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Articles de revues sur le sujet "Cyclic tests, push-over tests"
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Lin, S. S., C. H. Lai, C. H. Chen et T. S. Ueng. « Derivation of Cyclic p-y Curves From Instrumented Dynamic Lateral Load Tests ». Journal of Mechanics 26, no 2 (juin 2010) : 123–33. http://dx.doi.org/10.1017/s1727719100002987.
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AbstractIn this paper, an efficient method is proposed to derive cyclic p-y curves from either push-over or shaking table test results. The Fourier series function, satisfying the boundary conditions of a pile, is used to represent deflection behavior of the pile-soil system at each instant of time during loading interval. In order to obtain soil reaction along the pile shaft, convergence of the series after differentiation is guaranteed by applying the Cesaro sum technique. Results of four push-over tests and two other shaking table test results, conducted at the National Center for Research on Earthquake Engineering in Taiwan, are then used to verify the feasibility of the proposed method.
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Nezamian, Abolghasem, Riadh Al-Mahaidi et Paul Grundy. « Bond strength of concrete plugs embedded in tubular steel piles under cyclic loading ». Canadian Journal of Civil Engineering 33, no 2 (1 février 2006) : 111–25. http://dx.doi.org/10.1139/l05-091.
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Investigation of the load transfer of concrete plugs to tubular steel piles subjected to tension and compression and cyclic loading has been conducted at Monash University over the past 3 years. The work presented in this paper reports on the results of the combination of pull-out, push-out, and cyclic loading tests carried out on 15 steel tube specimens filled partially with reinforced concrete with variable lengths of embedment. The pull-out force was applied through steel reinforcing bars embedded in the concrete plug, and push-out forces were applied through a thick top circular plate on the top of the concrete plug. Test results included the cyclic loading, ultimate pull-out and push-out forces, slip of concrete plugs, and longitudinal and hoop strains along the piles for some specimens. The tests clearly showed that average bond strength significantly exceeds expectations and is higher than the results of previous investigations using plugs without reinforcement. The test results also indicated that cyclic loading tests reduced the bond strength due to the accumulation of damage to the plug–pile interface. The push-out and pull-out tests conducted under symmetric cyclic loading demonstrated that slip between the concrete plug and the steel tube increased with repeated loading, and the rate of slip growth increased with an increase in the peak load.Key words: tubular steel pile, reinforced concrete plug, bond, cyclic loading.
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Tokimasa, Katsuyuki. « Life Estimation of SUS304 Steel Subjected to Nonproportionally Combined Push-Pull and Cyclic Torsion at 973K ». Key Engineering Materials 345-346 (août 2007) : 323–26. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.323.
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The present paper summarizes the fully reversed strain-controlled creep-fatigue tests conducted on thin-walled tubular specimens of SUS304 austenitic stainless steel at 973K in air under push-pull, cyclic torsion, in-phase straining and 90deg out-of-phase straining of push-pull and cyclic torsion. It is shown that, as the results of analysis of the experimental data by the strain-range partitioning methodand the critical plane model parameter, a new inelastic-strain based parameter was proposed for life estimation of SUS304 subject to nonproportionally combined push-pull and cyclic torsion by the strain-range partitioning method.
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Vaško, A. « Fatigue Properties of Nodular Cast Iron at Low Frequency Cyclic Loading ». Archives of Metallurgy and Materials 62, no 4 (1 décembre 2017) : 2205–10. http://dx.doi.org/10.1515/amm-2017-0325.
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Abstract Three melts of ferrite-pearlitic nodular cast iron with different charge composition were used for fatigue tests. Wöhler fatigue curves and fatigue strength were obtained, and microstructure and fracture surfaces were investigated. The aim of the paper is to determine the influence of charge composition on microstructure, mechanical and fatigue properties of synthetic nodular cast irons and their micromechanisms of failure. Fatigue tests were realised at low frequency sinusoidal cyclic push-pull loading (stress ratio R = −1) at ambient temperature (T = 20 ±5°C). They were carried out with using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100 at frequency f ≈ 120 Hz. The results of fatigue tests at low frequency cyclic loading are compared with fatigue properties at high frequency cyclic loading.
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Fan, Jian Sheng, et Wen Liu. « Tests on Shear Studs Using Profiled Steel Sheeting Subjected to Cyclic Loading ». Applied Mechanics and Materials 578-579 (juillet 2014) : 196–200. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.196.
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Push-out tests were conducted to study the performance of shear studs in composite beams with profiled sheeting. All stud specimens were through-deck welded on steel beams. Three variables, i.e. the presence of profiled sheeting, the direction of the steel sheeting and the loading patterns were studied. Comparison between test results and predictions according to design specifications were also proposed. The research shows that, direction of the profiled steel sheeting has little influence on the ultimate load with shank shearing failure; shear failure of concrete rib decreases the shear strength; and the shear resistance of a parallel concrete rib is about twice of a transverse one.
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Itoh, Takamoto, Fumio Ogawa et Takahiro Morishita. « Fatigue Testing and Evaluation of Fatigue Strength under Multiaxial Stress State ; Why do we need fatigue testing ? » MATEC Web of Conferences 159 (2018) : 01050. http://dx.doi.org/10.1051/matecconf/201815901050.
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Types of multiaxial fatigue tests and their experimental results are presented in this paper. There are typical three types in multiaxial fatigue tests: the combining push-pull and reversed torsion loading test using hollow cylinder specimen, the biaxial tension-compression test using cruciform specimen and the inner pressure applied the push-pull loading test using the hollow cylinder specimen. In the combining a push-pull loading and a reversed torsion loading test, failure life under non-proportional loading in which principal directions of stress and strain were changed in a cycle was shortened compared to proportional loading in which those are fixed. Fatigue lives were well-correlated using a non-proportional strain range considering the effect of strain path and material dependence. In the biaxial tension-compression test, the failure life decreased with increase of the principal strain ratio. In the inner pressure applied the push-pull loading test, cyclic deformation behaviour due to complex loading paths of multiaxial fatigue tests with the inner pressure associated with push-pull and rev. torsion acted to reduce the failure lives. Experimental investigation of multiaxial failure life and elucidation of their governing mechanism is essential and it can broaden the applicability of structural components.
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Noster, Ulf, et Berthold Scholtes. « Isothermal strain-controlled quasi-static and cyclic deformation behavior of magnesium wrought alloy AZ31 ». International Journal of Materials Research 94, no 5 (1 mai 2003) : 559–63. http://dx.doi.org/10.1515/ijmr-2003-0098.
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Abstract The low-cycle and high-cycle fatigue behavior of the Mg-base wrought alloy AZ31 is investigated in the temperature range 20– 300 °C using total-strain-controlled push – pull tests. It is shown that the mechanical properties of the material are substantially influenced by the direction dependent formation of deformation twins and resulting deformation asymmetry. As a consequence tensile mean stresses develop during total-strain-controlled fatigue tests without mean strain.
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Valente, Marco. « Steel-Concrete Bond Deterioration under Repeated Loading for Different Confinement Levels ». Applied Mechanics and Materials 217-219 (novembre 2012) : 188–91. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.188.
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This paper presents the results of experimental tests and numerical analyses concerning the influence of repeated cyclic loading and reinforcement confinement on bond between steel rebar and concrete. Experimental tests of push-pull type were carried out at the Politecnico di Milano on concrete specimens provided with a steel cage of longitudinal bars and stirrups, and reinforced with a single steel rebar. The experimental tests were conducted under monotonic and repeated loading history. Bond strength degradation was observed due to repeated cyclic loading. Detailed three-dimensional finite element models of the specimens were developed to reproduce laboratory tests and parametric analyses were performed to provide a better understanding of the experimental results. The numerical analyses showed good agreement with the experimental results and confirmed that the applied repeated loading history caused significant bond deterioration. High values of reinforcement confinement enhanced bond strength and delayed the onset of bond deterioration.
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Saito, Shunsuke, Fumio Ogawa et Takamoto Itoh. « Fatigue Life Properties of Stainless Steels in Wide Ranged Biaxial Stress State ». Key Engineering Materials 795 (mars 2019) : 60–65. http://dx.doi.org/10.4028/www.scientific.net/kem.795.60.
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Multiaxial fatigue tests consisting of push-pull loading and cyclic inner pressure were carried out using hollow cylinder specimens of type 430 stainless and type 316 stainless steels at room temperature. 7 types of cyclic loading paths were employed by combining axial and hoop stresses: a Pull, an Inner-pressure, a Push-pull, an Equi-biaxial, a Square-shape, a LT-shape and a LC-shape. Fatigue lives vary depending on the loading path when those were evaluated by the maximum Mises’ equivalent stress on inner surface of the specimen. The fatigue lives of both the steels showed a similar tendency although some Pull tests take longer fatigue life when cracks initiated from inside surface of the specimen. This study investigated the crack initiation and propagation behaviors as well as the initiation of oil leakage to prove the behavior and discusses life evaluation for two steels under wide ranged biaxial stress state, too.
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Vaško, Alan, Juraj Belan et Eva Tillová. « Study of the fatigue behaviour of synthetic nodular cast irons at low and high frequency cyclic loading ». MATEC Web of Conferences 157 (2018) : 07014. http://dx.doi.org/10.1051/matecconf/201815707014.
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The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100. High frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both of them were carried out at sinusoidal cyclic push-pull loading (stress ratio R = -1) at ambient temperature (T ≈ 20 °C). The relationship σa = f (N) and fatigue strengths were determined experimentally; mechanical properties, microstructures and fracture surfaces were investigated.
