Report - PEER - University of California, Berkeley

PERFORMANCE AND DISPLACEMENT-BASED EARTHQUAKELOSS ESTIMATION OF URBAN AREASRui PINHO *ABSTRACTCode implementation of performance-based seismic design requires the definition of multipledesign levels, each of which is coupled with different performance limit states that structuresmust then comply to. The definition of such pairs of design and performance levels shouldideally be based on cost-benefit considerations derived from reliable and computationallyefficient loss models, which, at their core, feature sound deformation-based principles andprocedures that lead to an explicit and accurate account of structural performance. This workdescribes preliminary efforts in developing such a loss model, where distribution of damagestates at a specific location, and for any given earthquake ground motion, can be readilyestimated through a set of analytically-derived relationships that correlate buildingdisplacement capacity and height, which in turn can be related to displacement demand.Uncertainty in geometrical, material and limit state properties of a building class is alsoexplicitly accounted for, without compromising the elegance of the procedure. In this way,studies on regional or national levels may still be effectively carried out, even when thetriggering of multiple earthquake scenarios, as opposed to the use of probabilistic hazard mapsand uniform hazard spectra, is employed to realistically assess seismic demand and itsconsequences on the built environment.Keywords: Displacement-based assessment; Earthquake loss estimation; RC structures.1.1 Preamble1. INTRODUCTIONThe main objective of performance-based seismic design, for both new and existingstructures, is to control all earthquake losses, including direct and indirect economiclosses in addition to the fundamental life-safety objective. As widely acknowledged,this requires the definition of multiple design levels, each coupled with differentperformance limit states to which structures must then comply to. As noted byBommer (2004), however, arbitrary choices, as opposed to sound technical principles,seem to have played the decisive role in the choice of the design levels that arenowadays employed in the majority of seismic design codes (e.g., spectral* European School for Advanced Studies in Reduction of Seismic Risk (ROSE School), Pavia, Italy173