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1
Hardell, Jens. "High temperature tribology of high strength boron steel and tool steels." Licentiate thesis, Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1757/2007/36/index.html.
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Larsson, Rikard. "Constitutive Modelling of High Strength Steel." Thesis, Linköping University, Department of Management and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8157.
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<p>This report is a review on aspects of constitutive modelling of high strength steels. Aspects that have been presented are basic crystallography of steel, martensite transformation, thermodynamics and plasticity from a phenomenological point of view. The phenomenon called mechanical twinning is reviewed and the properties of a new material type called TWIP-steel have been briefly presented. Focus has been given on phenomenological models and methods, but an overview over multiscale methods has also been given.</p>
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Taylor, H. "Fatigue behaviour in high strength steel." Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372146.
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Ye, Jianjun. "Compression strength of unstiffened elements in cold-reduced high strength steel." Thesis, The University of Sydney, 2005. https://hdl.handle.net/2123/27906.
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Compression strength of unstiffened elements in cold—reduced high strength
steel G550 and G450 steel to Australian Standard AS 1397-1993 are
investigated experimentally and theoretically in this thesis.
The thesis describes two series of tests. The first one is material property tests
performed on tension and compression coupons cut from high strength steel
sheet in 0.6 mm or 1.0 mm thickness with nominal yield stress of 550 MPa and
1.5 mm thickness with nominal yield stress of 450 MPa. The second is
compression tests performed on stub angles cut from high strength steel sheet
in 0.6 mm and 1.0 mm thickness with nominal yield stress of 550 MPa.
A numerical simulation on the angle compression tests using the commercial
finite element computer program ABAQUS is also presented as part of this
thesis. The effect of changing variables, such as geometric imperfections and
end boundary conditions is also investigated. The ABAQUS analysis gives
accurate simulations of the tests and is in good agreement with the experimental
results.
The results of the column tests and ABAQUS simulation have been compared
with the design procedures in the Australian/New Zealand Standard for Cold-
Formed Steel Structures (AS/NZS 4600). The stub column tests show that the
current design rules give too conservative predictions of the compressive
section capacities of the column members used in their current form for G550
steel.
A design proposal is presented in this thesis to account for the effects peculiar to
high strength thin steels on the section and member capacities.
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Skoglund, Oskar. "Innovative structural details using high strength steel for steel bridges." Licentiate thesis, KTH, Bro- och stålbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259949.
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The use of high strength steel has the potential to reduce the amount of steel used in bridge structures and thereby facilitate a more sustainable construction. The amount of steel and what steel grade that can be used in bridge structures and other cyclic loaded structures are often limited by a material degradation process called fatigue. The fatigue resistance of steel bridges are to a large extent depending on the design of structural details and connections. The design engineer is limited by a few pre-existing structural details and connections – with rather poor fatigue resistance – to choose from when designing steel bridges, and is therefore often forced to increase the overall dimensions of the structure in order to cope with the design requirements of fatigue. This licentiate thesis aims at increasing the fatigue resistance of fatigue prone structural details and connections by implementing new and innovative structural solutions to the already pre-existing details given in the design standards. A typical fatigue prone detail is the vertical stiffener at an intermediate cross-beam, which will be in focus. By improving the fatigue resistance, less steel material will be required for the construction of new steel bridges and composite bridges of steel and concrete. It is shown in this thesis and the appended papers that the use of high strength steel for bridge structures can considerably reduce the amount of steel used, the steel cost and the harmful emissions. However, this is only true if the fatigue strength of critical details can be substantially improved. Furthermore, a few new and innovative structural details and modifications to already existing details are proposed in this thesis and in the appended papers, that have the potential to increase the fatigue resistance of steel bridges and composite bridges of steel and concrete. However, further analyses are required in order to make these structural details viable for construction.<br>Genom användandet av höghållfast stål så kan en mindre mängd material användas som i sin tur leder till ett mer hållbart byggande. Mängden stål och vilken stålkvalité som kan användas vid byggandet av stålbroar och andra cykliskt belastade konstruktioner avgörs ofta av nedbrytningsprocessen utmattning. Utmatningskapaciteten hos stålbroar är till stor del beroende av brons anslutningsdetaljer. Brokonstruktören har vid designstadiet ett begränsat antal beprövade anslutningsdetaljer att välja bland – vilka ofta har relativt låg utmattningskapacitet – och konstruktören är därmed ofta tvungen att öka konstruktionens dimensioner för att klara av kraven gällande utmattning. Den har licentiatuppsatsen har till syfte att förbättra utmattningskapaciteten för utmattningsbenägna anslutningsdetaljer i stål genom att införa nya och innovativa anslutningsdetaljer, bland de redan existerande detaljerna som finns i de olika standarderna. En utmattningskritisk detalj som kommer att ligga i fokus är anslutningen mellan livavstyvningen och tvärförbanden hos en I-balk. Genom att förbättra utmattningskapaciteten så kan en mindre mängd stålmaterial användas vid byggandet av stålbroar och samverkansbroar i betong och stål. I denna uppsatsen kunde det påvisas att höghallfast stål for broar kan betydligt sänka mängden stålmaterial, stålkostnaden och koldioxidutsläppen. Dock så gäller detta enbart om utmattningskapaciteten for kritiska anslutningsdetaljer kan ökas avsevärt. Dessutom, som en del av den har uppsatsen så har ett par nya och innovativa anslutningsdetaljer föreslagits som har potential att forbättra utmattningskapaciteten. Dock, så krävs ytterligare studier for att dessa förslag skall kunna användas i byggnation av nya stålbroar.<br><p>QC 20190925</p>
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Schuetz, Daniel Philip. "Investigation of high strength stainless steel prestressing strands." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47744.
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Bridges and other coastal structures in Georgia and throughout the Southeast are deteriorating prematurely due to corrosion. Numerous corrosion
initiated failures have occurred in precast prestressed concrete (PSC) piles and reinforced concrete (RC) pile caps, leading to the costly repair and
replacement of either the entire bridge or the affected members. With the Federal Highway Administration's goal of a 100-year bridge service life
and recent legislative action such as the Bridge Life Extension Act, new emphasis has been placed on the development and implementation of new
corrosion mitigation techniques.
