The Central and Eastern United States (CEUS) is a region that is characterized by low frequency-high consequence seismic events such as the New Madrid sequence of 18111812. The infrequent nature of earthquakes in the region has led to a perception that the seismic risk in the area is low, and the current building stock reflects this perception. The majority of steel-framed buildings in the CEUS were designed without regard to seismic loads. Such frames possess limited seismic resistance, and may pose an unacceptable risk if a large earthquake were to occur in the region. A key ingredient of building performance and seismic risk assessment is the fragility, a term that describes the probability of failure to meet a performance objective as a function of demand on the system. The effects of uncertainties on building seismic performance can be displayed by a seismic fragility relationship. This fragility can be used in a conditional scenario-based seismic risk assessment or can be integrated with seismic hazard to obtain an estimate of annual or lifetime risk. The seismic fragility analyses in this study focus on steel frames that are typical of building construction in regions of infrequent seismicity; such frames have received little attention to date in building seismic risk assessment. Current steel building stock in Shelby Co., TN has been represented by five code-compliant model frames with different lateral force-resisting systems, i.e., braced-frames, partially-restrained moment frames and a rigid moment frame. The performance of model frames under certain hazard levels was assessed using fragility curves. Different rehabilitation methods were discussed and applied. Results indicate that PR frames behave better than expected and rehabilitated frames perform quite well even under severe earthquakes.

Hospitals are regarded as some of the most important structures in society due to the service that they provide. Knowing this, governments spend large amounts of money on these facilities. Also, codes of design require to provide them more reserve capacity than that for conventional structures. However, large damages (such as collapses and permanent or temporary interruptions of their functionality) have still been observed in hospitals during strong earthquakes. Unfortunately, it is precisely after this type of event that their service is in high demand and failure in providing that service could lead to further disastrous or fatal consequences. Therefore, the use of protective technologies, combined with rational procedures of design, would help to reduce damage and probable losses of functionality in hospital structures. In this thesis, a procedure for seismic design of structures equipped with a type of protective technology, namely, buckling-restrained braces (BRBs), is proposed. Then, the results of experimental and numerical studies are presented to understand the benefits of using BRBs in structures. This study highlights that BRBs are very effective to dissipate seismic energy and can act as structural fuses, i.e. disposable devices that may be replaced after an earthquake without interruptions in the functionality of the structure. One of the advantages of the proposed procedure is that it takes into account explicitly the characteristics and contributions of both, the main structure and the BRBs. It is based on the assumption that a structure protected with BRBs can rationally be represented by a dual SDOF system whose parts yield at different displacement levels. Other advantages include: 1) better control of the displacement demands on the structure; 2) achievement of the fuse concept beforehand; and 3) rapid assessment of the probabilistic performance of the structure. The experimental studies consisted of testing steel and concrete models, with and without BRBs, on a shaking table. In addition to calibrate and validate the proposed method of design, the tests have helped to find that, due to BRBs: 1) the damping ratio is increased significantly; and 2) the dynamic response, to ground motions characteristic of the lakebed zone of Mexico City, is reduced in terms of lateral displacements, inter-storey drifts, floor velocities and floor accelerations. The numerical studies are: 1) a study of the response of typical hospitals improved with BRBs; 2) a study of residual displacements in conventional and dual systems; and 3) evaluation of the economic benefits of using BRBs in structures. On these studies, hypothetical hospitals located in the lakebed zone of Mexico City were considered. The results show that the use of BRBs is very beneficial in medium- and low-rise buildings, while adverse effects may be observed in high-rise structures.