Thèses sur le sujet "Cyclic tests, push-over tests"
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Bernardi, Martina. « Industrial steel storage racks subjected to static and seismic actions : an experimental and numerical study ». Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/322402.
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Industrial steel storage racks are pre-engineered lightweight structures commonly used to store goods from supermarkets to big warehouses. These systems are framed structures, usually made of cold-formed steel profiles and characterised by non-standard details. Their performance is quite complex and the prediction of their global response is more difficult than for the traditional steel frames. This difficulty is due to the racks’ main features: the use of cold-formed thin-walled steel sections which are sensitive to different buckling modes, the presence of regular perforation patterns on the uprights, the highly non-linear behaviour of joints, the influence of the structural imperfections and the significant frame sensitivity to second order effects. The behaviour of racks becomes even more complex when seismic or accidental events induce significant horizontal forces acting on the structures. The complexity and variability that characterise racks make it difficult to identify general design solutions. Hence, racks design is traditionally carried out by using the “design by testing” approach, which requires the experimental characterisation of the main structural components, of the joints and the sub-assemblies. The complexity of the racks also affects their numerical modelling, which results in complex analyses that must take into account all the aforementioned features. The work presented in this thesis focuses on the study of a typical steel pallet rack, identified as case study. The research aims to contribute to building up a comprehensive knowledge of the response of both the main rack components and of the whole structure. The main rack components were first individually studied. The behaviour of the uprights, of the base-plate joints and of the beam-to-column joints was experimentally investigated. The experimental data were then taken as reference for the calibration of FE models that enabled exploring each component’s performance. These models were then incorporated into the whole rack model. The response of the uprights was first investigated through stub column tests. The non-negligible interaction between axial force and bending moment of the upright response was then experimentally and numerically analysed to define the M-N domains. In addition, the rules provided by different European standards for the design of isolated members subjected to combined axial load and bending moment were considered and critically compared, identifying the main critical issues of the different design approaches. Although the contribution of joints on the rack global response is of paramount importance, to date, the knowledge is quite limited. In particular, the experimental studies of the behaviour of base-plate joints are still rather modest, especially for the cyclic range. Therefore, an experimental campaign on the rack base-plate joints was carried out: three levels of axial load were considered and the response in both the down-aisle and the cross-aisle direction was investigated under monotonic and cyclic loadings. Similarly, the beam-to-column joint was tested both monotonically and cyclically, taking into account its non-symmetric behaviour. Numerical models for both joint types were developed and validated enabling the characterisation of joints in the monotonic and cyclic range. This in-depth knowledge of the response of individual components facilitated the evaluation of the global rack behaviour. As a final stage of the research, full-scale tests of four-level two-bay racks were performed taking advantage of an innovative full-scale testing set-up and, on the basis of the experimental outcomes, the racks’ global behaviour was numerically investigated. Critical standards issues and needs for future research were further identified.
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Eschenbach, Wolfram. « Determination of the denitrification capacity of unconsolidated rock aquifers using 15N tracer experiments at groundwater monitoring wells - development of a new method to assess actual and future denitrification in aquifers ». Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0023-994C-3.
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Sousa, Francisco Martins Prata Fonseca. « Whole-brain mapping of cerebrospinal fluid velocity and displacement over the cardiac cycle using phase contrast MRI and optimization of a DENSE sequence ». Master's thesis, 2021. http://hdl.handle.net/10451/48167.
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Tese de mestrado integrado em Engenharia Biomédica e Biofísica (Sinais e Imagens Médicas), Universidade de Lisboa, Faculdade de Ciências, 2021O líquido cefalorraquidiano (LCR) tem um papel essencial na drenagem dos resíduos resultantes do metabolismo cerebral e o constante movimento a que este fluido está sujeito é vital para manter a homeostasia do cérebro. Com feito, alterações neste movimento, geralmente associadas com o envelhecimento ou com doença, levam a perturbações fisiológicas, como a doença de Alzheimer ou a hidrocefalia. Por esta razão, é fundamental consolidar e aprofundar o conhecimento referente a este fluido, nomeadamente perceber como varia a sua velocidade e deslocamento, pois só desta forma será possível desenvolver e aperfeiçoar a prevenção e tratamento destas perturbações. Com efeito, este fluido está em constante movimento e o seu comportamento está intimamente ligado ao ciclo cardíaco. Apesar de estudos anteriores sobre a velocidade e o deslocamento do líquido cefalorraquidiano através de métodos de Ressonância Magnética (RM), ainda não existe uma descrição completa sobre o comportamento deste fluido. O objetivo principal deste estudo, consistiu em obter uma descrição detalhada da velocidade e do deslocamento do LCR através da aquisição de imagens de ressonância magnética obtidas com contraste de fase, um método de referência no que toca ao estudo da velocidade de fluidos No entanto, utilizar RM de contraste de fase para adquirir velocidades mais baixas, como as do LCR, requer tempos de aquisição mais longos e, consequentemente, as imagens obtidas estão mais sujeitas a distorções. Assim, a segunda parte deste projecto partiu dos resultados de deslocamento obtidos através da RM com contraste de fase para otimizar os parâmetros de uma segunda sequência de MR. Esta sequência é relativamente recente e possibilita o estudo do deslocamento sub-milimétrico do LCR associado ao movimento do cérebro através da aplicação de gradientes sucessivos (DENSE). Porém, é necessária uma escolha rigorosa dos parâmetros utilizados de forma a obter resultados que retratem o deslocamento do LCR de uma forma rigorosa e exata. Na primeira parte deste projecto, quatro voluntários foram estudados utilizando RM com contraste de fase, entre outubro de 2019 e fevereiro de 2020, em concordância com as diretrizes éticas da University Medical Center em Utrecth, Países Baixos. As aquisições foram realizadas utilizando um scanner de RM Philips 7 T e dois tipos de contraste foram utilizados: contraste de fase com 1mm de resolução isotrópica e com uma codificação de velocidade de 5m/s, e imagens 3D com ponderação em T1 com 1mm de resolução isotrópica. As imagens foram obtidas para três orientações distintas: anterior posterior, inferior-superior, e direita-esquerda. Na segunda parte deste projecto, dois voluntários foram estudados, de janeiro a fevereiro de 2020, utilizando seis contrastes: contraste de fase com 1mm de resolução isotrópica, e imagens 3D com ponderação em T1 com 1mm de resolução isotrópica, uma sequência básica DENSE com 2mm de resolução isotrópica, uma sequência básica DENSE com 3mm de resolução isotrópica, uma sequência DENSE com uma preparação T2 com 3mm de resolução isotrópica e, finalmente, uma sequência DENSE com tempo de eco prolongado com 3mm de resolução isotrópica. No entanto, e ao contrário das imagens adquiridas na primeira parte deste projecto, as imagens da segunda parte foram obtidas apenas para a orientação inferior-superior. Todas as imagens adquiridas no decorrer desta dissertação foram obtidas com gating cardíaco. O gating cardíaco foi realizado através da utilização de um eletrocardiograma e de um oxímetro de pulso de modo a relacionar o evolução da velocidade e do deslocamento com o ciclo cardíaco. Neste projecto foi também desenvolvida uma pipeline que permite que a partir das imagens adquiridas seja possível estudar a velocidade e o deslocamento do LCR. Esta pipeline inclui diversos passos. O primeiro passo consistiu em realinhar e co-registar as imagens obtidas de forma a permitir uma análise voxel a voxel. Seguidamente, as imagens foram segmentas em três tipos de tecidos: LCR, substância cinzenta, e substância branca. Adicionalmente, as primeiras etapas foram realizadas através da utilização de toolboxs disponíveis no MATLAB como o SPM e o CAT12. Posteriormente, os artefactos presentes nas imagens, tais como as correntes-eddy, foram corrigidos. No decorrer deste projecto diversas regiões foram analisadas e foram divididas em dois grupos: regiões do sistema ventricular, nas quais se incluíram os ventrículos laterais, o terceiro e quarto ventrículo, o aqueduto de Sylvius e a Cisterna Magna; e regiões mais abrangentes, como a região anterior e posterior do cérebro. Estas áreas do cérebro foram selecionadas através da segmentação das imagens anatómicas. Finalmente, a velocidade de cada uma destas regiões foi extraída e integrada ao longo do ciclo cardíaco de maneira a calcular o deslocamento do LCR. Os resultados obtidos relativamente à velocidade mostraram consistência para os quatro voluntários deste projecto. Verificou-se que as regiões do sistema ventricular demonstram valores de velocidade consideravelmente mais elevados do que as regiões mais abrangentes. Com efeito, a região que apresentou valores absolutos de velocidade mais elevados foi o aqueducto de Sylvius. Adicionalmente, verificou-se que as velocidades são superiores na orientação caudal-cranial e inferiores na orientação direita-esquerda. Concluiu-se também que o valor de velocidade escolhido não foi o mais indicado para as regiões mais abrangentes pois a velocidade destas regiões é significativamente inferior e, desta forma, poderá ter existido perda de sinal do LCR. Posteriormente, ao integrar a velocidade obtida através da RM com contraste fase obtiveram-se mapas de deslocamento para as mesmas regiões cerebrais. Estes resultados mostraram-se consistentes e, tal como anteriormente observado, o deslocamento é consideravelmente superior para as regiões do sistema ventricular. A região inferior do cérebro foi a que apresentou valores de deslocamento mais elevados, o que pode ser justificado pelo facto desta região se encontrar mais próxima do coração e, desta maneira, o LCR ser ejetado das regiões que ocupa com maior velocidade. Adicionalmente, verificou-se que as maiores alterações do deslocamento ocorrem imediatamente após a sístole cardíaca. Seguidamente, foi possível, a partir dos valores de deslocamento obtidos, determinar um valor ótimo para a sensibilidade, relativamente ao deslocamento, da sequência DENSE. Contrariamente à primeira parte deste projecto, os resultados obtidos utilizando as sequências DENSE dizem respeito exclusivamente às regiões mais abrangentes. De facto, esta exclusão das regiões do sistema ventricular foi causada pela baixa resolução das imagens obtidas que, desta forma, não permitiram uma segmentação de áreas tão reduzidas com fiabilidade razoável. Os resultados desta análise mostram que a sequência utilizada cujos resultados de deslocamento se assemelham mais aos resultados obtidos através do contraste de fase foi a sequência que utilizou a preparação T2. Por oposição, as sequências básicas utilizadas mostraram semelhança reduzida com o método de comparação. Esta diferença observada foi justifica pela baixa resolução das imagens adquiridas, o que contribui para que não fosse possível eliminar o efeito de volume parcial. Adicionalmente, concluiu-se que o valor de sensibilidade para o deslocamento utilizado não foi o correto para estas regiões e, desta forma, houve perda de sinal adquirido justificando assim às diferenças encontradas entre os dois métodos. Concluindo, esta dissertação cumpriu o objetivo principal proposto, nomeadamente fazer uma descrição completa e quantificar a evolução da velocidade e do deslocamento do líquido cefalorraquidiano ao longo do ciclo cardíaco. Adicionalmente, o método de RM com contraste de fase mostrou ser um método fiável para o estudo do comportamento do LCR mesmo em regiões com velocidades mais lentas. Os resultados de deslocamento obtidos através da utilização do método DENSE permitiram confirmar o potencial desta técnica para medir deslocamentos sub-milimétricos. No entanto, este método ainda necessita de ser otimizado de forma a ser uma alternativa viável ao contraste de fase. Finalmente, os resultados obtidos neste estudo permitem que estudos futuros utilizem os valores máximos de cada região obtida de forma a otimizar futuras sequências.
