High Efficiency Particulate Air (HEPA) filters are defined as extended-medium, dry-type filters with: (1) a minimum particle removal efficiency of no less than 99.97 percent for 0.3 micrometer particles, (2) a maximum, clean resistance of 1.0 inch water column (in. WC) when operated at 1,000 cubic feet per minute (CFM), and (3) a rigid casing that extends the full depth of the medium. Specifically, ceramic media HEPA filters provide better performance at elevated temperatures, are moisture resistant and nonflammable, can perform their function if wetted and exposed to greater pressures, and can be cleaned and reused. This paper describes the modification and design of a large scale test stand which properly evaluates the filtration characteristics of a range of ceramic media filters challenged with a nuclear aerosol agent in order to develop Section FO of ASME AG-1.

To achieve thinner and longer floor slabs, rapid construction, and tight control of inservice deflections, modern concrete structures increasingly use high-strength, posttensioned prestressing steel as reinforcement. The resulting structures are called posttensioned (PT) concrete. Post-tensioned concrete slabs are widely believed to benefit from ‘inherent fire endurance.’ This belief is based largely on results from a series of standard fire tests performed on simply-supported specimens some five decades ago. Such tests are of debatable credibility; they do not capture the true structural behaviour of real buildings in real fires, nor do they reflect modern PT concrete construction materials or optimization methods. This thesis seeks to develop a more complete understanding of the structural and thermal response of modern prestressing steel and PT concrete slabs, particularly those with unbonded prestressing steel conditions, to high temperature, in an effort to steer current practice and future research towards the development of defensible, performance-based, safe fire designs. An exhaustive literature review of previous experimentation and real case studies of fire exposed PT concrete structures is presented to address whether current code guidance is adequate. Both bonded and unbonded prestressing steel configurations are considered, and research needs are identified. For unbonded prestressing steel in a localised fire, the review shows that the interaction between thermal relaxation and plastic deformation could result in tendon failure and loss of tensile reinforcement to the concrete, earlier than predicted by available design guidance. Since prestressing steel runs continuously in unbonded PT slabs, local damage to prestressing steel will affect the integrity of adjacent bays in a building. In the event that no bonded steel reinforcement is provided (as permitted by some design codes) a PT slab could lose tensile reinforcement across multiple bays; even those remote from fire. Using existing literature and design guidance, preliminary simplified modelling is presented to illustrate the stress-temperature-time interactions for stressed, unbonded prestressing steel under localised heating. This exercise showed that the observed behaviour cannot be rationally described by the existing design guidance. The high temperature mechanical properties of modern prestressing steel are subsequently considered in detail, both experimentally and analytically. Tests are presented on prestressing steel specimens under constant axial stress at high temperature using a high resolution digital image correlation (DIC) technique to accurately measure deformations. A novel, accurate analytical model of the stresstemperature- time dependent deformation of prestressing steel is developed and validated for both transient and steady-state conditions. Modern prestressing steel behaviour is then compared to its historical prestressing steel counterparts, showing significant differences at high temperature. Attention then turns to other structural actions of a real PT concrete structure (e.g. thermal bowing, restraint, concrete stiffness loss, continuity, spalling, slab splitting etc.) all of which also play inter-related roles influencing a PT slab’s response in fire. A series of three non-standard structural fire experiments on heavily instrumented, continuous, restrained PT concrete slabs under representative sustained service loads were conducted in an effort to better understand the response of PT concrete structures to localised heating. To the author’s knowledge this is the first time a continuous PT slab which includes axial, vertical and rotational restraint has been studied at high temperature, particularly under localised heating. The structural response of all three tests indicates a complex deflection trend in heating and in cooling which differs considerably from the response of a simply supported slab in a standard fire test. Deflection trends in the continuous slab tests were due to a combination of thermal expansion and plastic damage. The test data will enable future efforts to validate computational models which account for the requisite complexities. Overall, the research presented herein shows that some of the design guidance for modern PT concrete slabs is inadequate and should be updated. The high temperature deformation of prestressing steel under localised heating, as would be expected in a real fire, should be considered, since uniform heating of simplysupported elements is both unrealistic and unconservative with respect to tensile rupture of prestressing steel tendons. The most obvious impact of this finding would be to increase the minimum concrete covers required for unbonded PT construction, and to require adequate amounts of bonded steel reinforcement to allow load shedding to the bonded steel at high temperature in the event that the prestressing steel fails or is severely damaged by fire.

