Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-06-09T18:00:24Z No. of bitstreams: 2 Dissertação - Rebeca Freitas Vasconcelos - 2014.pdf: 2286500 bytes, checksum: 175252a3e36474a01ded5d6943e2492f (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-06-10T12:34:58Z (GMT) No. of bitstreams: 2 Dissertação - Rebeca Freitas Vasconcelos - 2014.pdf: 2286500 bytes, checksum: 175252a3e36474a01ded5d6943e2492f (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) / Made available in DSpace on 2016-06-10T12:34:58Z (GMT). No. of bitstreams: 2 Dissertação - Rebeca Freitas Vasconcelos - 2014.pdf: 2286500 bytes, checksum: 175252a3e36474a01ded5d6943e2492f (MD5) license_rdf: 19874 bytes, checksum: 38cb62ef53e6f513db2fb7e337df6485 (MD5) Previous issue date: 2014-08-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work presents the application of optimization techniques for the design of hollow core slabs and beams with precast and prestressed straight cable, considering the calculation of both the immediate losses as the time-dependent. For the slabs formulation allows the designer to obtain the optimal dimensions of the height of the panel, the diameters of the cables and the alveoli, and the number of cables. The beams are obtained beam height, diameter and the number of cables. Are still subject to the conditions of service for bending stresses, constructive limitations and failure conditions. Illustrative examples are presented using the Branch and Bound algorithm and Lingo (PLS), further comparison is made between the weight and the cost of the panel, and from the results of the algorithm and sizing Munte tables that follow Brazilian standards. We conclude that the optimal design has many advantages compared to conventional design, methods of discrete variation that best characterize the optimal variables of the problem, restrictions on the normal stresses ELS are crucial in obtaining the optimal dimensions of the structures and lower panels weight does not necessarily represent the lowest cost. / Este trabalho apresenta a aplicação de técnicas de otimização para o dimensionamento de lajes alveolares e vigas com cabo reto pré-moldadas e protendidas, considerando o cálculo tanto das perdas imediatas quanto das dependentes do tempo. Para as lajes, a formulação permite que o projetista obtenha as dimensões ótimas da altura do painel, dos diâmetros dos alvéolos e dos cabos, e do número de cabos. Nas vigas, são obtidas a altura da viga, o diâmetro e o número dos cabos. São, ainda, observadas as condições de serviço para esforços de flexão, limitações construtivas e condições de falha. Exemplos ilustrativos são apresentados usando o algoritmo de Branch and Bounde o Lingo(PLS). São feitos, ainda, comparativos entre o peso e o custo do painel e entre os resultados obtidos pelo algoritmo e tabelas de dimensionamento encontradas na literatura que seguem normas brasileiras. Conclui-se que o projeto ótimo apresenta inúmeras vantagens se comparado ao projeto convencional, que os métodos de variação discreta caracterizam melhor as variáveis ótimas do problema, que as restrições relativas às tensões normais do ELS são determinantes na obtenção das dimensões ótimas das estruturas e que painéis de menor peso não necessariamente representam o menor custo.

