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Dissertations / Theses on the topic 'Steel'
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1
Di, Martino Fabio. "Microstructural characterisation of continuously cooled steels and steel welds." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/13615.
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Fe-Mn-Si-C steels are currently the most widely used type of steel for structural, building and automotive applications. Additionally, these steels also find important applications within welded structures, due to their low cost and versatility with regard to chemical composition and heat treatments because of the possibility to tailor their final mechanical properties. The production of a specific component made out of such steels generally involves continuous cooling heat treatments. Therefore, the way in which an optimum balance is achieved between the heat treatment parameters, the alloy composition and the desired microstructure for a specific application, is a vital step in the investigation of Fe-Mn-Si-C steels.
2
Jamwal, Ranbir Singh. "Microstructural origins of variability in the tensile ductility of dual phase steels." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39477.
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Quantitative relationships among processing parameters, microstructure, and material properties are of considerable interest in the context of development of robust processing routes that optimize the required material properties. As a result, the scientific literature contains a large number of experimental and theoretical studies on microstructure-properties relationships. Fracture sensitive mechanical properties such as ductility, ultimate tensile strength, fatigue life, and fracture toughness depend on the average microstructural parameters as well as the distributions of microstructural parameters and their extrema.Development of quantitative relationships between such material properties and microstructural distributions and extrema has received considerably less attention, particularly in the wrought metals and alloys. Accordingly, an important objective of this research is to perform a systematic investigation in this direction.
The dependence of the fracture-sensitive mechanical properties on the microstructural distributions and extrema often leads to substantial variability in these properties: a set of specimens having the same average chemistry, the same average processing history, and the same average microstructural parameters such as volume fractions of different constituents can exhibit substantially different material properties. The present research (i) is concerned with high strength (~ 1000 MPa) high martensite (>50%) dual phase steel where the martensite is a topologically continuous phase (matrix) containing a dispersion of islands of ferrite, and (ii) focuses on understanding the microstructural origins of the variability in fracture sensitive mechanical properties, in particular variability in the room temperature uniaxial tensile ductility. The research involves quantitative microstructure characterization using stereology and digital image processing and quantitative fractography using scanning electron microscopy (SEM) and fracture profilometry. The analysis of the quantitative fractographic and microstructural data obtained in this research leads to useful guidelines for reducing the variability in the tensile ductility of the dual phase steel under investigation.
3
Simsir, Mehmet. "Investigation Of Fracture Behavior Of Steel/steel Laminates." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604834/index.pdf.
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A study is carried out into fracture behavior of steel/steel laminates both experimentally and through finite element analysis (FEM). The laminates produced by hot pressing consisted of low carbon and medium carbon steels with two volume fractions0.41 and 0.81. Fracture toughness, JIC has been measured using partial unloading technique assuming a critical value of crack extension. The technique is initially applied to monolithic material and then to the laminates in crack divider orientation. Evaluation of fracture toughness of laminates indicates that there is a substantial improvement of JIC with increase in the volume fraction. The systems under study were also evaluated by FEM modeling with the use MARC package program. To evaluate JIC, the problem has been evaluated in several steps
first two-dimensional plane strain problem is considered. This is followed by three-dimensional case and then by an artificially layered system, all for monolithic materials. Values of JIC derived were close to one another in all cases. Following this verification, the method, as implemented in layered monolithic system, was applied to laminates. This has shown that JIC of laminates can be predicted using FEM analysis, including the delamination. Values of JIC varied in the same manner as the experiment verifying that fracture toughness in the current system increases with increase in volume fraction. It has been concluded that modeling as implemented in this work can be used for useful composite systems incorporating hard/brittle reinforcements both in crack divider and crack arrester orientation.
4
Cyril, Nisha S. "Anisotropy and Sulfide Inclusion Effects on Tensile Properties and Fatigue Behavior of Steels." Connect to full text in OhioLINK ETD Center, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1198808409.
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Thesis (M.S.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science Degree in Mechanical Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 204-209.
5
Foundoukos, Nickolaos. "Behaviour and design of steel-concrete-steel sandwich construction." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/8819.
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Coyle, Neil Robert. "Development of fully composite steel-concrete-steel beam elements." Thesis, University of Dundee, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270046.
