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Critical Earthquake Response of Elastic-Plastic Structures and Rigid Blocks under Near-Fault Ground Motions: Closed-Form Approach via Double Impulse

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Book Series: Frontiers Theme Book ISBN: 9782889198702 Year: Pages: 64 DOI: 10.3389/978-2-88919-870-2 Language: English
Publisher: Frontiers Media SA
Subject: General and Civil Engineering --- Environmental Engineering
Added to DOAB on : 2016-01-19 14:05:46
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This eBook is the second in a series of books on the critical earthquake response of elastic-plastic structures or rigid blocks under near-fault ground motions, and includes four original research papers which were published in the specialty section Earthquake Engineering in ‘Frontiers in Built Environment’. Several extensions of the first book1 are included here. The first article is on the soil-structure interaction problem. The reduction of an original soil-structure interaction model into a single-degree-of-freedom (SDOF) model enables the application of the original theory for an SDOF model to such complicated soil-structure interaction model. The second article is concerned with the extension of the original theory for an SDOF model to a 2DOF model. Since the simple application of the original theory for an SDOF model to a multi-degree-of-freedom model is difficult due to out-of-phase phenomenon of multiple masses, a convex model theory is introduced and an upper bound of elastic-plastic response is derived. The third article is related to the stability problem of structures (collapse problems of structures) in which the P-delta effect is included. It is shown that the original theory for an SDOF model with elastic-perfectly plastic restoring-force characteristic can be applied to a model with negative second slope. The fourth article is an application of the energy balance approach to an overturning limit problem of rigid blocks. A closed-form expression of the overturning limit of rigid blocks is derived for the first time after the Housner’s pioneering work in 1963. The approach presented in this book, together with the first book, is an epoch-making accomplishment to open the door for simpler and deeper understanding of structural reliability of built environments in the elastic-plastic and nonlinear range.

Critical Earthquake Response of Elastic-Plastic Structures Under Near-Fault Ground Motions: Closed-Form Approach via Impulse Input

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ISBN: 9782889197422 Year: Pages: 55 DOI: 10.3389/978-2-88919-742-2 Language: English
Publisher: Frontiers Media SA
Subject: General and Civil Engineering
Added to DOAB on : 2017-08-30 10:14:31
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The specialty section Earthquake Engineering is one branch of Frontiers in Built Environment and welcomes critical and in-depth submissions on earthquake ground motions and their effects on buildings and infrastructures. Manuscripts should yield new insights and ultimately contribute to a safer and more reliable design of building structures and infrastructures. The scope includes the characterization of earthquake ground motions (e.g. near-fault, far-fault, short-period, long-period), their underlying properties, their intrinsic relationship with structural responses, and the true behaviors of building structures and infrastructures under risky and uncertain ground motions. More specific topics include recorded ground motions, generated ground motions, response spectra, stochastic modeling of ground motion, critical excitation, geotechnical aspects, soil mechanics, soil liquefaction, soil-structure interactions, pile foundations, earthquake input energy, structural control, passive control, active control, base-isolation, steel structures, reinforced concrete structures, wood structures, building retrofit, structural optimization, uncertainty analysis, robustness analysis, and redundancy analysis. This eBook includes four original research papers, in addition to the Specialty Grand Challenge article, on the critical earthquake response of elastic-plastic structures under near-fault or long-duration ground motions which were published in the specialty section Earthquake Engineering. In the early stage of dynamic nonlinear response analysis of structures around 1960s, a simple hysteretic structural model and a simple sinusoidal earthquake ground motion input were dealt with together with random inputs. The steady-state response was tackled by an equivalent linearization method developed by Caughey, Iwan and others. In fact, the resonance plays a key role in the earthquake-resistant design and it has a strong effect even in case of near-fault ground motions. In order to draw the steady-state response curve and investigate the resonant property, two kinds of repetition have to be introduced. One is a cycle, for one forced input frequency, of the initial guess of the steady-state response amplitude, the construction of the equivalent linear model, the analysis of the steady-state response amplitude using the equivalent linear model and the update of the equivalent linear model based on the computed steady-state response amplitude. The other is the sweeping over a range of forced input frequencies. This process is quite tedious. Four original research papers included in this eBook propose a new approach to overcome this difficulty. Kojima and Takewaki demonstrated that the elastic-plastic response as continuation of free-vibrations under impulse input can be derived in a closed form by a sophisticated energy approach without solving directly the equations of motion as differential equations. While, as pointed out above, the approach based on the equivalent linearization method requires the repetition of application of the linearized equations, the method by Kojima and Takewaki does not need any repetition. The double impulse, triple impulse and multiple impulses enable us to describe directly the critical timing of impulses (resonant frequency) which is not easy for the sinusoidal and other inputs without a repetitive procedure. It is important to note that, while most of the previous methods employ the equivalent linearization of the structural model with the input unchanged, the method treated in this eBook transforms the input into a series of impulses with the structural model unchanged. This characteristic guarantees high accuracy and reliability even in the large plastic deformation range. The approach presented in this eBook is an epoch-making accomplishment to open the door for simpler and deeper understanding of structural reliability of built environments in the elastic-plastic range.

