Seismic assessment and FRCM strengthening of post-war masonry residential buildings: A case study on building typologies

Abstract

This study presents a comprehensive seismic vulnerability assessment of early post-war multi-residential unreinforced masonry (URM) buildings in Slovenia, focusing on structures built between 1945 and 1963. Using an approach that links architectural configuration with structural behavior, over 400 buildings in Ljubljana were categorized into 24 distinct typologies based on shape, height, and structural characteristics. Four representative building types underwent detailed seismic performance evaluation using nonlinear static analysis. The analysis revealed that none of the examined buildings met current Eurocode 8 seismic requirements. Two retrofitting scenarios for enhancing the seismic resilience using Fiber Reinforced Cementitious Matrix (FRCM) were investigated: a selective approach focusing on critical structural elements, and a comprehensive strategy applied to all load-bearing walls. While both scenarios improved seismic performance, they generally fell short of achieving full Eurocode 8 compliance. Interestingly, the selective retrofitting approach demonstrated higher efficiency in some cases. A novel efficiency metric revealed that FRCM retrofitting was generally more effective in directions with lower initial wall percentages. The study highlights the challenges in upgrading existing URM buildings to modern seismic standards and suggests the need for typology-specific approaches to assessment and retrofitting. The findings underscore the importance of tailored strengthening strategies and indicate that achieving full compliance may require more comprehensive or alternative techniques for this vulnerable building stock.