This study investigates the complex issues surrounding the preservation of historic, single-lane, metal truss bridges. Essentially functionally obsolete, these structures are targeted for replacement due to current government transportation policies, funding requirements, and safety concerns. After these issues are discussed, a series of case studies from Hunterdon County, New Jersey, will highlight multiple bridge rehabilitation projects in which designs and plans were modified to suit the unique situations and conditions of each of these structures, without compromising historic integrity and improving safety. These bridges have important cultural value, and although in some cases the original structure may be lost or wholly reconstructed, the historic character of the bridge and area is retained. This thesis illuminates the difficulties that need to be overcome in attempting to successfully preserve historic, single-lane bridges and their rural context (while maintaining transportation functionality), and illustrates the important role of community involvement in the preservation process. / Department of Architecture

O presente trabalho apresenta uma análise numérica do desempenho térmico de painéis construídos utilizando o sistema light steel framing (LSF) submetido a ação térmica decorrente de um incêndio. O objeto de estudo foram painéis utilizados na construção de duas casas modelo localizadas na Universidade Tecnológica Federal do Paraná campus Curitiba, construídas com materiais disponíveis comercialmente no Brasil e as análises utilizaram propriedades disponibilizadas pelos fabricantes e pela norma brasileira. A análise numérica foi realizada no software ANSYS, com base no método dos elementos finitos em análise térmica transiente. O modelo foi validado com base em comparação com análises experimentais pesquisadas na literatura. Quatro painéis obtidos das casas modelo foram analisados. Os painéis que utilizaram lã de PET para preenchimento da cavidade foram também analisados com preenchimento de lã de vidro. Um painel simples, com a cavidade preenchida por ar foi analisado para ser usado como referência. Por fim, com a utilização de coeficientes de redução da resistência ao escoamento propostos pela ABNT NBR 14323:2001, determinou-se a redução da resistência do aço do perfil de acordo com o tempo de exposição ao incendio e o tempo de resistência ao fogo dos perfis. Com base nos resultados obtidos é possível afirmar que mesmo para os paneis com pior desempenho, a proteção obtida pode ser suficiente, a depender do carregamento aplicado ao montante e do Tempo requerido de resistência ao fogo necessário. O presente trabalho apresenta informação relevante sobre o desempenho térmico em situação de incêndio do sistema LSF constituído com materiais brasileiros. / The thermal performance of light steel framing (LSF) panels was the objective of this study. The study subject was panels used in the construction of two model houses located at Federal Technology University – Parana, built with materials commercially available in Brazil. The analysis was set with material properties from the manufacturer and in compliance with the Brazilian regulation, using the finite element method for a transient thermal analysis. The model validation was based on experimental tests available in the literature. Based on the validated model, the four panels have been analyzed. Two of the panels used PET wool in the cavity for insulation and the analysis was repeated with them replacing it for glass wool. A panel with no insulation was also analyzed to be used as reference. Based on the analysis results and the resistance reduction coefficients proposed by ABNT NBR 14323:2001, the resistance decrease of the studs due to the fire exposure and the panels resistance to fire were determined. Based on the obtained results, it can be affirmed that, depending on the applied load and the required Equivalent time of fire exposure, even the less protective configuration of the panels presented can be viable. The current study presented relevant information about the performance of LSF manufactured in Brazil when exposed to fire.

Les travaux de recherche discutés dans ce manuscrit concernent la conception des générateurs de puissance électrique pour l'aéronautique. L’augmentation de la puissance massique de ces équipements passe par une augmentation des vitesses de rotation, donc une augmentation des contraintes. Un premier point est de s'assurer de la bonne tenue mécanique des matériaux. Un deuxième point est de pouvoir prendre en compte les modifications du comportement magnétique (et donc in fine du couple) lorsqu'ils sont soumis à un état de contraintes multiaxial. L’étude présentée vise en particulier à illustrer l’influence d'états de contraintes biaxiaux sur le comportement magnétique des matériaux constitutifs du rotor. Le défi repose sur la mise en place de méthodes de caractérisation du comportement magnéto-mécanique dissipatif uniaxial et multiaxial des nuances développées par Aperam et utilisées par Thales Avionics pour leurs applications aéronautiques (en FeCo-2V et Fe-3%Si à grains non orientés). Des essais non conventionnels seront effectués sur des échantillons en forme de croix de manière à s'approcher des contraintes réellement subies par le rotor. Les essais sont effectués sur la machine d'essai triaxiale Astrée du LMT-Cachan. L'état de contraintes est estimé par corrélation d'images et par diffraction des rayons X. Des mesures magnétiques anhystérétiques et de pertes d'énergie sous contraintes sont reportées. D'autre part, un modèle multi-échelle multiaxial, décrivant le comportement d’un VER à partir de l'équilibre énergétique à l'échelle microscopique sera présenté. L’approche est fondée sur la comparaison des énergies libres de chaque domaine. Une comparaison probabiliste est faite pour déterminer les variables internes que sont les fractions volumiques des domaines. Différentes stratégies envisageables pour modéliser la dissipation statique seront discutées. Puis nous présentons l’approche magnéto-élastique que nous avons retenue visant à une meilleure considération de l’effet de la contrainte sur le comportement des matériaux ferromagnétiques. / The research presented in this thesis is motivated by the design of rotors for high speed rotating machines. The increased power density of these devices requires a higher rotation speed, leading to higher levels of centrifugal forces and stress in the rotor. A first point is to ensure good mechanical strength of the materials. A second point is to take into account changes in the magnetic behavior (and ultimately torque) when they are subjected to a multiaxial stress state. The present study aims at exploring the influence of biaxial stress states on the magnetic behavior of the materials of the rotor. The challenge lies in the development of methods for the characterization of the magneto-mechanical dissipative uniaxial and multiaxial behavior of metal sheets developed by Aperam Alloy and used by Thales Avionics for their aeronautical applications (in FeCo-2V and non-oriented Fe-3%Si). Non conventional experiments are performed on cross-shaped samples in order to apply biaxial stress representative of the loadings experienced by rotors of rotating machines. These experiments are performed on a multiaxial testing machine, Astrée. Stress level is estimated thanks to digital image correlation and X-ray diffraction Both anhysteretic and dissipative magnetic responses to magneto-mechanical loadings have been recorded. On the other hand, a multi-scale multiaxial model describing the behavior of a RVE from the energy balance at the microscopic scale is presented. The approach is based on a comparison of the free energy of each domain. A probabilistic comparison is made to determine the volume fraction of domains used as internal variables. Different strategies for modeling the static dissipation are discussed. Then we present the chosen magneto-elastic approach, improving the description of the effect of stress on ferromagnetic materials behavior.

