This paper describes a simplified methodology for the assessment of unreinforced masonry (URM) walls under out-of-plane two-way bending seismic action. The methodology involves a force-based check derived from the principle of virtual work. This check is proposed based on experimental observations of significant cracking resistance associated with two-way spanning URM walls, indicating methodologies considering such walls to be pre-cracked or to be non-laterally supported as overly conservative. The methodology incorporates several findings and developments from recent experimental campaigns: ranging from novel characterization tests on masonry couplets to incremental dynamic tests on full-scale buildings. Such incorporations include new formulation to calculate the torsional shear strength of a bed joint and accounting for possible changes in the boundary conditions of an OOP wall during dynamic loading. Testing standards as well as recommendations in several international guidelines for masonry structures addressing the input properties required to implement the proposed methodology are enlisted and reviewed. The methodology requires the definition of the period of vibration of the assessed URM walls, to calculate which plate theory based formulation is provided. Open research questions and potential avenues for further development of the methodology are ultimately highlighted.@en

Out-of-plane (OOP) mechanisms are one of the major causes of structural collapse in unreinforced masonry (URM) buildings as observed in recent as well as past seismic events. Among such failures, two-way bending mechanisms involving at least one restrained vertical edge constitute a very distinct majority. Nevertheless, very little research pertaining to such mechanisms can be found currently in literature. The paper takes a step forward in this topic through the execution and interpretation of dynamic tests on four full-scale single leaf and one full-scale cavity URM walls. Each tested full-scale specimen consisting of a OOP panel and two return walls, varying in terms of commonly encountered boundary conditions, applied overburden or the presence/absence of an opening. The specimens were subjected to sequences of incremental input motion till collapse and these results are presented in terms of deformed shapes, failure mechanisms and force-displacement hysteretic curves. State of the art analytical techniques based on the method of virtual work are applied to evaluate their reliability as simplified tools for assessing the behaviour of such wall subjected to OOP two-way bending excitation. The testing campaign resulted in all specimens exhibiting a rather brittle response, despite sustaining accelerations of 1 g without any damage.@en

This paper provides information related to the sensor measurements obtained from five different unreinforced masonry (URM) walls subjected to incremental dynamic shake-table tests at EUCENTRE, Pavia, Italy. This information has been made available to assist in the development and calibration of analytical and numerical models intended to simulate the out-of-plane (OOP) two-way bending response of URM walls. For further interpretation of the sensor recordings, and for a detailed discussion on the observed seismic performance of the specimens, the reader is referred to the article entitled “Experimental Response of URM Single Leaf and Cavity Walls in Out-Of-Plane Two-Way Bending Generated by Seismic Excitation” [1]. Videos documenting the failure of each specimen are also available on YouTube [2].@en

This data article provides experimental data obtained from the incremental dynamic shake-table testing of four single leaf unreinforced masonry (URM) walls constructed in Calcium Silicate (CS) bricks reported in “Two-way bending experimental response of URM walls subjected to combined horizontal and vertical seismic excitation” [1]. These walls were tested in the second phase of a larger experimental campaign addressing the out-of-plane (OOP) response of full-scale URM panels in two-way bending configurations at EUCENTRE, Pavia, Italy. Data corresponding to the first phase of testing for four single leaf and one cavity wall has already been made available through Tomassetti et al. [2] and the information necessary to interpret these results can be found in Graziotti et al. [3]. The walls of the tests reported in this data article were constructed in an intentionally weakened mortar but using the same Calcium Silicate (CS) bricks as Graziotti et al. [3]. The walls were also tested in boundary conditions that were not addressed in [3] and a specimen was also subjected to simultaneous horizontal OOP and vertical seismic excitation in one of the tests. Videos documenting the failure of specimens tested in both phases of the experimental campaign can be viewed online on YouTube [4].@en

This paper presents the results of incremental dynamic tests on full-scale unreinforced masonry (URM) walls constructed with an intentionally weakened mortar under two-way bending excitation in the out-of-plane (OOP) direction. A specimen was also subjected to simultaneous vertical and horizontal excitation. Walls were also tested in boundary conditions that have not been previously reported in the literature. Emphasis was placed on the development and interpretation of a characterisation test to estimate the torsional shear strength of bed-joints, a parameter of prime importance in the OOP two-way bending behaviour of URM walls. Analytical formulation to estimate the initial stiffness of walls based on the theory of plates is then proposed and validated. Being the first experimental campaign to address the dynamic OOP two-way bending response of full-scale URM wall panels provided the opportunity to propose simple yet mechanically rational methodologies with which both the peak force resistance as well as the displacement at which such resistance is attained can be easily estimated.@en

Damage observations from recent seismic events have confirmed that the activation of out-of-plane (OOP) local mechanisms is one of the major causes of structural collapse in unreinforced masonry (URM) buildings. Such failures are mostly due to the attainment of displacement levels incompatible with equilibrium configurations for the kinematic chain of the considered mechanism rather than the exceedance of stress capacity in structural elements. However, very little research can be found currently in literature regarding the two-way bending OOP failure mechanism of walls involving at least one restrained vertical edge despite it being one of the most commonly reported and surveyed cause of structural damage. The paper takes a step towards addressing this lack of knowledge in the form of dynamic testing of full-scale URM masonry walls. In particular, results of three of these tests are reported in this paper: a test on a specimen representing the calcium silicate inner/loadbearing wall, a test representing the clay outer wall, and a cavity wall composed of both leaves together.@en