9.1 Seismic vulnerability assessment techniques

Seismic vulnerability assessment is crucial for understanding how buildings might fare during earthquakes. It considers factors like structural characteristics, site conditions, and non-structural elements to gauge a building's potential performance.

Advanced techniques dive deeper, using detailed evaluations and sophisticated analysis methods. These assessments help prioritize buildings for retrofitting, determine appropriate performance levels, and guide the selection of effective upgrade strategies to enhance seismic safety.

Seismic Vulnerability Assessment Fundamentals

Factors of seismic vulnerability

Top images from around the web for Factors of seismic vulnerability

• 

  Frontiers | Seismic Vulnerability of Buildings in Historic Centers: From the “Urban” to the ... View original

  Is this image relevant?

• 

  9.1 Understanding Earth through Seismology | Physical Geology View original

  Is this image relevant?

• 

  Frontiers | Seismic Vulnerability of Buildings in Historic Centers: From the “Urban” to the ... View original

  Is this image relevant?

• 

  9.1 Understanding Earth through Seismology | Physical Geology View original

  Is this image relevant?

1 of 2

Top images from around the web for Factors of seismic vulnerability

• 

  Frontiers | Seismic Vulnerability of Buildings in Historic Centers: From the “Urban” to the ... View original

  Is this image relevant?

• 

  9.1 Understanding Earth through Seismology | Physical Geology View original

  Is this image relevant?

• 

  Frontiers | Seismic Vulnerability of Buildings in Historic Centers: From the “Urban” to the ... View original

  Is this image relevant?

• 

  9.1 Understanding Earth through Seismology | Physical Geology View original

  Is this image relevant?

1 of 2

• Structural characteristics

  • Building age and design era influence seismic performance based on evolving building codes
  • Construction materials affect strength and ductility (concrete, steel, masonry, wood)
  • Structural system type determines load path and energy dissipation (moment frames, shear walls)
  • Configuration irregularities create stress concentrations and torsional effects
    • Plan irregularities include L-shaped or U-shaped buildings
    • Vertical irregularities encompass soft stories or setbacks

• Site-specific factors

  • Soil conditions impact ground motion amplification (soft soils vs bedrock)
  • Proximity to active faults increases seismic hazard and potential for near-fault effects
  • Topography influences seismic wave propagation (basin effects, ridgetop amplification)

• Non-structural elements

  • Architectural components pose falling hazards (parapets, cladding, suspended ceilings)
  • Mechanical and electrical systems affect functionality and safety (HVAC, elevators, sprinklers)

• Occupancy and importance determine post-earthquake recovery priorities (hospitals, schools)

• Previous seismic damage or modifications alter structural behavior and capacity

Rapid visual screening methods

• FEMA P-154 Rapid Visual Screening (RVS) procedure standardizes assessment process

  • Data collection forms guide systematic evaluation
  • Scoring system quantifies relative seismic vulnerability

• Walkdown survey techniques gather crucial visual information

  • Exterior inspection identifies global structural characteristics
  • Interior inspection reveals internal vulnerabilities (if accessible)

• Key structural attributes to observe during screening

  • Lateral force-resisting system determines seismic performance (frames, walls)
  • Building height affects dynamic response and overturning potential
  • Soft stories create weak points in vertical load path
  • Heavy cladding or heavy elements increase seismic demands

• Documentation and photography preserve observations for later analysis

• Limitations of rapid screening methods include surface-level assessment and potential hidden defects

Advanced Seismic Vulnerability Assessment

Detailed seismic evaluation techniques

• Tier 1 screening provides initial assessment

  • Checklists for various building types identify potential deficiencies
  • Quick checks for strength and stiffness estimate global capacity

• Tier 2 deficiency-based evaluation analyzes specific weaknesses

  • Linear static procedures use equivalent lateral forces
  • Linear dynamic procedures incorporate modal response

• Tier 3 systematic evaluation employs advanced analysis

  • Nonlinear static procedures (pushover analysis) capture post-yield behavior
  • Nonlinear dynamic procedures (time history analysis) model full seismic response

• Performance-based seismic evaluation tailors assessment to specific goals

  • Define performance objectives based on stakeholder requirements
  • Analyze building response under various earthquake scenarios
  • Compare demands to capacities to determine performance level

• Capacity spectrum method graphically compares demand and capacity

• Fragility curve development quantifies probability of damage states

• Probabilistic seismic hazard analysis integration considers multiple earthquake sources

Interpretation of vulnerability assessments

• Risk categories and importance factors prioritize critical structures (hospitals, power plants)

• Seismic performance levels define acceptable damage states

  • Operational allows immediate post-earthquake use
  • Immediate Occupancy permits safe re-occupancy
  • Life Safety ensures low probability of life-threatening injury
  • Collapse Prevention avoids total or partial structural collapse

• Benefit-cost analysis for retrofit options weighs investment against risk reduction

• Prioritization criteria guide resource allocation

  • Life safety considerations protect building occupants
  • Economic impact assesses potential losses and business interruption
  • Building function and importance reflect community needs (emergency services)

• Retrofit strategy selection addresses identified vulnerabilities

  • Global interventions improve overall structural performance (base isolation)
  • Local interventions target specific weaknesses (column jacketing)

• Implementation planning ensures effective execution

  • Phasing of interventions minimizes disruption to building use
  • Occupancy considerations during retrofit maintain safety and functionality

• Post-retrofit reassessment and validation confirm effectiveness of interventions