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The recent devastating earthquakes have revealed that bridges are one of the most vulnerable components of transportation systems. These seismic events highlighted the need to mitigate the risk resulting from the failure of bridges. This study aims to consider the seismic risk of an extensive heritage of existing civil engineering structures proceeding with prioritization. This imposes the need to consider the design of a geographic information system (GIS) based on the analysis of the different components of risk: hazard, vulnerability, and risk. The assessment of the seismic vulnerability of bridges integrates the various structural and non-structural components of bridges, taking into account their specificities in Algeria. The application of this approach to the Oran region has resulted in the development of a tool using a database to process as much geolocated information as possible, thus contributing to more efficient crisis management, and making it possible to avoid bridge damage and failures that can result in loss of life and monetary losses. This tool could also be used for the inspection of bridges as well as the optimal prioritization of preventive and corrective measures necessary before a major earthquake hits the bridge network in the Oran Region.

The free vibration analysis of symmetrically laminated composite circular plates with curvilinear fibers is performed using the first-order shear deformation theory along with a curved hierarchical square finite element. The blending function method is used to describe accurately the geometry of the circular plate. The hierarchical shape functions are constructed from Legendre orthogonal polynomials. The element stiffness and mass matrices are integrated numerically by means of the Gauss-Legendre quadrature. The equations of motion are derived using Lagrange’s method. Results for the fundamental frequency are obtained for clamped and soft simply supported laminated composite circular plates with E-glass, graphite, and boron curvilinear fibers in epoxy matrices. The element is validated by means of the convergence test and comparison with published data for isotropic and laminated composite circular plates with rectilinear fibers. Contour plots of frequency as a function of fiber orientation angles for laminated composite circular plates with curvilinear fibers are presented. The fiber material and boundary conditions are shown to influence the distribution of frequency throughout the design space. Frequency curves as a function of fiber orientation angles for the first five modes of laminated composite circular plates with curvilinear fibers are also presented. They reveal that none of the first five modes of clamped and soft simply supported laminates is affected by crossing but modes 3 and 4 of clamped graphite/epoxy and boron/epoxy laminates are affected by veering.

The main objective of this work is to present the enhancement of photoluminescence (PL) and structural properties of Ce3+ and Eu3+ co-doped gadolinium orthosilicate Gd2SiO5 (GSO:Eu, Ce) scintillator elaborated by sol–gel method with different concentration of these rare-earth elements. The samples were characterized by X-ray diffraction, field emission-scanning electron microscopy (FE-SEM) and PL spectroscopy. XRD results confirm the crystallization of samples annealed at 1000°C for 4 h to the monoclinic Gd2SiO5 structure. The crystallographic parameters show that Eu3+/Ce3+ incorporated into Gd2SiO5 changes its structure. FE-SEM micrograph results show rod-shaped particles and EDAX spectra confirm the presence of the main constituent elements of the structure. PL showed that two emission peaks dominate the fluorescence spectra of Eu3+ in Gd2SiO5 and the emission intensity increases relatively with the doping concentration of Ce3+ ions. [ABSTRACT FROM AUTHOR]

This paper presents the vibration analysis of variable stiffness laminated composite (VSLC) elliptical plate by considering the curvilinear fibers. The problem is solved using the first-order shear deformation theory (FSDT) in conjunction with a curved trapezoidal p-element. The elements of the stiffness and mass matrices are determined analytically. The curved edges of the p-element are modeled accurately by the blending function method. A calculation code is developed to calculate the frequency parameters and the mode shapes, for different physical and mechanical parameters such as the fiber orientation angle, layup sequence, and boundary conditions. The obtained results show a good agreement with the existing solutions in the literature. New results for the natural frequencies of VSLC elliptical plate are offered. [ABSTRACT FROM AUTHOR]

The lay-ups of symmetric variable stiffness composite laminated elliptical plates with curvilinear fibers are optimized for the maximum frequencies of the lowest three modes using the layer-wise optimization method. Two design variables and three constraints are considered. The fiber paths are constructed using the method of shifted paths. The laminate is modeled as one curved hierarchical finite element. The formulation is based on the first-order shear deformation theory. The blending function method is used to model accurately the geometry. New results for the optimal lay-ups that maximize the natural frequencies of the lowest three modes are obtained. The method is validated based on convergence test and comparison with published results for symmetric constant stiffness composite laminated elliptical plates with rectilinear fibers. A parametric study is performed showing the effects of aspect ratio, thickness ratio, modulus ratio, number of layers, and boundary constraint on the optimal solutions. [ABSTRACT FROM AUTHOR]

