Report - PEER - University of California, Berkeley

collapse prevention level (Panagiotakos and Fardis, 2004a, 2004b). DC M is slightlyeasier to design for and achieve at the site and may provide better performance inmoderate earthquakes. DC H may give better performance under motions (much)stronger than the design seismic action. Unlike US codes, EC8 does not link selectionof the ductility class to seismicity or to the importance and occupancy of the building,nor puts any limit to their application. The choice is left to the National Annex, whichmay in turn leave it to the designer depending on the particular project.Unless the Country objects through its National Annex to Eurocode 8, it isallowed to design without employing the q-factor, but directly on the basis ofnonlinear analysis (pushover or time-history analysis). In that case ductile membersverified by comparing directly deformation supplies to demands. The definition ofacceptable member deformation limits is left to the National Annexes. To ensure aminimum global and local ductility in buildings designed on the basis of nonlinearanalysis, Eurocode 8 requires that they meet all DC M rules (for member detailing,strong columns-weak beams in frames, capacity design in shear, etc.). By allowingdesign directly through nonlinear analysis with member verification on the basis ofdeformations, the 1 st generation of Eurocode 8 paves the way for fully displacementanddeformation-based design in the 2 nd generation.2.2 Member Detailing for Deformation Demands Derived from the BehaviorFactor2.2.1 Required Curvature Ductility Factor µ φ at the End Section of PlasticHingesIn buildings designed with the common forced-based approach that employs the q-factor for the reduction of elastic forces, the value of q is taken to be related to theglobal displacement ductility factor, µ, through the Vidic et al. (1994) q-µ-T relation:µ δ =q, if T 1 ≥T C , µ δ =1+(q-1)T C /T 1 , if T 1