This thesis involves the mechanical testing, and proposed future test program of high-strength stainless steel (HSSS) prestressing strand to be used
in prestressed marine bridge piles. The metallurgy for two types of HSSS strand was selected from a previous study of the corrosion resistance,
mechanical properties, and feasibility of 6 candidate HSSS drawn wire samples. Duplex stainless steel (DSS) grades 2205 and 2304 were selected
for production of 7-wire 1/2" diameter prestressing strand. DSS wire rod was drawn, stranded, and heat-treated using the same production methods
and equipment as used for standard of practice, high carbon prestressing strand. The production process was documented to analyze the problems
facing this production method and suggest improvement and optimization.
After production, the strands were subjected to a series of mechanical tests. Tension testing was performed to provide a stress-strain curve for the
strands and related mechanical properties. Wire samples were also taken at varying points in the drawing process to give more information about
the work hardening of the stainless steels. Stress relaxation testing was performed on both strand and wire samples to assess the overall losses and
to provide comparisons between strand and wire test results as well as drawn wires before and after heat-treatment.
An experimental program for future study was designed to assess the HSSS prestressing strand behavior in precast piles. This testing involves
assessment of pile driving performance, pile flexural and shear behavior, strand transfer and development length, long-term prestressing force
losses, and material durability.
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Goodall, Graeme. "Welding High Strength Modern Line Pipe Steel." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96662.
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The effect of modern mechanized girth welding on high strength line pipe has been investigated. The single cycle grain coarsened heat affected zone in three grade 690 line pipe steels and a grade 550 steel has been simulated using a Gleeble thermo-mechanical simulator. The continuous cooling transformation diagrams applicable to the grain coarsened heat affected zone resulting from a range of heat inputs applicable to modern mechanized welding have been established by dilatometry and metallography. The coarse grained heat affected zone was found to transform to lath martensite, bainite, and granular bainite depending on the cooling rate. The impact toughness of the steels was measured using Charpy impact toughness and compared to the toughness of the grain coarsened heat affected zone corresponding to a welding thermal cycle. The ductile to brittle transition temperature was found to be lowest for the steel with the highest hardenability. The toughness resulting from three different thermal cycles including a novel interrupted intercritically reheated grain coarsened (NTR ICR GC HAZ) that can result from dual torch welding at fast travel speed and close torch spacing have been investigated. All of the thermally HAZ regions showed reduced toughness that was attributed to bainitic microstructure and large effective grain sizes. Continuous cooling transformation diagrams for five weld metal chemistries applicable to mechanized pulsed gas metal arc welding of modern high strength pipe steel (SMYS>550 MPa) have been constructed. Welds at heat inputs of 1.5 kJmm-1 and 0.5 kJmm-1 have been created for simulation and analysis. Dilatometric analysis was performed on weld metal specimens cut from single pass 1.5 kJmm-1 as deposited beads. The resulting microstructures were found to range from martensite to polygonal ferrite. There is excellent agreement between the simulated and as deposited weld metal regions. Toughness testing indicates improved energy absorption at -20 °C with increased cooling time.<br>L'effet des méthodes modernes de soudage circonférentiel mécanisé sur des aciers à forte résistance utilisés pour les tubes de canalisation a été investigué. La zone affectée thermiquement ayant subi une croissance de grain lors d'un cycle thermique simple de soudage a été simulée pour trois grades d'acier à tubes de canalisation 690 et un grade d'acier 550 à l'aide d'un appareil de simulation thermomécanique Gleeble. Les diagrammes de transformation en refroidissement continu pour la zone affectée thermiquement ayant subi une croissance de grains ont été établis pour un spectre de chaleur induite représentatif du procédé de soudage mécanisé en utilisant la dilatométrie ainsi que des analyses métallographiques. Il résulte que la zone affectée thermiquement ayant subi une croissance de grain connaît un changement de phase vers une martensite massive, une bainite ou une bainite granulaire selon le taux de refroidissement rencontré. La résistance des aciers étudiés a été mesurée par essais Charpy et comparée à la résistance obtenue pour la zone affectée thermiquement ayant subi une croissance de grains correspondant à un cycle thermique de soudage. Le plus bas température de transition ductile-fragile a été obtenue pour les grades d'acier ayant la plus grande aptitude à la trempe. La résistance résultante des structures obtenues pour trois différents cycles thermique, notamment un nouveau cycle thermique interrompu par recuit intercritique similaire à l'effet que peut avoir un soudage à double torche à déplacement rapide et espacement réduit, a été étudié. Toutes les zones affectée thermiquement montrent une baisse de résistance causée par l'apparition d'une structure bainitique et la croissance des grains.Les diagrammes de transformations en refroidissement continu ont été établis pour 5 alliages de soudage applicable pour le soudage pulsé à l'arc sous gas des aciers à tube modernes à haute résistance. Des soudures avec un apport de chaleur de 1,5 kJmm-1 et 0,5 kJmm-1 ont été utilisées pour les simulations et les analyses. Des essais de dilatométrie ont été faits sur des échantillons prélevés des cordons de soudure déposés en une passe à 1,5 kJmm-1. L'observation métallographique des échantillons présente une structure allant de la martensite à la ferrite polygonale. Une excellente concordance a été établie entre la structure du métal obtenu par simulation et telle que déposé. Les tests de résistance indiquent une amélioration de l'énergie absorbée à -20°C lorsque le temps de refroidissement est plus long.
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Björklund, Oscar. "Ductile Failure in High Strength Steel Sheets." Doctoral thesis, Linköpings universitet, Hållfasthetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-105213.
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Developments in computer-aided engineering and the rapid growth of computational power have made simulation-driven process and product development efficient and useful since it enables detailed evaluation of product designs and their manufacturing processes. In the context of a sheet metal component, it is vital to predict possible failure both during its forming process and its subsequent usage. Accurate numerical models are needed in order to obtain trustworthy simulation results. Furthermore, the increasing demands imposed on improved weight-to-performance ratio for many products endorse the use of high-strength steels. These steels often show anisotropic behaviour and more complex hardening and fracturing compared to conventional steels. Consequently, demand for research on material and failure models suitable for these steels has increased. In this work, the mechanical and fracture behaviour of two high-strength steels, Docol 600DP and Docol 1200M, have been studied under various deformation processes. Experimental results have been used both for material characterisation and for calibration of fracture criteria. One major requirement as concerns the fracture criteria studied is that they should be simple to apply in industrial applications, i.e. it should be possible to easily calibrate the fracture criteria in simple mechanical experiments and they should be efficient and accurate. Consequently, un-coupled phenomenological damage models have been the main focus throughout this work. Detailed finite element models including accurate constitutive laws have be used to predict and capture material instabilities. Most of the fracture criteria studied are modifications of the plastic work to fracture. Ductile tensile and ductile shear types of fracture are of particular interest in sheet metal applications. For these fractures the modification of the plastic work relates to void coalescence and void collapse, respectively. Anisotropy in fracture behaviour can be captured by the introduction of a material directional function. The dissertation consists of two parts. The first part contains theory and background. The second consists of five papers.
