Concentrically braced frames with replaceable brace modules (RBMs) have the potential of improving the constructability of braced frames, mitigating the structural damage during earthquakes, and minimizing the time of post-earthquake repairs. To fill the gaps between the component-level performance of RBMs and system-level behaviour of SCBFs with RBMs, this thesis focused on the overall system-level seismic performance of SCBFs with RBMs in three steps. Firstly, the effects of beam-column connection fixity on the behaviour of three SCBFs were investigated to determine what level of fixity, if any, is required to ensure adequate collapse capacity of an SCBF. Secondly, the effects of column design parameters on braced frame seismic performance were investigated, where two different brace-to-frame connections were considered: 1) conventional gusset plate connection and 2) the newly proposed connection detail with RBMs. Detailed numerical modelling was undertaken to develop improved provisions for designing columns in SCBFs. Finally, a large-scale experimental program was conducted to evaluate the seismic performance of braced frames with initial and replaced RBMs where realistic boundary conditions were provided. Three different beam-column connections that can be used in SCBFs with RBMs were designed and tested. Based on the current work, the recently proposed concept of replaceable brace modules, accompanied by the recommended methods for designing columns and detailing beam-column connections, appears to be a promising approach. The fabrication and installation are simpler, the seismic performance is similar to that of SCBFs with currently accepted connection detailing, and the approach can increase the post-earthquake reparability of steel concentrically braced frames. / Dissertation / Doctor of Philosophy (PhD)

Resumen Los sistemas de inyección directa han sido uno de los principales puntos focales de la investigación en motores, particularmente en sistemas Diésel, donde la geometría interna, movimiento de aguja y comportamiento del flujo afectan el spray externo y por tanto determinan completamente el proceso de combustión dentro del motor. Debido a regulaciones medioambientales y al potencial de los (más ineficientes) motores "Otto", grandes esfuerzos se están aportando en investigación sobre sistemas de inyección directa de gasolina. Los motores GDi tienen el potencial de incrementar sustancialmente la economía de combustible y cumplir con las regulaciones de gases contaminantes y de efecto invernadero, aunque aún existen muchos desafíos por delante. Esta tesis estudia en detalle una moderna tobera GDi que fue específicamente diseñada para el grupo de investigación conocido como Engine Combustion Network (ECN). Con metodologías punteras, este inyector ha sido usado en un amplio abanico de instalaciones experimentales para caracterizar el flujo interno y varias características clave de geometría y funcionamiento, y aplicarlo para evaluar cómo se relaciona con los efectos observados del comportamiento del chorro externo. Para la caracterización interna del flujo, el objetivo ha sido determinar la geometría de la tobera y el desplazamiento de aguja, caracterizar la tasa de inyección y el flujo de cantidad de movimiento, y evaluar el flujo cercano. Algunas metodologías nunca antes habían sido empleadas en inyectores GDi, y muchas otras lo han sido solo eventualmente. Para la geometría interna, el levantamiento de aguja y el flujo cercano, varias técnicas avanzadas con rayos-x fueron aplicadas en las instalaciones de Argonne National Laboratory. Para la tasa de inyección y flujo de cantidad de movimiento, las técnicas disponibles en el departamento han sido adaptadas desde Diésel y aplicadas en inyectores GDi multiorificio. Dado lo novedoso de las técnicas aplicadas, las particularidades de las metodologías han sido discutidas en detalle en el documento. Aún con la elevada turbulencia del flujo interno, el inyector se comporta de forma consistente inyección a inyección, incluso cuando el estudio se centra en la variabilidad orificio a orificio. Esto ha sido atribuido al comportamiento repetitivo de la aguja, evaluado en los experimentos. También fue observado que el flujo estabilizado tiene una variación de alta frecuencia que no pude ser explicado por el movimiento de la aguja, sino por el particular diseño de las toberas. El análisis de geometría interna realizado a ocho toberas nominalmente iguales resultó en la obtención de un punto vista único en la construcción de toberas y la variabilidad de dimensiones clave. Las medidas de tasa de inyección permitieron estudiar la respuesta hidráulica del inyector a varias variables como la presión de inyección, presión de descarga, temperatura de combustible y la duración de la señal de comando. Estas medidas fueron combinadas con medidas de flujo de cantidad de movimiento para estudiar el bajo valor del coeficiente de descarga, el cual fue atribuido al bajo levantamiento de aguja y coeficiente L/D de los orificios. Por otro lado, el estudio del spray externo resultó en la identificación de un importante fenómeno específico a este particular hardware, el colapso del spray. Las extensivas campañas experimentales, utilizando Schlieren e iluminación trasera difusa (DBI) permitieron identificar y describir las características macroscópicas del spray y las condiciones bajo las que el colapso ocurre. El colapso del spray se forma por una combinación de interacción de las diferentes plumas (causado por el flujo interno) y determinadas condiciones