Existing masonry buildings retrofitted by steel fiber reinforced mortar coatings: comparison of different analysis approaches

Recent experimental studies have investigated the use of Steel Fiber Reinforced Mortar (SFRM) coating applied only to the facades of existing masonry buildings, demonstrating its potential to enhance the overall seismic performance of the structure at both damage and safety limit states. Despite the growing availability of experimental data, the analytical and numerical approaches presented in the literature for assessing the structural performance of strengthened buildings still require further development and refinement for future inclusion in structural codes. This research is based on a real case study consisting of a three-story residential masonry building constructed in the 1960s–1970s and sited in Northern Italy. The building is analyzed through linear and nonlinear methods to predict its behavior both before and after retrofitting with SFRM coating. Linear analyses using the behavior factor “q” are performed by implementing an analytical, code-oriented model developed by the authors. This model allows predicting the resistance of masonry panels strengthened with SFRM coating starting from the mechanical properties usually recommended by structural codes to characterize both masonry and SFRM. In addition, nonlinear static analyses (pushover) are carried out using a macro-element modeling approach implemented in a commercial code. These two analyses methods are used to carry out a parametric study that investigates the influence of key parameters that primarily affect the global behavior of the building. The results provide insights into design applicability and practical implementation of these analysis approaches, highlighting both their potential benefits and possible limitations.