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Konstantarakis, Christos. "Hydrogen degradation of high strength steel weldments." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/47338.
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Thesis (Ocean. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science & Engineering, 1993.<br>Includes bibliographical references (leaves 37-43).<br>by Christos Konstantarakis.<br>M.S.<br>Ocean.E.
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Anderson, Cheryl Marie. "The weldability of high and ultra-high strength steel." Thesis, Swansea University, 2003. https://cronfa.swan.ac.uk/Record/cronfa42947.
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Weight reduction in body-in-white structures is necessary to make automobiles more fuel-efficient. A range of high and ultra-high strength strip steels have been developed, that will play a key role in achieving lower weights since the steels have the potential to achieve equivalent strength and crashworthiness at thinner gauges. However, the full potential of these advanced alloys can only be realised if they can be integrated into production facilities that rely on resistance spot welding as the predominant means of component joining. In particular, spot welds manufactured in these modern high strength steels will need to meet the strength and fracture resistance requirements that are based on automotive manufacturers' familiarity with low alloy steels. Dual phase steels are a range of modern alloys causing considerable excitement due to their combination of high strength, high ductility and improved crashworthiness in automotive components, compared to mild steel. Their commercial production routes rely on a metallurgical understanding of how chemical composition and thermomechanical treatments interrelate to produce appropriate microstructures. Their often complex alloy compositions mean that there is potential for significant changes to take place in the microstructure on resistance welding. This research programme has considered the important relationships from which resistance spot-welds, produced in high strength steels, derive their properties. This includes an investigation into the continuous cooling transformation behaviour of four dual phase alloys, in comparison to low alloy grades, and measurement of the mechanical properties associated with their microstructures. The thermal profiles generated within spot welds have been measured using a thermocouple technique. Advanced resistance spot welding processes, that can modify the metallurgical condition of a spot-weld, have been investigated with some success, both in terms of reductions in weld hardness following pulsed welding schedules, and an understanding of the effect of such schedules on the thermal cycle.
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Larsson, Rikard. "On Material Modelling of High Strength Steel Sheets." Doctoral thesis, Linköpings universitet, Hållfasthetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-80115.
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The work done in this thesis aims at developing and improving material models for use in industrial applications. The mechanical behaviour of three advanced high strength steel grades, Docol 600DP, Docol 1200M and HyTens 1000, has been experimentally investigated under various types of deformation, and material models of their behaviour have been developed. The origins of all these material models are experimental findings from physical tests on the materials. Sheet metal forming is an important industrial process and is used to produce a wide range of products. The continuously increasing demand on the weight to performance ratio of many products promotes the use of advanced high strength steel. In order to take full advantage of such steel, most product development is done by means of computer aided engineering, CAE. In advanced product development, the use of simulation based design, SBD, is continuously increasing. With SBD, the functionality of a product, as well as its manufacturing process, can be analysed and optimised with a minimum of physical prototype testing. Accurate numerical tools are absolutely necessary with this methodology, and the model of the material behaviour is one important aspect of such tools. This thesis consists of an introduction followed by five appended papers. In the first paper, the dual phase Docol 600DP steel and the martensitic Docol 1200M steel were subjected to deformations, both under linear and non-linear strain paths. Plastic anisotropy and hardening were evaluated and modelled using both virgin materials, i.e. as received, and materials which were pre-strained in various material directions. In the second paper, the austenitic stainless steel HyTens 1000 was subjected to deformations under various proportional strain paths and strain rates. It was experimentally shown that this material is sensitive both to dynamic and static strain ageing. A constitutive model accounting for these effects was developed, calibrated, implemented in a Finite Element software and, finally, validated on physical test data. The third paper concerns the material dispersions in batches of Docol 600DP. A material model was calibrated to a number of material batches of the same steel grade. The paper provides a statistical analysis of the resulting material parameters. The fourth paper deals with a simple modelling of distortional hardening. This type of hardening is able to represent the variation of plastic anisotropy during deformation. This is not the case with a regular isotropic hardening, where the anisotropy is fixed during deformation. The strain rate effect is an important phenomenon, which often needs to be considered in a material model. In the fifth paper, the strain rate effects in Docol 600DP are investigated and modelled. Furthermore, the strain rate effect on strain localisation is discussed.<br>SFS ProViking Super Light Steel Structures
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Clarin, Mattias. "High strength steel : local buckling and residual stresses." Licentiate thesis, Luleå, 2004. http://epubl.luth.se/1402-1757/2004/054.
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Wong, T. M. "Stress corrosion cracking in a high strength steel." Thesis, University of Canterbury. Engineering, 1986. http://hdl.handle.net/10092/6429.
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This thesis falls into four fields of study.
The first is a survey of relevant literature concerning the many theories of stress corrosion cracking and hydrogen embritt1ement. This includes descriptions of the mechanisms of stress corrosion cracking (SCC) and outlines electromechanical processes and stress - sorption theory. Four widely accepted mechanisms for environment assisted cracking are also outlined. They are, 1) Embritt1ement resulting from accumulated hydrogen at embritt1ement sites, 2) Lowering of surface energy by adsorption of hydrogen, 3) Hydrogen interaction with dislocations, and 4) Lowering of the binding energy by interaction of hydrogen.
The literature survey is a significant part of this thesis. The overall objective of the survey is to review a series of current SCC tests on high strength steels. The principal findings from these previous studies are summarized, they provide concrete evidence for the conclusion that SCC of high strength steels is due to hydrogen embrittlement.
The second part of the project deals with the development of a stress corrosion loading clevis suitable for testing compact tension specimens. Three existing constant load rigs were developed, and equipment was designed for the successful operation of the rigs.
Corrosive environment was applied to the standard compact tension specimen using a novel circulation system based on a magnetic plate stirrer. Corrosive solution (3.5% NaCl) was stirred by the magnetic plate, and the vortex created by the magnetic stirrer was used to create a pumping head.
The third area of work dealt with the testing of compact tension specimens of ULTIMO 200 steel using the developed apparatus. The experimental procedures used are based on the application of linear elastic fracture mechanics to stress corrosion cracking.