Nanoparticle-Reinforced Polymers

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ISBN: 9783039212835 9783039212842 Year: Pages: 334 DOI: 10.3390/books978-3-03921-284-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-08-28 11:21:27
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This book, a collection of 12 original contributions and 4 reviews, provides a selection of the most recent advances in the preparation, characterization, and applications of polymeric nanocomposites comprising nanoparticles. The concept of nanoparticle-reinforced polymers came about three decades ago, following the outstanding discovery of fullerenes and carbon nanotubes. One of the main ideas behind this approach is to improve the matrix mechanical performance. The nanoparticles exhibit higher specific surface area, surface energy, and density compared to microparticles and, hence, lower nanofiller concentrations are needed to attain properties comparable to, or even better than, those obtained by conventional microfiller loadings, which facilitates processing and minimizes the increase in composite weight. The addition of nanoparticles into different polymer matrices opens up an important research area in the field of composite materials. Moreover, many different types of inorganic nanoparticles, such as quantum dots, metal oxides, and ceramic and metallic nanoparticles, have been incorporated into polymers for their application in a wide range of fields, ranging from medicine to photovoltaics, packaging, and structural applications.

Keywords

chemical and physical interface --- surface modification of silica --- latex compounding method --- silica/NR composite --- thermoresponsive hyperbranched polymer --- gold nanoparticles --- in-situ synthesis --- colorimetric sensor --- silver ions --- Ag nanoparticles --- catalysis --- composite membrane --- separation --- SiO2 microspheres --- inorganic nanotubes --- PHBV --- nanomaterials --- morphology --- crystallization kinetics --- nanocomposite --- conductive polymer --- solar cell --- graphene --- graphene oxide --- power-conversion efficiency --- electrode --- active layer --- interfacial layer --- layered structures --- polymer-matrix composites --- mechanical properties --- gas barrier properties --- N-isopropylacrylamide --- N-isopropylmethacrylamide --- ratiometric temperature sensing --- FRET --- chain topology --- selective adsorption --- polymer-NP interface --- organic light-emitting diodes (OLEDs) --- PFO/MEH-PPV hybrids --- SiO2/TiO2 nanocomposite --- optoelectronic properties --- fluorescent assay --- fluorescence resonance energy transfer --- conjugated polymer nanoparticles --- gold nanoparticles --- melamine --- polymers --- composites --- carbon nanoparticles --- nano-hybrids --- nanocomposites --- sol–gel --- in situ synthesis --- metal oxides --- reduced graphene oxide --- graphene-like WS2 --- bismaleimide --- mechanical properties --- carrier transport --- polypropylene nanocomposite --- molecular chain motion --- electrical breakdown --- electric energy storage --- thermoplastic nanocomposite --- polyethylene --- power cable insulation --- electrical property --- structure-property relationship --- hybrid hydrogels --- nanoparticles --- nanosheets --- clays --- polymers --- adhesion --- n/a