Cerebrospinal fluid (CSF) plays an essential role in the drainage of cerebral waste, and its continuous motion is vital to maintain the brain’s homeostasis. Variations in this motion, associated with aging and disease, are observed in physical and physiological disorders, such as Alzheimer’s Disease. Therefore, a deep understating of this fluid motion, such as its velocity and displacement, is fundamental to strengthen our knowledge of these diseases and might be vital to their prevention and treatment. Despite previous studies reporting CSF velocity and displacement using magnetic resonance imaging techniques, a complete picture of this fluid motion has not yet been obtained. The aim of this study was to, first and foremost, obtain a general picture of CSF velocity and displacement using Phase Contrast (PC) MRI, a method of reference for velocity acquisition. Furthermore, this sequence was also used to optimize the parameters for an MRI technique called Displacement Encoding with Stimulated Echoes (DENSE), a sequence that was modified in order to be capable of measuring small displacements. Four healthy subjects were studied using whole-brain ultra-high field (UHF) MRI at 7 Tesla (T). The volunteers were scanned using two different MRI imaging sequences: Phase Contrast MRI at 1 mm isotropic resolution and 3D T1-weighted (T1w) at 1 mm isotropic resolution. Additionally, two healthy subjects were scanned using PC and four different DENSE acquisitions. Firstly, two basic DENSE sequences with 2mm and 3mm isotropic resolution were acquired. Next, a DENSE acquisition with a T2 prepared magnetization, and a DENSE sequence with a long echo time were acquired to avoid confounding effects from partial volume between tissue and CSF. The image processing pipeline included coregistration, segmentation, eddy current correction. Moreover, mean velocity and displacement maps were calculated for regions of interest previously selected. The results in this study obtained from the PC acquisitions show consistent velocity and displacement values across all subjects. Furthermore, CSF shows higher values for the ventricular regions, such as the aqueduct, and predominant motion in the anterior and feet direction. Comparatively, regions in the periphery of the brain display slower velocities and smaller displacements. The displacement values obtained with PC were used to optimize the displacement sensitivity used in the DENSE acquisition. The DENSE sequence acquired with a T2 magnetization preparation showed the most consistent results when compared to the Phase Contrast. In conclusion, this project managed to study and quantify CSF behavior in the brain, which allows for the optimization of future sequences that desire a more detailed study of this fluid’s in specific brain regions.
Livres sur le sujet "Cyclic tests, push-over tests"
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Gupta, Kuhika, et Hank Jenkins-Smith. Anthony Downs, “Up and Down with Ecology : The ‘Issue-Attention’ Cycle”. Sous la direction de Martin Lodge, Edward C. Page et Steven J. Balla. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199646135.013.34.
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This chapter comments on Anthony Downs’s 1972 seminal paper “Up and Down with Ecology: The ‘Issue-Attention’ Cycle,” which tackles the concept of “public” or “issue” attention. Focusing on domestic policy, particularly environmental policy in the United States, Downs describes a process called “issue-attention cycle,” by which the public gains and loses interest in a particular issue over time. This chapter summarizes studies that directly put Downs’s propositions to the test, laying emphasis on research that probes the existence of and interrelationships among the public attention cycle, media attention cycle, and government attention cycle. It then reviews the main arguments put forward by Downs before concluding with a discussion of promising avenues for future research as well as important theoretical and methodological questions that need further elucidation.
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Cox, Peter, et Till Koglin, dir. The Politics of Cycling Infrastructure. Policy Press, 2020. http://dx.doi.org/10.1332/policypress/9781447345152.001.0001.
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Academic texts on cycling research are expanding rapidly. A dominant theme among these is the use of infrastructure measures to assist promotion of cycling as part of a movement towards sustainable mobility. Physical infrastructure is currently posited as the primary key to unlock cycling’s potential as a primary mode of sustainable transport. Individual studies rarely stand together to be read back to back, in order to allow comparison between them. The privilege of academic conferences is that they allow the attendee to compare and contrast different academic agendas and concerns of researchers, and to engage in conversation between them. This volume provides a comparative assessment of existing and historic struggles over cycling infrastructure. The aim of this volume is to bring a selection of those parallel voices together and to initiate that dialogue for a wider audience. It is argued that planning is one element of the operation, but what results is often very different from even the most comprehensive strategic imagination. Underlying this chaos however, is a lurking sense that the broader lessons of infrastructure provision for cycling needs to be connected with the political analyses of infrastructuring that derive from wider studies. The book concludes that infrastructures are in constantly in flux, contentious and contended. Furthermore, it concludes that politics is also embodied; lived out in the spaces of mundane and everyday travel.
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Hodge, R. Anthony. Towards Contribution Analysis. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198817369.003.0018.
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Since the early 1990s, at least forty-five initiatives have been mounted to improve the environmental and social performance of the mining industry. Many changes in the formal legal and regulatory systems have also been introduced. However, no systematic approach has been adopted to test whether this effort is making a difference. Without such monitoring of success, the tension between companies, communities, and governments regarding the role of mining in society will continue. This chapter makes the case for using ‘contribution analysis’ to fill this gap, a systematic means to assess and track mining’s contribution to human and ecosystem well-being over the full project and product life cycles. This is a higher test than current practice. It brings out a fuller picture of the positives and negatives of natural resources and their management, provides greater opportunity for the perspectives of all interests to be heard, and is fairer.
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Church, David. Post-Horror. Edinburgh University Press, 2021. http://dx.doi.org/10.3366/edinburgh/9781474475884.001.0001.
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Horror’s longstanding reputation as a popular but culturally denigrated genre has been challenged by a new wave of films mixing arthouse minimalism with established genre conventions. Variously dubbed “elevated horror” and “post-horror” in popular film criticism, texts such as The Babadook, It Follows, The Witch, It Comes at Night, Get Out, The Invitation, Hereditary, Midsommar, A Ghost Story, and mother! represent an emerging nexus of taste, politics, and style that has often earned outsized acclaim from high-minded critics and populist rejection by wider audiences. Post-Horror is the first full-length study of one of the most important and divisive movements in twenty-first-century horror cinema. It argues that the affect produced by these films’ minimalist aesthetic has fueled taste-based disagreements between professional film critics, genre fans, and more casual viewers about whether the horror genre can or should be upheld as more than a populist entertainment form, especially as the genre turned away from the post-9/11 debates about graphic violence that consumed the first decade of the twenty-first century. The book thus explores the aesthetic qualities, historical precursors, affective resonances, and thematic concerns of this emerging cycle by situating these texts within revived debates between over the genre’s larger artistic, cultural, and entertainment value. Chapters include thematic analyses of trauma, gaslighting, landscape, existential dread, and political identity across a range of films straddling the line between art-horror and multiplex fare since approximately 2013.
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Flood, Gavin, dir. The Oxford History of Hinduism. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198733508.001.0001.
Texte intégralRésumé :
This history of Hindu religious practices examines traditions of asceticism, yoga, and devotion (bhakti), including dance and music, developed in Hinduism over a long period of time, placing the theme of practice within a broader trajectory of cultural history. Some of these practices, notably those denoted by the term yoga, are orientated towards salvation from the cycle of reincarnation and go back several thousand years, borne witness to in ancient texts called Upaniṣads, as well as in other traditions, notably early Buddhism and Jainism. Practices of meditation are also linked to asceticism (tapas) and its institutional articulation in renunciation (saṃnyāsa). There are devotional practices that might involve ritual, making an offering to a deity and receiving a blessing, dancing, or visualization of the master (guru) and a range of disciplines from ascetic fasting to taking a vow (vrata) for a deity in return for a favour. This whole range of meditative and devotional practices that have developed in the history of Hinduism are represented in this book.
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Jappelli, Tullio, et Luigi Pistaferri. The Age Profile of Consumption and Wealth. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199383146.003.0002.