The fourth area of work carried out was to perform slot length calibration experiments on CT specimens by using strain gauges.
The results indicated that the specimens pre-cracked in air with a higher dynamic load gave higher threshold stress intensities (KIscc ) than those pre-cracked in air with a lower dynamic load. An electron microscope study indicated evidence of a largely inter granular fatigue crack having occurred in the specimens pre-cracked with a high dynamic load.
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Gedeon, Steven Anthony. "Hydrogen assisted cracking of high strength steel welds." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14842.
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Wang, Jie. "Behaviour and design of high strength steel structures." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43758.
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High strength steels (HSS), which are generally considered to be those with yield strengths over 460 MPa, are being increasingly utilised in construction, particularly in high rise structural applications and where long and column-free spans are an important design requirement. In place of ordinary carbon steels, the use of HSS can enable structural elements with smaller cross-sections, resulting in significant material savings. However, compared to normal strength steels, the structural use of HSS is still quite rare. The European design code EN 1993-1-12 provides design rules for HSS up to S700, but was conceived as a simple extension of the rules in EN 1993-1-1 for normal strength steels. In order to contribute to the existing limited HSS data pool and to verify and develop the current Eurocode 3 design rules, a comprehensive experimental programme on hot-finished S460 and S690 square and rectangular hollow sections has been carried out. The testing programme covered different structural aspects at the material, cross-section and member levels and consisted of 40 tensile coupon tests, 11 compressive coupon tests, 11 stub column tests, 11 full section tensile tests, 22 in-plane bending tests, 12 eccentrically loaded stub column tests, 30 long column tests, as well as measurements of geometrical imperfections and residual stresses. Numerical models, validated against the test results, were also developed to examine the cross-section and member behaviour, and subsequently employed in a comprehensive parametric study in order to generate further data. Based on the combined test and numerical data set, as well as experimental results reported in the literature, the current HSS design rules in Eurocode 3, including the slenderness limits for cross-section classification, effective width equation, N-M interaction curves and column buckling curves, were assessed by means of reliability analyses in accordance with Annex D of EN 1990. To realise the potential of HSS in long span structures, a novel structural form was also examined, namely an HSS truss with prestressing cables housed within the tubular bottom chord. A total of 4 prestressed trusses, made of S460 square hollow sections with different prestress levels, were tested under static downward loading. The truss test results showed the enhanced structural efficiency brought about by the addition of prestressing cables and by the application of prestress. Additionally, 12 tensile and 10 compressive member tests with cables, representing the bottom chord of the truss under gravity and uplift loading, respectively, were carried out to investigate the behaviour of individual prestressed cable-in-tube members. Analytical models and numerical models were also established to compare with the test behaviour and to contribute to the development of design rules for prestressed cable-in-tube systems.
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Reis, Jonathan M. "Structural Concrete Design with High-Strength Steel Reinforcement." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277124990.
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Olsen, Eric. "Friction stir welding of high-strength automotive steel /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1911.pdf.
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Mai, Van Bac. "Fracture Behaviour in Cold-Reduced High-Strength Steel." Phd thesis, University of Sydney, 2019. https://hdl.handle.net/2123/29311.
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A comprehensive study on the ductile behaviour and fracture of high strength cold-reduced sheet G450 steel is presented. The aim of the study is to determine the material strength, ductility and fracture in different stress states including at both macro and structural scales. The objectives of the research are achieved through theoretical developments, extensive experimental studies and numerical investigations.
A couple damage-plasticity model derived from a generic thermodynamic framework is developed. The general formulation allows integration of stress effects (e.g. stress triaxiality and Lode angle) into the damage threshold and evolution, in addition to the ability to incorporate any form of yield criterion into the model. The key feature of the model development is that all model parameters are explicitly identified from experimental tests. In addition, the proposed model based on a combination of both plastic theory and continuum damage mechanics allows appropriately capture of the macroscopic material response.
Comprehensive experimental programmes are carried out at both the material and structural test levels where the advantages of a non-contact optical measurement (Digital Image Correlation) are successfully validated and applied. Material experiments consisting of tension and shear specimens are conducted for the determination of the material properties including fracture energy and the full-field of strain distribution and evolution. The tests of bolted connections, which are governed by block shear failure, are conducted to determine the connection strength, ductility and fracture. Strain maps in these structural tests provide an insight into the failure in the block shear limit state. In addition, all experimental data is used for determining model parameters and validating the numerical predictions.
Numerical simulation also plays an important role in this study. The proposed constitutive model is derived by an appropriate semi-implicit scheme in a general three-dimensional stress state before being incorporated into commercial numerical finite element software. All numerical predictions are validated at double scale until completion of tensile fracture consisting of macro and structural responses, which distinguishes this study from existing studies. Good predictions at the double scale show high levels of accuracy of the simulations. Further, numerical simulation of bolted connections failing in block shear serves as a supplement to experimental research and provides meaningful insight into the complex stress state. In conjunction with experimental observations, the numerical results also help to clarify the features of the recently updated block shear design equations specified in the AISI S100:2016 [1] and the AS/NZS 4600:2018 [2] standards. The proposed model has potential for further applications.<br>Access is restricted to staff and students of the University of Sydney . UniKey credentials are required. Non university access may be obtained by visiting the University of Sydney Library.
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Björklund, Oscar. "Modelling of Failure in High Strength Steel Sheets." Licentiate thesis, Linköpings universitet, Hållfasthetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77759.
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In this theses the high strength steel Docol 600DP and the ultra high strength steel Docol 1200M are studied. Constitutive laws and failure models are calibrated and veried by the use of experiments and numerical simulations. For the constitutive equations, an eight parameter high exponent yield surface has been adopted, representing the anisotropic behaviour, and a mixed isotropic-kinematic hardening has been used to capture non-linear strain paths. For ductile sheet metals three dierent failure phenomena have been observed: (i) ductile fracture, (ii) shear fracture, and (iii) instability with localised necking. The models for describing the dierent failure types have been chosen with an attempt to use just a few tests in addition to these used for the constitutive model. In this work the ductile and shear fracture have been prescribed by models presented by Cockroft-Latham and Bressan-Williams, respectively. The instability phenomenon is described by the constitutive law and the nite element models. The results obtained are in general in good agreement with test results. The thesis is divided into two main parts. The background, theoretical framework, mechanical experiments and nite element models are presented in the rst part. In the second part, two papers are appended.<br><p>In publication incorrect ISBN: 9789175198955</p>
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Olsen, Eric Michael. "Friction Stir Welding of High-Strength Automotive Steel." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/951.