Este trabalho apresenta dois tipos de ensaios não destrutivos para a correlação do módulo dinâmico com a resistência à compressão para elementos de concreto. Os métodos de ensaio são a ultrassonografia e o método de excitação por impulso utilizando o equipamento Sonelastic®. Neste trabalho estão descritos seus funcionamentos, aplicações e limitações. A ultrassonografia, através da propagação de ondas sonoras, fornece, indiretamente, o módulo de elasticidade dinâmico. Com o método de excitação por impulso obtêm-se as frequências naturais e os modos de vibração do elemento estudado, o que permite determinar seu módulo dinâmico. Primeiramente, estes ensaios foram utilizados em corpos-de-prova cilíndricos e lajes alveolares produzidas em laboratório para a obtenção das curvas de correlação e, em seguida, estes mesmos ensaios foram realizados na fábrica de concreto pré-moldado. Para elementos de geometria complexa, como é o caso das lajes alveolares, apresenta-se uma metodologia para a obtenção de uma equação analítica para o cálculo do módulo dinâmico no ensaio de excitação por impulso. Estes métodos tiveram o objetivo final de avaliar a resistência à compressão do concreto na pista de protensão da fábrica, e então determinar o melhor momento para a desforma e corte do cabo de protensão. Com ambos os métodos, obteve-se ótimas correlações do módulo dinâmico com a resistência à compressão dos elementos em laboratório. Na fábrica de concreto pré-moldado não foi possível obter uma curva de correlação representativa de toda a laje na pista de protensão, porém foi possível registrar um bom indicativo de que é possível obter boas correlações para futuras pesquisas no assunto / This work presents two types of non-destructive testing for the correlation of the dynamic elastic modulus with the compressive strength. The test methods are the ultrasonography and the impulse excitation using the Sonelastic® equipment. In this work the equipaments operations, applications and limitations are also described. The ultrasound test indirectly supplies the dynamic elastic modulus through the propagation of sound waves. The natural frequencies and the vibration modes of the studied elements are obtained through impulse excitation method allowing to determine its dynamic modulus. To start, these tests were used in cylindrical specimens and hollow core slabs produced in the laboratory to obtain the correlation curves, and then these same methods were performed in the pre-cast concrete plant. As for complex geometric elements, as in the case of hollow core slabs, a methodology is applied in order to obtain an analytic equation to calculate the dynamic modulus in the impulse excitation test. These methods had the final goal the evaluation of the strength of prestressed concrete lying on track of the plant, so as to determine the best moment to demold and cut the prestressed cable. Excellent correlations of the dynamic modulus with compressive strength of the elements made in laboratory were obtained using both methods. It was not possible to obtain in the precast concrete plant a representative correlation curve of the whole slab on the track, nevertheless, it was possible to record a good indication that it is possible to obtain good correlations for future research.

This thesis focuses on the investigation and development of an integrated optical biosensor based on enhanced Raman techniques that will provide label-free detection of biomolecules. This is achieved by using hollow core photonic crystal fibers (HC-PCF), nanoparticles, or both. HC-PCF is a unique type of optical fiber, with continuous ‘channels’ of air (typically) running the entire length. The channels serve to confine electromagnetic waves in the core of the fiber, and tailor its transmission properties. Using HC-PCF as a biosensor requires development of a robust technique to fill hollow-core photonic crystal fibers. Though several groups have reported selective filling of HC-PCF’s core, the processes are cumbersome and limit the choice of liquid to avoid multimode behavior. In my Master’s thesis, I presented a simple technique to non-selectively fill all the HC-PCF channels with samples. The non-selective filling preserves the photonic bandgap property of the fiber, and yields an extremely strong interaction of light and the sample that produces considerable enhancement of the Raman signal from the analyte. Up to now, non-selective filling was accomplished through capillary action and it delivered a Raman signal enhancement of approximately 30-fold, which is not sensitive enough to detect biomolecules at the clinical level. Moreover, there were issues of reliability and reproducibility, due to evaporation, filling