In the present work, attempts have been made to prepare scintillating nanoparticle composite films of Ce3+‐doped Y3Al5O12 (YAG:Ce) embedded in a polystyrene (PS) polymer. A YAG:Ce phosphor has been previously synthesized using the sol–gel method. YAG:Ce‐PS composite films of 250 ± 30 μm thickness were prepared using a solvent casting procedure with different PS/solvent concentration and a different mass ratio between nanoparticles of YAG:Ce and PS. X‐ray diffraction analysis confirmed that the YAG:Ce powders were successfully prepared. Using thermogravimetric analyses and differential scanning calorimetry, we found that the glass transition temperature (Tg) and thermal degradation were shifted to higher temperatures for composite films relative to pure PS. Photoluminescence showed the yellow emission of the Ce3+‐doped YAG phosphors, which was attributed to the 5d→4f transition of Ce3+ ion and the intensity of the emissions changed with the mass ratio of the YAG:Ce nanoparticles incorporated in the polymer and with the concentration of the polymer solution. [ABSTRACT FROM AUTHOR]

The p-version of the finite element method based on the first-order shear deformation theory (FSDT) is applied, to the free vibration of symmetric variable stiffness composite laminated (VSCL) elliptical plates, with curvilinear fibers. A curved hierarchical rectangular finite element is developed and used to model the elliptical plate. The geometry is described accurately by the blending function method. The element stiffness and mass matrices are integrated numerically using the Gauss-Legendre quadrature. The equations of motion are derived employing Lagrange's method. The numerical results are validated by means of convergence tests and compared with available data in the literature, for isotropic and constant stiffness composite laminated (CSCL) circular and elliptical plates. The contour plots of the fundamental frequency as a function of the fiber orientation angles are presented for clamped and soft simply supported symmetric VSCL elliptical plates. The effect of thickness ratio, aspect ratio, boundary conditions, and mechanical parameters on the frequencies of the lowest five modes is investigated and discussed. The mode shapes are examined by considering the effect of the fiber orientation angles and stacking sequences. [ABSTRACT FROM AUTHOR]

The optimal stacking sequence design for the maximum frequencies of the lowest three modes of symmetric variable stiffness composite laminated beams in air and in water is investigated for the first time using a layer-wise optimization method. Two fiber orientation angles in each layer are considered as design variables. The shifted path technique is used to construct the fiber paths. The p-version of the finite element method is used in conjunction with the Euler–Bernoulli beam theory coupled with torsion to calculate the frequencies. The numerical results are validated by comparison with published results for a single-layer constant stiffness composite beam with rectilinear fibers in air and in water. Extensive results are presented, which may serve as a benchmark for future research. Furthermore, a parametric study is performed showing the effects of geometrical and mechanical parameters and boundary conditions on the optimal solutions. [ABSTRACT FROM AUTHOR]

The optimum stacking sequence design for the maximum fundamental frequency of symmetrically laminated composite circular plates with curvilinear fibres is investigated for the first time using a layer-wise optimization method. The design variables are two fibre orientation angles per layer. The fibre paths are constructed using the method of shifted paths. The first-order shear deformation plate theory and a curved square p-element are used to calculate the objective function. The blending function method is used to model accurately the geometry of the circular plate. The equations of motion are derived using Lagrange’s method. The numerical results are validated by means of a convergence test and comparison with published values for symmetrically laminated composite circular plates with rectilinear fibres. The material parameters, boundary conditions, number of layers and thickness are shown to influence the optimum solutions to different extents. The results should serve as a benchmark for optimum stacking sequences of symmetrically laminated composite circular plates with curvilinear fibres. [ABSTRACT FROM AUTHOR]

In the present work, attempts have been made to prepare scintillating nanoparticle composite films of Ce 3+ -doped Y 3 Al 5 O 12 (YAG:Ce) embedded in a polystyrene (PS) polymer. A YAG:Ce phosphor has been previously synthesized using the sol-gel method. YAG:Ce-PS composite films of 250 ± 30 μm thickness were prepared using a solvent casting procedure with different PS/solvent concentration and a different mass ratio between nanoparticles of YAG:Ce and PS. X-ray diffraction analysis confirmed that the YAG:Ce powders were successfully prepared. Using thermogravimetric analyses and differential scanning calorimetry, we found that the glass transition temperature (Tg) and thermal degradation were shifted to higher temperatures for composite films relative to pure PS. Photoluminescence showed the yellow emission of the Ce 3+ -doped YAG phosphors, which was attributed to the 5d→4f transition of Ce 3+ ion and the intensity of the emissions changed with the mass ratio of the YAG:Ce nanoparticles incorporated in the polymer and with the concentration of the polymer solution., (© 2022 John Wiley & Sons Ltd.)