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The following thesis is a study on the ability to create acceptable welds in thin-plate, ultra-high-strength steels (UHSS) by way of friction stir welding (FSW). Steels are welded together to create tailor-welded blanks (TWB) for use in the automotive industry. Dual Phase (DP) 590, 780, and 980 steel as well as Transformation-Induced Plasticity (TRIP) 590 steel with thicknesses ranging from 1.2 mm to 1.8 mm were welded using friction stir welding under a variety of processing conditions, including experiments with dissimilar thicknesses. Samples were tested under tensile loads for initial determination if an acceptable weld had been created. Acceptable welds were created in both TRIP 590 and DP 590 at speeds up to 102 centimeters-per-minute. No acceptable welds were created in the DP 780 and DP 980 materials. A series of microhardness measurements were taken across weld samples to gain understanding as to the causes of failure. These data indicate that softening, caused by both excessive heat and insufficient heat can result in weld failure. Not enough heat causes the high concentration of martensite in these materials to temper while too much heat can cause excessive hardening in the weld, through the formation of even more martensite, which tends to promote failure mode during forming operations. Laser welding is one of the leading methods for creating tailor-welded blank. Therefore, laser welded samples of each material were tested and compared to Friction Stir Welded samples. Lower strength and elongation are measured in weld failure while the failure location itself determines the success of a weld. In short, an acceptable weld is one that breaks outside the weld nugget and Heat Affected Zone (HAZ) and where the tensile strength (both yield and ultimate) along with the elongation are comparable to the base material. In unacceptable welds, the sample broke in the weld nugget or HAZ while strength and elongations were well below those of the base material samples.
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Qu, Jinbo 1971. "Effect of microstructure on static and dynamic mechanical properties of high strength steels." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103281.
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The high speed deformation behavior of a commercially available dual phase (DP) steel was studied by means of split Hopkinson bar apparatus in shear punch (25m/s) and tension (1000s-1) modes with an emphasis on the influence of microstructure. The cold rolled sheet material was subjected to a variety of heat treatment conditions to produce several different microstructures, namely ferrite plus pearlite, ferrite plus bainite and/or acicular ferrite, ferrite plus bainite and martensite, and ferrite plus different fractions of martensite. Static properties (0.01mm/s for shear punch and 0.001s -1 for tension) of all the microstructures were also measured by an MTS hydraulic machine and compared to the dynamic properties. The effects of low temperature tempering and bake hardening were investigated for some ferrite plus martensite microstructures. In addition, two other materials, composition designed as high strength low alloy (HSLA) steel and transformation induced plasticity (TRIP) steel, were heat treated and tested to study the effect of alloy chemistry on the microstructure and property relationship.<br>A strong effect of microstructure on both static and dynamic properties and on the relationship between static and dynamic properties was observed. According to the variation of dynamic factor with static strength, three groups of microstructures with three distinct behaviors were identified, i.e. classic dual phase (ferrite plus less than 50% martensite), martensite-matrix dual phase (ferrite plus more than 50% martensite), and non-dual phase (ferrite plus non-martensite). Under the same static strength level, the dual phase microstructure was found to absorb more dynamic energy than other microstructures. It was also observed that the general dependence of microstructure on static and dynamic property relationship was not strongly influenced by chemical composition, except the ferrite plus martensite microstructures generated by the TRIP chemistry, which exhibited much better dynamic factor values. This may suggest that solid solution strengthening should be more utilized in the design of crashworthy dual phase steels.
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Alcock, J. R. "Magnetic domains in high strength constructional steels." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233698.
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Sederstrom, Jack Hunter. "Spot friction welding of ultra high-strength automotive sheet steel / /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1724.pdf.
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Chen, Jhewn-Kuang. "Effects of alloying elements upon austenite decomposition in high strength low alloy steels." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10102009-020227/.
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Ghasemi, Rohollah. "Hydrogen-assisted stress corrosion cracking of high strength steel." Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50416.
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In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under free corrosion potential and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate(1×10-6s-1) in 1 wt% and 3.5 wt% NaCl solutions under free corrosion potential. It was con-firmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.
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Rees, Gethin Iorwerth. "Modelling of microstructure in novel high strength steel welds." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/221884.
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Chen, Ju. "Behaviour of high strength steel columns at elevated temperatures." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B37206230.
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Chen, Ju, and 陳駒. "Behaviour of high strength steel columns at elevated temperatures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B37936554.
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Donohoe, C. J. "Corrosion fatigue of a high strength low alloy steel." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322985.
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Murrell, Pamela. "Fatigue and fracture of a high strength cast steel." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359549.
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Noury, Pourya. "On failure of high strength steel bridge roller bearings." Doctoral thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65215.
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This thesis is concerned with failure analysis of high strength steel bridge roller bearings.Paper Adescribes how the commonly used Hertz formulas for contact stresses underestimate the actual stresses in practice due to temperature differences, misalignments and other construction-related conditions. In this paper, finite element analyses of bridge roller bearings were carried out to investigate the accuracy of the traditional roller bearing design rules in view of issues such as girder deformability, misalignment imperfections and material nonlinearity. The results first indicated that roller bearings develop contact stress concentrations at the outer edges of the rollers. Second, it was shown that the contact stresses are very sensitive to misalignment imperfections between the bridge girder and the abutment. Third, it was shown that the roller bearings develop inelastic deformation at relatively low loads in relation to the design load.In Paper B, the finite element method was employed to gain an understanding of the behaviour of a cracked bridge roller bearing in service. The cracked roller was considered as a two-dimensional edge-cracked disk subjected to a diametrical compressive line load. The crack parameters, stress intensity factor Mode I, KI and Mode II ,KII were calculated for the relevant load configuration and angle of disk rotation. The calculated data for KIwere also used to check the accuracy of approximate stress intensity factor solutions reported earlier for Mode I. For plain Mode I loading very good agreement was found between the obtained results and data presented in Schindler and Morf (1994). Paper Cis aimed at finding the likely failure mechanism of a bridge roller bearing made of high strength martensitic stainless steel. Spectroscopy and finite element stress analysis of the roller indicated that an initial radial surface crack, found at an end face of the roller and close to the contact region, was induced by stress corrosion cracking (SCC). The initial crack subsequently changed shape and increased in size under growth through fatigue and finally formed a quarter-circle radial crack centred on the end face corner of the roller. Numerically computed stress intensity factors for the final crack showed that crack loading was predominantly in Mode II. For a crack size as observed on the fracture surface, the maximum service load, as specified by the manufacturer, enhanced by a certain roller bearing misalignment effect, was sufficient for failure through fracture.InPaper D, after a brief summary of the history of high strength stainless steel bearings, the paper reviews service experience of failed bearings in Sweden and elsewhere. Accompanying finite element analyses were performed in order to gain better insight into the likely failure mechanism. Finally, thiscomprehensive review leads to a conclusion that identifies the causes of the failures occurred and makes some recommendations.
