Seismic fragility of low-rise steel frames including SSI and site amplification effects

Abstract

We aim to assess the influence of soil–structure interaction (SSI) and site amplification (SAmp) effects on the seismic response of steel frame structures. In particular, idealized steel structures are examined. Typical soil materials and profiles are selected according to Eurocode 8 and simulated with finite elements using OpenSees. Then, incremental dynamic analyses are carried out using actual earthquake records of increasing intensity. The study of the steel frames is performed for two foundation models: (a) fixed-base and (b) Beam-on-Nonlinear-Winkler-Foundation spring-type foundation elements. The results of the dynamic analyses are indicatively presented and discussed based on both the relative displacement of the floors and the moment–rotation curve at the ends of the beams and columns. The thorough analysis and comparison of the results demonstrate the significant contribution of various subsoil configurations and SSI to the seismic behavior of steel frames. The methodology can be used to assess further the influence of SAmp and SSI on steel structures’ seismic fragility and vulnerability.