ambiente que promueven evaporación y entrada de aire. Fue determinado que a niveles de densidad y temperatura moderados se desarrolla el colapso, modificando completamente el comportamiento espera / Abstract Fuel injection systems have been one of the main focal points of engine research, particularly in Diesel engines, where the internal geometry, needle lift and flow behavior are known to affect the external spray an in turn completely determine the combustion process inside engines. Because of environmental regulation and the potential development of the more inefficient Otto engines, a lot of research efforts are currently focused into gasoline direct injection systems. GDi engines have the potential to greatly increase fuel economy and comply with pollutant and greenhouse gases emissions limits, although many challenges still remain. The current thesis studies in detail a modern type of GDi nozzle that was specifically developed for the international research group known as the Engine Combustion Network (ECN). With the objective of employing state-of-the-art techniques, this hardware has been used in a wide range of experimental facilities in order to characterize the internal flow and several geometrical and constructive aspects like needle lift; and assess how it relates to the effects seen external spray. For the internal flow characterization, the goal was to determine the nozzle geometry and needle displacement, to characterize the rate of injection and rate of momentum, and evaluate the near-nozzle flow. Some methodologies applied here have never been applied to a GDi injector before, and many have only been applied rarely. For the internal geometry, needle lift and near-nozzle flow, several advanced x-rays techniques were used at Argonne National Laboratory. For the rate of injection and rate of momentum measurements, the techniques available in CMT-Motores Térmicos have been adapted from Diesel spray research and brought to multi-hole GDi injectors. Given the novelty of the techniques used, the particular methodologies and setups are discussed in detail. Despite the high turbulence of the flow, it was seen that the injector behaves consistently injection to injection, even when studying variation in individual holes. This is attributed to the repetitive behavior of the needle that was observed in the experiments. It was also observed that the stabilized flow has a high frequency variability that could not be explained by random movement of the needle, but rather by the particular design of the nozzle. The geometrical analysis done to eight, nominally equal nozzles, allowed a unique view into the construction of the nozzle and provided insights about the variability of key dimensions. The rate of injection measurements allowed to study the hydraulic response of the injector to the main variables like rail pressure, discharge pressure, fuel temperature and command signal duration. These measurements were combined with the rate of momentum measurements to study the low value of the discharge coefficient, that ultimately was attributed to the low needle lift and low L/D ratio of the orifices. On the other hand, the study of the external spray yielded the identification of very important phenomena specific to this particular hardware, the spray collapse. The extensive experimental campaigns featuring shadowgraph (Schlieren) and Diffused Back Illumination (DBI) visualization techniques allowed identifying and describing the macroscopic characteristics of the spray and the conditions under which the collapse occurs. The spray collapse engenders from a combination of the internal flow that creates plume interaction, and ambient conditions that promote air entrainment and evaporation. At moderate density and temperature levels the collapse develops, completely modifying the expected trends in the behavior of the plumes. / Resum Els sistemes d'injecció directa han sigut un dels principals punts focals de la investigació en motors, particularment en sistemes dièsel, en què la geometria interna, el moviment de l'agulla i el comportament del flux afecten l'esprai extern i per tant determinen completament el procés de combustió dins del motor. Degut a regulacions mediambientals i al potencial dels (més ineficients) motors "Otto", grans esforços s'estan aportant en investigació sobre sistemes d'injecció directa de gasolina. Els motors GDi tenen el potencial d'incrementar substancialment l'economia del combustible i complir les regulacions de gasos contaminants i d'efecte hivernacle, encara que existeixen molts desafiaments per davant. Esta tesi estudia en detall una moderna tovera GDi que va ser especialment dissenyada per al grup d'investigació conegut com a ECN. Amb l'objectiu de desenvolupar metodologies punteres, este injector ha sigut usat en un ampli ventall d'instal·lacions experimentals per tal de caracteritzar el flux intern i diverses característiques clau de la seua geometria i funcionament, per tal d'avaluar com es relacionen amb els efectes observats del comportament de l'esprai extern. Per a la caracterització interna del flux, l'objectiu ha sigut determinar la geometria de la tovera i el desplaçament de l'agulla, caracteritzar la taxa d'injecció i el flux de quantitat de moviment, i avaluar el flux proper. Algunes metodologies no s'havien empleat abans en injectors GDi, i moltes altres ho han sigut únicament de manera eventual. Per a la geometria interna, l'alçament de l'agulla i el flux proper, s'han aplicat diverses tècniques avançades amb raigsx a les instal·lacions d'Argonne