Multiscale Turbulent Transport

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ISBN: 9783039282128 9783039282135 Year: Pages: 210 DOI: 10.3390/books978-3-03928-213-5 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2020-04-07 23:07:08
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Turbulent transport is currently a prominent and ongoing investigation subject at the interface of methodologies from theory to numerical simulations and experiments, and it covers several spatiotemporal scales. Mathematical analysis, physical modelling, and engineering applications represent different facets of a classical, long-standing problem that is still far from being thoroughly comprehended. The goal of this Special Issue is to outline recent advances of such subjects as multiscale analysis in turbulent transport processes, Lagrangian and Eulerian descriptions of turbulence, advection of particles and fields in turbulent flows, ideal or nonideal turbulence (unstationary/inhomogeneous/anisotropic/compressible), turbulent flows in biofluid mechanics and magnetohydrodynamics, and the control and optimization of turbulent transport. The SI is open to regular articles, review papers focused on the state of the art and the progress made over the last few years, and new research trends.

Ultrasonic Guided Waves

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ISBN: 9783039282982 9783039282999 Year: Pages: 376 DOI: 10.3390/books978-3-03928-299-9 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2020-04-07 23:07:09
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The propagation of ultrasonic guided waves in solids is an important area of scientific inquiry, primarily due to their practical applications for nondestructive characterization of materials, such as nondestructive inspection, quality assurance testing, structural health monitoring, and providing a material state awareness. This Special Issue of Applied Sciences covers all aspects of ultrasonic guided waves (e.g., phased array transducers, meta-materials to control wave propagation characteristics, scattering, attenuation, and signal processing techniques) from the perspective of modeling, simulation, laboratory experiments, or field testing. In order to fully utilize ultrasonic guided waves for these applications, it is necessary to have a firm grasp of their requisite characteristics, which include that they are multimodal, dispersive, and are comprised of unique displacement profiles through the thickness of the waveguide.

Keywords

electromagnetic wave --- group velocity --- time-frequency domain reflectometry --- dispersive medium --- ultrasonic guided wave --- nondestructive testing --- square steel bar --- non-detection zone --- surface flaw --- Rayleigh wave --- scattering --- modified BEM --- reconstruction --- adhesive joint --- single lap joint --- non-destructive testing --- damage identification --- Lamb waves --- scanning laser vibrometry --- signal processing --- ultrasonic guided waves --- axial transmission --- ultrasonic guided waves --- fiber optics --- fiber Bragg grating --- nondestructive testing --- structural health monitoring --- pipe inspection --- partial wave method --- slowness curves --- lamb wave --- stoneley wave --- mode sorting --- acoustic leakage --- rayleigh wave --- surface waves --- elastodynamics --- guided waves --- lamb wave --- dispersion curves --- phase velocity --- group velocity --- signal processing --- SH0 mode --- circumferential scanning --- synthetic aperture focusing --- exploding reflector model --- Lamb wave --- local wavenumber --- air-coupled transducer --- wavenumber domain filtering --- hybrid and non-contact system --- signal processing --- SNR --- split-spectrum processing --- ultrasonic guided waves --- signal processing --- defect detection --- spatial domain --- array analysis --- pipeline inspection --- ultrasonic guided waves (UGWs) --- metamaterial --- resonator --- low-frequency --- lamb wave --- adaptive filtering --- leaky normalized mean square --- ultrasonic guided waves --- pipeline inspection --- SNR enhancement --- signal processing --- guided wave --- multi-wire cable --- wave structure --- contact acoustic nonlinearity --- energy transfer --- rail --- ultrasonic guided wave --- semi-analytical finite element --- single mode extraction algorithm --- defect location --- signal processing --- defect detection --- torsional wave --- power spectrum --- sliding window --- pipeline inspection --- ultrasonic guided-waves (UGWs) --- magnetostrictive patch transducer --- shear mode --- soft magnetic patch --- dynamic magnetic field optimization --- signal strength enhancement --- acoustic emission --- nondestructive testing --- leakage location --- fault diagnosis --- n/a --- lamb waves --- composite --- ultrasonic testing --- numerical modelling --- pressure vessels

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