and coupling light into the fiber. The objective of this PhD research was to overcome these problems by developing a robust optical fiber platform based on Raman spectroscopy that can be used in a clinical setting. I initially focused on heparin, an important blood anti-coagulant that requires precise monitoring and control in patients undergoing cardiac surgery or dialysis. Since the Raman spectra of heparin-serum mixtures exhibits Raman peaks of heparin with poor signal-to-noise ratios, I concentrated on enhancing the heparin Raman signal and filtering out the spectral background of the serum to improve detection sensitivity. Reaching maximum enhancement of the Raman signal required a strong interaction of light and analyte, which can be achieved by using hollow core photonic crystal fiber as I had used in my Master’s research. Using a small piece of HC-PCF I was able to reach an enhancement in the heparin Raman signal of greater than 90-fold. With this degree of enhancement, I was able to successfully detect and monitor heparin in serum at clinical levels, something that had never been accomplished previously. After developing HC-PCF as a Raman signal enhancer, I focused on making the HC-PCF sensor robust, reliable and reusable. This was achieved by integrating the HC-PCF with a differential pressure system that allowed effective filling, draining and refilling of the samples in an HC-PCF, under identical optical conditions. To demonstrate the device’s detection capabilities, various concentrations of aqueous ethanol and isopropanol, followed by different concentrations of heparin and adenosine in serum, were successfully monitored. To further improve the sensitivity of the HC-PCF based Raman sensor, I incorporated surface enhanced Raman scattering (SERS), by introducing nanoparticles into the HC-PCF fibers. The research focused on determining the optimal volume and size of silver nanoparticles to achieve maximum enhancement of the Raman signal in the HC-PCF. The HC-PCF enhanced the Raman signal of Rhodamine 6G (R6G) approximately 90-fold. In addition, the optimal size and volume of AgNP enhanced the Raman signal of R6G approximately 40-fold, leading to a total enhancement of approximately 4,000 in HC-PCF. This was then used to demonstrate the application of a SERS based HC-PCF sensing platform in monitoring adenosine (a clinically important molecule), as well as malignant cells such as leukemia. Finally, I used hollow core crystal fibers to significantly enhance the efficiency of two-photon photochemistry. Although two-photon photochemical reactions are difficult to achieve with a small volume, I accomplished it by using a novel platform of HC-PCF to efficiently execute the two-photon induced photodecarbonylation reaction of cyclopropenone 1, and its conversion to the corresponding acetylene. The simple optical design configuration involved coupling an 800-nm tsunami laser to a short piece of HC-PCF filled with the sample. This allowed me to increase the efficiency of two-photon induced photochemistry by 80-fold, compared to a conventional spectrophotometer cuvette. Thus, this work leads to the use of HC-PCFs to more effectively study two-photon induced photochemistry processes, which was limited due to the difficulty of detecting photochemical events with a small excitation volume.

[EN] Several efforts have been made in experimental and theoretical research about shear to understand all the variables that influence the phenomenon. Nowadays, however, due to its complexity, the shear performance of structural concrete elements, especially those without any traditional transversal reinforcement, continue with no clear explanation of the problem. Uncertainty about the problem grows when new variables like fibres are incorporated into the shear study. Research works have demonstrated the effectiveness of steel fibre in improving the mechanical properties of concrete elements. Experimental results reveal that steel fibres have proven effective in improving shear resistance, and they confer some concrete elements more ductility. In adequate amounts, steel fibres can completely or partially substitute traditional shear reinforcements. This is why international codes have included some requirements to take into account the action of fibres on the shear response of concrete elements. However, most recommendations and requirements for steel fibre-reinforced concrete (SFRC) were originally created. New fibres with different materials properties and shapes, such as macrosynthetic fibres, are now available on the market. These fibres, some of which are made of polypropylene, are an alternative in the construction industry given their properties and final