Estimating Peak Inelastic Displacement of Steel SMRF Structures Subjected to a Single or Series of Strong Ground Motions with Scaled Response Spectra

The peak inelastic displacement of a building during strong ground motion (GM) correlates with the elastic period of the structure. Algan (1976) observed this while subjecting laboratory scale reinforced concrete building structures to dynamic base excitations. Later, Lepage (1996) expressed the relationship in a simple form after carrying out regression analysis on dynamic response data from a wide range of buildings. Both Algan and Lepage focused on reinforced concrete buildings. In this study, the presence of a similar correlation between peak inelastic displacement and initial, elastic period in steel special moment resisting frame (SMRF) type building structures is investigated. Two sets of GMs are used in response simulation of 3-story and 9-story SMRFs using OpenSEES. The uniaxial Giuffre-Menegotto-Pinto model, with isotropic strain hardening and uniaxial bilinear behaviors, is considered to have two steel material properties of the structures. The structures are subjected to a series of ground motions with ascending peak ground accelerations. The results are compared with the corresponding responses from non-deteriorated (pristine) structural systems subjected to the highest intensity ground motion from the mentioned ground motion series. Each ground motion is scaled to a target spectral acceleration with respect to the first period of the structure. It is found that a simple empirical expression could be used to estimate the peak inelastic displacement. The source of this rather unexpected behavior is investigated through extensive high-performance computational simulations of how fundamental dynamic characteristics relate to damage and/or softening in a building structural system, including damage accumulation.