This communication aims to provide further insight into the interaction between the classical limit point instability (“snap-through”) of a Von Mises arch and the Eulerian buckling of its constituent rods. The theoretical model incorporates the effects of symmetric geometric imperfections in the rods, as well as the reduction in axial stiffness resulting from second-order effects. The analysis is developed on a theoretical basis to elucidate the influence of key governing parameters—namely, arch shallowness, rod slenderness, and imperfection magnitude. Numerical simulations are performed to validate and illustrate the proposed formulation.

The Advanced GAmma Tracking Array (AGATA) has been installed at Laboratori Nazionali di Legnaro (LNL), Italy. In this installation, AGATA will consist, at the beginning, of 13 AGATA triple clusters (ATCs) with an angular coverage of 1π, and progressively the number of ATCs will increase up to a 2π angular coverage. This setup will exploit both stable and radioactive ion beams delivered by the Tandem–PIAVE-ALPI accelerator complex and the SPES facility. The new implementation of AGATA at LNL will be used in two different configurations, firstly one coupled to the PRISMA large-acceptance magnetic spectrometer and lately a second one at Zero Degrees, along the beam line. These two configurations will allow us to cover a broad physics program, using different reaction mechanisms, such as Coulomb excitation, fusion-evaporation, transfer and fission at energies close to the Coulomb barrier. These setups have been designed to be coupled with a large variety of complementary detectors such as charged particle detectors, neutron detectors, heavy-ion detectors, high-energy γ-ray arrays, cryogenic and gasjet targets and the plunger device for lifetime measurements. We present in this paper the conceptual design, characteristics and performance figures of this implementation of AGATA at LNL.

GALILEO, a new 4π high-resolution γ-detection array, based on HPGe detectors, has been developed and installed at the Legnaro National Laboratories. The GALILEO array greatly benefits from a fully-digital read-out chain, customized DAQ, and a variety of complementary detectors to improve the resolving power by the detection of particles, ions or high-energy γ-ray transitions. In this work, a full description of the array, including electronics and DAQ, is presented together with its complementary instrumentation.

The preservation of architectural heritage represents a major asset for economic development in several countries. Nevertheless, its protection remains a complex task due to its high vulnerability, especially in seismic zones. The intervention on the historical buildings requires the creation of a numerical and digital support shared by the different building specialists (architects, conservators, engineers, designers), which can contain all of the data relating to the construction. This will allow to ensure not only a better interchangeability between the different disciplines but also a correct and coherent conception and execution of the interventions. The introduction of 3D digitization tools, particularly the 3D laser scanner, plays a major role during the realization of the architectural survey. Indeed, the use of the architectural modeling software based on Building Information Modeling and Non-Uniform Rational Basis Spline allows first of all to move from the point cloud to an accurate 3D numerical model exploitable for various types of analysis, such as structural analysis, building archeology analysis, and thermal analysis. We propose through this article an unprecedented application of the 3D laser scanner on an example of vernacular architecture, constituting a truly unique type of “Medina.” The object of the study is an aggregate composed of five houses, falling inside the Kasbah of Algiers, which since 1992 has been classified as “universal heritage” by UNESCO. The architectural survey is followed by a demonstration of numerical modelling based on 10 grades of generation using two categories of software founded mainly on Building Information Modeling and Non-Uniform Rational Basis Spline. Two kinds of numerical models are obtained: a first architectural model will be exploited during the building archaeology principally based on the 3D scanning results and a second structural model that will be used for structural analysis through a Finite Element Analysis software.

ARDESIA is an SDD-based, X-ray spectrometer, optimized for synchrotron measurements that require high count rates (> 1 Mcounts/s/channel) and good energy resolution (< 130 eV of FHWM Mn-K-alpha line at optimum shaping time, <= 200 eV at short shaping times). The main target applications are XRF and XAFS techniques. The detection module consists of 2 x 2 pixel monolithic SDD (5 mm pitch) coupled with a 4-channel version of the CUBE CMOS preamplifier. The mechanical structure of the instrument has been realized to fit inside a sample chamber with a finger-like structure. The system grants proper cooling (-40 degrees C) and operation in vacuum. ARDESIA is also equipped with two auxiliary electronic boards: one for SDD powering and biasing and the other for closed-loop driving of two Peltier TECs. The output signals of the instrument are processed by digital pulse processors using short pulse processing times in order to achieve good spectroscopic performance at high count rates. Two different measurement campaigns were performed at synchrotron beamlines to assess the performance of the instrument. At the LNF DA Phi NE-Light DXR1 soft X-ray beamline, XRF measurements on low atomic number elements (down to C-K line, 277 eV) demonstrated the good energy resolution of the spectrometer and made possible to acquire the first XAFS spectrum of Silicon K-edge in a Pyrex (TM) glass sample. At the LISA CRG beamline at ESRF - Grenoble, XAFS measurements on different samples, such as kesterite and protochabourneite, were performed, demonstrating the high count rate capability and stability of the instrument over time.