cost. Initially, polypropylene fibres were used to control shrinkage cracking. Nevertheless, in the last decade the chemical industry has created larger fibres with better surface shapes, which allows polypropylene fibres to meet the requirements of international codes so they can be used in structural elements. Within this framework, the present PhD thesis aims to contribute to knowledge about fibre reinforced concrete (FRC), especially to study the effectiveness of polypropylene fibres when used as shear reinforcement. For this purpose, a literature review of the material, polypropylene fibre-reinforced concrete (PFRC) and its structural applications is first carried out. This study also discusses the parameters that affect the shear behaviour of traditional concrete and FRC. In order to evaluate the effectiveness of polypropylene fibres in shear, three experimental campaigns are presented. Each campaign represents a different level of study. The first corresponds to the material level, where the shear behaviour of PFRC is evaluated by push-off specimens. The second level involves studying shear in real scale elements. For this purpose, shear critical slender beams were manufactured and tested. The last level corresponds to real application of polypropylene fibres to act as shear reinforcement. In this campaign, deep hollow core slabs, with real sections and supports conditions, were tested. At each level, the shear behaviour of PFRC was evaluated against control reinforced concrete specimens, which were also tested during each campaign. / [ES] Varias investigaciones experimentales y teóricas han sido realizadas para entender el comportamiento a cortante de elementos de hormigón y sus variables. Sin embargo, hoy en día debido a la complejidad del tema, el comportamiento a cortante de elementos de hormigón armado y en especial aquellos que no tienen refuerzo transversal, continúan sin tener una explicación clara. Por otro lado, esta complejidad del cortante aumenta cuando nuevas variables, como las fibras, se incorporan al estudio. Investigaciones han demostrado la efectividad de las fibras de acero para mejorar las propiedades mecánicas de hormigón. Según resultados experimentales, la fibra de acero mejora la resistencia cortante y ductilidad de ciertos elementos. Y en cantidades adecuadas, la fibra puede sustituir total o parcialmente los refuerzos tradicionales de cortante. Es así que varios códigos internacionales han incluido requisitos para tener a las fibras en la respuesta estructural de elementos de hormigón. Sin embargo, estos requerimientos se han creado originalmente para el hormigón reforzado con fibra de acero (Steel fibre-reinforced concrete -SFRC). Nuevas fibras con diferentes materiales y formas, como las fibras macro-sintéticas, han sido introducidas en el mercado. Estas fibras, también llamadas fibras de polipropileno o poliolefina, son una alternativa en la construcción debido a su propiedades y costo final. Inicialmente, las fibras de polipropileno eran usadas únicamente en el hormigón para controlar la fisuración por retracción. Sin embargo, en la última década la industria química ha desarrollado fibras más grandes y con mejores prestaciones de adherencia, que permiten a estas fibras cumplir con requisitos para ser utilizadas estructuralmente. En este contexto, la presente tesis pretende ser una contribución al conocimiento sobre el hormigón reforzado con fibras (Fibre-reinforced concrete - FRC), especialmente en la efectividad de las fibras de polipropileno como refuerzo a cortante. Para esto, primero se realiza un estudio bibliográfico del hormigón reforzado con fibra de polipropileno (PFRC) como material y sus aplicaciones estructurales. Este estudio también tratará sobre los parámetros que afectan el comportamiento a cortante del hormigón tradicional y hormigón reforzado con fibras. Para evaluar la efectividad de las fibras de polipropileno en el cortante, se realizarán tres campañas experimentales. Cada campaña representa un nivel de estudio diferente. El primero es a nivel material en donde se evalúa el comportamiento a cortante a través de especímenes tipo Push-off. El segundo nivel, corresponde al estudio del cortante en elementos a escala real. Para esto se fabrican y ensayan vigas esbeltas críticas a cortante. El último nivel corresponde a una aplicación real de fibras de polipropileno actuando como refuerzo cortante. En esta campaña, se fabrican y ensayan placas alveolares de gran canto con secciones y condiciones de apoyos reales. / [CA] Diverses investigacions experimentals i teòriques han estat realitzades per entendre el comportament a tallant d'elements de formigó i les seues variables. No obstant això, hui