The increased amount of traffic combined with higher traffic loads leads to many existing bridges needing strengthening in the future to ensure their expected lifespan. This means the bridge owners will be focusing more on strengthening projects and smart solutions will be crucial for preserving a healthy bridge stock. When strengthening existing non-composite bridges (with steel girder and concrete deck) one potential method is to achieve composite action by installing shear connectors. The post-installed shear connectors prevent slip between the steel girders and the concrete. The composite action will reduce bending stresses and deflection of the bridge, due to the increase in moment of inertia and relocation of the neutral axis. Different types of shear connectors can be used for achieving composite action and each type of connector has its own installation method. The biggest distinction between the methods is how the connectors gain access to the steel girder for installation and what technique is used when installing them. This thesis presents the theory behind composite action, the current methods used for achieving composite action on existing bridges and to what extent a bridge can be strengthened by composite action. The thesis also provides a status of the existing road bridge stock around the world. The four case studies examined in this thesis have used different post-installed shear connectors to manage different strengthening problems like weight restriction, fatigue life of shear connectors and a unique problem on the Pitsund Bridge where loud bangs appeared from the bridge when truck passed in the morning. For the case study on the Pitsund Bridge an interview was conducted that explains the entire procedure of the project, from the noise problem to how the installation of coiled spring pins was performed. The bridge over Lule River at Akkatsfallen consists of two steel girders and a concrete deck. This bridge is chosen as a real case study to determine to what extent a bridge can increase its capacity by achieving composite action. The calculations are performed in accordance with the Eurocodes on both non- and full-composite action and the result is compared to the other case studies.

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A common bridge type is the steel-concrete bridge where the concrete deck is built over steel girders. In many earlier designs the bridge type was often built as non-composite, which means that the concrete deck and the steel girder has no shear connection at the steel-concrete interface and therefore bend as individual components. With the increased traffic loads of today some of the existing non-composite bridges have insufficient bending capacity, and therefore they must either be replaced or strengthened. To replace a bridge and construct a new one has many downsides, it is time consuming, expensive, and it consumes a lot of finite resources. Therefore, it is better if the bridges could be strengthened instead. Non-composite steel-concrete bridges can in some cases be strengthened by installing shear connectors that enable composite action between the concrete deck and steel girder. To enable full composite action, many shear connectors need to be installed (10-15 per meter). In some cases, full composite action is not needed to achieve a sufficient load capacity. Therefore, to save time and money and reduce material usage, it could be favourable if the amount of shear connectors could be lowered. The concept of using less shear connectors than required for full composite action is known as partial composite action and is defined as a ratio η that can vary between 0 and 1,0. If the ratio is 0, the structure is non-composite and if it is 1,0, it is fully composite. For every ratio between, the structure is partially composite. Partial composite action is not allowed by the standard for new composite bridges in Europe, EN 1994-2, which instead requires full composite action for new bridges. Since the conventional shear connector type, Welded Headed Stud (WHS) is impractical for post-installation this can yield large costs. This thesis therefore analyses the efficiency of strengthening non-composite bridges with partial composite action by post-installation of the shear connector type Coiled Spring Pins (CSPs), which is more suitable for post-installation compared to WHS since the installation can be made from underneath the bridge deck. The thesis consists of a theoretical study about composite action with a focus on partial composite action. In addition to the theoretical study, a case study is performed on an existing non-composite steel-concrete bridge, the bridge over Yxlö channel, which is situated south of Stockholm in Nynäshamn municipality. In the case study, hand-calculations to calculate the moment capacity for the bridge and the bending stresses in the bridge is made. In addition, a linear Finite Element-analysis (FE-Analysis) is made to evaluate the bending stresses in the cross-section. Further, in the FE-analysis, the horizontal slip and shear flow at the steel-concrete interface is evaluated. The calculations in the case study are made for 10 different degrees of shear connection from 0 - 1,0 with increments of 0,1. The results from the hand-calculations showed that partial composite action an efficient strengthening method, especially for lower degrees of shear connection. The moment capacity in the mid-section of the bridge could be increased between 16 and 41 % for shear connection ratios between 0,4 and 1,0, when applying plastic properties. If elastic properties were used, the increase in moment capacity for the same interval and section was 13 – 21 %, which shows that if it is possible to use plastic properties, the moment capacity could be increased more.  The results from the stress analysis in both the Hand- and FE-calculations showed that the stresses were reduced efficiently, especially for the top flange of the steel girder, where the stresses reduced 75-85 % for shear connection ratios between 0,4 & 1,0. The reduction of the stresses in the bottom flange were not as efficient, but still a reduction of 15 – 20 % is possible for shear connection ratio between 0,4 – 1,0. The overall conclusion from the thesis is that partial composite action can be an efficient strengthening method, and that non-composite bridges like the Yxlö Bridge could be strengthened with CSPs and have an effective increase of the bending moment capacity. This way the allowed axle- and bogie load on the bridge could be increased which could extend the technical life length of the bridge and reduce the need for new bridges.

