Stage 2 Stage 3
Contents
Damage
Time Element
Coverage
Scientific/experimental relationships based on the physics of the problem
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Issues:• Interior damage is a substantial part of the overall
damage• Interior damage is a function of exterior damage• Interior damage is caused mainly by water intrusion.
Solution: scientific and engineering based model• Assess damage on envelope components• Estimate rainfall rate and duration• Calculate impinging rain• Compute water intrusion through breaches• Transform water into interior damage
Interior Damage Model
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Buildings Vulnerability New Interior Damage Model
Plot Exterior vs. Interior damage curve for
component “i”
Transform Water contents (including vertical propagation) to Interior Damage
Load wind-borne breach area and existing defects breach area
For a given wind speedVW
Breach area AB(VW)
Defect Area AD(VW)
Estimate rainfall rate IV
Estimate rain duration dR
Convert vertical to horizontal rainfall rate IH
Water that enters the building through the breach is
( )BDRFVI A,A,d,C,IW f=
Increase velocity to VW = VW + 5 mph and
repeat loop
2
3
4
6
5
7
8
9
For a given Damage mode “i”
1
Last VW? Yes
No
Go to next damage mode and repeat loop
11
Inte
rior D
amag
e
Water
Con
vers
ion
fact
or C
F
Wind speed
Duration
10
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RAIN INTRUSION MODELRainfall rate and duration statistics
Rainfall rate (Beta-Tanh pdf)
Rain duration (Wakeby pdf)
Sources: NOAA and Prof. Jiang (FIU)Sources: NOAA and Prof. Jiang (FIU)
Building Interior Damage Model
AAWE’10 – Marco Island, FL
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Transform vertical rainfall rate to impinging rain to the building
From Blocken, 2009, Straube 2000 Willis & Tattelman (1989)
Raindrop diameter distributions
Building Interior Damage Model
Straube and Burnett Approx. Method
Rain Admittance
Factor (RAF)
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Low-Rise Interior Damage Assessment
Example of proposed interior model
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Interior Damage as a function of Wind Speed ‒ per component
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Low-Rise Buildings Vulnerability General Flowchart
Select Building
Type
Load Exterior Damage ArrayDA(l,comp.,α,VW )
Span Exterior Damage ArrayWind speeds: VW = 50:5:250
Angles: = 0 : 45 : 315
Estimate Total & Component
Costs
EstimateExterior Damage
Estimate Interior &
Utilities Dam.
Calculate Total Vuln.Aggregate Exterior +
Interior Vuln.
Damage Estimation
END
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Vulnerability Matrices
• Each column is a pdf of damage for a particular wind speed = probability(damage|wind speed)
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Vulnerability Curves for Mid-high rise Individual Apartments types
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MC
MC
aaaa
++
= MC VVVA
Exterior Damage Estimation Interior Damage Estimation
Mid/High-Rise Buildings Modular ApproachDamage Flowchart
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Mid/High-Rise
Expected Damage
Flowchart
IDStories#
ID(1)... ID(7) ID(8)EIDR +++=
MC
MC
aaaa
++
= MC VVVA
Stories# )VA(W... )VA(W )VA(WEEDR 11-nn +++
=
Wal
lsD
oor
Slid
ers
Win
dow
s
Rai
nfal
l rat
ein
/hr
[ ] Bldgee V)EIDRk(1EEDRkEDV ⋅−+=
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Agenda
• History• FPHLM: objectives, goals, and purpose• FPHLM overview• Conclusions
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Conclusions
• In response to Andrew catastrophic losses, Florida has embarked in an aggressive hurricane risk assessment and mitigation policy.
• The Florida Public Model is an important tool in that effort.
• The Florida Public Model is a state of the art catastrophe model whose latest developments include:– A new model for the prediction of interior damage due to
rain.– A modular approach for the vulnerability modeling of
mid/high rise building of any shape and height.
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Acknowledgement
• This research is supported by the State of Florida through a Department of Financial Services (FDFS) grant to the Florida International University International Hurricane Research Center. The opinions, findings, and conclusions expressed in this presentation are not necessarily those of the FDFS.