Methods for Determining the Key Parameters of Elastoplastic Seismic Isolators

Elastoplastic dampers (EPD) have found a wide application all over the world as standalone seismic restraints or elements of structural seismic isolation systems. This paper proposes a series of methodologies for determining the key parameters of the elastoplastic dampers, which involve the actuation force, force diagram, and the number of operating cycles. These methods build on the laws governing the variation of resistance forces in an EPD, the former being intricately dependent on plastic elements’ previous exposure to stress, as well as on the properties of steels they are made of. The paper further discusses the rigid-plastic and elastoplastic analyses, the pseudorigidity method algorithm, and the macromodel method, presenting analytical dependencies for simplest damper designs, as well as analytical and semi-analytical dependencies for the general-independent force curves of rectilinear element with rectangular cross-section, quarter-circle element, hardened elastoplastic material, and samples with circular cross-section. Examples are provided of the application of the proposed techniques, as well of experimental studies into the mechanical properties of elastoplastic elements. The proposed methods allow for a more comprehensive approach to calculating the design of the elastoplastic dampers for use in seismic protection systems.