Diante da evolução da composição das resinas compostas e do lançamento de compósitos do tipo bulk fill, faz-se necessário o estudo do desempenho dessa nova classe de materiais. Para isso, o presente estudo teve como objetivo avaliar propriedades como grau de conversão (GC) , dureza Knoop (KHN), resistência à flexão (RF) e tenacidade à fratura (KIC) de sete compósitos bulk fill (EverX Posterior, EXP; Filtek Bulk Fill Flow, FBFF; Fill-Up!, FU; SonicFill, SF; Surefil SDR, SDR; Tetric EvoCeram Bulk Fill, TECBF; Venus Bulk Fill, VBF) e um compósito nanohíbrido convencional (Charisma Diamond, CD). De forma complementar, foi realizado tratamento térmico a 170 °C por 10 minutos para melhor compreensão do comportamento desses materiais quanto ao potencial de conversão e à indução de tensões na interface carga/matriz. A avaliação do GC (n=3) foi realizada através de espectroscopia FTIR, a leitura da dureza Knoop foi realizada nas superfícies do topo e da base (n=3), e os ensaios de RF de três pontos (n=10) e KIC (n=10) em máquina de ensaios universais. Os resultados obtidos foram submetidos à analise de variância (complementados pelo teste de Tukey) ou teste Kruskal-Wallis, com nível de significância de 5%. A análise do GC (%) revelou diferença entre os materiais testados, sendo que todas as resinas bulk fill apresentaram valores maiores que a resina convencional: SF (75,7) > VBF (66,7) = EXP (66,4) = SDR (62,8), sendo esta também semelhante a FU (60,0); FU, TECBF (56,6), FBFF (56,6) e CD (54,5) apresentaram conversão semelhante. Os valores de KHN variaram de acordo com o material e com a superfície: apenas SF apresentou KHN semelhante (na superfície do topo) a CD, entretanto não foi possível realizar a leitura da superfície da base deste último material; SF, TECBF e FBFF apresentaram valores de KHN diferentes nas superfícies topo e base; EXP, FU, SDR e VBF mantiveram os valores de dureza do topo semelhantes à superfície da base. Para a RF (MPa), os resultados variaram de acordo com o material: EXP (122,54) = SF (101,09) = CD (99,15), sendo estes dois últimos semelhantes a FU (83,86) e TECBF (82,71), os quais não diferiram da resina SDR (65,18); esta última também mostrou comportamento semelhante a FBFF (60,85) e VBF (59,90). Quanto ao KIC (MPa.mm0,5), EXP (3,35) apresentou o maior valor, semelhante a SF (2,42), que por sua vez também foi igual ao compósito convencional CD (2,01); CD apresentou KIC semelhante a SDR (1,74); SDR = VBF (1,59) = TECBF (1,57); TECBF, FU (1,54) e FBFF (1,37) apresentaram valores semelhantes. Na dependência do material, o tratamento térmico aumentou os valores dos parâmetros estudados, apontando limitações da reação de polimerização dos compósitos estudados. Com base nos resultados obtidos, podese concluir que: resinas bulk fill apresentam elevado GC, superior à resina convencional estudada; a nova classe de materiais restauradores é capaz de polimerizar em profundidade e alguns materiais apresentam KHN semelhantes no topo e na base de espécimes de 4 mm de profundidade; RF e KIC variaram de acordo com o material, e o compósito EXP apresentou os maiores valores para ambos os testes. / Facing the evolution of the resin composites and the release of the bulk-fill composite type, it is necessary to study the performance of this new class of materials. For this, the present study aimed to evaluate properties such as degree of conversion (DC), Knoop hardness (KHN), flexural strength (FS) and fracture toughness (KIC) of seven bulk-fill composites (EverX Posterior, EXP; Filtek Bulk Fill Flowable, FBFF; Fill-Up!, FU; SonicFill, SF; Surefil SDR, SDR; Tetric EvoCeram Bulk Fill, TECBF; Venus Bulk Fill, VBF) and a conventional nanohybrid composite (Charisma Diamond, CD). Complementarily, heat treatment was performed at 170 °C for 10 minutes for better understanding the behavior of these materials. Evaluation of DC (n=3) was performed by FTIR spectroscopy, the evaluation of Knoop hardness was made on the top and bottom surfaces (n=3), and three point bending test (n=10) and KIC (n=10) were evaluated on a universal testing machine. The results were submitted to analysis of variance (complemented by Tukey test) or Kruskal-Wallis test with 5% significance level. Analysis of DC (%) revealed differences between tested materials, and all bulk-fill resins had higher values than the conventional resin: SF (75.7) > VBF (66.7) = EXP (66.4) = SDR (62.8), which was also similar to FU (60.0); FU, TECBF (56.6), FBFF (56.6) and CD (54.4) showed similar conversion. KHN values showed variations according to the material and the surface: only SF showed a similar KHN (on the top surface) to CD, however it was not possible to read the bottom surface of this latter material; SF, TECBF and FBFF presented different KHN values on the top and bottom surfaces; EXP, FU, SDR and VBF maintained top and bottom similar hardness values. For FS (MPa), the results varied according to the material: EXP (122.54) = SF (101.09) = CD (99.15), the latter two being similar to FU (83.86) and TECBF (82.71), which did not differ from SDR resin (65.18); the latter showed similar behavior to FBFF (60.85) and VBF (59.90). As for KIC (MPa.mm0.5), EXP (3.35) had the highest value, similar to SF (2.42), which in turn was also equal to the conventional composite CD (2.01); CD presented KIC similar to SDR (1.74); SDR = VBF (1.59) = TECBF (1.57); TECBF, FU (1.54) and FBFF (1.37) were similar. Depending on the material, heat treatment increased the values of the parameters, pointing limitations of polymerization reaction of the studied composites. Based on these results, it can be concluded that: bulk fill resins have high DC, higher than the conventional resin studied; the new class of restorative materials is capable of polymerizing in depth and some materials exhibited similar KHN at the top and bottom surfaces of 4 mm depth specimens; FS and KIC varied according to the material, and the EXP composite showed the highest values for both tests.

