PSI - Issue 78

Sara Silvana Lucchini et al. / Procedia Structural Integrity 78 (2026) 1079–1086

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Y1

Y3

Y4

Y5

Y10

Y9

Y8

(a)

Y1

Y3

Y4

Y5

Y10

Y9

Y8

(b) Fig. 4. Pushover analyses: failure mechanisms of main Y-oriented masonry piers. (a) unstrengthened building and (b) building retrofitted by 20 mm thick SFRM coating on the external surface (piers Y1, Y8, Y9 and Y10).

2.4. Parametric study

The analysis methods described in the previous paragraphs were used to carry out a parametric study aimed at investigating the influence of the SFRM thickness on the global seismic response. Increasing the thickness of the SFRM coating from 20 mm to 30 mm leads to a 6% increase in the building’s seismic capacity in the Y direction according to nonlinear analysis, and to a 4% increase according to linear analysis. The failure mechanisms of the perimeter piers tend to shift further toward flexural behavior due to the significant increase in shear strength. On the other hand, the unstrengthened internal piers are subjected to a lower seismic demand due to the increased stiffness of the perimeter piers, which consequently attract a larger portion of the seismic action. The limited increase in strength is attributable to the shift of the critical failure mechanism from diagonal shear to flexure, which, due to the absence of continuity of SFRM coating at the wall-to-foundation interface and the lack of coating-to-foundation steel connections, exhibits a relatively modest improvement. However, this shift represents a transition from a brittle to a ductile failure mode, which leads to a significantly improved performance in the pushover analyses in terms of seismic vulnerability assessment. The software also allows to model steel rebars to restore the continuity of SFRM coating at the wall-to foundation interface. Future works will focus on investigating the influence of these rebars on collapse mechanisms and on the overall seismic response of the building. 3. Conclusions and future developments A real case study consisting of a three-story residential masonry building constructed in the 1960s – 1970s and sited in Northern Italy was analyzed through linear and nonlinear methods to predict its behavior before and after retrofitting with SFRM coating. Both approaches identified the first floor as the most critical, due to the lower