Report - PEER - University of California, Berkeley

acceleration, or another parameter. IM’s are expressed typically as a function ofmean annual probability of exceedance, p[IM], which is specific to the location of thebuilding and its mechanical characteristics (e.g., first and second mode periods). Mostnonstructural components and systems, unlike structures, are not directly affected bythe ground shaking, but rather are affected by motion or shaking of the structure towhich they are attached or upon which they are supported. Therefore, fornonstructural components and systems, except those mounted at grade, the IM mustcharacterize not the intensity of the ground shaking, but rather the intensity of theresponse motion of the building structure at the points of attachment of thenonstructural components.FacilityinfoHazard analysisStruct'l analysisDamage analysisLoss analysisDecisionmakingp[IM|O,D ]p[EDP |IM ]p[DM|EDP ]p[DV|DM ]O, Dp [IM]p[EDP]p[DM]p[DV]SelectO, DO: LocationD: DesignIM : intensitymeasureEDP : engineeringdemand param.DM : damagemeasureDV : decisionvariableFigure 1. Steps in the performance assessment process (Moehle 2003).For building structures, the second step of the assessment process is to determineEngineering Demand Parameters (EDPs) that describe the response of the structureas a whole and of its individual structural components. This is accomplished bystructural response simulations using the ground shaking IMs and correspondingearthquake motions. Similarly, for nonstructural components, NonstructuralEngineering Demand Parameters (EDP-Ns) that describe the response of thenonstructural components and contents to earthquake shaking transmitted to them bythe supporting structure, must be determined. Many nonstructural components actessentially as rigid bodies and have no response that is distinctly different than themotion of the structure that supports them. For these classes of nonstructuralcomponents, EDP-Ns that quantify the structural response, e.g., peak interstory driftdemands, may be used directly to predict nonstructural performance. However, somenonstructural components have inherent flexibility and will either amplify or attenuatethe motions transmitted to them by the structure and in the process, will experiencemotions that are different from those experienced by the supporting structure. Forthis class of nonstructural components, the second step in the performance assessmentprocess is to select structural EDPs calculated from the predicted response of thestructure, that predict the severity of shaking the nonstructural components aresubjected to. An example of such a structural EDP is a floor response spectrum. Inessence, these structural EDPs serve as IMs for the nonstructural components. Then128