The development of new generations of synchrotron light sources aims at increasing their beam in term of flux and brightness. To cope with extremely high-brilliance sources, fluorescence detectors must go beyond their nowadays maximum throughput while keeping almost unchanged the performance. This paper has been carried out within the framework of the ARDESIA (ARray of DEtectors for Spectroscopy and Imaging Applications) project, whose primary aim is to develop a spectrometer with count-rate capability for applications like Xray absorption spectroscopy (XAS) and X-ray fluorescence (XRF). ARDESIA is a Silicon Drift Detector (SDD)-based, multichannel X-ray spectrometer, optimized for synchrotron applications requiring a high-count rate (>1Mcps per channel) and a high-resolution (e.g. below 150 eV of Full Width Half Maximum at peaking times faster than 200 ns) for X-ray fluorescence detection. This paper describes improvements made for the ARDESIA spectrometer on detection efficiency and overall counting rate capability to better match requirements of synchrotron experiments. These improvements have been obtained by increasing the number of channels, from 4 to 16, and the SDD thickness from 450 mu m to 800 mu m and 1000 mu m. The new detection module and the new complete spectrometer are described in detail. The first 16-channel detection module prototype has been developed with an average resolution of 128 eV at the Mn-K alpha at long peaking times (i.e. > 2 mu s) and 183.5 eV at short peaking time (i.e. 32 ns). Then, the qualification of the 4-channel 1mm-thick detector at the PETRA (Positron-Elektron-Tandem-Ring-Anlage) P65 beamline in DESY (Deutsches Elektronen-Synchrotron) is reported.

This work reports the results of the measurements using ARDESIA X-ray spectrometer in synchrotron measurements. ARDESIA is an SDD-based, multichannel X-ray spectrometer, optimized for synchrotron applications that require a high-count rate (> 1Mcps/channel) and high-resolution (<130eV of FHWM Mn-Kα line at optimum shaping time, ≤200eV at short shaping times) X-ray fluorescence detection. The main applications of the ARDESIA detector are X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) techniques. The detector is based on a monolithic array of 4 SDD with 25mm 2 active area (collimated to 16mm 2 ) each, which optimizes detector solid angle. After the optimization of the 4-channels detection module, the mechanical structure grants cooling, with a double Peltier strategy, vacuum, insulation from the harsh surrounding environment and possibility to place side-by-side several SDD modules to realize a larger number of channels. The detector signals are amplified by a monolithic four-channels CUBE preamplifier chip and processed by digital pulse processors (e.g. XGLab-DANTE, 4-channel XIA DXP-XMAP) to achieve good energy resolution at high count rates. Successful campaign of measurements at the DAΦNE DXR1 soft X-ray beamline in Frascati, Italy and ESRF LISA BM-08 beamline in Grenoble, France, such as XRF measurements in soft x-ray energy range, and long-duration consecutive XAFS measurements using various samples, confirm the qualification and performance of the instrument, in terms of energy resolution, throughput capability, immunity against external disturbances, and stability.

This work reports on the development of the ARDESIA spectrometer. ARDESIA is a SDD-based, multichannel X-ray spectrometer, optimized for synchrotron applications that require a high-rate (Mcps), high-resolution (below 150 eV FWHM at shaping time faster than 200 ns) soft X-ray detection. The main applications for which ARDESIA is designed are X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) techniques. A compact, low-noise detection module has been developed for the instrument. The detector signals are amplified by a monolithic four-channel CUBE preamplifier and processed by a digital pulse processor to achieve short pulse processing times, to highlight the good performances of the module at high count rates (about 1 Mcps per channel). In this work, the characterization of the second release of the ARDESIA detection module is reported. This second release has fixed few issues presented by the first one and it is now a stable solution for high performances X-ray spectroscopy. After that, the complete 4-channel instrument is presented. The instrument has been realized so that the detection module can properly fit inside a synchrotron scattering chamber with a finger-like structure. The mechanical structure grants cooling, with a double Peltier TEC strategy, vacuum, insulation from the harsh surrounding environment and potential for placing side-by-side several spectrometers.

