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Report - PEER - University of California, Berkeley

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The closure probability is significantly influenced by the dispersion and demandsresulting from the choice <strong>of</strong> the period at which the ground motions are scaled.5. FINDINGS AND CONCLUSIONSThe estimated closure probabilities for all cases investigated in this study were quitesmall. Hence, the effects <strong>of</strong> model variations were not immediately apparent thoughthe order <strong>of</strong> difference in the closure probabilities was considerable in some cases.Closure probabilities are controlled by the following factors: (i) the selectedcharacteristic period <strong>of</strong> the model, since ground motions need to be scaled to thespectral magnitude <strong>of</strong> the hazard spectra at this period — changes in the spectralordinates change the coefficients that appear in Equations 2 and 3 and are carriedthroughout the evaluation process; (ii) the dispersion <strong>of</strong> the response estimates —larger dispersions lead to larger estimates <strong>of</strong> damage; and (iii) the decision variablesrelating damage to closure — if decisions are not made rationally and consistent withthe degree <strong>of</strong> damage, then the integrity <strong>of</strong> the entire evaluation process can becompromised.ACKNOWLEDGEMENTSThis work is funded by a grant from the Pacific Earthquake Engineering Researchcenter which is supported in part by the Earthquake Engineering Research CentersProgram <strong>of</strong> the National Science Foundation under Award Number EEC-9701568.REFERENCESBauer. (2003). Simulation Models for the Nonlinear Seismic Response <strong>of</strong> the I-880Viaduct. M.S. Thesis, Department <strong>of</strong> Civil and Environmental Engineering,<strong>University</strong> <strong>of</strong> <strong>California</strong>, Davis.Berry, M., and M. Eberhard. (2003). “Column Deformation Demands at BarBuckling,” ASCE Structures Congress, Seattle.Cornell, C. A., F. Jalayer, R. O. Hamburger, and D. A. Foutch. (2002). “ProbabilisticBasis for 200 SAC Federal Emergency Management Agency Steel MomentFrame Guidelines.” ASCE Journal <strong>of</strong> Structural Engineering, 128 (4), 526–533.FEMA-350. (2000). Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings. Developed by the SAC Joint Venture for the FederalEmergency Management Agency, Washington D.C.OpenSees. (2004). “Open System for Earthquake Engineering Simulation.”http://opensees.berkeley.edu.Porter, K. (2004). “A Survey <strong>of</strong> Bridge Practitioners to Relate Damage to Closure.”<strong>California</strong> Institute <strong>of</strong> Technology, unpublished report.Somerville, P., and N. Collins. (2002). “Ground Motion Time Histories for the I880Bridge, Oakland.” URS Corporation, Pasadena, CA.76

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