Strength reduction factor (R factor) model and inelastic response spectra for forward-directivity ground motion

摘要

The accuracy of six existing R-factor models for estimating inelastic response spectra is evaluated by using a suite of forward-directivity (FD) records and single-degree-of-freedom (SDOF) oscillators. Structural loaddeformation mechanism is modelled using perfectly elastic-plastic, bilinear and stiffness degrading models.Two site conditions, rock site and soil site, are considered. A R-factor ratio (ratio of R factors from the existing R-factor Models to those from inelastic analyses) is used as a measure parameter. Results show that the Ordaz & Perez-Rocha model is suitable for use to estimate inelastic response spectra for FD ground motions. Based on the data set of FD records, a new R-factor model with considering the effect of site conditions is proposed. The accuracy of the new model has been checked, showing lower estimate error than the existing models.