en dia a causa de la complexitat del tema, el comportament a tallant d'elements de formigó armat i especialment aquells que no tenen reforç transversal, continuen sense tindre una explicació clara. D'altra banda, aquesta complexitat del tallant augmenta quan noves variables, com les fibres, s'incorporen a l'estudi. Investigacions han demostrat l'efectivitat de les fibres d'acer per a millorar les propietats mecàniques del formigó. Segons resultats experimentals, les fibres d'acer milloren la resistència a tallant i la ductilitat de certs elements. A més, en quantitats adequades, les fibres poden substituir total o parcialment els reforços tradicionals de tallant. És així que diversos codis internacionals han inclòs requisits per a tindre amb compte la resposta estructural de les fibres en els elements de formigó. No obstant això, aquests requeriments s'han creat originalment per al formigó reforçat amb fibres d'acer (Steel fibre-reinforced concrete -SFRC). Noves fibres amb diferents materials i formes, com les fibres macro-sintètiques, han estat introduïdes al mercat. Aquestes fibres, també anomenades fibres de polipropilè o poliolefina, són una alternativa a la construcció a causa de les seues propietats i cost final. Inicialment, les fibres de polipropilè eren usades únicament en el formigó per controlar la fissuració per retracció. No obstant això, en l'última dècada, la industria química ha desenvolupat fibres més grans i amb millors prestacions d'adherència, que permeten a aquestes fibres complir amb requisits per a ser utilitzades estructuralment. En aquest context, la present tesi pretén ser una contribució al coneixement sobre el formigó reforçat amb fibres (Fibre-reinforced concrete - FRC), especialment en l'efectivitat de les fibres de polipropilè com a reforç a tallant. Per això, primer es realitza un estudi bibliogràfic del formigó reforçat amb fibres de polipropilè (PFRC) com a material i les seues plicacions estructurals. Aquest estudi també tractarà sobre els paràmetres que afecten el comportament a tallant del formigó tradicional i del formigó reforçat amb fibres. Per avaluar l'efectivitat de les fibres de polipropilè en el tallant, es realitzaran tres campanyes experimentals. Cada campanya representa un nivell d'estudi diferent. El primer és a nivell material on s'avalua el comportament a tallant a través d'espècimens tipus Push-off. El segon nivell, correspon a l'estudi del tallant en elements a escala real. Per això es fabriquen i assagen bigues esveltes crítiques a tallant. L'últim nivell correspon a una aplicació real de fibres de polipropilè actuant com a reforç a tallant. En aquesta campanya, es fabriquen i assagen plaques alveolars de gran cantell amb seccions i condicions de suports reals. / Ortiz Navas, FR. (2020). Effectiveness of polypropylene fibres as shear reinforcement in structural elements [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/153147 / TESIS

Dans ce manuscrit, nous rapportons les développements, théoriques et expérimentaux, en cours à TRT ainsi qu’à TAV et au LAC, visant la réalisation d’un gyromètre résonant passif en fibre optique à cœur creux atteignant des performances permettant la navigation inertielle. Nous y décrivons mathématiquement l’effet Sagnac, effet relativiste à la base des mesures optiques dans les gyromètres. Ensuite, nous exposons en détail les méthodes utilisées à ce jour pour mesurer des rotations avec des gyromètres passifs par les différentes équipes de recherches. Nous explicitons les limitations de ces méthodes, et en quoi la fibre optique à cœur creux semble être la solution la plus prometteuse pour pallier les défauts des gyromètres passifs résonants actuels. Une partie de cette thèse est alors consacrée à l’étude des propriétés physiques des fibres à cœur creux (Kagomé et bande interdite photonique), telles que leur atténuation, leur capacité à maintenir la polarisation, et leur rétrodiffusion. Nous présentons la première mesure de zone aveugle (plage de faibles vitesses de rotations non mesurables par un gyromètre) dans un gyromètre résonant passif en fibre à cœur creux. Un modèle mathématique est posé pour expliquer le lien entre cette zone aveugle et la rétrodiffusion au sein de la cavité résonante. Nous décrivons ensuite un protocole expérimental permettant de s’affranchir de cette limitation dans notre gyromètre. Nous détaillons enfin la mise en œuvre de ce protocole et caractérisons les performances ainsi atteintes par notre gyromètre / In this manuscript, we report the theoretical and experimental developments at TRT, TAV and LAC, aiming the realization of a hollow-core passive resonant fiber optical gyroscope that can achieve navigation grade performances. We