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Hartman, Trent J. "Friction Stir Spot Welding of Ultra-High Strength Steel." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3302.
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Friction stir spot welding (FSSW) is quickly becoming a method of interest for welding of high strength steel (HSS) and ultra high strength steel (UHSS). FSSW has been shown to produce high quality welds in these materials, without the drawbacks associated with fusion welding. Tool grade for polycrystalline cubic boron nitride (PCBN) tools has a significant impact on wear resistance, weld quality, and tool failure in FSSW of DP 980 steel sheet. More specifically, for a nominal composition of 90% CBN, the grain size has a significant impact on the wear resistance of the tool. A-type tools performed the best, of the three grades that were tested in this work, because the grain size of this grade was the finest, measuring from 3-6 microns. The effect of fine grain size was less adhesion of DP 980 on the tool surface over time, less abrasive wear, and better lap shear fracture loads of the welds that were produced, compared to the other grades. This is explained by less exposure of the binder phase to wear by both adhesion and abrasion during welding of DP 980. A-type tools were the most consistent in both the number of welds per tool, and the number of welds that reached acceptable lap shear fracture loads. B-type tools, with a bimodal grain size distribution (grain size of 4 – 40 microns) did a little bit better than C-type tools (grain size of 12-15 microns) in terms of wear, but neither of them were able to achieve consistent acceptable lap shear fracture load values after the first 200 welds. In fact only one out of five C-type tools was able to produce acceptable lap shear fracture loads after the first 100 welds.
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Sarma, Abhijit. "High strain properties of advanced high strength spot welded steels." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5997.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 14, 2008) Includes bibliographical references.
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Li, Yang. "Blast Performance of Reiforced Concrete Beams Constructed with High-Strength Concrete and High-Strength Reinforcement." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35261.
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This thesis focuses on the dynamic and static behaviour of reinforced concrete beams built using high-strength concrete and high-strength steel reinforcement. As part of this study, a total of 8 high-strength concrete beams, built with and without steel fibres, and reinforced with high strength ASTM A1035 bars are tested under simulated blast loading using the University of Ottawa shock-tube, with an additional 3 companion beams tested under quasi-static loading. The variables considered in this study include: concrete type, fibre content, steel reinforcement ratio and steel reinforcement type. The behaviour of the beams with high-strength steel bars is compared to a companion set of beams reinforced with conventional steel reinforcement. The criteria used to evaluate the blast performance of the beams includes: overall blast capacity, maximum and residual displacements, secondary fragmentation and crack control. The dynamic results show that high strength concrete beams reinforced with high-strength steel are able to resist higher blast loads and reduce displacements when compared to companion beams with conventional steel reinforcement. The results also demonstrate that the addition of steel fibres is effective in controlling crack formation, minimizing secondary blast fragments, reducing displacements and further increasing overall blast capacity. However, the use of high-strength steel and high-strength concrete also shows potential for brittle failures under extreme blast pressures. The static results show that specimens with high-strength steel bars do not increase beam stiffness, but significantly increase peak load carrying capacity when compared to beams with the same ratio of conventional steel reinforcement. The analytical research program aims at predicting the response of the test beams using dynamic inelastic single-degree-of-freedom (SDOF) analysis and includes a sensitivity analysis examining the effect of various modelling parameters on the response predictions. Overall the analytical results demonstrate that SDOF analysis can be used to predict the blast response of beams built with high-strength concrete and steel reinforcement with acceptable accuracy.
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Yang, Jer-Ren. "Development of microstructure in high-strength weld deposits." Thesis, University of Cambridge, 1988. https://www.repository.cam.ac.uk/handle/1810/221894.
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The microstructure of high-strength weld deposits has been investigated using thermodynamic analysis and phase transformation theory, backed by experimental confirmation. The microstructures of both the fusion and reheated zones of multirun alloy-steel weld deposits have been studied. The transformation mechanism of acicular ferrite has been established, and a theory for reaustenitisation in steel weld deposits has also been proposed. In addition to the studies on weld metals, some model alloys were fabricated and tested in order to confirm some of the predictions made by the new theory for reaustenitisation. All the weld metals studied in the investigation possess good hardenability. The primary microstructures of the fusion zone of these deposits consist mainly of acicular ferrite with very little allotriomorphic ferrite.
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Eizadjou, Mehdi. "Design of Advanced High Strength Steels." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17315.
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A new advanced high strength steels (AHSS) is designed based on Fe-C-Mn-Al composition. Martensitic steel is processed in intercritical region to achieve an ultrafine-grained duplex γ–(α + α') microstructure. The focus was on tuning the degree of austenite plasticity via controlling its stability, called austenite engineering. Interest in austenite engineering stems from transformation-induced plasticity (TRIP) effect, which is known to enhance ductility. The thermodynamic and kinetic analyses were used to optimize the annealing condition. The evolution of microstructure and mechanical properties was studied using different techniques. Due to high heating rate, the austenite reversion occurred before recrystallization of the ferrite. The final microstructure was duplex steel with globular-shaped grains. High volume fraction of the austenite phase was obtained (f_γ>40%) in very short time annealing. By increasing annealing temperature and time, austenite fraction and grain size increased. However, due to dilution of the austenite from stabilizers elements, the stability of the austenite dropped and transformed into martensite during quenching. This led in variety of austenite stabilities that resulted in different combination of mechanical properties. The critical factors influencing the onset of TRIP effect is studied and it was found that both early and delayed onset of the TRIP effect will lead to worse ductility. Hence, to achieve ultrahigh strength and excellent ductility, austenite stability shall be controlled to precisely trigger out TRIP. This study find out that discontinuous yielding or Lüders bands phenomenon can be used in ultrafine duplex steels to improve ductility. The results showed that superb combination of strength (σ_YS>1.0GPa and σ_UTS>1.4GPa) and ductility (ε_t≥20%) could be achieved in short time annealing of less than 10 minutes. This work evidence that tuning the austenite to a marginal stability enables us to design strong and ductile steels.