National Laboratory. Per a la taxa d'injecció i el flux de quantitat de moviment, les tècniques disponibles al departament han sigut adaptades des de Dièsel i aplicades a injectors GDi multi-orifici. Considerant la novetat de les tècniques aplicades, les particularitats de les metodologies es discuteixen en detall al document. A pesar de l'elevada turbulència del flux intern, l'injector es comporta de manera consistent injecció a injecció, inclús quan l'estudi se centra en la variabilitat orifici a orifici. Aquest fet s'ha atribuït al comportament repetitiu de l'agulla, avaluat als experiments. També es va observar que el flux estabilitzat té una variació d'altra freqüència que no pot ser explicat pel moviment de l'agulla, sinó pel particular disseny de les toveres. L'anàlisi de la geometria interna realitzat a vuit toveres nominalment iguals va permetre obtenir un punt de vista únic en la construcció de toveres i la variabilitat de dimensions clau. Les mesures de taxa d'injecció van permetre estudiar la resposta hidràulica de l'injector a diverses variables com la pressió d'injecció, la pressió de descàrrega, la temperatura del combustible i la duració de la senyal de comandament. Estes mesures van ser combinades amb mesures de flux de quantitat de moviment per tal d'estudiar el baix valor del coeficient de descàrrega, el qual va ser atribuït al baix alçament de l'agulla i al coeficient L/D dels orificis. D'altra banda, l'estudi de l'esprai extern va permetre identificar un important fenomen específic d'aquest hardware particular: el col·lapse de l'esprai. Les extensives campanyes experimentals, utilitzant Schlieren i il·luminació darrera difusa (DBI) van permetre identificar i descriure les característiques macroscòpiques de l'esprai i les condicions sota les quals el col·lapse té lloc. El col·lapse de l'esprai es forma per una combinació d'interacció de les diverses plomes (causat pel flux intern) i determinades condicions ambient que promouen evaporació i entrada d'aire. Es va determinar a quins nivells de densitat i temperatura moderats es desenvolupa el col·lapse, modificant completament el comportament esperat de l'esprai. / Vaquerizo Sánchez, D. (2018). Study on Advanced Spray-Guided Gasoline Direct Injection Systems [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/99568

Reinforced concrete (RC) structures constitute a significant portion of the building inventory in earthquake-prone regions of the United States. Accurate analysis tools are necessary to allow the quantitative assessment of the performance and safety offered by RC structures. Currently available analytical approaches are not deemed adequate, because they either rely on overly simplified models or are restricted to monotonic loading. The present study is aimed to establish analytical tools for the accurate simulation of RC structures under earthquake loads. The tools are also applicable to the simulation of reinforced masonry (RM) structures. A new material model is formulated for concrete under multiaxial, cyclic loading conditions. An elastoplastic formulation, with a non-associative flow rule to capture compression-dominated response, is combined with a rotating smeared-crack model to capture the damage associated with tensile cracking. The proposed model resolves issues which characterize existing concrete material laws. Specifically, the newly proposed formulation accurately describes the crack opening/closing behavior and the effect of confinement on the strength and ductility under compressive stress states. The model formulation is validated with analyses both at the material level and at the component level. Parametric analyses on RC columns subjected to quasi-static cyclic loading are presented to demonstrate the need to regularize the softening laws due to the spurious mesh size effect and the importance of accounting for the increased ductility in confined concrete. The impact of the shape of the yield surface on the results is also investigated. Subsequently, a three-dimensional analysis framework, based on the explicit finite element method, is presented for the simulation of RC and RM components under cyclic static and dynamic loading. The triaxial constitutive model for concrete is combined with a material model for reinforcing steel which can account for the material hysteretic response and for rupture due to low-cycle fatigue. The reinforcing steel bars are represented with geometrically nonlinear beam elements to explicitly account for buckling of the reinforcement. The strain penetration effect is also accounted for in the models. The modeling scheme is validated with the results of experimental static and dynamic tests on RC columns and RC/RM walls. The analyses are supplemented with a sensitivity study and with calibration guidelines for the proposed modeling scheme. Given the computational cost and complexity of three-dimensional finite element models in the simulation of shear-dominated structures, the development of a conceptually simpler and computationally more efficient method is also pursued. Specifically, the nonlinear truss analogy is employed to capture the response of shear-dominated RC columns and RM walls subjected to cyclic loading. A step-by-step procedure to establish the truss geometry is described. The uniaxial material laws for the concrete and masonry are calibrated to account for the contribution of aggregate interlock resistance across inclined shear cracks. Validation analyses are presented, for quasi-static and dynamic tests on RC columns and RM walls. / Ph. D.