Many of the existing steel-concrete bridges may need to be strengthened, as heavier vehicles areallowed on the Swedish roads. These bridges could possibly be strengthened by post-installingshear connectors. The shear connectors may enhance the load-bearing capacity through a higherdegree of composite action between the steel and concrete interface.For post-installing of shear connectors, it is advantageous to use a method that allows forinstallation from underneath the bridge as it avoids disrupting the traffic flow. The authors havehence focused on a shear connector called coiled spring pin (CSP); a sheet of metal rolled intoa coil. It’s inserted by hydraulic jacking into a pre-drilled hole and maintained in position dueto radial spring force, avoiding the need for welding.Information and data are collected from beam tests performed at Luleå technical university, theEurocodes and literature.This study investigates and identifies the behaviour and characteristics of a partial compositegirder reinforced with CSPs. The study compares the results obtained from the laboratory testsand the FEM-simulations. Furthermore, this research examines the factors that contribute to theaccuracy of the FEM models and investigates the influence of the CSP placement on the overallload-bearing capacity.Both the FEM simulations and laboratory tests indicate that the girders exhibit strength benefitsfrom applying CSPs. An optimal position for the connectors could not be determined, as theresults presented in the simulations was not proved by the laboratory tests. The simulationsindicate benefits with central placed CSPs, in contrast to the laboratory test where no differencesfrom the placement were shown, although only two test setups were used.

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Master of Science / Department of Biochemistry / Qize Wei / Proper regulation of mitosis and cytokinesis is fundamentally important for all living organisms. During anaphase, antiparallel microtubules are bundled between the separating chromosomes, forming the central spindle (also called the spindle midzone), and the myosin contractile ring is assembled at the equatorial cortex. Regulators of central spindle formation and myosin contractile ring assembly are mostly restricted to the interdigitated microtubules of central spindles and they can be collectively called midzone components. It is thought that characteristic microtubule configurations during mitosis and cytokinesis are dictated by the coordinated action of microtubule-stabilizing and -destabilizing factors. Although extensive investigations have focused on understanding the roles of microtubule-bundling/stabilizing factors in controlling central spindle formation, efforts have been lacking in aiming to understand how microtubule-destabilizing factors regulate the assembly of central spindles. This dissertation describes the role of a novel microtubule-destabilizing factor termed CCDC69 (coiled-coil domain-containing protein 69) in controlling the assembly of central spindles and the recruitment of midzone components. Endogenous CCDC69 was localized to the nucleus during interphase and to the central spindle during anaphase. Exogenous expression of CCDC69 in HeLa cells destabilized microtubules and disrupted the formation of bipolar mitotic spindles. RNA interference (RNAi)-mediated knockdown of CCDC69 led to the formation of aberrant central spindles and interfered with the localization of midzone components such as aurora B kinase, protein regulator of cytokinesis 1 (PRC1), MgcRacGAP/HsCYK-4, and pololike kinase 1 (Plk1) at the central spindle. CCDC69 knockdown also decreased equatorial RhoA staining, indicating that CCDC69 deficiency can impair equatorial RhoA activation and ultimately lead to cytokinesis defects. Four coiled-coil domains were found in CCDC69 and the C terminal coiled-coil domain was required for interaction with aurora B. Disruption of aurora B function in HeLa cells by treatment with a small chemical inhibitor led to the mislocalization of CCDC69 at the central spindle. Further, vitro kinase assay showed that Plk1 could phosphorylate CCDC69. Taken together, we propose that CCDC69 acts as a scaffold and a microtubule-destabilizing factor to control the recruitment of midzone components and the assembly of central spindles.