I takt med att allt fler kulturhistoriskt värdefulla byggnader rivs i landets kommuner utarmas Sveriges kulturarv enligt Riksantikvarieämbetet. Vilken betydelse har då en kulturhistorisk värdebeskrivning i den kommunala beslutsprocessen? Lidingö stad valdes som fallstudie eftersom man där beslutat att riva öns landmärke, en fackverksbro av järn och nitad stål, Gamla Lidingöbron, invigd 1925. Bron är med sin karaktäristiska konstruktion och stora bågspann ett starkt etablerat signum vid öns infart. Den har flera likheter med Gamla Årstabron i Stockholm som till skillnad från Gamla Lidingöbron är statligt ägd, utsedd till byggnadsminne och därmed skyddad. Det framkom i denna studie att Gamla Lidingöbrons kulturhistoriska värde inte hade diskuterats inför rivningsbeslutet 2012 samt att en för ändamålet beställd värderingen saknades i beslutsunderlaget. Planarbetet för en ny bro, ”Lilla Lidingöbron”, som senare lades fram fick kritik från alla remissinstanser som yttrade sig om kulturmiljö eftersom de ansåg att den äldre stålbron borde bevaras. Kommunen uppmanades att ta fram ett bevarandealternativ. Kritiken ledde inte till någon omprövning trots existerande alternativa förslag.  Det enda som skedde var att beskrivningen av brons värde till slut skrevs in i den nya detaljplanen med ordalag tagna ur värderapporten. På vissa ställen dock vända till sin motsats (sid 20-25). Det tillades även där att den kulturhistoriska värderapporten hade använts inför inriktningsbeslutet 2012 trots att det inte var så. Beslutet visade sig ha rötter till tidigt 2000-tal vilket beskrivs i en bilaga.  En utblick görs mot beslutsprocessen för Gamla Danviksbron i Stockholm, byggd 1922, i syfte att exemplifiera hur ett redan taget rivningsbeslut faktiskt kan ändras efter att kulturvärdet åberopats av remissinstans. Till skillnad från Lidingö kommun samarbetade man därefter med de sakkunniga i byggnadsvård för att bevara Gamla Danviksbron.  Slutsatsen är att en kulturhistorisk värdebeskrivning är viktig då den informerar och vägleder om vad som är värdefullt, vad man bör bevara och varför. Dock kan en sådan rapport förlora sin mening när det finns politiska intressen som favoriserar andra lösningar. Likaså när tjänstemän och politiker helt enkelt inte har kunskap om kulturhistoriska värden eller saknar kompetens att samordna olika aktörers intressen när det kommer till att integrera kulturvärden, miljö och innovativa lösningar (bevara och förnya) – med ekonomi och funktion. / As more buildings with established cultural-historical value are being demolished around the country, Sweden's cultural heritage risks being depleted according to The Swedish National Heritage Board. What then is the impact of a cultural-historical value report in the municipal decision-making process? The municipality of Lidingö was chosen as an example because of its decision to demolish the island's landmark bridge; the Old Lidingö bridge (Gamla Lidingöbron), an iron and steel truss bridge from 1925. This bridge, with its characteristic construction, and large arched span, is a strongly established symbol for the island. It has several similarities with the protected state-owned Old Årsta bridge in Stockholm. In this study, it emerged that an existing cultural-historical report, describing the bridge’s high value, was not taken into consideration as a basis for the decision made by the municipality in 2012. During the planning work for a new bridge, Little Lidingö bridge, the municipality received criticism from concerned parties (e.g. Stockholm County Administrative Board) that commented on the cultural value, because they felt that the bridge should be preserved. The municipality was encouraged to develop a conservation-focused alternative. In response to the criticism, the officials did not reconsider the decision. They merely included more of the content of the cultural-historical value report in the detailed development plan. In some of the added paragraphs the meaning of the words was reversed (page 20-25). The development plan also states that the report had been considered prior to the demolition decision, although it had not been. Indications that the 2012 decision had its roots in the early 2000s are included in the appendix. To compare with similar decisions, a brief look is also taken at Stockholm municipality, where the decision-making process regarding the Old Danvik Bridge, built in 1922, is given as an example of how they instead changed direction, and collaborated with experts in cultural conservation.In conclusion, a cultural-historical value description is extremely important. It provides a basic description of what is valuable, what should be preserved and why. However, such a report may lose its impact if there is a political agenda moving in another direction. Another reason that this type of document might be devalued is if officials and politicians lack knowledge of cultural history, or the skills to coordinate the interests of different actors; integrating cultural values, the environment, and innovative solutions (preserving and innovating) – with economics and function.