This study assesses coupled shear walls (CSWs) equipped with passive damping systems using the damped continuum models developed as Coupled-Two-Beams (CTB). CTB models consisting of various distributed-parameter damping mechanisms are established. Numerical solutions for the dynamic analysis of these continuum systems are developed using a simple Finite Element (FE) model. It is illustrated how passive damping systems, viscous dampers and viscoelastic dampers, with various installation arrangements can be modeled with the use of the equivalent shear damping in a CTB system. Based on the dynamic analysis, the accuracy of damped CTBs with respect to different damping cases are verified. Two controlling parameters are introduced to evaluate the effect of both stiffness and supplementary damping on dynamical responses. The parametric study of passively-damped wall systems subjected to seismic loading is performed by emphasizing the effect of global bending and controlling parameters. Based on the important responses obtained from the dynamic analyses, optimal features of distributed damping such as damping length and its value are investigated with regard to the damping controlling parameter. This work shows that the developed CTB systems with the shear damping model are suitable tools for the dynamic analysis and the preliminary design of CSWs equipped with velocity-dependent dampers. (C) 2017 Elsevier Ltd. All rights reserved.

The potential occurrence of internal parametric resonance phenomena has been recently indicated as a potential contributory cause of the appearance of critical dynamic states in long-span suspension bridges. At the same time, suspension bridges, in view of their flexibility, are prone to aeroelastic response, such as vortex shedding, torsional divergence and flutter. In this paper, a non-linear dynamic model of a suspension bridge is devised, with the purpose of providing a first attempt toward a unified framework for the study of aeroelastic and internal resonance instabilities. Inspired by the pioneering work of Herrmann and Hauger, the analyses have been based on a linearized formulation that is able to represent the main structural non-linear effects and the coupling given by aerodynamic forces. The results confirm that the interaction between aeroelastic effects and non-linear internal resonance leads to unstable conditions for wind speeds which can be lower than the critical threshold for standard aeroelastic predictions.

This paper assesses efficiency of the continuum method as the idealized system of building structures. A modified Coupled Two-Beam (CTB) model equipped with classical and non-classical damping has been proposed and solved analytically. In this system, complementary (non-classical) damping models composed of bending and shear mechanisms have been defined. A spatial shear damping model which is non-homogeneously distributed has been adopted in the CTB formulation and used to equivalently model passive dampers, viscous and viscoelastic devices, embedded in building systems. The application of continuum-based models for the dynamic analysis of shear wall systems has been further discussed. A reference example has been numerically analyzed to evaluate the efficiency of the presented CTB, and the optimization problems of the shear damping have been finally ascertained using local and global performance indices. The results reveal the superior performance of non-classical damping models against the classical damping. They show that the critical position of the first modal rotation in the CTB is reliable as the optimum placement of the shear damping. The results also prove the good efficiency of such a continuum model, in addition to its simplicity, for the fast estimation of dynamic responses and damping optimization issues in building systems.

This study addresses energy dissipation mechanisms to investigate the effects of the internal and external viscous damping on structural characteristics in coupled shear walls. A discrete Reference Beam (RB) is firstly proposed and a Distributed Internal Viscous Damping (DIVD), composed by bending and shear mechanisms, is defined. Meanwhile, the linear classical damping is considered. A low-order finite element method (FEM) is adopted for lateral analyses. For the sake of simplicity, a Generalized Sandwich Beam (GSB) is then developed through the replacement of the set of connecting beams of the RB by an equivalent elastic and dissipative core and a FEM is employed for its dynamic analysis. The passive damping modeling through the GSB is presented using continuous models. Concerning slender structures, the GSB is reduced to a Coupled Two-Beam (CTB) including the damping effects. The analytical solution of the CTB is presented to be a benchmark for the FE solutions. The validity of both numerical and analytical solutions is confirmed via numerical examples. The effectiveness of proposed damping models on dynamical responses and vibration characteristics are tested with respect to continuum-based controlling parameters, and a qualitative model is consequently proposed to appropriately choose the damping mechanisms depending upon the parameters of coupled shear walls. The suitability of various damping models is finally compared to current damping predictors and full-scale measured data given for RC buildings. The results reveal that the bending and shear damping are somehow efficient where the linear classical damping is incapable to be always a proper mechanism. (C) 2016 Elsevier Ltd. All rights reserved.

