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Summary This work discusses the simplified estimation of earthquake-induced nonlinear displacement demands as required by nonlinear static procedures, with particular attention on short-period masonry structures. The study focuses on systems with fundamental periods between 0.1 and 0.5 s, for which inelastic amplification of the elastic displacement demand is more pronounced; hysteretic force-displacement relationships characteristic of masonry structures are adopted, because these structures are more commonly found within the considered period range. Referring to the results of nonlinear dynamic analyses of single-degree-of-freedom oscillators, some limitations of the Eurocode 8 and Italian Building Code formulations are first discussed, then an improved equation is calibrated that relates inelastic and elastic displacement demands. Numerical values of the equation parameters are obtained, considering the amount of hysteretic energy dissipation associated with various damage mechanisms observed in masonry structures. Safety factors are also calculated to determine several percentiles of the displacement demand. It is shown that the proposed equation can be extended to more dissipative systems. Finally, the same formulation is adapted to the estimation of seismic displacements when elastic analysis procedures are employed. Copyright © 2017 John Wiley & Sons, Ltd.

Summary The seismic assessment of the local failure modes in existing masonry buildings is currently based on the identification of the so-called local mechanisms, often associated with the out-of-plane wall behavior, whose stability is evaluated by static force-based approaches and, more recently, by some displacement-based proposals. Local mechanisms consist of kinematic chains of masonry portions, often regarded as rigid bodies, with geometric nonlinearity and concentrated nonlinearity in predefined contact regions (unilateral no-tension behavior, possible sliding with friction). In this work, the dynamic behavior of local mechanisms is simulated through multi-body dynamics, to obtain the nonlinear response with efficient time history analyses that directly take into account the characteristics of the ground motion. The amplification/filtering effects of the structure are considered within the input motion. The proposed approach is validated with experimental results of two full-scale shaking-table tests on stone masonry buildings: a sacco-stone masonry facade tested at Laboratorio Nacional de Engenharia Civil and a two-storey double-leaf masonry building tested at European Centre for Training and Research in Earthquake Engineering (EUCENTRE). Copyright © 2015 John Wiley & Sons, Ltd.

SUMMARY The current formulation of Eurocode 8 Part 3 and the Italian building code for the seismic assessment of existing buildings accounts for epistemic (knowledge-based) uncertainties by means of the identification of knowledge levels with associated values of the so-called confidence factors, applied only as a reduction of material strengths. This formulation does not always produce consistent results and it does not explicitly account for other sources of uncertainty. The paper proposes a probabilistic methodology for the quantification of appropriately defined factors, allowing consideration of the different sources of uncertainty involved in the seismic assessment of masonry buildings by means of nonlinear static analyses. This simple approach, also including an alternative formulation of the confidence factors related with material properties, allows to obtain results which are consistent with the acquired level of knowledge and correctly account for the different sources of uncertainty without requiring to carry out any stochastic nonlinear analysis. Copyright © 2013 John Wiley & Sons, Ltd.

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.

SUMMARY The macroelement technique for modelling the nonlinear response of masonry panels is particularly efficient and suitable for the analysis of the seismic behaviour of complex walls and buildings. The paper presents a macroelement model specifically developed for simulating the cyclic in-plane response of masonry walls, with possible applications in nonlinear static and dynamic analysis of masonry structures. The model, starting from a previously developed macroelement model, has been refined in the representation of flexural–rocking and shear damage modes, and it is capable of fairly simulating the experimental response of cyclic tests performed on masonry piers. By means of two internal degrees of freedom, the two-node macroelement permits to represent the coupling of axial and flexural response as well as the interaction of shear and flexural damage. Copyright © 2013 John Wiley & Sons, Ltd.

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 facade. 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 facade is presented in terms of displacements, velocities, and accelerations recorded during the shaking table tests. A one-sided rocking response of the facade was observed prior to collapse. The impacts were clearly identified in the acceleration records. The facade 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 facade. Copyright © 2013 John Wiley & Sons, Ltd.

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 facade 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.