L’articulation du genou est sujette à de nombreuses pathologies pouvant entraîner des instabilités. Les démarches thérapeutiques incluent communément le port d’orthèses, dans le but de stabiliser ou limiter les mouvements articulaires. Malgré une forte prescription, l’évaluation de ces dispositifs manque encore de standardisation.En lien avec des médecins et des industriels, différents outils ont été développés pour évaluer leur efficacité biomécanique. Un modèle éléments finis d’un membre inférieur appareillé a notamment permis d’étudier l’effet de divers paramètres de conception d’une genouillère sur les pressions exercées et sur sa capacité à limiter un mouvement pathologique. Ce modèle a servi à valider un banc de test pouvant contribuer à l’innovation et la certification. Afin d’appréhender les problèmes de confort, le glissement des orthèses sur la peau a été caractérisé par des mesures de champ. Enfin, leurs actions in vivo ont été mesurées à l’aide d’un arthromètre sur des patients présentant une laxité.Les résultats mettent en évidence l’importance des caractéristiques techniques des orthèses et la spécificité du patient sur leurs niveaux d’action. Ainsi, il est possible de cibler des pathologies en jouant sur certains facteurs. Cependant, comparé aux structures de stabilisation passive (ligaments), le rôle des orthèses s’avère limité aux conditions de faibles sollicitations mécaniques. Néanmoins, leurs effets actifs et proprioceptifs (contrôle neuro-musculaire) seraient également à considérer.Ces outils s’avèrent complémentaires ; ils ouvrent la voie à des démarches d’évaluation standardisées et pourront également aider au développement de nouveaux produits. / The knee joint is vulnerable to various injuries and degenerative conditions, potentially leading to instabilities. Usual treatments involve orthoses, which are medical devices aimed at supporting, aligning or immobilizing the joint. However, the evaluation of these devices lacks standardisation despite high prescription and demand.In relation with clinicians and manufacturers, different tools were developed to assess their biomechanical efficiency. Firstly, a finite element analysis (FEA) of a braced lower limb was used to investigate the effects of brace design on its ability to prevent a pathological motion and understand the force transfer mechanisms. This model provided a basis to validate an experimental surrogate limb with the aim of providing an innovation and certification tool for manufacturers. In an attempt to apprehend comfort issues, full-field measurements of brace migration and FEA of contact pressures were performed. Finally, their in vivo actions were measured on ACL-deficient patients using a laxity testing device.Results highlight the importance of brace technical characteristics and patient-specificity on characterized levels of action and comfort. Furthermore, some key design factors allowed to target devices to particular pathologies. However, when compared to in vivo passive stabilizing structures (ligaments), the efficiency of knee braces was restrained to low load conditions. Nevertheless, these devices may also have a substantial effect on active stabilizing mechanisms such as neuro-muscular control.These tools were found to be complementary and may hopefully pave the way to a standardised procedure for evaluating and developing new designs.

Made available in DSpace on 2014-07-29T15:25:15Z (GMT). No. of bitstreams: 1 tese mariliia teixeira costa - ciencias da saude.pdf: 592941 bytes, checksum: bbd7a80041fff15e5e5a8747d934ef5f (MD5) Previous issue date: 2011-07-04 / Black extrinsic tooth stains appear on the smooth surfaces of teeth, parallel to the marginal gum and are considered a specific form of biofilm due to the high content of calcium, phosphate and insoluble iron salt. This study evaluated the profile of bacterial biofilms in patients with black extrinsic tooth stain with or without fixed metal braces installed. Four bacteria were investigated using conventional multiplex PCR (Polymerase Chain Reaction), black-pigmented bacteria: Prevotella nigrescens and Prevotella intermedia and non pigmented bacteria: Streptococcus mutans and Actinomyces spp. The study enrolled 52 patients, 25 females and 27 males. They were divided into two groups: Group I: 26 patients with black extrinsic tooth stains and Group II: 26 without stains. Twenty patients had fixed orthodontic brackets of stainless steel. The results showed that in both group (I and II) 61.5% of patients had at least one of the bacteria investigated. The P. nigrescens was the most frequently bacteria detected [Group I (30.7%) and Group II (46.1%)], P. intermedia was detected in 3.8% in Group I and 11.5% in Group II. The non pigmented bacteria were found in similar rates in Groups I and II, 19.2% vs 11.5% for Actinomyces spp and 23.1% vs 30.7% for S. mutans. There were no statistically significant differences when comparing the frequencies of each bacterium between groups, indicating that bacterial profiles were similar between patients with or without black extrinsic stains. When analyzed the frequencies of bacteria in the biofilm in black extrinsic tooth stain in patients with braces results indicated that it did not alter the frequency of bacteria found, however, it was observed that the presence of fixed orthodontic appliance significantly reduces the associations between bacteria in the biofilm of black extrinsic stains (p <0.05). / As manchas dentárias extrínsecas negras aparecem nas superfícies lisas dos dentes, paralelas à gengiva marginal, e são consideradas uma forma de biofilme dentário devido ao grande conteúdo de cálcio, fosfato e sal insolúvel de ferro. Este estudo foi realizado com o objetivo de avaliar o perfil bacteriano dos biofilmes dentários de pacientes portadores ou não de manchas dentárias extrínsecas negras, com ou sem aparelho ortodôntico metálico fixo instalado. Para isto foi utilizada a técnica de multiplex PCR (Polymerase Chain Reaction) para investigar a presença das bactérias pigmentadoras de negro: Prevotella nigrescens e Prevotella intermedia e as bactérias não pigmentadoras de negro: Streptococcus mutans e Actinomyces spp nos biofilmes. A amostra consistiu de 52 pacientes, 25 do gênero feminino e 27 do gênero masculino. A amostra foi dividida em dois grupos: Grupo I: 26 pacientes portadores de manchas e Grupo II: 26 pacientes não portadores de manchas. Do total da amostra, 20 pacientes estavam sob terapia ortodôntica fixa, utilizando bráquetes de aço inoxidável. Os resultados mostraram que tanto no grupo I, quanto no grupo II, em 61,5% dos pacientes foi detectada pelo menos uma das bactérias investigadas. P. nigrescens foi a bactéria mais frequentemente detectada no Grupo I (30,8%) e no Grupo II (46,1%), enquanto P. intermedia foi detectada em 3,8% no Grupo I e 11,5% no Grupo II. As bactérias não pigmentadoras de negro foram encontradas em frequências similares nos Grupos I e II (19,2% versus 11,5% para Actinomyces spp e 23,1% versus 30,7% para S. mutans). Não foram encontradas diferenças estatisticamente significativas quando comparando as frequências de cada bactéria entre os grupos, indicando que os perfis bacterianos são similares entre pacientes que apresentam e os que não apresentam manchas extrínsecas negras. Quando analisadas as frequências das bactérias nos biofilmes nas manchas dentárias extrínsecas negras dos pacientes portadores de aparelho ortodôntico, os resultados indicaram que o aparelho não alterou a frequência das bactérias encontradas, porém, foi observada redução significante das associações entre as diferentes bactérias no biofilme das manchas extrínsecas negras (p<0,05).

