Seismic displacement response spectrum estimated from the frame analogy soil amplification model

This paper describes the development of a simple and rational manual procedure, termed the “frame analogy soil amplification” (FASA) model, which can be used to construct realistic seismic soil response spectra that account completely for the effects of soil resonance. FASA is based on the analogy of the dynamic response behaviour of a building to represent the dynamic behaviour of a horizontally layered soil column, when subject to earthquake excitations transmitted from bedrock. The theoretical foundation of FASA requires relatively few data for verification and calibration purposes. Thus, it is particularly suited to applications in regions of low and moderate seismicity where field data are typically limited. The procedure becomes even more powerful when its capability is extended to predict the response spectral displacement (RSD). This paper presents (1) a summarised account of the conception and development of the FASA-RSD model, (2) a comparison of the model predictions with response spectra computed from shear wave analysis (using the computer program SHAKE) and with response spectra recorded from the 1989 Loma Prieta earthquake, and (3) the application of FASA including commentaries and an illustrative example.