PSI - Issue 44

Gaetana Pacella et al. / Procedia Structural Integrity 44 (2023) 1324–1331 Gaetana Pacella et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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no-tensile strength has been assigned to the shell elements of the spandrels along horizontal direction, and no tensile strength along vertical direction has been assigned to the piers. The pushover curves obtained with the two different models are showed in Fig.4, for both WS (Fig. 4a) and RS (Fig.4b) cases. The comparisons between the curves prove a good matching between EF and 2D-shell model: the differences of the elastic response are very slight, as well as for post elastic one. Moreover, it is emerged that to consider effective spandrels (RS case) involved significant increment of base shear than WS case, whereas the ductility of the wall reduces. Indeed, the ultimate displacements of the 2D-shell model resulted higher than those of the EF due to the constitutive models adopted in the two cases, for instance the use of plastic hinges does not allow to consider the cross-sections partialization due to not-tensile resistance of material. Comparative analyses prove that the two different structural models of the wall give analogous results, even they refer to different schematization approaches of structural elements and material. Obviously, the quite good equivalence is conditioned by a reasonable modeling process, which can be performed only on the base of a sound engineering judgment deriving from expertise and appropriate knowledge of the problem. The authors have adopted such king of EF solution in some other case studies available, for instance, in Sandoli and Calderoni 2021, Calderoni et al. 2017. To this aim, in Fig. 5a another example of idealization of irregular wall is indicated. It refers to a URM wall belonging to a building located in Catania, the so called ‘via Martoglio building’ (Liberatore 2001). The central pier has been schematized with two equivalent sub-piers connected by a couple of pendulums at each story. Moreover, to ensure the transferring of the axial coming from upper story to the pier at ground-story, the spandrel over the central opening at first story has been schematized by considering the following cases: (i) case TR, in which the spandrel has been modelled was an infinitely rigid element; (ii) case TD, in which the spandrel has a finite stiffness computed by assuming a cross-section height equal to the half of the entire piers over the opening (from the first to the last story). Fig. 5b shows the comparisons in terms of elastic force-displacement behavior, where a good agreement between EF and 2D-shell model has been achieved for each analyzed case.

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Fig. 3. Elastic analysis for (a) WS and (b) RS.

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Fig. 4. Non-linear analysis for (a) WS and (b) RS