Damping modification factors for the design of seismic isolation systems in Peru

This study proposed a simple nonlinear equation to estimate damping modification factors (DMFs) to modify the elastic response spectral values for damping ratios between 10% and 50%. The DMFs are computed from the displacement, acceleration, and velocity response spectral of single-degree-of-freedom (SDOF) systems of 198 earthquake acceleration time histories from 40 earthquakes events of Peruvian database, grouped into three types of soil: hard soil, intermediate soil, and soft soil. For each soil group, 11 scaled records were selected according to the ASCE 7-16 standard to match the design spectrum of the Peruvian technical standard for seismically isolated structures E.031. Simplified approximate nonlinear period-dependent expressions were provided to compute DMFs from the Peruvian strong-motion database and were compared with DMFs available in the literature and national seismic design codes. The study showed discrepancies with the regulations worldwide.