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Steel-Concrete-Steel (SCS) composite construction consists of two relatively thin steel plates with the space between filled with concrete. Various forms of this construction exist, using overlapping shear studs and single bar connectors to provide shear reinforcement to the concrete and provide a shear transfer at the interface. The problem with current systems that rely purely upon shear studs or bar connectors is that they are prone to slip between the steel faceplates and concrete core. This slip leads to a loss of composite action causing a loss of stiffness and a reduced fatigue life. An extensive experimental programme consisting of 32 beam specimens and 34 other small scale specimens formed the basis for the study of the behaviour of surfaced SCS specimens under a variety of load conditions. The results of this test program showed that surfaced SCS specimens behaved in a more composite manner. This increase in composite action manifested itself in a number of ways. • Reduced slip between steel plate and concrete core • Increased stiffness of specimen • More even crack distribution This extensive experimental study was backed up with an analytical study to understand and predict the behaviour of the surfaced SCS elements. This study has led to a new method of predicting the capacity of such sections, to a greater degree of accuracy than current methods allow. Further to this a FE parametric study was carried out to investigate the sensitivity of the elements to changes in the main geometrical and material variables.
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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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McCann, Robert K. "Loading Capacity of Massillon Steel Joist and Truscon Steel Joist." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494286003564687.
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Mahdavian, Mahsa. "Innovative Cold-Formed Steel Shear Walls with Corrugated Steel Sheathing." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849608/.
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This thesis presents two major sections with the objective of introducing a new cold-formed steel (CFS) shear wall system with corrugated steel sheathings. The work shown herein includes the development of an optimal shear wall system as well as an optimal slit configuration for the CFS corrugated sheathings which result in a CFS shear wall with high ductility, high strength, high stiffness and overall high performance. The conclusion is based on the results of 36 full-scale shear wall tests performed in the structural laboratory of the University of North Texas. A variety of shear walls were the subject of this research to make further discussions and conclusions based on different sheathing materials, slit configurations, wall configurations, sheathing connection methods, wall dimensions, shear wall member thicknesses, and etc. The walls were subject to cyclic (CUREE protocol) lateral loading to study their deformations and structural performances. The optimal sit configuration for CFS shear walls with corrugated steel sheathings was found to be 12×2 in. vertical slits in 6 rows. The failure mode observed in this shear wall system was the connection failure between the sheathing and the framing members. Also, most of the shear walls tested displayed local buckling of the chord framing members located above the hold-down locations. The second section includes details of developing a Finite Element Model (FEM) in ABAQUS software to analyze the lateral response of the new shear wall systems. Different modeling techniques were used to define each element of the CFS shear wall and are reported herein. Material properties from coupon test results are applied. Connection tests are performed to define pinching paths to model fasteners with hysteretic user-defined elements. Element interactions, boundary conditions and loading applications are consistent with full scale tests. CFS members and corrugated sheathings are modeled with shell elements, sheathing-to-frame fasteners are modeled using nonlinear springs (SPRING2 elements) for monotonic models and a general user defined element (user subroutine UEL) for cyclic models. Hold-downs are defined by boundary conditions. A total of three models were developed and validated by comparing ABAQUS results to full scale test results.
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Nekouie, Esfahani Mohammadreza. "Laser welding of dissimilar carbon steel to stainless steel 316L." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19760.
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Laser welding of metals and alloys is extensively used in industry due to its advantages of controlled heating, narrow weld bead, low heat affected zone (HAZ) and its ability to weld a wide range of metals and dissimilar metals. Laser welding of dissimilar metals such as carbon steels and stainless steel is still a challenging task, particularly due to the formation of brittle phases in the weld, martensitic formation in the HAZ and solidification cracking in the fusion zone. These issues can significantly deteriorate the strength of the welded joint. The aim of this work is to investigate the fundamental phenomena that occur inside the dissimilar weld zone and their effect on weld quality. In order to establish the key process variables, an initial study concentrated on the effect of different laser process parameters on dissimilar weld quality. In the second part of the work, a comprehensive study was performed to understand and subsequently control the alloying composition in laser dissimilar welding of austenitic stainless steel and low carbon steel. A dissimilar weld that is predominantly austenitic and homogeneous was obtained by controlling the melt pool dynamics through specific point energy and beam alignment. The significance of dilution and alloying elements on joint strength was established. A coupled CFD and FEM numerical model was developed to assist in understanding the melt pool dynamics and transportation processes of alloying elements. The model has been validated by a series of laser welding experiments using various levels of specific point energy. The laser welding characteristics in terms of geometric dimensions, surface morphology, alloying concentration, and dilution, were compared, and it is concluded that the specific point energy and laser beam position are the key parameters that can be controlled to obtain a weld bead with characteristics most suitable for industrial applications. In the third part of the work, a comparative study was performed to understand the significance of cooling rate, and alloying composition on the microstructure and phase structure of the dissimilar weld zone. Results show that the HAZ within the high carbon steel has significantly higher hardness than the weld area, which severely undermines the weld quality. A new heat treatment strategy was proposed based on the results of the numerical simulation, and it is shown to control the brittle phase formation in HAZ of high carbon steel. A series of experiments was performed to verify the developed thermo-metallurgical FEA model and a good qualitative agreement of the predicted martensitic phase distribution is shown to exist. Although this work is presented in the context of dissimilar laser welding of mild steel to stainless steel, the concept is applicable to any dissimilar fusion welding process.