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Yosefani, Anas. "Flexural Strength, Ductility, and Serviceability of Beams that Contain High-Strength Steel Reinforcement and High-Grade Concrete." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4402.
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Utilizing the higher capacity steel in design can provide additional advantages to the concrete construction industry including a reduction of congestion, improved concrete placement, reduction in the required reinforcement and cross sections which would lead to savings in materials, shipping, and placement costs. Using high-strength reinforcement is expected to impact the design provisions of ACI 318 code and other related codes.
The Applied Technology Council (ATC-115) report "Roadmap for the Use of High-Strength Reinforcement in Reinforced Concrete Design" has identified key design issues that are affected by the use of high-strength reinforcement. Also, ACI ITG-6, "Design Guide for the Use of ASTM A1035 Grade 100 Steel Bars for Structural Concrete" and NCHRP Report 679, "Design of Concrete Structures Using High-Strength Steel Reinforcement" have made progress towards identifying how code provisions in ACI 318 and AASHTO could be changed to incorporate high-strength reinforcement.
The current research aims to provide a closer investigation of the behavior of beams reinforced with high-strength steel bars (including ASTM A615 Grade 100 and ASTM A1035 Grades 100 and 120) and high-strength concrete up to 12000 psi. Focus of the research is on key design issues including: ductility, stiffness, deflection, and cracking.
The research includes an extensive review of current literature, an analytical study and conforming experimental tests, and is directed to provide a number of recommendations and design guidelines for design of beams reinforced with high-strength concrete and high-strength steel. Topics investigated include: strain limits (tension-controlled and compression-controlled, and minimum strain in steel); possible change for strength reduction factor equation for transition zone (Φ); evaluation of the minimum reinforcement ratio (þmin); recommendations regarding limiting the maximum stress for the high-strength reinforcement; and prediction of deflection and crack width at service load levels. Moreover, this research includes long-term deflection test of a beam made with high grade concrete and high-strength steel under sustained load for twelve months to evaluate the creep deflection and to insure the appropriateness of the current ACI 318 time-dependent factor, λ, which does not consider the yield strength of reinforcement and the concrete grade.
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Lui, Wing Man. "Design of cold-formed high strength stainless steel tubular columns and beam-columns /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20LUI.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.<br>Includes bibliographical references (leaves 149-154). Also available in electronic version. Access restricted to campus users.
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Thompson, Alan. "High Strain Rate Characterization of Advanced High Strength Steels." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2831.
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The current research has considered the characterization of the high strain rate constitutive response of three steels: a drawing quality steel (DDQ), a high strength low alloy steel (HSLA350), and a dual phase steel (DP600). The stress-strain response of these steels were measured at seven strain rates between 0. 003 s<sup>-1</sup> and 1500 s<sup>-1</sup> (0. 003, 0. 1, 30, 100, 500, 1000, and 1500 s<sup>-1</sup>) and temperatures of 21, 150, and 300 °C. In addition, the steels were tested in both the undeformed sheet condition and the as-formed tube condition, so that tube forming effects could be identified. After the experiments were performed, the parameters of the Johnson-Cook and Zerilli-Armstrong constitutive models were fit to the results. <br /><br /> In order to determine the response of the steels at strain rates of 30 and 100 s<sup>-1</sup>, an intermediate rate tensile experiment was developed as part of this research using an instrumented falling weight impact facility (IFWI). An Instron tensile apparatus was used to perform the experiments at lower strain rates and a tensile split-Hopkinson bar was used to perform the experiments at strain rates above 500 s<sup>-1</sup> <br /><br /> A positive strain rate sensitivity was observed for each of the steels. It was found that, as the nominal strength of the steel increased, the strain rate sensitivity decreased. For an increase in strain rate from 0. 003 to 100 s<sup>-1</sup>, the corresponding increase in strength at 10% strain was found to be approximately 170, 130, and 110 MPa for DDQ, HSLA350, and DP600, respectively. <br /><br /> The thermal sensitivity was obtained for each steel as well, however no correlation was seen between strength and thermal sensitivity. For a rise in temperature from 21 to 300 °C, the loss in strength at 10% strain was found to be 200, 225, and 195 MPa for DDQ, HSLA350, and DP600, respectively for the 6 o?clock tube specimens. <br /><br /> For all of the alloys, a difference in the stress ? strain behaviour was seen between the sheet and tube specimens due to the plastic work that was imparted during forming of the tube. For the DP600, the plastic work only affected the work-hardening response. <br /><br /> It was found that both the HSLA350 and DDQ sheet specimens exhibited an upper/lower yield stress that was amplified as the strain rate increased. Consequently the actual strength at 30 and 100 s<sup>-1</sup> was obscured and the data at strain rates above 500 s<sup>-1</sup> to be unusable for constitutive modeling. This effect was not observed in any of the tube specimens or the DP600 sheet specimens <br /><br /> For each of the steels, both the Johnson-Cook and Zerilli-Armstrong models fit the experimental data well; however, the Zerilli-Armstrong fit was slightly more accurate. Numerical models of the IFWI and the TSHB tests were created to assess whether the experimental results could be reproduced using the constitutive fits. Both numerical models confirmed that the constitutive fits were applied correctly.
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De, Carufel Sarah. "Effect of High-Performance Steel Materials on the Blast Behaviour of Ultra-High Performance Concrete Columns." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35380.