Texte intégralRésumé :
The life-cycle model yields a number of important empirical predictions about consumption and saving behavior. First, the growth rate of consumption depends on the difference between the expected real interest rate and the rate of time preference and varies with the elasticity of intertemporal substitution. Second, individuals seek to smooth the marginal utility of consumption over time. Third, young consumers should be accumulating resources for retirement, and hence have an adequate level of wealth at retirement. Finally, the elderly should be decumulating resources. To test these predictions, one can draw on a vast array of data on interest rates, consumption, income, and wealth. Some come from time series and national accounts, others from cross-sectional or longitudinal surveys of households. This chapter introduces stylized facts that emerge from a first examination of such data, pointing out the merits but also the drawbacks of the available sources.
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Epstein, Ben. The Only Constant is Change. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190698980.001.0001.
Texte intégralRésumé :
The Only Constant Is Change presents and tests the political communication cycle (PCC), a model describing how political actors and organizations make decisions about if, how, and when to innovate their political communication practices. Generally speaking, political communication goals have remained largely stable over time, but the strategies used to accomplish these goals have changed a great deal. The PCC describes the recurring process of political communication innovation through American political history. This model incorporates the technological, political, and behavioral factors influencing how and when changes in political communication activity take place. The PCC is made up of three phases that also serve as an organizational structure for the book. First is the technological imperative, which focuses on how new information and communications technologies (ICT) are developed and what types of ICTs may be more or less likely to be used to innovate political communication. Next, the political choice phase incorporates the behavioral processes embedded in how different types of actors choose whether to innovate or not. This phase is the most critical and is analyzed through case studies evaluating how campaigns, social movements, and interest groups have or have not changed their political communication activities over time. Finally, the stabilization phase encompasses the process of how once innovative techniques become the new status quo though the establishment of new norms, regulations, and institutions. The book explores these changes through historical and contemporary analysis, which offers important context and tools to understand political communication through history and today.
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Torgerson,, Paul R., C. N. L. Macpherson et D. A. Vuitton. Cystic echinococcosis. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198570028.003.0060.
Texte intégralRésumé :
Cystic echinococcosis (CE)\cystic hydatid disease is one of the most widespread and important global helminth zoonoses. The parasite Echinococcus granulosus is maintained in a wide spectrum of intermediate hosts, including sheep, goats, camels, cattle, pigs and equines. A number of wild intermediate hosts occur, including cervids in the northern part of the North American continent and Eurasia, marsupials in Australia and wild herbivores in East and southern Africa. The application of a range of molecular techniques to the characterization of the parasite has confirmed the existence of mostly host-adapted strains and genotypes of the parasite and several new species have been proposed. The ubiquitous domestic dog serves as the most important definitive host for the transmission of the parasite throughout its wide geographical range.A wide range of diagnostic techniques, including necropsy, arecoline purgation, coproantigen ELISA and DNA based tests are available for detecting E. granulosus infection in the definitive host. In intermediate animal hosts, diagnosis at post mortem still remains the most reliable option. In humans, imaging techniques including ultrasound, nuclear magnetic resonance (NMR) or computer aided tomography (CAT-scan provide not only a method of diagnosis but also reveal important clinical information on the location, condition, number and size of the hydatid cysts in man. Of these ultrasound is the most widely used diagnostic technique and is the only imaging technique for screening of populations in rural areas, where the disease is most common. A classification system has been developed which can be used to assess the likely development of a cyst and hence guide the clinician in treatment options for the patient. Treatment relies on surgery and/or percutaneous interventions, especially ‘Puncture, Aspiration, Injection, Re-aspiration’ (PAIR) and/or antiparasitic treatment with albendazole (and alternatively mebendazole).CE is largely a preventable disease. Successful elimination programmes have focused on frequent periodic treatments of dogs with anthelmintics and the control of slaughter of domestic livestock. In many regions elimination or even control remains a problem as the parasite is endemic over vast areas of low income countries where there may be limited resources for control. In some areas, such as former communist administered countries, the parasite is resurgent. New tools are becoming available to control the parasite, including a highly effective vaccine in sheep which prevents the infection in sheep and breaks the transmission cycle. In addition cost effective methods are being developed which may be appropriate in low income countries where financial resources are not available for intensive control programmes that have been successful in high income countries.
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Lysack, Krista. Chronometres. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198836162.001.0001.
Texte intégralRésumé :
What does it mean to feel time, to sense its passing along the sinews and nerves of the body as much as the synapses of the mind? And how do books, as material arrangements of print and paper, mediate such temporal experiences? Chronometres: Devotional Literature, Duration, and Victorian Reading is a study of the time-inflected reading practices of religious literature, the single largest market for print in Victorian Britain. It examines poetic cycles by John Keble, Alfred Tennyson, Christina Rossetti, and Frances Ridley Havergal; family prayer manuals, Sunday-reading books and periodicals; and devotional gift books and daily textbooks. Designed for diurnal and weekly reading, chronometrical literature tuned its readers’ attentions to the idea of Eternity and the everlasting peace of spiritual transcendence, but only in so far as it parcelled out reading into discrete increments that resembled the new industrial time-scales of factories and railway schedules. Chronometres thus takes up print culture, affect theory, and the religious turn in literary studies in order to explore the intersections between devotional practice and the condition of modernity. It argues that what defines Victorian devotional literature is the experience of its time signatures, those structures of feeling associated with its reading durations. For many Victorians, reading devotionally increasingly meant reading in regular portions and often according to the calendar and workday in contrast to the liturgical year. Keeping pace with the temporal measures of modernity, devotion became a routinized practice: a way of synchronizing the interior life of spirit with the exigencies of clock time. This kind of devotional observance coincided with the publication, between 1827 and 1890, of a diverse array of largely Protestant books and print that shared formal and material relationships to temporality. By dispensing devotion as daily or weekly doses of reading, chronometrical literature imagined and arranged time in relation to time’s materiality. But in so doing, it also left open temporal spaces that could be filled by readers, some of whom marked temporality through their own practices like annotation and scrapbooking, which publishers were then quick to emulate. Chronometrical literature likewise produced a host of embodied cognitions that could include moments of absorption but, equally, ones of boredom and mental drift. Such texts therefore did not necessarily discipline Victorian readers according to the demands of the clock or even of religious doctrine. For their regular yet malleable temporal arrangements also meant that readers might discover their own agencies and affects through encounters with print, such that devotional readers themselves came to participate in a reciprocal process of both reading and writing in time. Chronometres considers how the deliverances afforded through time-scaled reading are persistently materialized in the body, both that of the book and of the reader. Recognizing that literature and devotion are not timeless abstractions, it asks how the materiality of books, conceived as horological relationships through reading, might bring about the felt experience of time. Even as Victorian devotion invites us to tarry over the page, it also prompts the question: what if it is “Eternity” that keeps time with the clock?
Chapitres de livres sur le sujet "Cyclic tests, push-over tests"
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Hoogeveen, Troy, et Joe White. « A Macro Modelling Blind Prediction of a Cyclic Push-Over Test on a Full Scale Masonry House ». Dans Seismic Hazard and Risk Assessment, 505–17. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-74724-8_34.
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Vostral, Sharra L. « Of Mice and (Wo)Men : Tampons, Menstruation, and Testing ». Dans The Palgrave Handbook of Critical Menstruation Studies, 673–86. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-0614-7_50.
Texte intégralRésumé :
Abstract Vostral provides much-needed insight into the link between women’s bodily experiences with tampons and twentieth-century developments in material science, corporate research, and gynecological observations about menstrual cycles. She examines how design modifications to tampons, changes in material composition, and the cultivation of women test subjects exposed scientific assumptions, ideas about safety, and attitudes concerning gendered and menstruating bodies. Focusing on the practical work of tampon testing, Vostral examines the impact of broad cultural conditions: prevailing ideas about women’s bodies, gender differences, and the role of science and medicine in optimizing well-being. Finally, she shows how patterns of social power and privilege configured this research, with evidence taking different forms over time.
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Saber, Mohamed, Sameh A. Kantoush, Tetsuya Sumi, Yusuke Ogiso, Tahani Alharrasi, Takahiro Koshiba, Mohammed Abdel-Fattah et al. « Integrated Study of Flash Floods in Wadi Basins Considering Sedimentation and Climate Change : An International Collaboration Project ». Dans Natural Disaster Science and Mitigation Engineering : DPRI reports, 401–22. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2904-4_15.
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AbstractRecently, Wadi flash floods (WFFs) have happened frequently in arid environments, resulting in great damage the society and the environment. In Oman, severe WFFs have occurred repeatedly within the last 10 years causing a huge impact on human lives and properties. This paper aims at introducing the framework of an international collaboration project between Japan and Oman for WFF management considering sediment dynamics and climate changes. Four research groups were established: climate change (G1), rainfall-runoff modeling (G2), sediment yield and transport (G3), and sedimentation and infiltration processes (G4). Several field investigations were conducted since 2017 until now. The detailed field survey to assess the deposited sediment in a dry reservoir by using sediment bars, and infiltration test, as well as drone survey were addressed. Some of the preliminary results and findings from the field investigation is discussed. The results show there is an adverse impact of sedimentation clogging on the infiltration process at the reservoirs. Based on the historical rainfall data analysis, there is a systematic increasing trend of the annual average precipitation with remarkable cycles over the MENA region and Oman. The knowledge obtained from this project is expected to be valuable to understanding sediment dynamics at Wadi basins.
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Al Jahdhami, Abdel Rahman Mohammed, Serge Gabarre et Cécile Gabarre. « Gamifying the English Language Classroom to Motivate Omani Teenagers ». Dans Practical Perspectives on Educational Theory and Game Development, 54–83. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-5021-2.ch003.
