Numerical Investigation of Masonry Strengthened with Composites

Abstract

In this work, two main fiber strengthening systems typically applied in masonry structures have been investigated: composites made of basalt and hemp fibers, coupled with inorganic matrix. Starting from the experimental results on composites, the out-of-plane behavior of the strengthened masonry was assessed according to several numerical analyses. In a first step, the ultimate behavior was assessed in terms of P (axial load)-M (bending moment) domain (i.e., failure surface), changing several mechanical parameters. In order to assess the ductility capacity of the strengthened masonry elements, the P-M domain was estimated starting from the bending moment-curvature diagrams. Key information about the impact of several mechanical parameters on both the capacity and the ductility was considered. Furthermore, the numerical analyses allow the assessment of the efficiency of the strengthening system, changing the main mechanical properties. Basalt fibers had lower efficiency when applied to weak masonry. In this case, the elastic properties of the masonry did not influence the structural behavior under a no tension assumption for the masonry. Conversely, their impact became non-negligible, especially for higher values of the compressive strength of the masonry. The stress-strain curve used to model the composite impacted the flexural strength. Natural fibers provided similar outcomes, but a first difference regards the higher mechanical compatibility of the strengthening system with the substrate. In this case, the ultimate condition is due to the failure mode of the composite. The stress-strain curves used to model the strengthening system are crucial in the ductility estimation of the strengthened masonry. However, the behavior of the composite strongly influences the curvature ductility in the case of higher compressive strength for masonry. The numerical results discussed in this paper provide the base to develop normalized capacity models able to provide important information on the out-of-plane behavior of masonry elements strengthened with inorganic matrix and several kinds of fibers, both synthetic and natural.

Seismic and Energetic Interventions on a Typical South Italy Residential Building: Cost Analysis and Tax Detraction

“…Based on the results of seismic evaluation studies, it is very often required the seismic retroffiting or at least the seismic upgrading of masonry constructions. Therefore, in order to avoid building collapses and consequent human victims, over the years various traditional (Italian Ministers Council Presidency Decree (DPCM), 2011 ;Formisano, 2014Formisano, , 2017Formisano and Marzo, 2017) and innovative (Bertolesi et al, 2017;Mosoarca et al, 2017;Ramaglia et al, 2018) intervention techniques have been developed.…”

Ductility Capacity Assessment of Masonry Members Strengthened With Composites

“…In fact for high mechanical fiber reinforcement ratios, ω , the maximum value of the bending moment is achieved for a zero axial load. It is due to an alteration of the p-m domain [11]. Furthermore, the ductility capacity presents a strong reduction already for small increments of the mechanical fiber reinforcement ratio, ω .…”

“…For composite systems made with organic matrix, the experimental tests confirm a linear trend [15] as accepted in the modern building codes and guidelines. The stress-strain constitutive relationship can be easily homogenized [11], meaning that the global behavior of two constituents of the composite is attributed to fibers only, by using equivalent properties. The entire stress-strain relationship can be homogenized to the fiber constituent.…”

“…Intervention strategies were performed in many engineering applications, according to manufacturer suggestions or by means of simplified approaches. Simplified approaches incentive an excessive amount of strengthening systems reducing both the efficiency [11,12] and the ductility capacity [3]. Under dynamic loads to increase the flexural capacity could not be one of the best strategies [13,14].…”

“…cementitious or lime-mortar) the stiffness and strength of the matrix provides a non-negligible effects on ultimate behavior of strengthened elements [18]. These effects are often deleterious on the ductility of strengthened elements [11]. Furthermore, for masonry heritage value, it can be important to safeguard the masonry using a composite more compatible with the mechanical properties of the substrate [19].…”