Influence of load history on the force-displacement response of in-plane loaded unreinforced masonry walls

A new macromodel for the assessment of the seismic response of infilled RC frames

“…In particular, the shear modulus of masonry G m (not evaluated by laboratory tests) has been assigned based on comparison between the initial numerical response of prototype TA2 and its experimental counterpart (see Table ) and in accord with the results of past experimental tests on hollow block masonry, eg, Magenes et al The peak shear stress corresponding to the diagonal shear mechanism ( τ 0 ) has been assumed equal to the sliding strength evaluated by triplet tests in Pavia (this hypothesis appears to be reasonable because the experimental diagonal failure was mostly characterised by sliding along the horizontal bed joints). Instead, the shear deformation corresponding to peak strength ( γ 0 ) and the shear stress ( τ y ) corresponding to substantial deviation from the linear behaviour have been calibrated so as to achieve an accurate simulation of the envelope of the experimental response and taking into account the results of the shear tests reported in literature on unreinforced masonry panels made of hollow blocks . As a result of many trial runs, the shear stress τ y has been assumed approximately equal to the mean of the experimental values reported in the previous studies (values in the range from 0.11 to 0.47 MPa) while the shear deformation γ 0 has been fixed out the range of values reported in the previous studies (from 0.21% to 0.38%) to obtain a satisfying accuracy of the numerical response.…”

“…Instead, the shear deformation corresponding to peak strength ( γ 0 ) and the shear stress ( τ y ) corresponding to substantial deviation from the linear behaviour have been calibrated so as to achieve an accurate simulation of the envelope of the experimental response and taking into account the results of the shear tests reported in literature on unreinforced masonry panels made of hollow blocks . As a result of many trial runs, the shear stress τ y has been assumed approximately equal to the mean of the experimental values reported in the previous studies (values in the range from 0.11 to 0.47 MPa) while the shear deformation γ 0 has been fixed out the range of values reported in the previous studies (from 0.21% to 0.38%) to obtain a satisfying accuracy of the numerical response. This latter result has proved to be effective for the specific masonry type, leading to a reasonable simulation of the post‐peak strength degradation of the examined infilled prototypes.…”

Equivalent-Frame Modeling of Two Shaking Table Tests of Masonry Buildings Accounting for Their Out-Of-Plane Response

“…It comes with a limited computational cost when compared to more detailed methods and therefore allows for performing nonlinear dynamic analyses of buildings. These other methods, such as the macro-modeling of masonry structures through continuum material models (Lotfi and Shing, 1991;Berto et al, 2002), are often based on homogenization (Milani et al, 2007;Zucchini and Lourenço, 2009;Milani, 2011) or the more complex and computationally demanding micromodeling approaches (Lourenço and Rots, 1997;Wilding et al, 2017;Zhang et al, 2017) in which units and interfaces are modeled explicitly. Compared to these models, the equivalentframe approach has a reduced cost and a simpler calibration procedure, which is based directly on structural element tests, since phenomenological laws are generally applied to describe the nonlinear behavior of entire elements (piers, spandrels) and to impose their displacement capacity through simple criteria, such as drift or chord rotation limits, applied at the structural element level (Lagomarsino and Cattari, 2015;Chácara et al, 2019).…”

Numerical study on factors that influence the in‐plane drift capacity of unreinforced masonry walls

“…Future research should address the sensitivity of the wall response to the loading history; a first study in this regard has been completed. 50 Furthermore, uncertainties related to drift capacity models should be quantified. This is in the authors' opinion beyond the scope of numerical studies; in order to capture also epistemic uncertainties, it will be necessary to compare drift capacity models to sets of experimental tests.…”