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Students in Oman have negative attitudes towards learning English. An action research where a gamification implementation including various elements such as a leaderboard, badges, and a progress bar was conducted. Three instruments were used to investigate how gamification could increase the learners' motivation: motivation tests, interview protocols, and complete participant observations. The motivation tests were analyzed using Wilcoxon signed-rank test. The interview and observation data were analyzed using a thematic coding qualitative method. Results revealed that over the two cycles of implementation of the gamified approach to learning English, 92% of students demonstrated an increase in their motivation to learn English. The interviews revealed the specific aspects of the gamified approach that contributed to this increase. Extrinsic motivation was replaced by intrinsic motivation. This leads to implications for a future study where the gamified approach to teaching could be trialed across different classes and subjects in the same school.
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Clark, Duncan, et Mark Wilks. « Molecular Diagnostics ». Dans Tutorial Topics in Infection for the Combined Infection Training Programme. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198801740.003.0018.
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Molecular diagnostics in infection generally relate to the detection and/ or characterization of nucleic acid sequences of infectious agents in clinical samples which are used to provide: ● A laboratory diagnosis. ● A means of monitoring patients at risk of developing disease caused by a particular infection. ● A method to predict through genotypic analysis the susceptibility or resistance to appropriate treatments. ● A measurement of the response to therapy. A few key laboratory techniques underpin the majority of molecular diagnostic tests that are currently used in the field of infection, and include: ● Block-based polymerase chain reaction (PCR). ● Real-time PCR, including quantification. ● Strand displacement amplification. ● Transcription mediated amplification. ● DNA sequencing. These can be commercially sourced, which has the advantage of CE marking, or developed in-house, sometimes referred to as laboratory developed tests (LDTs). Whatever the source, the underlying principles are often the same and rigorous evaluation and validation is required for the adoption of any molecular test in the diagnostic laboratory. The majority of molecular diagnostic tests require the amplification of a specific DNA sequence and its subsequent detection by a variety of means. As such, small sequences of DNA from the infectious agent are amplified from a relatively low copy number in the clinical sample. For example, after thirty to forty cycles of PCR, a single copy of a sequence can theoretically be amplified to over a billion copies. This PCR product, commonly termed amplicon, can provide a template for any further testing with the same PCR test and therefore potentially act as a source for false positive results. Molecular diagnostic laboratories have requirements to keep the different stages of the molecular test separate and minimize the risk of amplicon contamination. Most facilities will have a ‘clean PCR laboratory’ that is used to store the clean reagents such as primers, probes, enzyme mastermixes, and no clinical samples, nucleic extracts, or amplification reactions are ever taken into this environment. Another laboratory is used for the nucleic acid extraction of the clinical samples and this environment is often used to set up the PCR reactions.
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Subraya, B. M. « Test Preparation Phase I ». Dans Integrated Approach to Web Performance Testing, 77–101. IGI Global, 2006. http://dx.doi.org/10.4018/978-1-59140-785-0.ch004.
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The core theme of the previous chapters is that a methodical and structured approach to PT is rather necessary right from the early phases of the development cycle. This will ensure predictability and controllability of application performance in practice. The preparatory activities associated with PT (Figure 4.1) are of great importance and are distributed over the life cycle phases of requirement elicitation and analysis, High Level Design (HLD), Detail Level Design (DLD), and several sets of system builds. These activities help define and provide continuity between the high level requirements for application performance, strategies for testing, a framework for designing the tests (see Barber, 2004), and artifacts used to plan and carry out tests. This chapter contains a detailed consideration of the definition phase while Chapters 5 and 6 highlight issues related to the design and build phases associated with the preparatory activities as shown in Figure 4.1.
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Kaplesh, Pooja, et Severin K. Y. Pang. « Software Testing ». Dans Software Engineering for Agile Application Development, 189–211. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-2531-9.ch008.
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Testing software is a process of program execution with the intent to find errors. For this purpose, various testing techniques have been used over time. Testing software is an intensive field of research in which much development work has been done. This field will become increasingly important in the future. There are many techniques for software testing. This chapter gives an overview of the entire range of software testing with suggestions for their implementation. One focus is on testing in an agile development process why the different types of software tests are important, and their cycle and methodology are described. In addition, different levels, types, and a comparative study on different types of tests are presented. The chapter also includes suggestions for performing the various tests and an effective approach to testing a software system.
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Horvath, Joachim, Karina Meyer et Alex Wiegmann. « Intuitive Expertise and Irrelevant Options ». Dans Oxford Studies in Experimental Philosophy Volume 3, 275–310. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198852407.003.0012.
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In the ‘push-dilemma,’ a train is about to run over several people and can only be stopped by pushing a heavy person onto the tracks. Most lay people and moral philosophers consider the ‘push-option,’ i.e., pushing the heavy person, as morally wrong. Peter Unger (1992, 1996) suggested that adding irrelevant options to the push-dilemma would overturn this intuition. This chapter tests Unger’s claim in an experiment with both lay people and expert moral philosophers. This allowed an investigation of the ‘expertise defense,’ which various philosophers have suggested as an answer to ‘experimental restrictionists,’ who argue that experimental philosophy undermines the trustworthiness of intuitions about hypothetical cases. Overall, the chapter finds that adding irrelevant options increases the ratings for the push-option. Moreover, the intuitions of expert moral philosophers are no less susceptible to the presence of irrelevant options than lay people’s intuitions. The chapter discusses how these findings bear on the expertise defense.
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Wang, Sihao, Yuqing Liu, Jun He et Chuanxi Li. « Push-out test on shear behavior of joint structure between corrugated steel web and concrete lower slab ». Dans Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 374–80. CRC Press, 2018. http://dx.doi.org/10.1201/9781315189390-44.
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Ertürk, Emin, Derya Yılmaz et Işın Çetin. « Optimum Currency Area Theory and Business Cycle Convergence in EMU ». Dans Handbook of Research on Global Indicators of Economic and Political Convergence, 67–91. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-5225-0215-9.ch004.
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Which countries should be in Economic and Monetary Union (EMU)? This question has been debated frequently in the aftermath of the Sovereign Debt Crisis. But this has been asked in every stages of European integration. This discussion has rooted in the Optimum Currency Area (OCA) theory. The theory simply reveals that; if the countries have similar business cycles, one size fits all monetary policy would able to address the problems of member countries. Otherwise, no single monetary policy could be able to satisfy all members. In this respect, we test the business cycle convergence in EMU12 countries over time and we have also analyzed the effects of crisis on this convergence. We have found that business cycles converged over time in these countries. This convergence rises in the times of crisis as they slump together after the shock, but falls sharply in the aftermath of the crisis. This reflects the divergent recovery paths of the countries and put a pressure on single monetary policy especially after crisis.
Actes de conférences sur le sujet "Cyclic tests, push-over tests"
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Wappler, Andreas, Lukas Knittel, Andrzej Niemunis et Hans Henning Stutz. « On the Erasing of the Cyclic Preloading by Monotonic Deformations in Granular Soils ». Dans ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79696.
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Abstract For the design and construction of Offshore Wind Energy Turbines (OWT), it is essential to predict deformations in the subsoil. Wind and waves cause a high-cycle loading on these structures. To ensure their servicability, reliable soil models for predicitions of cumulative displacement over the expected OWT lifetime are needed. In this work, the explicit constitutive High-Cycle Accumulation Model (HCA-Model) by Niemunis et al. [1] has been modified to account for the influence of large monotonic strains on the rate of subsequent cyclic accumulation. In this research project, 21 drained cyclic triaxial tests on saturated, cylindrical Karlsruhe fine sand samples were performed. The packages of cycles were applied on the specimens one after another. Between the packages, the average stress state was monotonically changed. To examine the reduction of the so called cyclic preloading, the tests were analysed regarding the accumulated strain throughout the packages of cycles in each test and the monotonic strain resulting from the change of the average stress state between the packages. In addition, finite-element calculations on an exemplary shallow foundation of an OWT were performed. Two packages of cycles with modification of the cyclic preloading were studied. The reduction of the cyclic preloading was evident.
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Xu, C., B. Y. Zhang et Z. H. Hou. « The Fatigue Performance of High Performance Concrete Composite Girder ». Dans IABSE Congress, New York, New York 2019 : The Evolving Metropolis. Zurich, Switzerland : International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.0062.
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<p>The application of high performance concrete has been increasingly concerned in the negative flexural region of steel‐concrete continuous composite girder because of its favorable tensile performance. However, the unclear cyclic and ultimate performance of a high performance concrete composite girder results to the problems which hinder the further application. In this case, a series of fatigue negative bending tests on HPC composite girders and fatigue push‐out tests on stud connectors in HPC were executed. The test results showed that the fatigue slip in the HPC composite girder was smaller than the normal concrete composite girder, and the fatigue life of stud in HPC was longer than the one in normal concrete. Meanwhile, according to the comparison between the stud fatigue live evaluations and test results, the AASHTO‐based evaluations were comparatively with larger safety redundancy, and JSCE was close to the test results but had smaller safety redundancy.</p>
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Dooris, Andrew, Leigh Potter et Paul Ares. « Determining Edge of Failure of a Spinal Wear Bearing ». Dans ASME 2011 6th Frontiers in Biomedical Devices Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/biomed2011-66001.