mathematically describe the Sagnac effect, which is a relativistic effect used to optically probe mechanical rotations. Then, we detail the state of the art in passive resonant fiber optical gyroscope development. We identify their limitations, and explain why the hollow core fiber seems to be the best solution to cope with the actual limitations of such gyroscopes. We then focus on two different types of hollow core fibers: Kagome and photonic bandgap. We evaluate their performances in terms of transmission, polarization holding and backscattering. We describe the first measurement of a lock in region in a hollow core fiber passive optical gyroscope, i.e the range of rotation rates that cannot be measured because of backscattering. A mathematical model is propounded to link the lock in to the backscattering of the cavity. We then discuss the experimental protocol that we implemented to circumvent this limitation. Finally, we characterize the performances of our gyroscope based on these features

Diploma thesis is processed in the form design documentation for constrution. New bulding of the kindergarten is situated in a cadastre unit of Blansko town. Building is located on a flat terrain.„T“ shaped building is designes as a double-storey in one part, second part of the building is single-story. A construction systém is bricked from ceramic block and it has no basement. The building is roofed by non-walkable flat roof. Part of the building is roofed by a ealkable flat terrace. A ceiling construction is made by hollow core slab. The kindergarten is consisted of three departmen, each for 20 children. There is a kizchen, offices, technical area and office for a logopedie in the building

This diploma thesis solves the project of materniti house in moderate terrain. Kindergarten is located on the lands p.č. 967/1, st. p.č. 2354, st. p.č. 1553/1 in Hradec Králové. The building has two floors. Kindergarten is designed for a maximum of 40 children and more than 10 employees. The building serves as a pre-school education for children. The building has a load-bearing wall systém. The external walls, load-bearing walls and partition walls are lined with sand-lime bricks KM BETA SENDWIX. The external walls are insulated with mineral wool thickness 180mm. The ceilings are made of prestressed hollow core slabs spiroll thickness of 250mm. The building´s roof is warm flat roof. The facade is unventilated. Wooden windows are from Slavona. Entrance doors are wooden double doors from Slavona.

Utvecklingen av framtidens flerbostadshus ställer höga krav på en bjälklagslösnings tekniska egenskaper. Plattbärlagsbjälklaget som idag utgör det vanligaste förekommande bjälklagsvalet vid uppförandet av flerbostadshus kan ses som en lösning som kombinerar en god bärförmåga med stora möjligheter ur teknisk synpunkt. Målet med denna undersökning har varit att jämföra det traditionella plattbärlaget med en nyutvecklad bjälklagslösning baserad på produkten förspänt håldäcksbjälklag (HD/F). Jämförelsen har utgått från de aktuella kraven som enligt Boverkets byggregler (BBR) idag ställs på bjälklag och fokuserat på aspekter ur ljud, brand och fuktsynpunkt. Dessutom har jämförelsen beaktat de maximala spännvidder som respektive lösning kan dimensioneras för. Resultatet av de genomförda undersökningarna visade på att den nyutvecklade bjälklagslösningen är tillräckligt konkurrenskraftig för att i framtiden få ett större användande inom flerbostadshus. Medan plattbärlagets fördelar utmärker sig ur ljudsynpunkt möjliggör dock användandet av den nyutvecklade lösningen längre spännvidder och kortare torktider. / The development of apartment buildings puts high demands on the technical characteristics of floor systems. The lattice girder system which today represents the most commonly utilized floor system when building apartment buildings, is characterized by a good load-bearing ability along with great opportunities from a technical point of view. The aim of this analysis was to compare the traditional lattice girder system with a newly developed floor system based on hollow core slabs. The comparison is based on the current technical requirements set by Boverkets byggregler (BBR) and has its main focus on subjects related to sound, fire and moisture matters. The comparison has also accounted for the maximum spans which can be used for each solution respectively. The results of the investigation show that the newly developed floor system is competitive enough to be used in future apartment buildings. While the advantages of the lattice girder system are distinctive from a sound point of view, the utilization of the newly developed floor solution enables longer spans and shorter curing time.