Lightweight cellular concrete (LCC) is an aerated or foamed concrete where 25-80% of the concrete matrix consists of air voids. The high volume of air voids reduces the strength but significantly decreases the weight of the material, which has made it an attractive alternative to soil for retaining structure backfills. Though the use of LCC has increased, little research has been performed on the large-scale behavior of retaining structures containing LCC as backfill. This research test attempts to fill knowledge gaps found with regard to the use of LCC in a mechanically stabilized earth (MSE) wall with a trapezoidal or sliver fill by examining the nature of LCC strength criteria from large-scale failure, failure mechanisms, and failure criteria. A large-scale test box (10 ft. wide x 12 ft. long x 10 ft. high), surrounded by a steel resisting frame, was constructed and filled with a silty sand backfill soil in a 1:1 stair-stepped slope and an LCC sliver fill. The west-facing wall was a two-paneled MSE wall with 16 ribbed steel strip reinforcements running through the LCC backfill. The LCC was poured over three days in equal height lifts to ensure stability. A total of 64 sample cylinder molds and four split mold shear boxes were filled with LCC during placement to help identify LCC material properties, which included density, unconfined compressive strength (UCS), and shear strength. A surcharge test was performed on the large-scale test box six days after initial placement of the LCC due to the unanticipated high strength gain and density found within the placed LCC. Instrumentation collected data on displacement, shear plane, lateral wall pressure, and reinforcement strain throughout testing. Initially, four hydraulic jacks were used during surcharge testing to induce a uniform surcharge load to fail the sliver-fill MSE wall. The strength limit of the steel resisting frame was reached before failure, at which point the number of hydraulic jacks was switched to three for a more critical loading condition. The test was again terminated before complete failure when the steel resisting frame strength limit was met. Though failure was not completed, the sliver-fill MSE wall failure had initiated before testing was terminated at a surcharge load of 70 psi. Results identify the initiation of shear failure within the LCC at about 65 psi, with maximum lateral and axial displacements of about 0.5 in. and 1.2 in., respectively. The shear failure occurs at about 52% of the average UCS of 123 psi. An arcuate shear plane, contrary to the traditional bilinear MSE wall failure surface with inextensible reinforcements, was identified within the LCC backfill, which initiated from the toe of the MSE wall and ended about 8 ft. back from the top of the MSE wall, using lateral displacements from Sondex tube profilometers in the backfill.

This article deals with the analysis and evaluation of the structural behavior of segmented tower constructions in large-scale experimental investigations. For this purpose, a tower model with dry horizontal joints on a scale of approximately 1:10 is constructed and loaded. The objective of these large-scale investigations is to determine the load-bearing behavior of concrete segment towers subjected to normal force (external prestressing), bending, shear force and torsion and to derive more efficient and realistic design models. The transfer of shear stresses between individual segments is ensured by frictional resistance in the horizontal joints due to prestressing. The current design models are based on plane flange surfaces at the top and bottom of the segments as well as their ideal circular ring shape. This assumes a constant normal stress distribution for the compression connection. Within the large-scale experimental tests, findings for uneven force distribution in the horizontal joints due to prestressing and shear bending were obtained, that have a significant impact on the design models. However, for the evaluation of the results and the projection onto the real construction components, the scale effects must be urgently taken into account.