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Mechanical test samples are often characterized using time-varying loads, either through slow monotonic changes in quasi-static testing, or through more rapid cyclic changes in dynamic testing. Spinal implant static and fatigue strengths are typically evaluated using such protocols, including such as standards ASTM F1717, ASTM F2077, and ASTM F2346. In contrast, wear tests such as ASTM F2423 and ASTM F2624 and ISO 18192-1, apply a single set of loading parameters over millions of cycles. These parameters are selected based on known, but limited, physiologic data. Wear tests however may be very sensitive to input parameters. Moreover, variations in surgical technique, patient anatomy, and pathology greatly alter the loading environment on the device. Wear tests ideally would evaluate the device under both the expected duty cycle as well as under varying test parameters.
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Zhang, Shutong, Sebastian Romo, Rafael Arthur Giorjao, Jorge Penso, Haixia Guo, Simon Yuen, Lisa Ely et Antonio J. Ramirez. « Comparison of Ni-Steel Dissimilar Joints for Coke Drum External Weld Repairs Based on Isothermal Low-Cycle Fatigue Tests ». Dans ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-62939.
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Abstract Low-cycle fatigue failure has been widely accepted as the key mechanism causing damages of coke drums during cyclic thermal-mechanical loadings. Common damages of coke drums known as bulging and cracking are associated with accumulative plasticity caused by thermal and mechanical strains. External repairs using temper-bead welding techniques are implemented to repair welds in the damaged areas of coke drums, which provide structural support to the vessels. Compared with matching filler metals, Ni-base fillers including alloy 625 and alloy 182 are compatible with both low-alloy steel base metal and internal clads in terms of weldability and thermal expansion. However, the differences of yield strengths and cyclic hardening behaviors of nickel-base alloys from base metals compromise the fatigue resistances of weld joints. In this study, alloy 182 and alloy 625 repair coupons were evaluated and compared based on isothermal low-cycle fatigue tests. Low-cycle fatigue behaviors of both weld metals and 1.25Cr-0.5Mo base metal were measured at 1.0%, 1.5% and 2.0% strain amplitudes. Test results indicate both nickel-base filler metals exhibit overmatching strength over the base metal due to cyclic hardening. Low-cycle fatigue tests of Heat Affected zone (HAZ) samples show the failures of alloy 625 weld joints occur in the base metal, while the failures of alloy 182 weld joints occur along the fusion boundary. The observations show strength mismatch and fatigue resistance are the key factors to determine failure locations of the joints. In addition, cyclic hardening coefficients based on kinematic hardening model were extracted from experimental data to simulate the cyclic behaviors of the weld joints. Finite element simulation results were shown to be consistent with experimental data at stabilized cycles. Cyclic behaviors of weld metal and base metal within a weld transition sample were calculated based on the numerical model.
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Watakabe, Tomoyoshi, Kazuyuki Tsukimori, Akihito Otani, Makoto Moriizumi et Naoaki Kaneko. « Study on Strength of Thin-Walled Tee Pipe for Fast Breeder Reactors Under Seismic Loading ». Dans ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28619.
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In recent years, earthquakes over design condition were observed in Japan. Confirming the ultimate strength and design safety margin of mechanical components is important for the seismic integrity. This study focused on piping components, and it was one of the most important mechanical components for protecting boundary of coolant. Failure tests of thick-walled piping components for Light Water Reactors (LWRs) described previously in the literature. According to these tests, the failure mode of thick-walled piping components under seismic cyclic loading was low cycle fatigue. However, failure tests have scarcely been performed on thin-walled piping components pressurized at low levels for Fast Breeder Reactors (FBRs). This paper presents dynamic failure tests of thin-walled piping components in FBRs. Based on the test results, the failure mode, the ultimate strength, and the elastic-plastic behavior are discussed.
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Takahashi, Koji, Kazuya Matsuo, Kotoji Ando et Yoshio Urabe. « Estimation of Low-Cycle Fatigue Life of Elbow Pipes Considering the Multi-Axial Stress Effect ». Dans ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78678.
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Elbow pipes are commonly used in the piping systems of power plants and chemical plants. The stress states at the elbow part are complex and quite different from those of the straight pipes. It is well known that the fatigue lives of metals under simple push-pull conditions can be successfully predicted by Manson’s universal slope method. However, the low-cycle fatigue lives of elbow pipes under combined cyclic bending and inner pressure cannot be predicted by this method, though the reasons for this have not been clarified. In this work, the low-cycle fatigue tests and finite element analysis of elbows under cyclic bending and inner pressures were carried out. The results showed that the multi-axial stress factor, which is a ratio of hoop stress and axial stress, at elbows is quite high. Considering the multi-axial stress factor, a revised Manson’s universal slope method is proposed in this paper. Using the proposed method, we were able to predict conservatively the low-cycle fatigue lives of elbows under combined cyclic bending and inner pressure.
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Yamamoto, Ikuo, Toshiyuki Kosaka, Hirofumi Nakatsuka, Peter Halswell, Lars Johanning et Sam Weller. « Development of Strong Mooring Rope With Embedded Electric Cable ». Dans ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19319.
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Abstract Synthetic fibre ropes are in widespread use in maritime applications ranging from lifting to temporary and permanent mooring systems for vessels, fish farm, offshore equipment and platforms. The selection of synthetic ropes over conventional steel components is motivated by several key advantages including selectable axial stiffness, energy absorption and hence load mitigation, fatigue resistance and low unit cost. The long-term use of ropes as safety critical components in potentially high dynamic loading environments necessitates that new designs are verified using stringent qualification procedures. The International Organization for Standardization (ISO) is one certification body that has produced several guidelines for the testing of synthetic ropes encompassing quasi-static and dynamic loading as well as fatigue cycling. The paper presents the results of tension-tension tests carried out to ISO 2307:2010, ISO 18692:2007(E) and ISO/TS 19336:2015(E) on 12-strand rope with embedded electric cable constructions manufactured by Ashimori Industry Co. Ltd from Vectran fibres. The purpose of the tests was to characterise the performance of a novel strand construction (SSR) and compare this to a conventional 12-strand construction. Utilising the Dynamic Marine Component test facility (DMaC) at the University of Exeter several key performance metrics were determined including; elongation, minimum break load (MBL), quasi-static, dynamic stiffness and embedded cable resistance. During the ISO 2307:2010(E) test programme the samples were tested dry and during the ISO 18692:2007(E) and ISO/TS 19336:2015(E) test programmes the samples were fully submerged in tap water after being soaked in water for at least 24 hours. Two methods were used to quantify sample extension: i) an optical tracking system and ii) a potentiometer. Axial compression fatigue and cyclic loading endurance tests were also carried out on Vectran sample. Failure of the Vectran sample or embedded cable did not occur during tests carried out using DMaC. Further tests and sample analysis were also carried out by Ashimori Industry Co. Ltd. Quasi-static bedding-in at 50% MBS and cyclic load endurance test with 6000 cycles between 3.57% MBS and 53.6% MBS was completed. The Effective Working Length (EWL) was 3.821 m before testing and 3.974m after testing. The resistance of the cable increased from 9.6962 Ω to 9.7693Ω during the test and importantly the embedded cable did not fail. Each tensile loading cycle of the rope caused a measurable variation in wire resistance; approximately 0.01Ω. The data obtained during these tests will provide insight into the behaviour of these materials, which will be of use to rope manufacturers and mooring system designers, in addition to offshore equipment and vessel operators.
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Alderlieste, Etienne A., Jelke Dijkstra et A. Frits van Tol. « Experimental Investigation Into Pile Diameter Effects of Laterally Loaded Mono-Piles ». Dans ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50068.
Texte intégralRésumé :
This paper presents the results of model tests on laterally loaded mono-pile foundations in sand. The tests have been performed in a geotechnical centrifuge. The objective of the research is to quantify large diameter effects of these mono-piles on the lateral capacity and the stiffness response for cyclic lateral loading. These large diameters are out of the validity range of the commonly used design methods. For this reason prototype pile diameters up to 4.4 m with a length over diameter ratio of 5 have been investigated. The results show an increase in pile diameter from Ds = 2.2 m to Dl = 4.4 m leads to a significant increase in static lateral capacity and stiffness from cyclic load tests. All tests have been performed with constant L/D = 5, Id = 60% and a load eccentricity up to e = 4.8 m. However, the current test series needs to be extended to higher initial densities and the load control should be more strictly regulated before a clear diameter dependence, for pile diameters > 2.2 m, is proven.
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Vikse, Normann, Ove T. Gudmestad, Per R. Nystro̸m et Pavel Liferov. « Small Scale Model Tests on Subgouge Soil Deformations ». Dans ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29249.
Texte intégralRésumé :
There are several challenges related to Arctic offshore oil and gas field developments. Among these is the design of pipelines transporting hydrocarbons in the field or to shore. Special considerations must be carried out to take into account the Arctic conditions. One of the most critical concerns for pipelines in shallow waters is the possible damage due to ice ridge gouging. The ice ridge keels can in some areas of the Arctic be as deep as up to 30 meters, ref. Gudmestad et al., (1999), and may damage the pipeline even if that is trenched below the mudline. Laboratory small scale tests executed to establish qualitative figures of the soil and buried pipe behavior below the gouge are reported in this paper. The tests were conducted at 1g and aimed to visualize the effects of gouging on the soil below and the buried pipe segment. A box (115 × 50 × 40 cm) filled with different types of soils (sand and silty sand) was used for the tests. The model ice keel was made of a steel plate hanging from a wooden frame and mounted on top of the box such that only horizontal translation was allowed. For several of the tests, pipe segments were embedded into the soil. The performed tests indicated the presence of subgouge soil deformations and their dependence of several gouge-related parameters. It was observed that the pipes experienced cyclic movements, being first dragged forward-downwards as the model keel approached the pipeline and then re-bounding when the keel passed over. The tests showed that the maximum pipe displacement decreases exponentially with the pipe burial depth. Naturally formed soil mound in front of the keel during gouging showed to influence vertical pipeline displacement. Furthermore, horizontal pipe movements were larger at lower attack angles of the ice keel. The authors are by no means the first to ponder the subject of subgouge soil deformations and pipeline response. Many researchers have reported their studies before; see e.g. Woodworth-Lynas et al. (1996), Nixon et al. (1996), Yang and Poorooshasb (1997), Phillips et al. (2005) and Konuk et al. (2006). The authors are also fully aware of the challenges related to scaled testing of the soil-structure and do not assume the obtained results to be scaled up. Nevertheless, the reader may find some observations to be of interest while evaluating the present (disputed) approach to the problem.
