Seismic response of SDOF systems representing masonry-infilled RC frames with damping systems

The seismic response of simplified models for masonry-infilled RC frames (MIRCFs) with damping systems is investigated through extensive nonlinear time history analysis of inelastic SDOF systems with a linear dashpot. Based on mean response data for simulated ground motions, response reduction efficiency of supplemental viscous damping in the simplified models, and the influence of various model properties are investigated. Furthermore, the applicability of conventional damping correction factors to the simplified models for MIRCFs with damping systems is evaluated by interpolating ductility demands of the inelastic SDOF systems without supplemental viscous damping with respect to reduced seismic demands. Due to unacceptably significant errors from the damping correction factors in the estimation of ductility demands, regression equations for estimating ductility demand reductions achieved by supplemental viscous damping are proposed based on the mean response for the simulated ground motions. Also, the applicability of the proposed regression equations to the near-fault ground motions is validated, and a correction term is proposed for the improvement of fitting. The proposed regression equations can be utilized to estimate supplemental viscous damping ratios achieving target ductility demands of existing MIRCFs on the preliminary design stage.