For intermediate floors in residential and office buildings, as well as in parking garages and malls, there is a wide use of hollow core concrete slabs in Sweden today. Hollow core slabs are precast and prestressed concrete elements with cylindrical-shaped voids extending along the length of the slab. These structural elements have the advantage compared to cast-in-situ concrete slabs that they have a high strength, due to the prestressing, and that the voids allow for a lower self-weight. Additionally, the voids allow for a reduction in the use of concrete material. These characteristics offer possibilities to build long-span floors with slender designs. However, a consequence of the slenderness of the slabs is that such floors have an increased sensitivity to vibrations induced by various dynamic loads. In residential and office buildings vibrations are primarily caused by human activity, and therefore concerns related to the serviceability of such floors are raised. These vibrations are often not related to problems with structural integrity, but rather to different aspects of comfort of the residents or workers. The aim of this thesis is to provide additional information regarding the dynamic behavior of hollow core floors. An experimental modal analysis has been performed on an existing floor in an office building. The dynamic properties in the form of natural frequencies, mode shapes, damping ratios and frequency response functions were derived and analyzed from these measurements. Subsequently, several finite element models were developed, aiming to reproduce the experimental dynamic behavior of the studied floor. The measurements initially showed some unexpected dynamic responses of the floor. For this reason, more advanced methods of signal analyses were applied to the data. The analyses showed that the slab has some closely spaced modes and that the modes of the floor are complex to a certain degree. The finite element models were studied with different configurations. In particular, the effect the model size, boundary conditions, material properties and potential structural discontinuities have on the dynamic response of the slab was studied. Sufficiently good agreement has been achieved between the experimental and numerical results in terms of natural frequencies and mode shapes. The acceleration amplitude responses of the numerical models were generally higher than the ones obtained from the measurements, which leads to difficulties in matching of the frequency response functions. / Håldäck i betong används idag i stor utsträckning som bjälklag i bostads- och kontorsbyggnader, liksom i parkeringsgarage och köpcentra. Håldäcksbjälklag består av prefabricerade och förspända betongelement, med cylindriska hål som sträcker sig i plattans längsriktning. Dessa konstruktionselement har fördelen, jämfört med platsgjutna betongplattor, att de har en hög hållfasthet på grund av förspänningen och att hålen möjliggör en lägre egenvikt. Dessutom gör hålen att en mindre mängd betongmaterial behövs. Dessa egenskaper ger möjligheter att bygga golv med långa spännvidder och slank design. En konsekvens av slankheten är emellertid att sådana golv har en ökad känslighet för vibrationer som orsakas av olika dynamiska belastningar. I bostads- och kontorsbyggnader orsakas vibrationer främst av mänsklig aktivitet, och därför finns det en del oro relaterad till sådana golvs brukbarhet. Dessa vibrationer är oftast inte relaterade till frågor om strukturell integritet, utan snarare till olika aspekter av boendes eller arbetares känsla av komfort. Syftet med detta examensarbete är att bidra till kunskapen om håldäcksbjälklags dynamiska beteende. En experimentell modalanalys har utförts på ett befintligt golv i en kontorsbyggnad. De dynamiska egenskaperna i form av egenfrekvenser, modformer, dämpning och frekvenssvarsfunktioner erhölls och analyserades med hjälp av dessa mätningar. Därefter utvecklades flera finita element modeller för att reproducera det experimentellt uppmätta dynamiska beteendet hos det studerade golvet. Mätningarna visade initialt något oväntade dynamiska responser från golvet. Av denna anledning applicerades mer avancerade signalanalysmetoder på datan. Analyserna visade att plattan har några moder inom ett litet frekvensintervall och att moderna till en viss grad är komplexa. De finita element modellerna studerades med olika konfigurationer. I synnerhet studerades effekten av modellstorleken, randvillkoren, materialegenskaperna och potentiella strukturella diskontinuiteter på golvets dynamiska respons. Tillräckligt bra överensstämmelse har uppnåtts mellan de experimentella och numeriska resultaten i form av egenfrekvenser och modformer. Accelerationsamplituderna för de numeriska modellerna var i allmänhet högre än de som erhölls under mätningarna, vilket leder till svårigheter att matcha frekvenssvarsfunktionerna.