The purpose of the work is the determination of flexural properties for thebiocomposite Durapulp. The study includes laborative tests on Durapulp andreference materials, commonly used in the building sector. Stiffness and strength of Durapulp show that it has the potential as a replacement for conventional wood-based materials.

Rotating Euler-Bernoulli beams and non-homogeneous Timoshenko beams are widely used to model important engineering structures. Hence the vibration analyses of these beams are an important problem from a structural dynamics point of view. The governing differential equations of both these type of beams do not yield any simple closed form solutions, hence we look for the inverse problem approach in determining the beam property variations given certain solutions. Firstly, we look for a rotating beam, with pinned-free boundary conditions, whose eigenpair (frequency and mode-shape) is same as that of a uniform non-rotating beam for a particular mode. It is seen that for any given mode, there exists a flexural stiffness function (FSF) for which the ith mode eigenpair of a rotating beam with uniform mass distribution, is identical to that of a corresponding non-rotating beam with same length and mass distribution. Inserting these derived FSF's in a finite element code for a rotating pinned-free beam, the frequencies and mode shapes of a non-rotating pinned-free beam are obtained. For the first mode, a physically realistic equivalent rotating beam is possible, but for higher modes, the FSF has internal singularities. Strategies for addressing these singularities in the FSF for finite element analysis are provided. The proposed functions can be used as test functions for rotating beam codes and also for targeted destiffening of rotating beams. Secondly, we study the free vibration of rotating Euler-Bernoulli beams, under cantilever boundary condition. For certain polynomial variations of the mass per unit length and the flexural stiffness, there exists a fundamental closed form solution to the fourth order governing differential equation. It is found that there are an infinite number of rotating beams, with various mass per unit length variations and flexural stiffness distributions, which share the same fundamental frequency and mode shape. The derived flexural stiffness polynomial functions are used as test functions for rotating beam numerical codes. They are also used to design rotating cantilever beams which may be required to vibrate with a particular frequency. Thirdly, we study the free vibration of non-homogeneous Timoshenko beams, under fixed-fixed and fixed-hinged boundary conditions. For certain polynomial variations of the material mass density, elastic modulus and shear modulus, there exists a fundamental closed form solution to the coupled second order governing differential equations. It is found that there are an infinite number of non-homogeneous Timoshenko beams, with various material mass density, elastic modulus and shear modulus distributions, which share the same fundamental frequency and mode shape. They can be used to design non-homogeneous Timoshenko beams which may be required for certain engineering applications.