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Previous events have demonstrated the vulnerability of reinforced concrete infrastructure to blast loading. In buildings, ground-story columns are key structural components, and their failure can lead to extensive damages which can cause progressive collapse. To prevent such disasters, the steel reinforcement in such columns must be properly detailed to ensure sufficient strength and ductility. The use of modern concrete materials such ultra-high performance concrete (UHPC) is one potential solution to improve the blast performance of columns. UHPC shows high compressive strength, high tensile resistance and superior toughness, properties which make it ideal for use in the blast-resistant design of columns. The combined use of UHPC and high-performance steels can potentially be used to further enhance the blast resistance of columns. This thesis presents an experimental and analytical study which investigated the use of high-performance materials to increase the blast capacity and ductility of reinforced concrete columns. As part of the experimental study, a total of seventeen columns were tested under simulated blast loading using the University of Ottawa Shock-Tube. Parameters investigated included the effect of concrete type (NSC and UHPC), steel reinforcement type (normal-strength, high-strength or highly ductile), longitudinal reinforcement ratio, seismic detailing and fiber properties. The test program included two control specimens built with normal-strength concrete, five specimens built with UHPC in combination with high-strength steel, and ten columns built with highly ductile stainless steel reinforcement. Each column was subjected to a series of increasing blast pressures until failure. The performance of the columns is investigated by comparing the displacements, impulse capacity and secondary fragmentation resistance of the columns. The results show that using high-performance steels increases the blast performance of UHPC columns. The use of sufficient amounts of high-strength steel in combination with UHPC led to important increases in column blast capacity. The use of ductile stainless steel reinforcement allowed for important enhancements in column ductility, with an ability to prevent rupture of tension steel reinforcement. The study also shows that increasing the longitudinal reinforcement ratio is an effective means of increasing the blast resistance of UHPC columns
The thesis also presents an extensive analytical study which aimed at predicting the response of the test columns using dynamic inelastic, single-degree-of-freedom (SDOF) analysis. A sensitivity analysis was also performed to examine the effect of various modelling parameters on the analytical predictions. Overall, it was shown that SDOF analysis could be used to predict the blast response of UHPC columns with reasonable accuracy. To further corroborate the results from the experimental study, the thesis also presents an analytical parametric study examining the blast performance of larger-scale columns. The results further demonstrate the benefits of using UHPC and high-performance steel reinforcement in columns subjected to blast loading.
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Pape, John Andrew. "Fretting fatigue damage accumulation and crack nucleation in high strength steels." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/18382.
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Linares, Arregui Irene. "Mechanical behaviour of a bainitic high strength roller bearing steel." Licentiate thesis, KTH, Hållfasthetslära (Avd.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25423.
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Lord, Michael. "Design and modelling of ultra-high strength steel weld deposits." Thesis, University of Cambridge, 1999. https://www.repository.cam.ac.uk/handle/1810/221873.
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Ellwood, R. D. "Fatigue performance of downgauged high strength steel automotive suspension component." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636792.
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Work has been carried out to determine whether the weight of a current production suspension component can be reduced, without a reduction in the fatigue performance, through the use of high strength steels and modern welding technologies. The reliability and accuracy of Finite Element (FE) modelling and fatigue prediction techniques have also been investigated. The three steels used in this study, 2.25 mm mild steel, 2.0 mm HSLA and a 1.8 mm dual phase grade showed increasing fatigue performance with tensile strength for unwelded samples. Fusion Metal Active Gas (MAG) welded H-beam samples showed the 2.0mm HSLA material to exhibit better fatigue performance than the mild steel and dual phase materials. Calculating the fatigue lives of these samples using a type F weld from BS7608 significantly overestimated the fatigue performance. Testing the full-scale component biaxially with CARLOS road load data showed the fatigue performance to increase with increasing thickness with the mild steel sample exhibiting a crack length of 5 mm at approximately 3 million km. FE modelling fatigue predictions using a Type F weld curve from BS7608 showed extremely good correlation with the experimental results with an minimum error of only 8% obtained for the mild steel samples.
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Sarandily, A. "High strength autoclaved cementitious matrices and steel fibre reinforced composites." Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374519.
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Barmicho, Ilona. "Fatigue Life Assessment of Cut Edges in High Strength Steel." Thesis, KTH, Lättkonstruktioner, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185017.
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The interests in more effective and lighter structures have increased the use of high strength steels for higher performances. Plate materials are optimized so thinner structures and higher material strengths are reached, this leads to the cut quality might be a new issue. In this investigation steel thickness of 6 and 16 mm with minimum yield strength from 355 to 960 MPa are fatigue tested with constant amplitude tensile loading. The specimens were cut using waterjet and also with thermally cut methods such as plasma and oxygen. Before fatigue testing the cut surfaces were measured and roughness Rz values were obtained. Empirical and analytical results of the surface roughness influencing the fatigue strength for different steel strengths are presented. Since thermal cutting methods have been developed over the years the FAT values are higher for those IIW are recommending. When the quality of the cut surface can be kept high the fatigue strength will also be higher than those recommended. This means having a cutting process that provides smooth surfaces such as waterjet and plasma cutting the fatigue life will be longer.
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Shetye, Nitish. "Life-Cycle Energy Analysis of a High Strength Steel Application." Thesis, KTH, Lättkonstruktioner, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290157.
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Steel is one of the most important engineering and construction material. It is used everywhere around us from making tiny nuts and bolts to massive cargo ships. It is a basic component in building societies and the development of mankind. The demand of steel is influenced by the population of the world and the per-capita consumption.
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Seru, Vikas Vineeth, and Venkata Ramana Murthy Polinati. "Modelling and Simulation of Hydrogen Diffusion in High Strength Steel." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-21128.
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This research is about modelling and simulation of how the hydrogen diffuses in high strength steels. The hydrogen diffusion in the material was examined by using finite element software with the help of material properties and some existing data. For modelling and simulating the diffusion analysis in finite element software, a cylindrical type dog-bone shaped specimen was chosen. To determine the diffusion at the centre of specimen, a cross-sectional area of the material was selected to proceed for the analysis. Abaqus software was considered as finite element software to progress the hydrogen diffusion and tensile testing of the specimen. Diffusion analysis was studied under the analogy of heat transfer and also, diffusion analysis with the addition of mechanical load was studied under the analogy of coupled temperature displacement in the Abaqus software. This process has executed for two types of high strength steels 316L and 304L stainless steels. The crack is also considered for analysis to check how it affects the specimen. Further, The 316L and 304L stainless steel results were compared to review that which steel is better to withstand the hydrogen diffusion rate and mechanical load on the material.
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Taufik, Syahril. "Behaviour of bolted connections with high strength and stainless steel." Thesis, Swansea University, 2008. https://cronfa.swan.ac.uk/Record/cronfa43058.
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Sederstrom, Jack H. "Spot Friction Welding of Ultra High-Strength Automotive Sheet Steel." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/842.
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Spot friction welding (SFW) was performed on ultra high strength steel (UHSS) steel sheet commonly used in automobile manufacturing. Alloys studied included DP780, DP780EG, DP980, and DF140T sheet steel of varying thickness from 1.2 mm to 1.4 mm. Welding was accomplished using a PCBN standard tool. Weld strengths were then compared to a proposed AWS standard. Initial hardness readings were taken in cross sectioned samples. Grain structure in a SFW is presented. Resistance spot welds were created in three steels. This study focuses on the strength of SFW joints as compared to traditional resistance spot welding (RSW) in welding like materials to one another. Cycle times of SFW were also evaluated and compared to production rate cycle times of RSW.