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Zhang, Qian, Abhijit Dasgupta et Peter Haswell. « Viscoplastic Constitutive Properties and Reliability of Lead-Free Sn3.9Ag0.6Cu Solder ». Dans ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41840.
Texte intégralRésumé :
The viscoplastic constitutive properties of Sn3.9Ag0.6Cu lead-free alloy are presented and compared with baseline data from eutectic Sn63Pb37 solder. Steady-state creep models are obtained from creep and monotonic tests at three different temperatures for both solders. Based on steady-state creep results and creep test data, a transient creep model is developed for both Pb-free and Sb37Pb solders. One-dimensional incremental model of the test setup is developed to simulate constant-load creep, monotonic, and isothermal cyclic mechanical tests performed over various temperatures, strain rates and stresses using a thermo-mechanical-microstructural (TMM) test system, developed by the authors. By fitting simulation results to monotonic testing data, plastic models are also achieved. The devoloped viscoplastic constitutive models are evaluated in a two-dimensional nonlinear Finite element analysis of a PBGA352 package under a −55°C∼125°C thermal cycling environment. The viscoplastic behavior of Pb-free solder is compared with that of eutectic Sn37Pb solder.
Rapports d'organisations sur le sujet "Cyclic tests, push-over tests"
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Briggs, Nicholas E., Robert Bailey Bond et Jerome F. Hajjar. Cyclic Behavior of Steel Headed Stud Anchors in Concrete-filled Steel Deck Diaphragms through Push-out Tests. Northeastern University. Department of Civil and Environmental Engineering., février 2023. http://dx.doi.org/10.17760/d20476962.
Texte intégralRésumé :
Earthquake disasters in the United States account for $6.1 billion of economic losses each year, much of which is directly linked to infrastructure damage. These natural disasters are unpredictable and represent one of the most difficult design problems in regard to constructing resilient infrastructure. Structural floor and roof diaphragms act as the horizontal portion of the lateral force resisting system (LFRS), distributing the seismically derived inertial loads out from the heavy concrete slabs to the vertical LFRS. Composite concrete-filled steel deck floor and roof diaphragms are ubiquitously used in commercial construction worldwide due to the ease of construction and cost-effective use of structural material. This report presents a series of composite steel deck diaphragm Push-out tests at full scale that explore the effect that cyclic loading has on the strength of steel headed stud anchors. The effect that cyclic loading has on structural performance is explored across the variation of material and geometric parameters in the Push-out specimens, such as concrete density, steel headed stud anchor placement and grouping, steel deck orientation, and edge conditions. As compared to prior tests in the literature, the push-out tests conducted in this work have an extended specimen length that includes four rows of studs along the length rather than the typical two rows of studs, and an ability to impose cyclic loading. This provides novel insight into force flows in the specimens, failure mechanisms, and load distribution between studs and stud groups.
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Wang, Wei, Michael Brown, Matteo Ciantia et Yaseen Sharif. DEM simulation of cyclic tests on an offshore screw pile for floating wind. University of Dundee, décembre 2021. http://dx.doi.org/10.20933/100001231.
Texte intégralRésumé :
Screw piles need to be upscaled for offshore use e.g. being an alternative foundation and anchor form for offshore floating wind turbines, although the high demand of vertical installation forces could prevent its application if conventional pitch-matched installation is used. Recent studies, using numerical and centrifuge physical tests, indicated that the vertical installation force can be reduced by adopting over-flighting which also improved axial uplift capacity of the screw pile. The current study extends the scope to axial cyclic performance with respect to the installation approach. Using quasi-static discrete element method (DEM) simulation it was found that the over-flighted screw pile showed a lower displacement accumulation rate, compared to a pitch-matched installed pile, in terms of load-controlled cyclic tests. Sensitivity analysis of the setup of the cyclic loading servo shows the maximum velocity during the tests should be limited to avoid significant exaggeration of the pile displacement accumulation but this may lead to very high run durations.
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Kinikles, Dellena, et John McCartney. Hyperbolic Hydro-mechanical Model for Seismic Compression Prediction of Unsaturated Soils in the Funicular Regime. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, décembre 2022. http://dx.doi.org/10.55461/yunw7668.
Texte intégralRésumé :
A semi-empirical elasto-plastic constitutive model with a hyperbolic stress-strain curve was developed with the goal of predicting the seismic compression of unsaturated sands in the funicular regime of the soil-water retention curve (SWRC) during undrained cyclic shearing. Using a flow rule derived from energy considerations, the evolution in plastic volumetric strain (seismic compression) was predicted from the plastic shear strains of the hysteretic hyperbolic stress-strain curve. The plastic volumetric strains are used to predict the changes in degree of saturation from phase relationships and changes in pore air pressure from Boyle’s and Henry’s laws. The degree of saturation was used to estimate changes in matric suction from the transient scanning paths of the SWRC. Changes in small-strain shear modulus estimated from changes in mean effective stress computed from the constant total stress and changes in pore air pressure, degree of saturation and matric suction, in turn affect the hyperbolic stress-strain curve’s shape and the evolution in plastic volumetric strain. The model was calibrated using experimental shear stress-strain backbone curves from drained cyclic simple shear tests and transient SWRC scanning path measurements from undrained cyclic simple shear tests. Then the model predictions were validated using experimental data from undrained cyclic simple shear tests on unsaturated sand specimens with different initial degrees of saturation in the funicular regime. While the model captured the coupled evolution in hydro-mechanical variables (pore air pressure, pore water pressure, matric suction, degree of saturation, volumetric strain, effective stress, shear modulus) well over the first 15 cycles of shearing, the predictions were less accurate after continued cyclic shearing up to 200 cycles. After large numbers of cycles of undrained shearing, a linear decreasing trend between seismic compression and initial degree of saturation was predicted from the model while a nonlinear increasing-decreasing trend was observed in the cyclic simple shear experiments. This discrepancy may be due to not considering post shearing reconsolidation in the model, calibration of model parameters, or experimental issues including a drift in the position of the hysteretic shear-stress strain curve. Nonetheless, the trend from the model is consistent with predictions from previously- developed empirical models in the funicular regime of the SWRC. The developments of the new mechanistic model developed in this study will play a key role in the future development of a holistic model for predicting the seismic compression across all regimes of the SWRC.
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Schiller, Brandon, Tara Hutchinson et Kelly Cobeen. Cripple Wall Small-Component Test Program : Wet Specimens II (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembre 2020. http://dx.doi.org/10.55461/ldbn4070.
Texte intégralRésumé :
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 4 (WG4): Testing, whose central focus was to experimentally investigate the seismic performance of retrofitted and existing cripple walls. This report focuses stucco or “wet” exterior finishes. Paralleled by a large-component test program conducted at the University of California, Berkeley (UC Berkeley) [Cobeen et al. 2020], the present study involves two of multiple phases of small-component tests conducted at the University of California San Diego (UC San Diego). Details representative of era-specific construction, specifically the most vulnerable pre-1960s construction, are of predominant focus in the present effort. Parameters examined are cripple wall height, finish style, gravity load, boundary conditions, anchorage, and deterioration. This report addresses the third phase of testing, which consisted of eight specimens, as well as half of the fourth phase of testing, which consisted of six specimens where three will be discussed. Although conducted in different phases, their results are combined here to co-locate observations regarding the behavior of the second phase the wet (stucco) finished specimens. The results of first phase of wet specimen tests were presented in Schiller et al. [2020(a)]. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto ten cripple walls of 12 ft long and 2 or 6 ft high. One cripple wall was tested with a monotonic loading protocol. All specimens in this report were constructed with the same boundary conditions on the top and corners of the walls as well as being tested with the same vertical load. Parameters addressed in this report include: wet exterior finishes (stucco over framing, stucco over horizontal lumber sheathing, and stucco over diagonal lumber sheathing), cripple wall height, loading protocol, anchorage condition, boundary condition at the bottom of the walls, and the retrofitted condition. Details of the test specimens, testing protocol, including instrumentation; and measured as well as physical observations are summarized in this report. Companion reports present phases of the tests considering, amongst other variables, impacts of various boundary conditions, stucco (wet) and non-stucco (dry) finishes, vertical load, cripple wall height, and anchorage condition. Results from these experiments are intended to support advancement of numerical modeling tools, which ultimately will inform seismic loss models capable of quantifying the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100,Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Wei, Fulu, Ce Wang, Xiangxi Tian, Shuo Li et Jie Shan. Investigation of Durability and Performance of High Friction Surface Treatment. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317281.
