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Summary: The assessment of the out‐of‐plane response of masonry structures has been largely investigated in literature assuming that walls respond as rigid or semi‐rigid bodies, and relevant equations of motion of single‐degree‐of‐freedom and multi‐degree of freedom systems have been proposed. Therein, energy dissipation has been usually modelled resorting to the classical hypotheses of impulsive dynamics, delivering a velocity‐reduction coefficient of restitution applied at impact. In fewer works, a velocity‐proportional damping force has been introduced, by means of a viscous coefficient being constant or variable. A review of such models is presented, a criterion for equivalence of dissipated energy is proposed, equations predicting equivalent viscous damping ratios are derived and compared with experimental responses. Finally, predictive equations are examined in terms of incremental dynamic analyses for large sets of natural ground motions. [ABSTRACT FROM AUTHOR] more...

SUMMARY The evaluation of the dynamic behaviour of rocking elements is directly correlated to the energy dissipated because of the impacts at the base interface, which can be represented by means of a coefficient of restitution. This schematization is commonly accepted as representative of the out-of-plane response of stone masonry walls. An experimental campaign (in a lab environment) aiming at assessing the value of this coefficient for a sacco granite masonry wall is presented in this work. The rocking motion at a predefined bed joint level was induced in the tested specimens in order to validate a novel test setup designed to assess the coefficient of restitution value by means of a realistic reproduction of the rocking behaviour of a single element, under the hypothesis of an infinitely stiff system above the bed joint level. As the main objective of the work was to assess the rocking behaviour of a masonry wall that looses energy at the impacts at a certain joint level, the flexural behaviour was not desirable and had to be avoided. For this purpose, a test setup based on the equivalent block approach was developed. In the final section of this work, comparisons between experimental and numerical results are presented together with some preliminary conclusions on the appropriate modelling strategy and the values of the coefficient of restitution to be used for the seismic assessment of the out-of-plane rocking behaviour of this type of sacco stone masonry walls. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR] more...

SUMMARY The present work describes a shaking table experimental campaign specifically developed for the characterisation of the out-of-plane response of a full scale stone masonry façade. After the description of the specimen and the selection of the input motion presented in a companion paper (Part 1), the experimental campaign is illustrated and extensively described. The out-of-plane behaviour of the sacco masonry façade is presented in terms of displacements, velocities, and accelerations recorded during the shaking table tests. A one-sided rocking response of the façade was observed prior to collapse. The impacts were clearly identified in the acceleration records. The façade overturning occurred with the expected failure mode, as predicted in the design of the test. Finally, some conclusions are drawn regarding the observed behaviour and particular features of this type of stone masonry constructions, which may influence the global behaviour of the façade. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR] more...

SUMMARY The out-of-plane response of walls in existing stone masonry buildings is one of the major causes of vulnerability commonly observed in post-earthquake damage surveys. In this context, a shaking table (ST) test campaign was carried out on a full-scale masonry façade mainly focusing on the characterization of its out-of-plane overturning behaviour. The structure tested on the ST is a partial reproduction of an existing building from Azores, damaged during the 9 July 1998 Faial earthquake. The definition of the tested specimen as well as the selection of the input ground motion is reported in this paper. A specific emphasis is given to the definition of the time-history to be applied during the tests because it was felt as an essential and crucial part of the work to obtain the desired overturning behaviour. The accelerogram to be imposed was selected from a large set of accelerograms (74) by means of a step-by-step procedure on the basis of several numerical analyses resorting to the rocking response of rigid blocks. A companion paper (Part 2) focuses on the ST test results and detailed data interpretation. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR] more...

Damage observations from recent seismic events have confirmed that the activation of out-of-plane local mechanisms is one of the major causes of structural collapse in unreinforced masonry buildings. Particularly vulnerable are cavity walls commonly used in residential building in regions such as Central and Northern Europe, Australia, New Zealand, China and several other countries. Usually, the inner leaf has a load-bearing function, carrying vertical loads transmitted by floors and roof while the outer leaf, having only aesthetic and insulation functions, is lightly loaded. The two leaves are typically connected by means of metallic ties. The high out-of-plane vulnerability, which may prevent the exploitation of the global capacity associated with the in-plane capacity of the structural walls, is mainly due to the high slenderness of the masonry leaves and the lack, or ineffectiveness, of ties between leaves. Often ties are too widely spaced and/or heavily degraded. Despite the complexity of the composite behaviour of such a construction typology, no dynamic tests on cavity walls are reported in current literature. For this reason, four out-of-plane shaking table tests were conducted on full-scale unreinforced masonry assemblies of three cavity wall panels with different tie distributions (inner calcium silicate brick wall and outer clay brick wall) and one single-leaf wall constructed using calcium silicate brick masonry. The experimental arrangement allowed the specimens to be tested under different input signals and loading conditions, inducing an out-of-plane one-way bending action in the walls. The research is aimed at understanding the seismic behaviour of cavity walls, their failure mechanisms and how they are affected by boundary conditions and degree of connection between the two leaves. The paper describes the main experimental results, including deformed shapes, damage patterns, force-displacement relationships, and the capacities in term of acceleration sustained by the specimens. Additionally, the energy dissipation involved in the mechanism has been investigated in terms of coefficient of restitution and damping ratio. All the processed data are freely available upon request (see http://www.eucentre.it/nam-project ). [ABSTRACT FROM AUTHOR] more...

• Applied Element Method models validated against tests on cavity-wall systems. • Dynamic response of out-of-plane-loaded masonry specimens adequately captured. • Actual crack propagation explicitly represented until up full collapse. • Simplified assumptions introduced for decreasing analysis time. • Potential limits and actual capabilities of the adopted model widely discussed. Structural failure of existing unreinforced masonry buildings, when subjected to earthquake loading, is often caused by the out-of-plane response of masonry walls. Their out-of-plane resistance could vary considerably depending on several factors, such as boundary conditions, vertical overburden and construction technique. Amongst the latter, the cavity wall system, originally introduced in Northwest Europe in the 19th century and then spread to several countries including USA, Canada, China, Australia and New Zealand, has been shown to be particularly vulnerable towards out-of-plane actions. In this work, the use of the Applied Element Method was investigated and subsequently considered for reproducing the experimentally observed out-of-plane shake-table response of unreinforced masonry full-scale cavity wall specimens subjected to both one-way and two-way bending. Finally, given the adequate results obtained and aimed at investigating further both potential limits and actual capabilities of the adopted modelling strategy, the latter was also extended to the simulation of the dynamic out-of-plane-governed failure mode of a full-scale building specimen tested up to complete collapse. [ABSTRACT FROM AUTHOR] more...