This thesis focuses on improving the performance of the THz time-domain spectroscopy system using second-order nonlinear crystals for THz generation and detection in terms of bandwidth, sensitivity, and THz field strength. The theories for the THz generation based on optical rectification and detection technique, electro-optical sampling, based on Pockels effect are introduced in Chapter 2. In Chapter 3, some experiments are presented to characterize the performances of the THz system based on a 180 fs Yb:KGW femtosecond laser amplifier operating at 1035 nm. The Yb-based femtosecond laser is becoming increasingly popular due to its robustness, high repetition rate, and high average power. However, the NIR bandwidth of these femtosecond lasers is limited by the gain bandwidth of the gain medium, and achieving pulse durations shorter than 180 fs is challenging. Consequently, the full bandwidth of THz time-domain spectroscopy systems is constrained by such laser systems. In order to broaden the THz bandwidth of such THz time-domain spectroscopy systems, our work in Chapter 4 combines the Yb:KGW femtosecond laser amplifier with an argon-filled hollow-core photonic crystal fiber pulse shaper to spectrally broaden the near-infrared pulses from 3.5 to 8.7 THz, increasing the measured THz bandwidth correspondingly from 2.3 THz to 4.5 THz. This is one of the first works to have broadband THz system based on Yb-based femtosecond lasers in the year of 2018. In Chapter 5, the tilted-pulse-front phase matching in the THz generation and detection scheme is demonstrated using the same surface-etched phase gratings on the front surfaces of the 2 mm-thick GaP generation and detection crystals. This scheme overcomes the THz generation and detection bandwidth limit of thick crystals imposed by the traditional collinear phase matching, while allowing the long nonlinear interaction length. This results in a THz spectral range from 0.1 to 6.5 THz with a peak at 3 THz and a peak dynamic range of 90 dB. In the range between 1.1 and 4.3 THz, the system dynamic range exceeds 80 dB. Based on this contact grating-based THz generation, the next step involves generating high-field THz above 2 THz. For high-field THz generation, the most renowned technique is the tilted-pulse-front technique, which generates high-field THz below 2 THz in a LiNbO₃ crystal. Most nonlinear optics experiments in the THz regime rely on such THz sources. To generate high-field THz above 2 THz, one promising candidate is organic THz crystals. However, most organic crystals require a pump laser with a wavelength exceeding 1200 nm, necessitating a more complex laser system. Additionally, the low damage threshold of these crystals are susceptible to compromise the stability of the measurements. Other techniques, such as air plasma and metallic spintronics, can generate ultra-broadband high-field THz from 0.1 to 30 THz, but the pulse energy within certain frequency windows is relatively low, rendering these THz sources less effective for nonlinearly driving specific optical transitions. On the other hand, semiconductor crystals as THz generation crystals, have a high damage threshold and can achieve good phase matching at wavelength around 800 or 1000 nm. In Chapter 6, high-field THz generation with a peak field of 303 kV/cm and a spectral peak at 2.6 THz is achieved with a more homogenous grating on the surface of a 1 mm-thick GaP generation crystal in a configuration collimating the near-infrared generation beam with a pulse energy of 0.57 mJ onto the generation crystal. The experiments also show that the system operates significantly below the GaP damage threshold and THz generation saturation regime, indicating that the peak THz field strength can approach 1 MV/cm, with a 5 mJ near-infrared generation pulse. This is the first high-field THz source based on semiconductor crystals capable of generating high-field THz above 2 THz. With such a THz source, we can conduct nonlinear optics experiments above 2 THz, including the study of phonon-assisted nonlinearities, coherent control of Bose-Einstein condensation of excitons and polaritons in semiconductor cavities, and saturable absorption in molecular gases.