For bridges to cope with increased requirements such as increased loads, strengthening work can be carried out. In cases where older steel-concrete bridges do not have a composite action, an alternative is to create composite-action to achieve a higher flexural strength. It is introduced by post-installing shear connectors. There are many different alternatives of shear connectors that can be used, hence a number that can be installed from below the bridge to minimize the impact on the traffic. Coiled Spring Pins are of the interference fit type connector and are put in place from below the bridge by first drilling a hole upward through the upper steel flange and then into the concrete slab. Then, the spiral bolt is pushed up into the drilled hole by means of a hydraulic hammer. Using data from push-out tests and non-linear material models for steel and concrete, a non-linear finite element analysis was created using the commercial finite element software Abaqus. The analysis is based on dimensions and load cases that will mimic a planned full-scale beam test that will be carried out later in 2019. To verify that the material and the model behave in a realistic manner, an analysis was initially performed on a beam without composite-action, and a full-composite action beam with infinitely rigid connectors. These were then compared with hand calculations according to Eurocode. When the material models were verified, it is seen that the materials steel and concrete work for themselves in the analysis without composite-action and together in the analysis with full composite-action. The data for the spiral bolts is than defined instead of infinitely rigid connectors and new analyzes were performed to see the effect of the coiled spring pins properties. The results show that a significant increase in the point load in the middle of the beam can take place before failure occurs after installation of this type of shear connector. Already at a low number of connectors and a low shear connection-ratio, a significant increase in the flexural strength is seen in the beam. By using partial-composite action, with a lower number of spiral bolts, a significant higher flexural strength can be achieved in an economical way. / När kraven på att broar ska klara av ökade laster, kan förstärkningsarbeten utföras. I de fall där äldre stål-betongbroar saknar samverkanseffekt, är det ett alternativ att inför samverkan för att uppnå en högre böj-hållfastighet. Det införs genom att man installerar skjuvförbindare i efterhand. Det finns många olika alternativ av skjuvförbindare som kan användas, därav ett antal som går att installera underifrån bron för att minimera påverkan på trafiken. Spiralbultar (Coiled Spring Pins) är av typen presspassnings-förbindare och sätts på plats underifrån bron genom att det först borras ett hål uppåt genom övre stålflänsen och sedan upp i betongplattan. Därefter pressas spiralbulten upp i det borrade hålet med hjälp av en hydraulisk hammare. Med hjälp av data ifrån push-out-tester samt icke-linjära material modeller för stål och betong, skapades en icke-linjär analys i det finita element metods programmet Abaqus. Analysen är uppbyggd med dimensioner och lastfall som ska efterlikna ett planerat full-skaligt balktest som kommer utföras under 2019. För att verifiera att materialet och modellen beter sig realistiskt, utförs en analys på en balk utan samverkan, samt en full-samverkans balk med oändligt styva förbindare. Dessa jämförs sedan med handberäkningar enligt Eurokod. När materialmodellerna var verifierade sågs det att materialen stål och betong arbetar för sig själva i analysen utan samverkan och tillsammans i analysen med full-samverkan. Data för spiralbultarna lades sedan in istället för oändligt styva förbindare och nya analyser utförs för att se påverkan av spiralbultarnas egenskaper. Resultaten visade att en betydande ökning av punklasten i mitten av balken kan ske innan brott uppstår vid installation i efterhand av denna typen skjuvförbindare. Redan vid ett lågt antal förbindare och ett lågt skjuv-förhållande ses en betydande ökning av böj-hållfastigheten i balken. Genom att använda delvis-samverkan med ett lägre antal spiralbultar kan man på ett ekonomiskt sätt uppnå en betydligt högre böj-hållfasthet.

