FAS-compatible synthetic signals for equivalent-linear site response analyses

An alternative approach to generate the seismic input for equivalent-linear (EQL) site response analyses is proposed. The proposed approach encompasses the strengths from current time histories (THs) and random vibration theory (RVT) methods. It consists of the generation of synthetic signals in the time domain (analogous to the TH method) that are constructed to have a Fourier amplitude spectrum (FAS) compatible with the design response spectrum (analogous to the RVT method). Through this approach, the use of extreme value statistics (used in RVT and known to overestimate amplification functions) is avoided. Moreover, the need to develop an appropriate suite of realistic acceleration series, which is the most challenging and time-consuming part of the TH-based approach, is also circumvented. The methodology is evaluated through a comprehensive analysis that includes different site conditions, input spectral shapes, duration scenarios, levels of inelastic demand, and number of synthetic signals used.