PerformanceBased Earthquake Engineering To transform earthquake engineering assessment
Performance-Based Earthquake Engineering To transform earthquake engineering assessment and design. . . Traditional Approach Perform. -Based Approach • Non-scientifically defined seismic hazard • Scientifically-defined seismic hazard • Indirect design approaches • Undefined and uncertain outcomes • Direct design approaches • Defined outcomes with probabilities of achieving them
Assessment by Static Pushover Analysis (FEMA 273/356 and ASCE 41) Base Shear Demand Joe’s Beer! Food! Very rare events (2%/50 yrs) Rare events (10%/50 yrs) Occasional events (20%/50 yrs) Frequent events (50%/50 yrs) Operational Life Safe Structurally Stable Lateral Deformation Ref: R. O. Hamburger
Performance-Based Earthquake Engineering O P E N Base Shear O P E N Collapse Onset Damage Threshold Deformation PBEE today IO PBEE tomorrow 25% 0 0 LS 0. 0001 1 7 50% 0. 001 30 CP 100% 0. 01 180 0. 25 FEMA 356 Performance Levels $, % replacement Casualty rate Downtime, days
Probability of Damage State Damage Assessment: Nonstructural Fragilities Severe damage to gypsum board and distorsion of metal frame (Replace partition) Wide cracks in gypsum boards (Replace gypsum boards) Smallcracksonly Small cracks only Small (Patch, Retape & Paint) Interstory Drift Ratio Ref: E. Miranda
Performance-Based Methodology • Collapse & Casualties Decision Variable • Direct Financial Loss • Downtime Damage Measure drift as an EDP Engineering Demand Parameter Intensity Measure
Incremental Dynamic Analysis – Collapse GROUND MOTION INTENSITY 44 Ground Motion Records STRUCTURAL RESPONSE (DRIFT) 6
Mean Annual Frequency of Collapse CDF 2. 7 Collapse Performance n Margin: Sa, collapse = 2. 7 MCE n 5% Probability of collapse under design MCE = 5% 5% n Hazard Curve 2/50 Mean Annual Frequency: MAFcol = 1. 0 x 10 -4 (0. 5% in 50 years)
Nonstructural Damage and Losses (Caltech)
PBEE Methodology: IM-EDP-DM-DV Ground Motion Hazard Characterization n n IM Definition (Sa, …) Selection and Scaling of Ground Motions Simulation: IM – EDP n n Choice of EDPs (Drift, Floor Accel. , other …) Fidelity of simulations to model collapse Damage Modeling: EDP – DM n n Taxonomy of components Definition of conditional EDP-DM “damage function” Loss Modeling: DM – DV n n Definition of conditional DM-DV loss functions Downtime and injuries/fatalities are a challenge
Performance Assessment Components Decision Variable Relating Performance to Risk Decision Making Damage Measure Quantifying Damage Measures Engineering Demand Parameter Simulation of System Response Intensity Measure Earthquake Hazard Characterization
Integrative Testbeds Buildings - Van Nuys - UC Sciences - SRB UCB Campus Bridges - Humboldt Bay - I-880 Viaduct Bay Area Highway Network
Performance Assessment Components Decision Variable Relating Performance to Risk Decision Making Damage Measure Quantifying Damage Measures Engineering Demand Parameter Simulation of System Response Intensity Measure Earthquake Hazard Characterization
Performance Assessment Components Decision Variable DV: $ loss, functionality, downtime, casualties Damage Measure DM: physical condition & consequences/ramifications Engineering Demand Parameter EDP: Drift Ratio (peak, residual), Floor Acceleration, Local Indices (Qp, strain, …) Intensity Measure IM: Sa(T 1), multiple Sa’s, epsilon, Sdinelastic, duration
PBEE – Probability Framework Equation Impact Performance (Loss) Models and Simulation Hazard IM – Intensity Measure EDP – Engineering Demand Parameter DM – Damage Measure DV – Decision Variable n(DV) – Probabilistic Description of Decision Variable (e. g. , Mean Annual Probability $ Loss > 50% Replacement Cost)
Comprehensive System Simulation REF: Yang, Conte, Elgamal (UCSD) REF: Boulanger (UCDavis)
NS Components & Contents Problem Insight – Small Equipment DM EDP = PFA Hutchinson IM = Sa(T 1) -Cascade approach -Transmissibility important
Integrated Simulation/Assessment Platform Computation Information Technology Algorithms, Solvers, Parallel/distributed computing Software framework, Databases, Visualization, Internet/grid computation Models Simulation & Reliability Models for Materials, Components, and Systems http: //opensees. berkeley. edu
Integrative Testbeds Buildings n Van Nuys n UC Sciences UCB Campus Bridges n Humboldt Bay n I-880 Viaduct Bay Area Highway Network
Evolution of PBEE Concept Individual Buildings: Building Ratings: Groups of Buildings: • Evaluation • Retrofit • Probable Maximum Loss • Other • Portfolio Analysis • Regional Loss Studies • Mitigation Studies e. g. , FEMA 273/356 e. g. , ST-RISK e. g. , ATC 13, HAZUS Performance Objectives Ref. W. Holmes Percentage or Dollars Casualties Repair Costs Downtime
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