Report - PEER - University of California, Berkeley

The specimens listed in Table 2 have design details typical of pre-1967 constructionand were subjected to similar simulated earthquake load histories in the laboratory.However, as suggested by the data in Table 2 there are variations in both the designdetails and gravity loading. These variations contribute to variability in the observeddamage patterns and progression.3. IDENTIFYING DAMAGE STATES, ENGINEERING DEMANDPARAMETERS AND METHODS OF REPAIR3.1 Engineering Demand ParametersWithin the context of this study, an engineering demand parameter (EDP) is a scalaror functional quantity that defines the earthquake demand on a joint at any point inthe load history. Since the objective of the current study is to develop models for usein predicting joint damage given an EDP value, we are seeking to find the EDP thatmost accurately and precisely predicts joint damage. Since data characterizing theresponse of the laboratory test specimens discussed previously are used to developmodels linking EDPs with damage states and methods of repair, the domain ofpotential EDPs is limited to the data published by the experimental researchers.A review of the literature and the experimental data provides a basis foridentifying a series of five potential EDPs:• Maximum inter-story drift: Drift is a simply demand measure provided by allresearchers, and there is consensus within the earthquake engineeringcommunity that drift is a measure of earthquake demand. However, interstorydrift comprises flexural deformation of beams and columns as well asjoint deformation. Thus, it is an imperfect measure of joint deformationdemand.• Number of load cycles: Like drift, the number of load cycles is a simplydemand measure provided by all researchers and there is consensus withinthe earthquake engineering community that the number of load cycles has animpact on the observed response of components.• Maximum joint shear strain: Joint shear strain represents a substantialimprovement over inter-story drift, since it is a measure only of jointdeformation demand. However, joint shear strain data are provided by fewresearchers; the sparsity of these data may increase model uncertainty.• Drift in combination with the number of load cycles: The results of previousresearch suggest that earthquake demand on a component is bestcharacterized by a function that includes a measure of displacement demandand a measure of the number of load cycles. Given the availability of drift asa measure of joint deformation demand, a functional EDP that includes interstorydrift and number of load cycles is proposed:F +b d= aD cN(2)213