[pt] Edifícios com as mais diversas finalidades estão sujeitos a eventos extremos, tais como impacto de veículos, explosões, e perdas súbitas de membros essenciais para a garantia da sua estabilidade. O colapso progressivo pode ser definido como o processo no qual um dano localizado leva a uma ruína em cadeia, causando a queda de um edifício inteiro ou de parte considerável dele. A perda repentina de determinado membro essencial devido às cargas excepcionais pode desencadear o colapso progressivo de uma estrutura, causando enormes prejuízos humanos e econômicos. O colapso progressivo é fenômeno de natureza dinâmica e não linear, sendo assim, a sua modelagem é complexa. A técnica mais empregada para avaliação do colapso progressivo de estruturas é o método dos caminhos alternativos, que verifica o comportamento da estrutura ante a remoção de um membro essencial de suporte, analisando assim sua capacidade de redistribuição de esforços e resistência ao aumento súbito de carga em uma situação crítica. O trabalho realizou sucessivas análises de modelos da estrutura de um edifício em concreto armado, adotando grau de complexidade progressivo a cada uma delas, utilizando o método dos caminhos alternativos. Analisou-se ao final a efetividade e a importância de cada uma das etapas de análise empregadas no trabalho. A estrutura dimensionada conforme a norma brasileira de concreto armado necessitou de ajustes para atender aos requisitos mínimos de resistência ao colapso progressivo. / [en] Buildings with the most diverse purposes are subject to extreme events, such as vehicle impact, explosions, and sudden loss of members essential to their stability. Progressive collapse can be defined as the process in which a localized damage leads to chain failure, causing the fall of an entire building or a large part of it. The sudden loss of an essential member due to exceptional loads can trigger the progressive collapse of a structure, causing enormous human and economic damage. Progressive collapse is a dynamic nonlinear phenomenon, so its modeling is complex. The most employed technique for evaluation of progressive collapse is the alternative load path method, which verifies the structure behavior after the sudden loss of a load-bearing element, checking its stress redistribution capacity and strength to load increase in critical situations. This work realized successive analysis of structural models of a reinforced concrete building, adopting a progressive complexity to each of them, using the alternative path method. At the end, the effectiveness and importance of each of the analysis steps employed at work were analyzed. The structure designed acoording to the reinforced concrete brazilian standard needed adjustments to meet the minimum resistance requirements of progressive collapse.