Replacement beam formulations represent a family of 1D continuum models suitable for approximate analyses of the structural arrangements of buildings. In this paper, an energy equivalence approach is applied to coupled shear walls to develop suitable replacement beam models. Assuming properly compatible coupling fields between walls, a novel three-field coupled two-beam approach, therein providing shear and axial deformations, is proposed. The corresponding mathematical formulation provides closed-form solutions for simple loading cases with homogenous properties. Considering slender coupled shear walls, as typically found in tall buildings, the coupled two beams can be reduced to a two-field formulation, i.e., a parallel assembly of an extensible Euler-Bernoulli beam and a rotation-constraining beam. The latter model is solved analytically, and expressions for the tip displacement and base bending moment are presented. A finite element model is then presented and demonstrated to be an efficient tool for static and dynamic analyses. The effects of the axial deformation and degree of coupling on slender coupled shear wall responses are described as being dependent upon two suitable parameters. Various approximate relations are also proposed for design purposes. Finally, the validity of both analytical solutions and the finite element model is confirmed via numerical examples. Copyright (C) 2015 John Wiley & Sons, Ltd.

This report outlines the main features of a new bridge recently completed in Salorno (Bolzano), Italy. The new structure deserves to be highlighted because of its particular structural and aesthetic concept. A bridge with an overall "gull wing" geometry was conceived to provide a unitary solution to the contemporary crossings of A22 highway and Adige River, combining the use of post-tensioned concrete and structural steel, and thereby providing a hybrid and efficient structural scheme. This solution was suggested mainly to solve the amalgamation requirement with the riverbank, to guarantee a minimum bridge depth where clearance constraints were present and finally to identify an optimal erection strategy by reducing the effective span over the watercourse.

The dynamic response of tall buildings plays a significant role in determining both design wind loading and seismic behavior. The degree of energy dissipation, or damping, that a building can provide directly affects the resonant response and thus the effective design loading. In this paper, Replacement Beam Method as a Sandwich beam is presented for coupled shear walls and a one-dimensional finite element method (FEM) has been adopted for lateral analyses of building systems. In this method in addition to structural elements stiffnesses, the damping mechanism has been defined as Distributed Internal Viscous Damping (DIVD) model along shear walls and connecting beams, while acting as bending and shearing mechanisms. Then, an equivalent continuum model of coupled walls, the so called Generalized Sandwich Beam (GSB), has been provided capturing both elastic and dissipative performance by adopting strain and dissipation energy balance of the set of connecting beams, respectively. By means of such GSB model, a non-uniformly distributed damping model has been also modeled simulating dissipation at higher elevations of coupled walls as an equivalent damping effect of additional dissipative devices. A reference example has been analyzed numerically to investigate the performance of proposed damping models in basic dynamic characteristics of coupled shear walls such as damped eigenproblems, damping ratio, and near-resonance transversally response. The results have shown the proper efficiency of such damping models in addition to simple application in analysis and primary design of tall building coupled shear wall systems.

In this paper, the dynamic response of a Timoshenko beam with distributed internal viscous damping (DIVD) is analyzed with the aim to ascertain their relative effects on the whole range of beam slenderness. With respect to some previous and quite recent works, some further and fundamental generalizations are therefore introduced. First, the decoupling of shear and bending damping mechanisms, with or without the presence of the external classical viscous contribution. This splitting allows the outlining of the relevant influences on the dynamic response associated to any singular damping mechanism and the evaluation of the modal critical damping. As a second contemporary step, an explicit dependency is set upon the shear slenderness of the beam model, allowing to study the dependence of each single damping mechanism upon the relevant kinematic model, spanning from truly Bernoulli's behavior to mainly Shear controlled responses. According to the selected damping model, the dynamic behavior automatically selects the characteristics of kinematical response (relative levels of shear and bending contributions) depending of the minimization of the total internal energy (i.e. elastic energy and dissipation). In the folds of this study, the problem of optimal piece-wise constant distribution of DIVD is finally also addressed, firstly showing that is possible to find non-trivial and interesting solutions.

The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer.

The first implementation of the AGATA spectrometer consisting of five triple germanium detector clusters has been installed at Laboratori Nazionali di Legnaro, INFN. This setup has two major goals, the first one is to validate the γ-tracking concept and the second is to perform an experimental physics program using the stable beams delivered by the Tandem–PIAVE-ALPI accelerator complex. A large variety of physics topics will be addressed during this campaign, aiming to investigate both neutron and proton-rich nuclei. The setup has been designed to be coupled with the large-acceptance magnetic-spectrometer PRISMA. Therefore, the in-beam prompt γ rays detected with AGATA will be measured in coincidence with the products of multinucleon-transfer and deep-inelastic reactions measured by PRISMA. Moreover, the setup is versatile enough to host ancillary detectors, including the heavy-ion detector DANTE, the γ-ray detector array HELENA, the Cologne plunger for lifetime measurements and the Si-pad telescope TRACE. In this paper the design, characteristics and performance figures of the setup will be described.