Analysis of the soil structure-interaction effects on the seismic vulnerability of mid-rise RC buildings in Lisbon

Soil-structure interaction (SSI) effects are usually omitted in the seismic vulnerability analyses of buildings. However, it has been proved that they might notably affect their performance. In fact, European codes establish should be included certain structures: with considerable second order (p-Δ) or mid/high-rise These characteristics shared by reinforced concrete (RC) buildings Portugal, which represent a amount its building stock. Moreover, significant percentage (50%) have constructed prior to restrictive codes, i.e., without adequate design. To obtain reliable results when including SSI effects, state-of-the-art reveals proper modelling soil and foundations carried out. Nevertheless, most related studies based on ideal structural configurations. addition, found there is lack guidance, even quantification effects. Therefore, this paper focuses quantifying RC means two approaches: Beam Nonlinear Winker method (BNWM) direct soil. The aim propose practically include thoroughly characterise behaviour. applied case study mid-rise Lisbon. A clay-type commonly Lisbon characterised, carrying out under undrained conditions. 3D finite elements procedures proposed reproduce complex nonlinear constitutive law behaviour entire system (soil + foundation structure) as realistically possible. compared terms safety verification fragility assessment. shown modal deformed shape same SSI. Nonetheless, demonstrated increasing flexibility leads higher periods damage. For study, maximum capacity models can reduced up 15% if considered.