A pushover-based simplified approach for predicting post-earthquake residual displacements in low-rise RC frames

The prediction of post-earthquake residual displacements in Reinforced Concrete (RC) structures is crucial for assessing the usability of buildings after seismic events. Even in the absence of significant structural damage, permanent deformations can indeed compromise a building’s functionality, potentially necessitating demolition. This study proposes a simplified method based on nonlinear static analysis to estimate residual displacements of RC frames, thereby avoiding the high computational cost of dynamic nonlinear analyses. The proposed method, structured into four sequential and interrelated phases, is validated considering different case studies consisting of RC frames characterized by both different numbers of stories (two and three stories) and different structural failure mechanisms (strong columns-weak beams and weak columns-strong beams mechanisms). Both dynamic and static numerical analyses were performed using OpenSees software integrated within a MATLAB subroutine. The results demonstrate that the proposed approach provides a reliable approximation of post-earthquake residual displacements of RC-frames, offering a computationally efficient alternative to more complex dynamic analyses; at present it applies to two- and three-storey, single-bay frames that are regular in plan and elevation, limits typical of any first-mode pushover method, while further validation on irregular, infilled and taller buildings is underway.