Det blir allt vanligare att använda laminerat glas som ett konstruktionsmaterial. Men glas är ett känsligt och genomskinligt material som kan ge en obehaglig känsla om det spricker. Särskilt om det handlar sig om en glaskonstruktion som ska hålla en stor del av en byggnad. En glaskonstruktion bör upplevas trygg att vistas i. Idag är det svårt att ersätta bärande konstruktionsdelar med glas i Sverige  eftersom det inte finns några särskilda dimensioneringsregler för glas. I det här examensarbetet genomförs en undersökning om hur laminerat glas böjer sig när det utsätts för belastning och varierande temperaturer under en kort tid. Det studeras hur tjockleken på mellanskiktet påverkar spänningen samt skjuvstyvheten i glasen. För att få relevanta jämförelser studeras även beteendet hos en osprucken och en sprucken laminerad balk. Med hjälp av litteraturstudier och teoretiska beräkningar har beteendet hos laminerade glasbalkar med olika förutsättningar undersökts. Resultatet visar att belastningar som verkar på en laminerad balk under en kort tid leder till ett varierande beteende och deformationer beroende på temperatur, skjuvstyvhet och tjocklek hos laminatet. Det upptäcktes ett gränsvärde vid temperaturen 50 °C där en förändring sker i sambandet mellan laminatets tjocklek, temperatur och nedböjningen. Beteendet och deformationen hos en laminerad balk varierar också beroende på om balken är sprucken eller inte. / It is becoming increasingly common to use laminated glass as a construction material. But glass is a sensitive and translucent material that can give an unpleasant feeling if it cracks. Especially if it is a glass structure that will hold a large part of a building. A glass structure should be considered safe to stay in. Today, it is difficult to replace supporting structural parts with glass in Sweden due to the lack of design rules. In this thesis, a study is conducted on how laminated glass bends when exposed to mechanical loads and varying temperatures for a short time. It is studied how the thickness of the middle layer plays a role, how the tension and the shear stiffness vary in the glass. In order to obtain relevant comparisons, the behavior of an unbroken and a cracked laminated beam is also studied. With the help of literature studies and theoretical calculations, the behavior of laminated beams under different conditions was examined. The results show that loads that act on a laminated beam for a short time lead to varying behavior and deformations depending on temperature, shear stiffness and interlayer thickness. A limit value was detected at the temperature of 50 °C where a change in the relation between interlayer thickness, temperature and deformation occurs. The behavior and deformation of a laminated beam also varies whether the laminate is cracked or not cracked.

This thesis deals with analyses of thermoplastic welded joints. Experiments were performed, in which the not-welded specimens and specimens with cruciform welded joints were tested by tensile and three-point bending test. For these measurements, polypropylene and polyethylene specimens were used. Afterwards, the analyses of specimen models were made in the ANSYS programme. The results of the analyses were compared with figures of the analytic calculations and measurements.

This diploma thesis deals with the comparison of different properties of fibre-reinforced concrete according to the type of fibres. The main monitored property is flexural strength, tested on prisms with a cross section of 150x150 mm and a length of 600 mm. Four concretes of natural aggregate and four concrete of lightweight aggregate were prepared for the experiment. There were 2 reference concrete and 6 fibre-reinforced concrete. Three types of fibres were used: steel, polypropylene and glass. More than 2500 kg of concrete was produced. The aim of the thesis is to assess the influence of fibres on the flexural strength and other characteristics of fibre-reinforced concrete.

El presente artículo de estudio analizó la resistencia al fuego del concreto con adición de cenizas de cascara de arroz (CCA) y bagazo de caña de azúcar (CBCA). Se adoptó un método experimental como diseño de investigación, que produjo setenta y dos probetas cilíndricas (72) y cincuenta y cuatro vigas (54), para ensayos a compresión y flexión respectivamente. Se utilizaron cenizas en porcentajes de 5% y 10% y además una combinación binaria de 5% y 5% de ambas cenizas como reemplazo parcial de cemento. Las muestras fueron ensayadas luego de 28 días de curado a temperaturas de 24 °C (ambiente), 300 °C y 500 °C, con una duración de 2h de exposición y luego de 24 horas de enfriamiento al aire libre. Los resultados muestran un aumento de resistencia promedio a la compresión y flexión de hasta un 95% y 25%, respectivamente, luego de ser expuestos a temperaturas elevadas con respecto a las muestras de control. / This study article analyzed the fire resistance of concrete with the addition of rice hull ash (CCA) and sugarcane bagasse (CBCA). An experimental method was adopted as the research design, which produced seventy-two cylindrical specimens (72) and fifty-four beams (54), for compression and bending tests respectively. Ashes were used in percentages of 5% and 10% and a binary combination of 5% and 5% of both ashes as a partial replacement for cement. The samples were tested after 28 days of curing at temperatures of 25 ° C (ambient), 300 ° C and 500 ° C, with a duration of 2 hours of exposure and after 24 hours of cooling in the open air. The results show an increase in average resistance to compression and flexion of up to 95% and 25%, respectively, after being exposed to high temperatures compared to the control samples. / Trabajo de investigación

In this time are for design of wooden elements available simplified procedures for fire modeling which defines ČSN EN 1991-1-2. But it is not experimentally tested the impact of adhesive on the final value of fire resistance of laminated panels. This diploma thesis solves basic normative practices that could explain the durability of glue bond against increased temperatures. in the practical part will be undertaken to experimentally assess the impact of various kinds of adhesive-based (epoxy, formaldehyde, PUR and EPI) on the glued bond durability against increased temperature. Glued joints that will be subjected to gradual temperature exposure in order to assemble the dependence of the temperature influence on the final strength of the joint according to the type of adhesive.

