Report - PEER - University of California, Berkeley

Report - PEER - University of California, Berkeley Report - PEER - University of California, Berkeley

peer.berkeley.edu
from peer.berkeley.edu More from this publisher
12.07.2015 Views

OVERVIEW OF A COMPREHENSIVE FRAMEWORK FOREARTHQUAKE PERFORMANCE ASSESSMENTGregory G. DEIERLEIN 1ABSTRACTThe Pacific Earthquake Engineering Research (PEER) Center is developing a comprehensiveperformance-based methodology to provide a framework for the next generation of seismicdesign codes and criteria. The performance assessment process follows a logical progression ofsteps, beginning with seismic hazard characterization, and continuing through simulation ofstructural response, damage modeling and assessment, and loss modeling. The outcomes ofeach process are articulated through four generalized variables, termed the earthquake IntensityMeasure (IM), Engineering Demand Parameters (EDP), Damage Measures (DM), and DecisionVariables (DV). A rigorous probabilistic framework permits consistent characterization of theinherent uncertainties throughout the process. Through its modular architecture, the frameworkfacilitates a systems approach to organize the multidisciplinary research necessary to developthe models, criteria, and tools necessary for its implementation. The proposed methodology canbe implemented directly for performance assessment, or can be used as the basis forestablishing simpler performance criteria and provisions for performance-based design.Keywords: Performance based design; Earthquake engineering; Probabilistic.1. INTRODUCTIONPerformance-based earthquake engineering (PBEE) seeks to improve seismic riskdecision-making through assessment and design methods that have a strong scientificbasis and that express options in terms that enable stakeholders to make informeddecisions. Publication of the first generation of PBEE procedures in the United States(FEMA-273 1997 and ATC-40 1996) marked a major advancement to formalizeconcepts that had been envisioned by the earthquake engineering profession for manyyears (Krawinkler and Miranda, 2004). The basic concept of these procedures isshown in Figure 1, where a building is being loaded by earthquake-induced lateralforces that result in nonlinear response and damage. Relations are then establishedbetween structural response indices (interstory drifts, inelastic componentdeformations, and member forces) and performance-oriented descriptions such asImmediate Occupancy, Life Safety and Collapse Prevention.1 Professor, John A. Blume Earthquake Engrg. Center, Stanford University, e-mail: ggd@stanford.edu15

OPEOPEOPEBaseShear000IO LS CP25% 50% 100%0.0001 0.001 0.01 0.251 7 30 180Figure 1. Schematic of PBEE assessment process and performance metrics.As with the introduction of any new technologies, there are limitations in thefirst-generation PBEE procedures that warrant further development. Among these arethe following: (1) Engineering demands and the calibrations between demands andcomponent performance are based on simplified analysis techniques, which are notamenable to the use of more realistic inelastic time-history simulation technologies;(2) Associations between engineering demands and component performance arebased somewhat inconsistently on relations between laboratory tests, analyticalmodels, and engineering judgment; (3) Relationships between building systemperformance and component limit states (e.g., definition of “Life Safety” performancebased on a single component deformation) are tenuous; and (4) Except for theprobabilistic definition of the seismic hazard, the methods are largely deterministicand do not rigorously account for the uncertainties in performance prediction.One of the key improvements of the PBEE approach under development byPEER is to provide a more explicit and transparent evaluation of system performancemetrics, that are more informative to stakeholders. Referring to the lower axes inFigure 1, these metrics provide quantitative measures of economic loss, life safetyrisks (casualties), and downtime. Metrics of this sort are common in regional seismicloss assessment. In this sense, the proposed framework will help unify detailedbuilding-specific engineering provisions with more empirically based regional lossassessment methods, such HAZUS (Kircher et al. 1997a,b).2. PERFORMANCE ASSESSMENT FRAMEWORKAs outlined in Table 1, the proposed assessment methodology is articulated by fourprocesses, which are roughly distinguished along disciplinary lines. Associated witheach process is an output variable, which provides for a systematic transfer ofinformation from one process to another. The assessment begins with definition of a16DeformationFEMA 273/356 Performance Levels$, % replacementCasualty rateDowntime, days

OVERVIEW OF A COMPREHENSIVE FRAMEWORK FOREARTHQUAKE PERFORMANCE ASSESSMENTGregory G. DEIERLEIN 1ABSTRACTThe Pacific Earthquake Engineering Research (<strong>PEER</strong>) Center is developing a comprehensiveperformance-based methodology to provide a framework for the next generation <strong>of</strong> seismicdesign codes and criteria. The performance assessment process follows a logical progression <strong>of</strong>steps, beginning with seismic hazard characterization, and continuing through simulation <strong>of</strong>structural response, damage modeling and assessment, and loss modeling. The outcomes <strong>of</strong>each process are articulated through four generalized variables, termed the earthquake IntensityMeasure (IM), Engineering Demand Parameters (EDP), Damage Measures (DM), and DecisionVariables (DV). A rigorous probabilistic framework permits consistent characterization <strong>of</strong> theinherent uncertainties throughout the process. Through its modular architecture, the frameworkfacilitates a systems approach to organize the multidisciplinary research necessary to developthe models, criteria, and tools necessary for its implementation. The proposed methodology canbe implemented directly for performance assessment, or can be used as the basis forestablishing simpler performance criteria and provisions for performance-based design.Keywords: Performance based design; Earthquake engineering; Probabilistic.1. INTRODUCTIONPerformance-based earthquake engineering (PBEE) seeks to improve seismic riskdecision-making through assessment and design methods that have a strong scientificbasis and that express options in terms that enable stakeholders to make informeddecisions. Publication <strong>of</strong> the first generation <strong>of</strong> PBEE procedures in the United States(FEMA-273 1997 and ATC-40 1996) marked a major advancement to formalizeconcepts that had been envisioned by the earthquake engineering pr<strong>of</strong>ession for manyyears (Krawinkler and Miranda, 2004). The basic concept <strong>of</strong> these procedures isshown in Figure 1, where a building is being loaded by earthquake-induced lateralforces that result in nonlinear response and damage. Relations are then establishedbetween structural response indices (interstory drifts, inelastic componentdeformations, and member forces) and performance-oriented descriptions such asImmediate Occupancy, Life Safety and Collapse Prevention.1 Pr<strong>of</strong>essor, John A. Blume Earthquake Engrg. Center, Stanford <strong>University</strong>, e-mail: ggd@stanford.edu15

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!