Assessment of an Existing RC Frame Subjected to Differential Settlements using Nonlinear Finite Element Analysis

The paper concerns the assessment of a reinforced concrete frame subjected to uneven strong settlements. The structure is representative of existing Italian residential buildings designed for gravity loads only. Fibre-based nonlinear finite element models are developed, to evaluate structural performance and damage propagation under increasing displacements. The results obtained from a simple, yet quite common approach in progressive collapse analyses, based on a 2D model of a single frame, are compared to the outcomes of 3D models of the whole structure, considering two different spatial layouts for foundations. The contribution of secondary beams and foundation footing to the overall spatial stability of the building is then quantified.