A novel combined piezoelectric-composite actuator configuration is proposed and analytically modeled in this work. The actuator is a low complexity, active compliant mechanism obtained by coupling a modified star cross sectional configuration composite beam with a helicoidal bimorph piezoelectric actuator coiled around it. This novel actuator is a good candidate as a hinge tension-torsion bar actuator for a helicopter rotor blade flap or blade tip and mirror rotational positioning. In the wing tip case, the tip deflection angle is different only according to the aerodynamic moment depending on the hinge position of the actuator along the chord and applied voltage because there is no centrifugal force. For an active blade tip subject to incompressible flow and 2D quasi steady airloads, its twist angle is related not only to aerodynamic moment and applied voltage but also to coupling terms, such as the trapeze effect and the tennis racquet effect. Results show the benefit of hinge position aft of the aerodynamic center, such that the blade tip response is amplified by airloads. Contrary to this effect, results also show that the centrifugal effects and inertial effect cause an amplitude reduction in the response. Summation of these effects determines the overall blade tip response. The results for a certain hinge position of Xh=1.5% chord aft of the quarter chord point proves that the tip deflection target design range[-2,+2] can be achieved for all pitch angle configurations chosen.

The supply and demand situation is crucial for the oil and gas industry during the first half of the 21st century. For the future, we will see two trends going in opposite directions: a decline in discoveries of conventional oil and gas reservoirs and an increase in world energy demand. Therefore, the need to develop and produce unconventional oil and gas resources, which encompass coal-bed methane, gas-shale, tight sands and heavy oil, will be of utmost importance in the coming decades. In the past, large-scale production from tight gas reservoirs occurred only in the U.S. and was boosted by both price incentives and well stimulation technology. A conservative study from Rogner (1997) has shown that tight gas sandstone reservoirs would represent at least over 7,000 trillion cubic feet (Tcf) of natural gas in place worldwide. However, most of the studies such as the ones by the U.S. Geological Survey (U.S.G.S.) and Kuuskraa have focused on assessing the technically recoverable gas resources in the U.S. with numbers ranging between 177 Tcf and 379 Tcf. During the past few decades, gas production from tight sands field developments have taken place all around the world from South America (Argentina), Australia, Asia (China, Indonesia), the Russian Federation, Northern Europe (Germany, Norway) and the Middle East (Oman). However, the U.S. remains the region where the most extensive exploration and production for unconventional gas resources occur. In fact, unconventional gas formations accounted for 43% of natural gas production and tight gas sandstones represented 66% of the total of unconventional resources produced in the U.S. in 2006. As compared to a conventional gas well, a tight gas well will have a very low productivity index and a small drainage area. Therefore, to extract the same amount of natural gas out of the reservoir, many more wells will have to be drilled and stimulated to efficiently develop and produce these reservoirs. Thus, the risk involved is much higher than the development of conventional gas resources and the economics of developing most tight gas reservoirs borders on the margin of profitability. To develop tight gas reservoirs, engineers face complex problems because there is no typical tight gas field. In reality, a wide range of geological and reservoir differences exist for these formations. For instance, a tight gas sandstone reservoir can be shallow or deep, low or high pressure, low or high temperature, bearing continuous (blanket) or lenticular shaped bodies, being naturally fractured, single or multi-layered, and holding contaminants such as CO2 and H2S which all combined increase considerably the complexity of how to drill a well. Since the first tight gas wells were drilled in the 1940's in the U.S., a considerable amount of information has been collected and documented within the industry literature. The main objective of this research project is to develop a computer program dedicated to applying the drilling technologies and methods selection for drilling tight gas sandstone formations that have been documented as best practices in the petroleum literature.