Les géosynthétiques (GSY) sont des matériaux polymériques utilisés dans la construction d’ouvrages géotechniques et environnementaux, en remplacement et/ou en complément de matériaux naturels. Dans les installations de stockage de déchets non dangereux (ISDND), les GSY sont utilisés comme dispositif d’étanchéité et de drainage (barrière de sécurité) afin de prévenir les infiltrations de lixiviats vers la nappe phréatique.De nos jours, la rareté des sites adaptés à la construction de nouvelles ISDND conduit de nombreux opérateurs à opter pour la création de casiers de stockage en appui sur d’anciens casiers. Dans ces ouvrages en rehausse (extensions d’ISDND), une barrière de sécurité est généralement disposée entre les anciens casiers et les nouveaux casiers. Toutefois, dans cette configuration spécifique, les risques d’instabilité au glissement translationnel de l’ouvrage sont favorisés par la présence de plusieurs interfaces GSY représentant autant de surfaces de glissement préférentielles. Par ailleurs, ces risques sont accentués par le caractère compressible des déchets qui favorise l’apparition de tassements différentiels et/ou d’effondrements localisés (formation de cavités) sous la barrière de sécurité, susceptibles d’engendrer une perte d’intégrité (tensions / déformations excessives) de cette dernière. Dès lors, la compréhension des mécanismes associés à ces phénomènes de glissement translationnel et de déformation des GSY apparait capitale pour la réussite d’un tel projet.Dans ce contexte, les travaux objet du présent mémoire de thèse se sont attachés à mieux appréhender le comportement mécanique des systèmes GSY et de leurs interactions. Cette analyse a été effectuée sous l’angle de la stabilité au glissement translationnel (à l’échelle de l’ouvrage : grande échelle) et de l’intégrité structurelle des GSY au sein des barrières de sécurité sur cavité (petite échelle).Pour y parvenir, une analyse multi-approches associant étude analytique, modélisation numérique et étude expérimentale a été mise en oeuvre.Tout d’abord, le volet analytique a porté sur une analyse comparative de dix méthodes utilisées pour l’évaluation de la stabilité au glissement translationnel et de huit méthodes de dimensionnement des GSY de renforcement sur cavité. Ces études comparatives ont permis non seulement d’évaluer les écarts entre ces méthodes, mais aussi d’identifier celles qui se prêtent le mieux à une application en extension d’ISDND.Ensuite, une Méthode Rationnelle de Modélisation des systèmes Géosynthétiques (MeRaMoG) a été développée afin de prendre en compte fidèlement le comportement mécanique des GSY et de leurs interfaces (notamment la non-linéarité du comportement en traction des GSY). Grâce à la MeRaMoG qui a été validée expérimentalement, les mécanismes intervenant et contrôlant les phénomènes de glissement et de déformation des barrières de sécurité sur talus et sur cavité ont été investigués.Enfin, un Dispositif Expérimental grande-échelle pour l’étude de la Performance des GSY de renforcement sur Cavité (DEPGeC) a été développé. Le DEPGeC est un prototype permettant de simuler le comportement mécanique des GSY sur une cavité rectangulaire et sous une contrainte de confinement pouvant atteindre 100 kPa. L’utilisation du DEPGeC a permis d’évaluer l’influence de la contrainte de confinement, de la raideur du GSY de renforcement et d’un ancrage rigide sur les déformations des GSY. / Geosynthetics (GSYs) are polymeric materials that are used in engineering and environmental constructions to replace or in addition to natural materials. In landfills, GSYs are used as a lining system to prevent leachate infiltration into groundwater.Nowadays, the scarcity of suitable sites to establish new landfills leads more and more landfill owners to build new landfill cells over older ones. In such type of construction commonly called piggy-back landfill, a new GSY lining system is often implemented between old and new cells. However, in this specific configuration, the risk of translational instability of the construction is increased since the lining system involved several interfaces with low shear strength. Such instability is related to the failure of the various interfaces within the GSY lining system and hence to the sliding of GSY layers on each other. Moreover, the potential occurrence of differential settlements and / or localized collapses (cavity) which are related to the compressible nature of the waste within the old cell could tear (excessive tensile forces / strains) the GSY lining system under the overload of the new waste. Therefore, understanding the mechanisms controlling translational slip phenomena and deformation of GSYs is essential to ensure a proper design of such a project.In this context, this PhD thesis focused on better understanding of the mechanical behaviour of GSY systems and their interactions. The study was conducted using firstly a global analysis (large scale, all over the piggy-back landfill) of the lining system in terms of translational slips between the various GSYs. Secondly, this study investigated the integrity of the GSY lining system subjected to a cavity (small scale analysis).To achieve this goal, a multi-approaches investigation involving analytical study, numerical modelling and experimental study was performed.First, the analytical part focused on a comparative analysis based on ten methods used to assess the factor of safety of translational slip and on eight methods used for the design of GSY reinforcement over cavities. These comparative studies have not only assessed the differences between these methods, but also identified those best suited to be applied in the context of piggy-back landfills.Then, a rigorous method (MeRaMoG) that addressed the key aspects of the mechanical behaviour of GSYs and interfaces (e.g., the nonlinear axial stiffness of GSYs), was developed for the numerical modelling of multi-layered geosynthetic systems. Through MeRaMoG which was experimentally validated, the mechanisms controlling the translational slip and deformation of the geosynthetic lining system on side slopes and cavity were investigated.Finally, a new large-scale testing device (DEPGeC) was developed to assess the efficiency of a GSY reinforcement to bridge a cavity. The DEPGeC is a prototype that was used to simulate the mechanical behaviour of multi-layered GSY systems over a rectangular cavity and under a confining load of up to 100 kPa. Using the DEPGeC, the influence of the applied vertical load, the stiffness of the GSY reinforcement and a perfect anchorage on the deformations of GSY, was investigated.