The subject of this diploma thesis is the construction of a timber foot bridge over the wolf run in the Šumava National Park. The total length of the bridge is 240 m with two ground plan bends. The foot bridge includes three viewing decks, two of which are covered with shed roofs. The foot bridge is divided into 16 segments. Each segment is 15 m long with a width of 2.2 meters. The ground plan dimensions of the viewing decks are approximately 15x7 and 15x11 m. As the main structural material has been chosen glued laminated timber of the strength class GL28h, other elements are made of solid timber of the strength class C24. The thesis includes an introductory document, options analysis, technical report, static analysis, bill of material and drawings.

As typically designed, the beam-column-brace connections of buckling-restrained braced steel frames have undesirable failure modes that compromise the integrity and performance of the frames and are costly to repair. To decrease the time and resources needed to repair the frames following an earthquake, a new connection design was developed that attempts to confine yielding to replaceable frame components. The design incorporates a gap in the beam beyond the edge of the beam-gusset weld that acts as a hinge and reduces moment forces transferred to the connection; it is bridged by splice plates that are bolted to the beam top flanges. The splice plates and buckling-restrained braces are the only frame components that are expected to yield. To investigate the performance of the proposed connection design, a prototype bay was designed and two test specimens were fabricated and tested. Each specimen represented a corner of the prototype braced bay and consisted of a beam, column, gusset plate, brace core extension assembly, splice plates, and lateral bracing angles. Both standard design procedures and newly developed criteria were used to design the connection. In preparation for testing, a method was developed for estimating the hysteretic response of a buckling-restrained brace. By using this method to program an actuator, the specimens could be tested without using actual braces, resulting in a significant reduction in testing cost. Testing was conducted using two 600 kip actuators; the first followed a static loading protocol with a maximum design drift of 6.5%, and the second replicated the prototype BRB's response. The tests yielded promising results: both specimens withstood the maximum displacements and avoided yielding in the beams, columns, and gusset plates; yielding did occur in the splice plates and BRB core extension assembly, as anticipated. Possible limitations in the design may arise under the presence of increased shear loads, concrete floor slabs, or out-of-plane loading. Additional testing is recommended.

No description available.