The Insurance Bureau of Canada released a report in 2013 that evaluated the seismic risk of two major metropolitan areas of Canada, with projected losses of $75bn in British Columbia along the Cascadia subduction zone, and $63bn in the east through the Ottawa-Montreal-Quebec corridor. Such reports should prompt researchers and designers alike to rethink the way that seismic design is approached in Canada to develop resilient and sustainable cities for the future. To mitigate the economic losses associated with earthquake damage to buildings in seismically active areas, controlled rocking steel braced frames have been developed as a seismically resilient low-damage lateral-force resisting system. Controlled rocking steel braced frames (CRSBFs) mitigate structural damage during earthquakes through a controlled rocking mechanism, where energy dissipation can be provided at the base of the frame, and pre-stressed tendons pull the frame back to its centred position after rocking. The result is a building for which the residual drifts of the system after an earthquake are essentially zero, and the energy dissipation does not result from structural damage. Design methods for the base rocking joint and the capacity-protected frame members in CRSBFs have been proposed and validated both numerically and experimentally. However, the is no consensus on how to approach the design of the frame members, questions remain regarding how best to design CRSBFs to prevent building collapse, and no experimental work has been done regarding how to connect the CRSBF to the rest of the structure to accommodate the rocking motion. Because the force limiting mechanism of a CRSBF is rocking only at the base of the frame, the frame member forces are greatly influenced by the higher-mode response, resulting in more complex methods to design the frame members. This thesis begins by outlining two new design procedures for the frame members in controlled rocking steel braced frames that target both simplicity and accuracy. The first is a dynamic procedure that requires a truncated response spectrum analysis on a model of the frame with modified boundary conditions to consider the rocking behaviour. The second is an equivalent static procedure that does not require any modifications to the elastic frame model, instead using theory-based lateral force distributions to consider the higher modes of the rocking structure. Neither method requires empirical calibration to estimate the forces at the target intensity. The base rocking joint design is generally in good agreement between the various research programs pioneering the development of the CRSBFs. However, the numerous parameters available to select during the design of the base rocking joint give designers an exceptional amount of control over the performance of the system, and little research is available on how best to select these parameters to target or minimise the probability of collapse for the building. This thesis presents a detailed numerical model to capture collapse of buildings with CRSBFs as their primary lateral force resisting system and uses this model to generate collapse fragility curves for different base rocking joint design parameters. The parameters include the response modification factor, the hysteretic energy dissipation ratio, and the post-tensioning prestress ratio. This work demonstrates that CRSBFs are resilient against collapse, as designing the base rocking joint with response modification factors as large as 30, designing the post-tensioning to prevent yielding at moderate seismic hazard levels, and using zero energy dissipation could lead to designs with acceptable margins of safety against collapse. While the design procedures are shown to be accurate for estimating the frame member force demand for the targeted intensity level, there is still a high level of uncertainty around what intensity of earthquake a building will experience during its lifespan, and there is no consensus on what intensity should be targeted for design. To address this, the ability of the capacity design procedures to provide a sufficiently low probability of collapse due to excessive frame member buckling and yielding is evaluated and compared to the probability that the building will collapse due to excessive rocking of the frame. The results of the research presented here suggest that the probability of collapse due to either frame member failure or excessive rocking should be evaluated separately, and that targeting the intensity with a 10% probability of exceedance in 50 years is sufficient for the design of the frame members. Finally, critical to the implementation of CRSBFs in practice is how they may be connected to the rest of the structure to accommodate the uplifting of the CRSBF while rocking under large lateral forces. An experimental program was undertaken to test three proposed connection details to accommodate the relative uplifts and forces. The connections that accommodate the uplifts through sliding performed better than that which accommodated the uplifts though material yielding, but the best way to transfer the forces and accommodate the uplifting without influencing the overall behaviour of the system is to position the connection such that it does not need to undergo large uplifts and carry lateral force simultaneously. A detailed numerical model of the experimental setup is presented and is shown to simulate the important response quantities for each of the tested connections. Using the results of this work, designers worldwide will be confident to design CRSBFs for structures from the base rocking joint to the selection of floor-to-frame connections for a complete system design while ensuring a safe and resilient building structure for public use and well-being. / Thesis / Doctor of Philosophy (PhD) / Traditional approaches to seismic design of buildings have generally been successful at preventing collapse and protecting the lives of the occupants. However, the buildings are often left severely damaged, often beyond repair. To address these concerns, controlled rocking steel braced frames have been proposed as part of a new construction technique to mitigate or prevent damage to steel buildings during earthquakes, but several aspects of the design and overall safety have yet to be explored or demonstrated. This thesis proposes and validates new tools to design controlled rocking steel braced frames and provides recommendations on how best to design them to achieve a safe probability against collapse. Details are proposed and presented for components to connect the controlled rocking steel braced frames into the rest of the structure. The findings of this thesis will aid practitioners looking to deliver resilient and sustainable structural designs for buildings in our cities of the future.

