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As a result of changes in seismicity in the Groningen area, a need has arisen to be able to rapidly assess and prioritize entire inventories of unreinforced masonry churches. As a part of being able to provide resource optimization to determine which structures are in most need of intervention, a multilevel methodology to assess seismic performance is presented. The process involves both data collection and vulnerability assessments. This multilevel approach involves progressive refinements to the data collected and to the complexity of the analyses conducted. Five data collection phases are used in conjunction with three progressively more complex methods for the seismic assessment. The first level of assessment uses only statistical information of the structures with information that can be obtained through desktop reviews. The second level of analysis uses key characteristics of wall thickness and height to develop simple models for each wall in each church. This level of analysis requires at least a preliminary site visit. In the third level of analysis, a more refined model of the church is developed from detailed site surveys of the structure where each wall is modelled and assessed. The process involves the assessment of the in-plane behaviour of either whole churches or single walls (global response) and the out-of-plane behaviour of single elements (local response). The study applies the approaches outlined in the NEN NPR9998 2017 combined with the Italian Standards for the cultural heritage. This paper outlines this Seismic Multilevel Assessment of Churches methodology and how it applies to an inventory of 52 unreinforced masonry churches in the Groningen area, The Netherlands.

This research work is related to the evaluations of some modelling assumptions of the stick–slip phase of the Friction Pendulum™ System (FPS) on the seismic response of base-isolated buildings. Although several theoretical and experimental research findings show the complexity of the FPS nonlinear behaviour, the current international seismic design codes allow the designer to model the FPS nonlinear response using simple bilinear constitutive relationship in order to reduce the computational effort for modelling and performing the analyses. Therefore, the problem that has to be faced by practitioners and researchers is related to the way of modelling the stick–slip phase and the corresponding friction phenomena with a simple bilinear constitutive model. This research work has been encouraged by some experimental evidence and performed for investigating, through a large parametric study, the influence that many modelling assumptions may have on the global and local responses of buildings. The study has been carried out without claiming to be innovative but for being a valuable tool in the design practice and, mainly, in modelling the nonlinear response of the FPS with the bilinear simplification allowed by design codes.

Base isolators are effective tools that favor a high level of building performance under lateral load, providing protection to both structural and non-structural elements. In this context, this paper discusses the possibility of employing materials with different frictional properties to enhance the response of flat- and curved-surface base isolators. Two innovative devices, referred to as “BowTie” and “BowC”, are introduced and discussed in some detail. A series of non-linear time history analyses is then conducted using a customized computer program and considering a number of case study structures, designed applying a displacement-based approach. The results of the analyses are used to discuss the key differences between variable friction and constant friction sliding isolation devices. It is shown that the newly proposed isolators may represent an improvement on classic base isolation solutions, in light of their higher energy absorption capacity, which contributes to significantly enhancing their performance.

We revisit the recent experiments [Billy et al., Nature 453, 891 (2008); Roati et al., Nature 453, 895 (2008)] that have lead to the observation of Anderson localization for matter waves in one-dimensional speckle and quasiperiodic potentials. We show that in presence of localization the tails of the asymptotic density distribution can be described by the diagonal term of the projection over the eigenstates of the disordered potential, and that this is equivalent of assuming a phase randomization of the off-diagonal terms. This provides an alternative and complementary viewpoint to the usual description in terms of localization of single plane wave components as a result of multiple scattering from the random potential. For the quasiperiodic case, we also discuss the implications of using continuous or discrete models.