[ES] Ante el desafío que implica la reducción de los efectos del cambio climático, la industria nuclear se ha postulado como una buena alternativa para sustituir la producción de energía eléctrica a partir de combustibles fósiles. No obstante, debe constatar la seguridad de las centrales, para lo que resulta indispensable poder predecir su comportamiento ante escenarios operacionales y accidentales. A tal efecto, y dada la imposibilidad de disponer de datos de planta para analizar estos transitorios, se generan bases de datos en instalaciones a escala reducida a partir de experimentos, siendo necesarios métodos y estrategias de escalado que permitan extrapolar los comportamientos termohidráulicos. Pese a la relevante contribución que suponen los experimentos al campo de la seguridad nuclear, en ocasiones se cuestiona la validez de sus resultados para reproducir el comportamiento de las centrales. Este hecho motiva la ejecución de test counterpart entre distintas instalaciones, que contribuyen a abordar la problemática del escalado, así como a demostrar la adecuación de los códigos termohidráulicos para predecir una respuesta realista de los sistemas. La presente tesis doctoral explora la posibilidad de aumentar el número de experimentos counterpart a partir de la definición de nuevos escenarios y su simulación con el código termohidráulico TRACE5. Con este fin, se han desarrollado modelos de las instalaciones ATLAS y LSTF, y se han estudiado y simulado experimentos counterpart ya existentes entre dichas instalaciones. La identificación de los fenómenos termohidráulicos más significativos, y el análisis de su escalado y distorsión, configuran la base de conocimientos para abordar el diseño de los nuevos test. En la tesis, en particular, se plantea un escenario tipo station blackout para LSTF partiendo de las condiciones iniciales y de contorno de un test previo en ATLAS. La simulación del experimento confirma la idoneidad de ATLAS y LSTF para realizar experimentos counterpart, en los que la fenomenología relevante es similar, y pone de manifiesto algunas limitaciones de estas instalaciones en cuanto a la extrapolabilidad de ciertos fenómenos, debido a las distorsiones originadas por la diferencia de escala y tecnología. / [CA] Davant del desafiament que implica la reducció dels efectes del canvi climàtic, la indústria nuclear s'ha postulat com una bona alternativa per a substituir la producció d'energia elèctrica a partir de combustibles fòssils. No obstant això, ha de constatar la seguretat de les centrals, per al que resulta indispensable poder predir el seu comportament davant d'escenaris operacionals i accidentals. A aquest efecte, i donada la impossibilitat de disposar de dades de planta per a analitzar aquests transitoris, es generen bases de dades en instal·lacions a escala reduïda a partir d'experiments, sent necessaris mètodes i estratègies d'escalat que permeten extrapolar els comportaments termohidràulics. Malgrat la rellevant contribució que suposen els experiments al camp de la seguretat nuclear, de vegades es qüestiona la validesa dels seus resultats per a reproduir el comportament de les centrals. Aquest fet motiva l'execució de test counterpart entre distintes instal·lacions, que contribuïxen a abordar la problemàtica de l'escalat, així com a demostrar l'adequació dels codis termohidràulics per a predir una resposta realista dels sistemes. La present tesi doctoral explora la possibilitat d'augmentar el nombre d'experiments counterpart a partir de la definició de nous escenaris i la seua simulació amb el codi termohidràulic TRACE5. Amb aquest fi, s'han desenvolupat models de les instal·lacions ATLAS i LSTF, i s'han estudiat i simulat experiments counterpart ja existents entre les dites instal·lacions. La identificació dels fenòmens termohidràulics més significatius, i l'anàlisi del seu escalat i distorsió, configuren la base de coneixements per a abordar el disseny dels nous test. En la tesi, en particular, es planteja un escenari tipus station blackout per a LSTF partint de les condicions inicials i de contorn d'un test previ en ATLAS. La simulació de l'experiment confirma la idoneïtat d'ATLAS i LSTF per a realitzar experiments counterpart, en els que la fenomenologia rellevant és semblant, i posa de manifest algunes limitacions d'aquestes instal·lacions quant a l'extrapolabilitat de certs