earthquake vulnerability and exposure analysis session 2 mr. james daniell risk analysis earthquake...
TRANSCRIPT
Earthquake Vulnerability and Exposure Analysis
Session 2
Mr. James Daniell
Risk AnalysisEarthquake Risk Analysis 1
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Learning Objectives
Learn about the inventory elements at risk that are exposed to the hazard
Learn how to collect data for exposure Know the difference between empirical and
analytical methods for vulnerability analysis Know the types of vulnerability scales for
buildings and infrastructure Know the importance of socio-economic
vulnerability assessment and its role in the decision making processes
Apply vulnerability assessment to a real situation
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What elements are at risk?
All forms of man-made structures are at risk. It is important to know the key elements to
characterise a region. Building Infrastructure - Any man-made
construction, either urban or rural.
Residential Commercial Industrial
‘Elements at risk’, infrastructure, residential, commercial, industrial
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What elements are at risk?
Transportation Road, rail, air and other transport-related networks
Large Loss Facilities Sports stadiums, marketplaces, churches/temples/mosques,
schools and other high population density infrastructure
Critical/High-Risk Loss Facilities Hospital and health care facilities, public buildings,
telecommunications, airports, energy systems, bridges and other facilities critical to the recovery of a region post-earthquake
Other Lifelines – Utilities, Pipelines Oil, gas and water supply pipelines/distribution systems,
wastewater and electricity systems
Transportation, large loss facilities, critical loss, high-risk, lifelines
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What do we collect for exposure data?
Is the data there? It depends on scale and country type
Local – Council data, local government agencies, aerial photos, individual architectural, structural drawings
Regional – State-based agencies, statistical offices, census data, investment and business listings, employment figures, existing GIS data.
National – National statistical agencies, census data, global databases, remote sensing
Exposure scale, Local, Regional, National
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What type of data is needed for exposure Elements at risk
characterization Number, type, location, size, height, age, construction cost, land value, irregularities, material and mechanical properties
Population details Day/night occupancy of people
Microzonation data Geological data, shear wave velocities, coastal information, elevation, nearby slopes and fault information
Government/Regional data Building code knowledge, previous earthquake damage reports, social and economic datasetsPopulation data, Microzonation, Government data, building code.
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Construction Material + Design
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So what is physical earthquake vulnerability?
“Susceptibility of the ‘elements at risk’ to the earthquake hazard” If a structure is likely to be damaged in an earthquake, it has a
HIGH vulnerability What are the main factors contributing to vulnerability?
Age & Condition
Irregularities
Location
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Ground Motion and its relationship to damage
Buildings vibrate at a certain fundamental building period depending on their building structure, height, stiffness and mass.
Seismic waves with periods close to that of the building will cause resonance (strong vibrating of the building)
A lot of earthquake energy is generally contained in the short-period waves and thus smaller buildings must be designed for larger forces.
Resonance, fundamental period, flexible vs. stiff buildings
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Vulnerability of the built environment
Single building vs. Group of buildings structural analysis For a group of buildings, there are three different
calculation methods for earthquake vulnerability; empirical, analytical or hybrid.
Empiricalconstructed from historic earthquake damage loss ratios and assessment.
Analyticalconstructed via
mathematical and mechanical formulae to characterize the given
damage per ground motion
HybridA combination of various
empirical data with an analytical method
Empirical, Analytical, Hybrid vulnerability methods.
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Empirical vs. Analytical Vulnerability
Empirical, Analytical, Qualitative, Hybrid vulnerability methods.
Increasing complexity
Decreasing complexity
Increasing uncertainty
Decreasing uncertainty (better!)
Increasing Computation Time
Decreasing Computation Time
More Parameters needed
Less Parameters needed
Empirical
AnalyticalQualitative
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Empirical Vulnerability Methods Damage Probability
Matrices Historical ratios of probable damage for each building type for a given ground motion.
Vulnerability Indices and Curves A continuous function of intensity vs. damage – “fragility curves”.
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Empirical Vulnerability Methods
Bal et
al., 2
006,
200
8
Screening Methods – These methods involve assigning a vulnerability rating, given different structural characteristics on a infrastructure-by-infrastructure basis usually via site visit. This also works well for vulnerability lifelines.
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Analytical and Hybrid Vulnerability Methods
Analytical vulnerability indices and collapse-based methods rarely used.
Capacity Spectrum methods – finding the intersection point between hazard and vulnerability.
Analytical curves, Collapse-Based, Capacity Spectrum Method
F
FOR
Group of buildings of same building type and hazard is defined by response of a single similar building
Capacity of the building: what can the building withstand?
Demand on the building: the earthquake hazard applied to the building
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Damage Classes
Damage Class
Adapted from Rossetto and Elnashai, 2003
Expected building damage ratios are calculated using vulnerability methods, and are classified in a number of limit/damage states – none, slight, partial, moderate, severe and collapse or otherwise.
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Capacity Spectrum Method By finding the performance point, the spectral response is
used by pre-defined probabilities of lifelines or infrastructure failure.
Important to know, as the most common in the world.
Performance Point, fragility function
Where the performance point is, changes the damage states of the buildings.
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What is socio-economic vulnerability to earthquakes?
Socio-economic vulnerability is concerned with the study of the impact of earthquakes on social and economic systems – “community vulnerability”
The flow-on effects of earthquakes in terms of recovery and damage to life systems sometimes outweigh the physical damage effects of earthquakes.
Socio-economic vulnerability of a community is often modeled by Design of models which explain vulnerability and the root
causes which create it, and The development of indicators and indexes which attempt to
map vulnerability over time and space
Socio-Economic vulnerability, flow-on effect, recovery, fragility, resilience
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What is socio-economic vulnerability to earthquakes?
Socio-economic vulnerability is concerned with the study of the impact of earthquakes on social and economic systems – “community vulnerability”
The flow-on effects of earthquakes in terms of recovery and damage to life systems sometimes outweigh the physical damage effects of earthquakes.
Socio-economic vulnerability of a community is often modeled by Design of models which explain vulnerability and the root
causes which create it, and The development of indicators and indexes which attempt to
map vulnerability over time and space
Socio-Economic vulnerability, flow-on effect, recovery, fragility, resilience