Investigation of soft story effect in RC structures using different strengthening methods

Abstract

Earthquakes are natural disasters that cause significant destruction and loss of life. One of the primary causes of these devastating effects is structural irregularities. Among these irregularities, soft-story irregularity is among the most critical, significantly reducing the seismic performance of structures. This usually occurs when the ground story is built higher than the other stories, which causes a sudden decrease in the rigidity of that story and an increase in lateral deformations. In this study, the effects of different strengthening techniques on the seismic behavior of reinforced concrete structures with soft-story irregularity were comparatively investigated. A regular structure model was used as a reference, alongside a soft-story model and four different retrofitting strategies: reinforced concrete jacketing, addition of shear walls, carbon fiber reinforced polymers (CFRP) wrapping, and integration of viscous dampers. The seismic performance of the models was evaluated using nonlinear time-history analyses and pushover analyses. There is a lack of comprehensive evaluations that compare multiple methods within the same structural model. For this reason, each strengthening method was comparatively assessed in terms of its contribution to stiffness enhancement, ductility improvement, displacement reduction, energy dissipation capacity, and architectural applicability in this study.