fenòmens, a causa de les distorsions originades per la diferència d'escala i tecnologia. / [EN] Faced with the challenge of reducing the effects of climate change, the nuclear industry has been postulated as a good alternative to replace the production of electricity from fossil fuels. However, it must verify the safety of the plants, for which it is essential to be able to predict their behavior in operational and accidental scenarios. To this end, and given the impossibility of having plant data to analyze these transients, databases are generated in reduced-scale facilities from experiments, being necessary scaling methods and strategies that allow the extrapolation of thermohydraulic behaviors. Despite the relevant contribution that experiments make to the field of nuclear safety, the validity of their results to reproduce the behavior of plants is sometimes questioned. This fact motivates the execution of counterpart tests between different facilities, which contribute to addressing scaling issues, as well as to demonstrate the adequacy of the thermal-hydraulic codes to predict a realistic response of the systems. This Ph.D. Thesis explores the possibility of increasing the number of counterpart experiments based on the definition of new scenarios and their simulation with the TRACE5 thermal-hydraulic code. In order to achieve this goal, models of the ATLAS and LSTF facilities have been developed, and counterpart experiments already existing between these facilities have been studied and simulated. The identification of the most significant thermal-hydraulic phenomena and the analysis of their scaling and distortion, configure the knowledge basis to approach the design of the new tests. In the Thesis, in particular, a station blackout scenario for LSTF based on the initial and boundary conditions of a previous test in ATLAS is proposed. The simulation of the experiment confirms the suitability of ATLAS and LSTF to perform counterpart experiments, in which the relevant phenomenology is similar. Moreover, it reveals some limitations of these facilities in terms of the extrapolability of certain phenomena, due to the distortions caused by the difference in scale and technology. / Lorduy Alós, M. (2022). Análisis termohidráulico de la instalación ATLAS. Aplicaciones de la metodología de escalado [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181700

Fires following earthquake (FFE) have historically produced enormous post-earthquake damage and losses in terms of lives, buildings and economic costs, like the San Francisco earthquake (1906), the Kobe earthquake (1995), the Turkey earthquake (2011), the Tohoku earthquake (2011) and the Christchurch earthquakes (2011). The structural fire performance can worsen significantly because the fire acts on a structure damaged by the seismic event. On these premises, the purpose of this work is the investigation of the experimental and numerical response of structural and non-structural components of steel structures subjected to fire following earthquake (FFE) to increase the knowledge and provide a robust framework for hybrid fire testing and hybrid fire following earthquake testing. A partitioned algorithm to test a real case study with substructuring techniques was developed. The framework is developed in MATLAB and it is also based on the implementation of nonlinear finite elements to model the effects of earthquake forces and post-earthquake effects such as fire and thermal loads on structures. These elements should be able to capture geometrical and mechanical non-linearities to deal with large displacements. Two numerical validation procedures of the partitioned algorithm simulating two virtual hybrid fire testing and one virtual hybrid seismic testing were carried out. Two sets of experimental tests in two different laboratories were performed to provide valuable data for the calibration and comparison of numerical finite element case studies reproducing the conditions used in the tests. Another goal of this thesis is to develop a fire following earthquake numerical framework based on a modified version of the OpenSees software and several scripts developed in MATLAB to perform probabilistic analyses of structures subjected to FFE. A new material class, namely SteelFFEThermal, was implemented to simulate the steel behaviour subjected to FFE events.