Preliminary Investigation of the Influence of Soil-Structure Interaction on the Nonlinear Dynamic Response of Steel MRFs with Dissipative Connections

Within an ongoing German-funded research project, a series of beam-to-column joints with dissipative bolted connections was developed for Moment-Resisting Frames designed for moderate seismicity. Due to the new provisions of the German National Annex to EN 1998-1, seismic hazard has gained increased importance, resulting in extended seismic areas and higher spectral acceleration. Additionally, in soft soil formations, the seismic response of a structure may be influenced by its interaction with the soil-foundation system, thus deviating from the traditional fixed-base design/assessment assumption. While the motivation was to find solutions to address these challenges, the approach was to develop pre-qualified dissipative beam-to-column joints classified as semi-rigid and equal/partial-strength for office and industrial buildings that could allow for the use of behavior factors in the range of 1.5–3. End-plate connections based on the German catalogue of typical connections were optimized to perform beyond the elastic range and experimentally investigated on full-scale frame specimens under monotonic and cyclic loading. Alongside an introduction and a description of the case-study structural system (i.e., a steel MRF with dissipative connections), the current paper is focused on the: description of the numerical structural model; consideration of foundation and underlying soil conditions; nonlinear response history analysis of the steel MRF assuming fixed boundary conditions; influence of the SSI on the structural response; main conclusions.