Thesis deals with flexural-lateral buckling of asymmetric cross sections, especially assessment according to ČSN EN 1993-1-1. Models are based on bar, shell and solid finite element method. Assessment of software Scia Engineer and RFEM are analysed in bar model. Plate and volume model uses shell and solid elements and initial imperfections. Computing is geometrically nonlinear. Correspondence of bar and plate model is studied. Optimal amplitude is suggested. Simple beam loaded with continuous line loading is taken as an example.

Cette thèse s’inscrit dans une démarche d’amélioration des connaissances des instabilités des éléments comprimés et fléchis sensibles aux effets du second ordre. Il s’agit de traiter la prise en compte des imperfections initiales dans l’analyse de la structure et d’adapter les critères actuels de vérification pour les structures tubulaires de type échafaudage. Les formulations existantes, proposées dans la littérature et les codes de calculs, sont souvent issues d’hypothèses, et conduisent à des incohérences entre les critères de vérification en section, et les critères de vérification en instabilité. L’approche développée traite l’interaction entre la résistance en section et les phénomènes d’instabilités, et inclut l’influence des imperfections initiales. Ces effets seront, dans la mesure du possible, découplés. À ce titre, une méthode a été conçue pour permettre la définition des imperfections initiales d’une structure, de manière à être la plus précise possible. Cette méthode, basée sur la définition d’une imperfection unique, d’allure identique à la déformée critique du mode de flambement prépondérant, est une méthode précise, entièrement définie permettant de tenir compte des caractéristiques géométriques, des caractéristiques mécaniques intrinsèques, des conditions aux limites et de la forme du chargement, dans la définition de l’imperfection initiale unique d’une structure. Une campagne d’essai a été réalisée en collaboration avec le SFECE, visant à analyser le comportement expérimental au flambement de sections tubulaires formées à froid. Des essais de flambement sur des échelles d’échafaudage, provenant de divers fournisseurs européens, ont été effectués. Une étude statistique des résultats expérimentaux a permis de mettre en évidence que le facteur d’imperfection actuellement défini pour les sections tubulaires formées à froid est bien trop pénalisant à l’égard des sections usitées dans le domaine des échafaudages. Afin de répondre à la problématique, de nouveaux critères de vérification en instabilité ont également été établis en utilisant une approche similaire à celle d’Ayrton-Perry. Ces nouveaux critères permettent de s’affranchir de la modélisation des imperfections initiales tout en offrant une estimation sûre et précise du facteur de sollicitation d’une structure. Des études comparatives ont été menées de manière à s’assurer de la sécurité des formulations proposées par rapport aux critères de vérification en section de la norme actuelle. / This thesis is part of an effort to improve knowledge of the instabilities of beam-columns sensitive to second-order effects. The works deal with the means to take into account the initial imperfections in the structural analysis and to adapt the current verification criteria for tubular section structures, such as scaffold structures. The existing formulations, proposed in the literature and calculation codes, are often based on hypotheses, and thus lead to inconsistencies between, on the one hand, the verification criteria in section, and on the other hand, the verification criteria in instability. The developed approach takes into account the interaction between section resistance and instability phenomena, and includes the influence of initial imperfections (initial defect of aplomb, lack of straightness, residual stresses). As far as possible, these effects will be decoupled. As such, a method has been developed to allow the definition of initial imperfections of a structure, to be as accurate as possible. This method, based on the definition of a single imperfection, identical in appearance to the shape of the predominant critical buckling mode, is a precise, fully defined method to take into account the geometric characteristics, intrinsic mechanical characteristics, limits and the form of loading, in the definition of the initial imperfections of a structure. A test campaign was carried out in collaboration with the French Syndicate of Scaffolding, Formwork and Shoring (SFECE), aiming to analyze the experimental behavior of buckling of cold-formed tubular sections. Nine buckling tests on scaffold ladders, from various European suppliers, have been carried out. A statistical study of the experimental results has made it possible to highlight that the imperfection factor currently defined for the cold-formed tubular sections is far too penalizing for the sections used in the field of scaffolds. In order to respond to the problem, new instability criteria have also been established using a similar approach to that of Ayrton-Perry. These new criteria make it possible to free ourselves from the modeling of initial imperfections while offering a safe and accurate estimate of the stress factor of a structure. A comparative study was conducted in order to ensure the safety of the proposed formulations as regards the section verification criteria of the NF EN 1993-1-1 current standard.