A Step Towards a Unified Analysis of Soil-Structure Interaction Problems of Steel Strategic Structures

Analysis and design of strategic infrastructures require an integration of structural and geotechnical procedures, especially whenever actions due to earthquakes are relevant and strict limit state functions apply. With this perspective, the analysis of soil structure interaction (SSI) problems requires adequate techniques to describe how different soil conditions can impact the structural response. In this framework, the finite element theory plays a key role, and a proper definition of the material behavior at the element level needs to be achieved. Here, the development and the application of the bounding surface concept might be placed to describe, with the same general framework, several materials that own very different properties. In this preliminary work, the implementation of a bounding surface steel material in OpenSees is reported, representing the first stage of a wider framework, where the soil and the structure will be studied with the relative constitutive laws, both deriving from the same mechanical concept that is the bounding surface theory. In particular, a uniaxial bounding surface formulation for steel materials, namely SANISTEEL, has been implemented and numerical benchmarks have been exploited to highlight the valuable performance of its implementation in Opensees.