This dissertation of limited scope traces the attempts by Gorbachev (1985-1991) to reform an economic, political and social system which was in a state of terminal decline. The origins of its demise, it is argued, lay in the ossified command economy inherited from Stalin. The enormous damage inflicted on Soviet agriculture during collectivisation in the 1930s~ when millions of productive peasants died, proved to be a fatal blow to that sector. Tlms, Gorbachev followed a two-fold strategy ofrefonn. Glasnost (openness) was introduced to allow constructive debate on economic and social matters. Despite a hesitant beginning, the right to criticise allowed the emergence of more radical campaigners, such as Yeltsin who demanded greater democracy. Significantly, the revival of ethnic nationalist demands in the republics led to disintegration. Perestroika (restructuring) was intended to modernise and boost living standards. The economy faltered but the market was not yet in place / History / M.A. (History)

In recent years, the increasing impacts of landslide hazards on human lives and lifeline facilities worldwide has advanced the necessity to find out both economically acceptable and useful techniques to predict the occurrence and destructive power of landslides. Though many projects exist to attain this goal, the current investigation set out to establish an understanding of the initiation and propagation mechanisms of landslides via numerical simulations, so that mitigation strategies to reduce the long-term losses from landslide hazards can be made. In this research, the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) have been used to investigate the mechanical and hydraulic behaviour of granular materials involved in landslides. The main challenge is to provide rational analyses of large scale landslides via small scale numerical simulations. To solve this problem, dimensional analyses have been performed on a simple granular column collapse model. The influence of governing dimensionless groups on the debris runout distance and deposit height has been studied for the terrestrial and submerged granular flows. 3D DEM investigations of granular flows in plane strain conditions have been performed in this research. The input parameters of the DEM model have been calibrated by the numerical triaxial tests, based on which, the relationships between the microscopic variables and the macroscopic soil strength properties are analysed. Using the simple granular column collapse model, the influences of column aspect ratio, characteristic strain, model size ratio and material internal friction angle on the runout distance and deposit height of granular materials have been examined. Additionally, the deformation and energy evolution of dry granular materials are also discussed. The DEM-CFD coupling model has been employed to study the mechanical and hydraulic behaviour of highly mobilized terrestrial / submarine landslides. This model has been validated via numerical simulations of fluid flow through a porous soil sample and grain batch sedimentations. The simulations of granular flows in the submerged environment have led to some meaningful insights into the flow mechanisms, such as the mobilization of sediments, the generation and dissipation of excess pore water pressures and the evolution of effective stresses. Overall, this study shows that the proposed numerical tools are capable of modelling the mechanical and hydraulic behaviour of terrestrial and submarine landslides.

Immunodeficient honey bee (Apis mellifera) colonies suffer from broad range of parasites including eukaryotic protozoa. Despite this fact, the eukaryotic parasites are still poorly documented in the Czech Republic. The presence of eukaryotic parasites (Nosema ceranae, Nosema apis, Crithidia mellificae and Apicystis bombi) was observed in different apiaries in the Czech Republic. The samples were taken in 9 apiaries in 53 beehives during the 2014/2015 season. From each beehive, 10 adult of honey bees were taken from the peripheral comb in triplicate. DNA was isolated from every sample of honey bees. The parasites were detected by polymerase chain reaction (PCR) with specific primers. The treatment fall of parasitic mite Varroa destructor was obtained from beekeepers for season of 2014. Crithidia mellificae was detected by 5 types of specific primers (SEF, SER; SSU, SSU rRNA, Cyt b, Tryp cyt b) and positive amplicons were cloned and sequenced. The obtained sequences were compared with GeneBank and showed similarity from 98-100% to sequences of Lotmaria passim (Trypanosomatid). Crithidia mellificae was not detected. L. passim had prevalence of 79,2% and is reported in the Czech Republic for the first time. Primer Tryp-cyt b is recommended for the routine detection of L. passim. Nosema ceranae was...

[pt] Esta pesquisa está relacionada à avaliação das condições de estabilidade de tensão em pontos de operação do sistema elétrico. A modelagem de geradores / compensadores síncronos e compensadores estáticos são analisadas. Estabeleceram-se os melhores modelos com controle de tensão ativo e com perda do controle. A questão da adequação do controle de tensão foi tratada através da análise dos elementos da matriz de sensibilidade entre as grandezas controladoras e as tensões controladas. Os índices de estabilidade de tensão foram calculados. Em todos os casos, a perda de controle de tensão tem impacto negativo sobre as condições de estabilidade de tensão. Nos casos com ação de controle inadequada, independe da relação inversa entre grandeza controladora e tensão controlada, um aumento da tensão na barra controlada teve um impacto positivo sobre as condições de estabilidade de tensão, e uma diminuição da tensão na barra controlada teve impacto negativo sobre as condições de estabilidade de tensão. Esse é o resultado esperado também quando a ação de controle é adequada. / [en] This research is related to the evaluation of voltage stability conditions of operating points of the power system. It has been studied the modelling of synchronous generators/synchronous compensators and static var compensators. The best models were established with active voltage control and with loss of control. The issue of voltage control was treated through analysis of the matrix sensitivity elements between the controlling variables and voltages at controlled buses. The voltage stability indexes were evaluated. In all cases, control loss proved to have a negative impact on voltage stability conditions. In cases with inadequate control action, results are non-dependent of the opposed relation between the controlling variable and voltage at controlling bus, an increase on voltage at controlled busbar proved to have a positive impact on voltage stability conditions, and a decrease on voltage at controlled busbar proved to have a negative impact on voltage stability conditions. This is also expected when the control action is appropriate.