Texte intégralRésumé :
The Indiana Department of Transportation (INDOT) completed a total of 25 high friction surface treatment (HFST) projects across the state in 2018. This research study attempted to investigate the durability and performance of HFST in terms of its HFST-pavement system integrity and surface friction performance. Laboratory tests were conducted to determine the physical and mechanical properties of epoxy-bauxite mortar. Field inspections were carried out to identify site conditions and common early HFST distresses. Cyclic loading test and finite element method (FEM) analysis were performed to evaluate the bonding strength between HFST and existing pavement, in particular chip seal with different pretreatments such as vacuum sweeping, shotblasting, and scarification milling. Both surface friction and texture tests were undertaken periodically (generally once every 6 months) to evaluate the surface friction performance of HFST. Crash records over a 5-year period, i.e., 3 years before installation and 2 years after installation, were examined to determine the safety performance of HFST, crash modification factor (CMF) in particular. It was found that HFST epoxy-bauxite mortar has a coefficient of thermal expansion (CTE) significantly higher than those of hot mix asphalt (HMA) mixtures and Portland cement concrete (PCC), and good cracking resistance. The most common early HFST distresses in Indiana are reflective cracking, surface wrinkling, aggregate loss, and delamination. Vacuum sweeping is the optimal method for pretreating existing pavements, chip seal in particular. Chip seal in good condition is structurally capable of providing a sound base for HFST. On two-lane highway curves, HFST is capable of reducing the total vehicle crash by 30%, injury crash by 50%, and wet weather crash by 44%, and providing a CMF of 0.584 in Indiana. Great variability may arise in the results of friction tests on horizontal curves by the use of locked wheel skid tester (LWST) due both to the nature of vehicle dynamics and to the operation of test vehicle. Texture testing, however, is capable of providing continuous texture measurements that can be used to calculate a texture height parameter, i.e., mean profile depth (MPD), not only for evaluating friction performance but also implementing quality control (QC) and quality assurance (QA) plans for HFST.
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Schiller, Brandon, Tara Hutchinson et Kelly Cobeen. Cripple Wall Small-Component - Test Program : Comparisons (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembre 2020. http://dx.doi.org/10.55461/lohh5109.
Texte intégralRésumé :
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 4 (WG4): Testing, whose central focus was to experimentally investigate the seismic performance of retrofit and existing cripple walls. Amongst the body of reports from WG4, in the present report, a suite of four small cripple wall test phases, in total 28 specimens, are cross compared with varied exterior finishes, namely stucco (wet) and non-stucco (dry) exterior finishes. Details representative of era specific construction, specifically the most vulnerable pre-1960s construction are of predominant focus in the present effort. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto cripple walls of 12 ft in length and 2 ft or 6 ft in height. All specimens in this report were constructed with the same boundary conditions and tested with the same vertical load. Parameters addressed in this report include: wet exterior finishes (stucco over framing, stucco over horizontal lumber sheathing, and stucco over diagonal lumber sheathing); and dry exterior finishes (horizontal siding, horizontal siding over diagonal sheathing, and T1-11 wood structural panels) with attention towards cripple wall height and the retrofit condition. The present report provides only a brief overview of the test program and setup; whereas a series of three prior reports present results of test groupings nominally by exterior finish type (wet versus dry). As such, herein the focus is to cross compare key measurements and observations of the in-plane seismic behavior of all 28 specimens.
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Schiller, Brandon, Tara Hutchinson et Kelly Cobeen. Cripple Wall Small-Component Test Program : Wet Specimens I (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembre 2020. http://dx.doi.org/10.55461/dqhf2112.
Texte intégralRésumé :
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 4: Testing and focuses on the first phase of an experimental investigation to study the seismic performance of retrofitted and existing cripple walls with sill anchorage. Paralleled by a large-component test program conducted at the University of California [Cobeen et al. 2020], the present study involves the first of multiple phases of small-component tests conducted at the UC San Diego. Details representative of era-specific construction, specifically the most vulnerable pre-1960s construction, are of predominant focus in the present effort. Parameters examined are cripple wall height, finish materials, gravity load, boundary conditions, anchorage, and deterioration. This report addresses the first phase of testing, which consisted of six specimens. Phase 1 including quasi-static reversed cyclic lateral load testing of six 12-ft-long, 2-ft high cripple walls. All specimens in this phase were finished on their exterior with stucco over horizontal sheathing (referred to as a “wet” finish), a finish noted to be common of dwellings built in California before 1945. Parameters addressed in this first phase include: boundary conditions on the top, bottom, and corners of the walls, attachment of the sill to the foundation, and the retrofitted condition. Details of the test specimens, testing protocol, instrumentation; and measured as well as physical observations are summarized in this report. In addition, this report discusses the rationale and scope of subsequent small-component test phases. Companion reports present these test phases considering, amongst other variables, the impacts of dry finishes and cripple wall height (Phases 2–4). Results from these experiments are intended to provide an experimental basis to support numerical modeling used to develop loss models, which are intended to quantify the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100, Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Rathgeber, Christoph. Experimental devices to investigate degradation of PCM. IEA SHC Task 58, juin 2021. http://dx.doi.org/10.18777/ieashc-task58-2021-0001.
Texte intégralRésumé :
Deliverable 2 of Subtask 3P is a collection of questionnaires regarding experimental devices that are used by the experts of Task 58 / Annex 33 to investigate the degradation of Phase Change Materials (PCM). Three types of experiments are considered: Tests on degradation of PCM over thermal cycling (type I), tests on degradation of PCM with stable supercooling (type II), and tests on degradation of phase change slurries (type III).
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Schiller, Brandon, Tara Hutchinson et Kelly Cobeen. Cripple Wall Small-Component Test Program : Dry Specimens (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembre 2020. http://dx.doi.org/10.55461/vsjs5869.
Texte intégralRésumé :
This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measures and documents seismic performance of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Three primary tasks support the earthquake loss-modeling effort. They are: (1) the development of ground motions and loading protocols that accurately represent the diversity of seismic hazard in California; (2) the execution of a suite of quasi-static cyclic experiments to measure and document the performance of cripple wall and sill anchorage deficiencies to develop and populate loss models; and (3) nonlinear response history analysis on cripple wall-supported buildings and their components. This report is a product of Working Group 4: Testing, whose central focus was to experimentally investigate the seismic performance of retrofitted and existing cripple walls. This present report focuses on non-stucco or “dry” exterior finishes. Paralleled by a large-component test program conducted at the University of California, Berkeley (UC Berkeley) [Cobeen et al. 2020], the present report involves two of multiple phases of small-component tests conducted at University of California San Diego (UC San Diego). Details representative of era-specific construction–specifically the most vulnerable pre-1960s construction–are of predominant focus in the present effort. Parameters examined are cripple wall height, finish style, gravity load, boundary conditions, anchorage, and deterioration. This report addresses all eight specimens in the second phase of testing and three of the six specimens in the fourth phase of testing. Although conducted in different testing phases, their results are combined here to co-locate observations regarding the behavior of all dry finished specimens. Experiments involved imposition of combined vertical loading and quasi-static reversed cyclic lateral load onto eleven cripple walls. Each specimen was 12 ft in length and 2-ft or 6-ft in height. All specimens in this report were constructed with the same boundary conditions on the top, bottom, and corners of the walls. Parameters addressed in this report include: dry exterior finish type (shiplap horizontal lumber siding, shiplap horizontal lumber siding over diagonal lumber sheathing, and T1-11 wood structural panels), cripple wall height, vertical load, and the retrofitted condition. Details of the test specimens, testing protocol (including instrumentation), and measured as well as physical observations are summarized. Results from these experiments are intended to support advancement of numerical modeling tools, which ultimately will inform seismic loss models capable of quantifying the reduction of loss achieved by applying state-of-practice retrofit methods as identified in FEMA P-1100 Vulnerability-Base Seismic Assessment and Retrofit of One- and Two-Family Dwellings.
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Kramer, Robert. LED Street Lighting Implementation Research, Support, and Testing. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317274.
Texte intégralRésumé :
This report describes the results of technical analysis, field tests, and laboratory tests that were performed for LED highway lighting options by the Energy Efficiency and Reliability Center (EERC) at Purdue University Northwest for the Indiana Department of Transportation (INDOT). This effort was conducted over the past 3 years to evaluate and test the technology and viability of using modern highway lighting technology to enhance energy efficiency, safety, security, and economic development of communities and roadways. During the testing period there was a continuous discussion between INDOT and EERC regarding the laboratory and field testing of INDOT approved luminaires submitted by vendors. There were multiple discussions with INDOT and vendors regarding the individual details and issues for the 29 luminaires that were tested. A comparison study was conducted by EERC of the various alternatives and comparison to currently installed luminaires. Data was collected for field tests of the luminaires by EERC and INDOT personnel for the luminaires. Field data was evaluated and compared to lighting models using vendor supplied ies data files. Multiple presentations were made at 3 separate Purdue Road Schools regarding the results and procedures of the testing program by EERC in conjunction with INDOT. A total of 22 final reports, considered confidential by INDOT, for individual vendor luminaires have been prepared as part of this effort. These reports were submitted sequentially to INDOT as testing was completed during the course of this effort. A total of 29 luminaires were tested. Some luminaire testing was terminated during testing due to design issues or vendor requests. All testing was summarized in the INDOT specification sheet attached to each report. Observations regarding the consistency of the supplied test luminaire with the requirements of Section 7.2 of the INDOT test procedure “Procedure for evaluation and approval list requirements for solid state ballasted luminaires ITM 957-17P” is provided in the Appendix to the report for each luminaire. Details regarding how these tests were performed and the respective associated evaluation of performance and reliability are provided in the report. This effort included: consideration of published and vendor information; appraisal of products consistent with national industry standards; review of physical design, thermal performance; laboratory testing of photopic performance, reliability, life cycle data and characteristics, and power characteristics; technical and probabilistic risk studies; and field testing and analysis of LED light sources including comparison to currently installed conventional light sources. Assistance in preparing INDOT standards for highway lighting was provided on multiple occasions.