Property Modification Factors for Seismic Isolators: Design Guidance for Buildings

Keywords: seismic isolation, ASCE 7-2016 Standard, system property modification factors, bounding methods of analysis

Abstract: This report provides guidance on the application of the provisions of the 2016 ASCE 7 Standard for the analysis and design of seismically isolated buildings. These new provisions introduced a systematic approach for the determination of the bounding values of the mechanical properties of the isolators on the basis of experimental data of prototype isolators and considerations for the effects of the environment, aging and uncertainty. The report presents an overview of the concept of system property modifi cation factors that is used in the establishment of the bounding values and proceeds with two systematic examples, one for an elastomeric and one for a sliding isolation system. Moreover, the new provisions are critically reviewed for consistency between the requirements for establishing bounding values and the prescribed acceptance criteria in the testing of prototype isolators. Changes are proposed to the standard to avoid inconsistencies.