PSI - Issue 44

Roselena Sulla et al. / Procedia Structural Integrity 44 (2023) 998–1005 Sulla et al./ Structural Integrity Procedia 00 (2022) 000–000

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properties; Brick Masonry (BM), by considering a masonry with regular fabric and high properties. The values assumed in this study correspond to the ones indicated in the (Circolare n. 7, 2019). Moreover, three floor types are considered, with live load q k equal to 3 kN/m 2 : Rigid Floor (RF), considering a Reinforced Concrete (RC) which can be assumed as a rigid diaphragm; Semi-Rigid Floor (SRF) with an intermediate in-plane stiffness; Flexible Floor (FF) referring to a simple timber floor, with negligible in-plane stiffness. Overall, nine pushover analyses are performed, by means of software 3MURI Professional (www.stadata.it), adopting the equivalent frame model. Preliminarily, the pushover analyses are conducted along the +X direction, with the aim of activating the in-plane response of the reference masonry walls under investigation. A static force distribution is considered for all the analyses without load eccentricity. Finally, in all the models the axial force within the spandrels is not taken into account. The resulting pushover curves, for the ideal case study, are reported in Fig. 4a. It should be noted that the response is influenced by both masonry and floor types. In particular, in the case of ISM, negligible differences result by varying the floor type. On the contrary, noticeable differences are obtained in the case of high-strength masonry, assumed in this case corresponding to BM. Fig. 4b shows the in-plane failure mechanism of the frame equivalent to the reference masonry wall, for each masonry and floor type considered. A mixed failure mechanism is observed in all the cases analyzed. In detail, bending failure in spandrels is observed at all floors, whereas the piers present mainly bending failure at ground floor, even though some piers fail in bending and in shear at upper floors. No tensile failure mechanisms were detected in the cases analyzed. The results obtained demonstrate that in the case study analyzed the response mainly depends on masonry strength. a b

Fig. 4. (a) Pushover curves; (b) piers and spandrels mechanisms comparisons (analyses in +X direction considering static forces).

4. Conclusions In this paper, strength models referring to nonlinear analysis have been summarized for piers and spandrels according to the Italian design code.