Résumé : Ce projet de maîtrise s’intéresse au comportement ultime d’une structure en acier, contrôlée sismiquement par des amortisseurs élastomères et des contreventements en chevron. Les séismes peuvent causer des dommages considérables quand les infrastructures et les bâtiments ne sont pas construits selon les normes et les techniques appropriées. Par conséquent, réduire l’impact des séismes revient particulièrement à construire des ouvrages sécuritaires en tenant compte bien entendu du paramètre économique. Ainsi Gauron, Girard, Paultre et Proulx ont étudié en 2009, un système de reprise de forces latérales, constitué uniquement de treventements en chevron montés en série avec des amortisseurs en caoutchouc naturel fibré ayant de nombreux avantages. Premièrement, le système reste élastique sous le séisme de design en réduisant les efforts sismiques linéaires par un facteur supérieur à R[indice inférieur d] = 3 par rapport à un cadre conventionnel. Deuxièmement, il est capable de contrôler les déplacements sous la limite du CNBC 2010 (Code National du Bâtiment du Canada 2010), et même de réduire ces derniers dans certains cas. Par conséquent, il permet de réduire les sections des poutres et des poteaux des cadres par rapport à une structure conventionnelle ainsi que les coûts de réparation après un séisme. Toutefois, le comportement à l’état limite ultime d’un tel système, ses limites et ses réserves de sécurité restaient à déterminer. Ainsi, l’objectif global de ce projet de recherche est de déterminer les différents mécanismes de ruine possibles de ce système, d’établir des limites et réserves de sécurité, et de préciser, après avoir formulé certaines recommandations, à quelles conditions il peut être utilisé dans le dimensionnement de nouvelles structures. Pour atteindre les objectifs fixés, deux essais quasi statiques ont été réalisés sur deux cadres en acier dimensionnés avec le système. Des essais dynamiques ont aussi été réalisés afin d’avoir les propriétés viscoélastiques des amortisseurs. Le premier essai a mis en évidence un mécanisme de ruine inattendu et prématuré qui a souligné un défaut majeur dans les connexions des diagonales avec l’amortisseur. Le second essai a révélé un des mécanismes de ruine envisagés initialement où le caoutchouc se déchire après l’initiation du flambement dans la diagonale comprimée. Les résultats expérimentaux ont montré que l’amortisseur constitue le maillon faible du système, et que des efforts parasites peuvent réduire significativement la capacité portante des structures dimensionnées avec un tel système. Dans les deux cas, les résultats ont montré que la méthode de dimensionnement du système tel qu’elle est définie actuellement mérite d’être améliorée. En ce sens, des recommandations relatives au dimensionnement des différents éléments des structures dimensionnées avec le système ont été élaborées, particulièrement en ce qui concerne le caoutchouc et les connexions. // Abstract : This thesis focuses on the ultimate behavior of steel structures, controlled seismically by elastomeric dampers and chevron bracings. Earthquakes can cause considerable damages when infrastructures and buildings are not built considering appropriate standards and technics. Therefore, mitigating the impact of earthquakes means essentially building safe structures by taking account of economic parameters too. Thus Gauron, Girard, Paultre and Proulx studied in 2009 a seismic force resisting system consisting only of chevron braces connected in series with fiber-reinforced natural rubber dampers that offers many benefits. First, the system remains elastic under the design earthquake by reducing linear seismic efforts by a factor of R[subscript d] = 3 compared to a conventional frame. Secondly, it allows to control the displacements under the limits of NBCC 2010 (National Building Code of Canada 2010), and even to reduce them in some cases. Therefore, it allows a reduction of sections of beams and columns of conventional frames and it prevents repairing costs of the structure after an earthquake. However, the ultimate limit state behavior of this system, its limitations and safety reserves have not been determined yet. Thus, the overall objective of this project is to determine the different possible failure mechanisms of the system, to set its limits and safety reserves, and to state after some recommendations, how it can be used in the design of new structures. To achieve these objectives, two quasi static tests were performed on two steel frames designed with the new system. Dynamic tests were also conducted to get the viscoelastic properties of the damping material. The first quasi static test revealed an unexpected and premature failure mechanism that pointed out a major flaw in the connections of the braces with the damper. The second test revealed one of the failure mechanisms originally expected where the rubber tears after buckling of the compression brace. The experimental results have shown that the damper is the weak element in the system, and that additional forces can significantly reduce the structural capacity of structures designed with the system. In both cases, the results have shown that the actual design method of the system should be improved. Thus, recommendations for the design of elements of structures designed with this system have been developed, particularly with regard to the rubber and brace connections.

Design of a steel supporting structure for one-storeyed hall based on ground plan of 60 x 80 m, clear height 10 m and total height 13,3 m. In the front part there is along the whole widht designed two-storeyed skeleton structure penetrating into the hall. From the second floor rods supported frontal part which exceeds ground plan by 2 m and on the right side is closed by pre-set cylindric structure with radius 8,6 m which covers the right frontal corner of building. The cylindric structure is around its perimeter distanced max 3,6 m from hall grand plan and is supported by posts. Both spaces had saddle roof with 8% slant, gutter edge in height 11,6 m, top line in height 12,8 m. Walls are around perimeter closed by horizontal atic in height of 13,3 m. Shape and dimensional design, load specification – stady, utility, climacic load. Calculation of imide forces and further static dimensioning of the main supporting elements and selected details. Elaboration of design documentation (dosposition, production drawing of the anchorage plan, details definited by project supervizor).

The aim of this diploma thesis was the design of three possible variants, how to span the wide and deep valley with a bridge. After an evaluation, situation of the highway on the only wide load-bearing structure which is constituted by a box girder with transverse cantilevers supported by prefabricated bar braces, was chosen as an optimal solving. The load- bearing structure made of post- tensioned concrete is going to be incrementally launched and be supported by one-column pillars along an axis of the motorway. The work is composed of a detailed design of this preferred variant, which is processed according to the ultimate and serviceability limit state including the construction stage analysis of the bridge by the construction technology by an incremental launching method.