Det här examensarbetet går ut på att jämföra EKS 11 och SS-EN 1991-1-7 olika beräkningsmodeller för olyckslaster. Ifall en byggnad endast har ett trapphus som enda nödutgång krävs det att den dimensioneras för olyckslaster. Dessa olyckslaster delas upp i två olika grupper, kända- och okända olyckslaster. Kända olyckslaster är exempelvis påkörning när byggnaden ligger nära en väg och explosion ifall det finns exempelvis gasledningar i byggnaden. Okända olyckslaster är de laster där man inte kan dimensionera för ett exakt värde. Istället dimensionerar man för att minska konsekvenserna av lasten där främsta alternativet är att använda de krav som ställs på väsentliga bärverksdelar och applicera dem på de bärande konstruktionsdelarna. Alternativt när byggnaden inte har gasledningar så kan man beräkna för okända laster genom att dimensionera via värdet som uppkommer från en gasexplosion, 34 kN/m2. Dimensioneringen anpassas efter ett verkligt projekt konstruerat av Structor. Tidigare problem har uppstått vid tolkning av eurokodens beräkningsgång och därför har eks 11 kommit med förtydliganden och med mer triviala lösningar kring olyckslaster. Beräkningsgången för de olika olyckslasterna ser olika ut beroende på om man följer eks 11:s metod eller eurokodens metod. Målet med arbetet är att förtydliga skillnaderna mellan de olika beräkningsgångarna och se vad som ligger till grund för dom. För att kunna skapa en bredare förståelse kring olyckslaster har eurokoden, EKS 11, litteratur och Structor varit till stor hjälp. Examensarbetet är avgränsat till olyckslaster när det bara finns ett trapphus som enda utrymningsväg där det sker en jämförelse mellan EKS 11 och SS-EN 19911-7. Resultatet visar att de två olika beräkningsgångarna ger två olika svar vid beräkning av både kända- och okända laster. Ekvationerna för att räkna fram olyckslaster i de olika standarderna tar hänsyn till olika saker vilket leder till olika resultat. Slutsatsen som går att dra är att det alltid finns olika förutsättningar för varje projekt. Därför bör det göras en riskanalys i projekteringsskedet för att avgöra vilken standard som ska användas för det aktuella projektet. / This dissertation is based on a comparison between the two different procedures on accidental actions in the Swedish norm EKS 11 and SS-EN 1991-1-7. If a construction only has a stairwell as the only emergency exit it requires that accidental actions determines. These accidental actions are categorized mainly to known and unknown accidental actions. Known accidental actions are for example collision by a vehicle or a gas leak from a gas pipe in the building. Unknown accidental actions are those loads that cannot be completely determined. Instead an analyze how to decrease the damage by accidental actions are used. The main approach is to value members as key elements, in effect making them strong enough to withstand a prescribed hazard loading. An alternative if the construction does not have any gas pipes is to use the pressure of 34 kN/m2 to represent the static equivalent from a notional gas explosion. The values in the work are based from a project constructed by the Swedish company Structor. Previously difficulties have occurred while comprehending the Eurocode’s calculation procedures therefore the new Swedish norm EKS have clarified a lot about accidental actions. The calculation procedures results in two different answers between the Eurocode and the Swedish norm EKS. The aim with this dissertation is too clarify the differences between them and perceive the reasons behind it. To be able to have a wider understanding of the subject accidental actions a screening has occurred of the Eurocode, the Swedish norm EKS and literature. The Swedish company Structor has also shared a lot of knowledge on the subject. The dissertation has been limited to accidental actions on stairwells as the only emergency exit and a comparison between the Swedish norm EKS 11 and SS-EN1-7. The outcome of the two different calculations shows two different results of the known and unknown accidental actions. The equations for calculating accidental action in the different standards considerate different things which leads to different results. The conclusion is that there always are different conditions in every project. Therefor a risk assessment should be done before the construction begins to determine which standard is the most suitable for the project.