11
Nip, Ka Ho. "Cyclic behaviour of carbon steel and stainless steel tubular members." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/42999.
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Concentrically braced frames are a common form of earthquake resistant structure. Performance of the structure is largely dependent on the ability of the key dissipative components, in this case the diagonal bracing members, to undergo significant inelastic deformations. Whilst many earlier studies have examined the hysteretic response of bracing members, comparatively less attention has been given to the ultimate behaviour and failure conditions. There are also significant uncertainties in existing models for predicting the ductility capacity of braces owing to their semi-empirical nature as well as the scatter of test results. This research project examines the cyclic behaviour of tubular braces made of a familiar structural material, carbon steel, and an increasing popular alternative structural material, stainless steel, which is known for its high tensile ductility. As part of the current study, laboratory tests were performed on hot-rolled carbon steel, cold-formed carbon steel and cold-formed austenitic stainless steel hollow section members and materials coupon cut from them. A total of 24 tensile coupon tests, 62 cyclic material tests and 16 cyclic member tests were conducted. Strain-life relationships of the materials under low and extremely low cycle fatigue regimes were established from the results of the cyclic material tests. These data were also used for calibrating material cyclic hardening models, which were incorporated in numerical models of hollow section members. These models, verified against the results of the cyclic member tests from this study and other research programmes, were employed in parametric studies to investigate the influence of member geometry and material properties on the behaviour of the bracing members. Although the three materials exhibit similar strain-life relationships, cold-formed stainless steel members perform better in terms of displacement ductility and energy dissipation, which is due to the cyclic hardening and higher post-yield stiffness of the stainless steel material. Implications of these findings on the design of earthquake resistant concentrically braced frames are discussed and design guidance for stainless steel bracing members is proposed.
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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.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.
QC 20190925
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Zlotniov, Susanna. "Life After Steel." Research Showcase @ CMU, 2015. http://repository.cmu.edu/theses/92.
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The success of a city’s transition initiatives depends on how effectively members of a community can work together. Transitioning a community often involves major shifts in lifestyle and social realities that may expose a gap between administrative goals and varying residential needs. This gap can cause tensions between stakeholders and ultimately break down transition efforts.
Visual storytelling can empower members of a community to become more informed, engaged, collaborative and productive during transition while fostering a more coherent connection to place. Pittsburgh’s rich historical narratives, rooted in its steel industry, can provide an understanding of time and place, and help all current residents, and new residents in particular, connect with social histories enabling them to envision possible futures. My thesis project focused on determining how to deliver these stories in an effective way.
My project approach was to be as immersive as possible throughout the research process. It involved exploring the city and discovering its historical narratives for myself as well as interviewing Pittsburgh residents to better understand their perspectives around the importance of learning local history. I discovered that residents don’t know a lot about Pittsburgh’s industrial heritage and that local narratives are often not physically accessible.
Following these insights, I aimed to create a solution that would engage and raise overall awareness of Pittsburgh’s historical narratives among local residents. Research insights informed my final proposed design: a citywide information system embedded within Pittsburgh’s public bus stop infrastructure. This system presents historical narratives in a spatial context across the city’s urban landscape, helping residents realize the relationship between past, present, and possible futures.
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Atlayan, Ozgur. "Hybrid Steel Frames." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50562.
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The buildings that are designed according to the building codes generally perform well at severe performance objectives (like life safety) under high earthquake hazard levels. However, the building performance at low performance objectives (like immediate occupancy) under low earthquake hazards is uncertain. The motivation of this research is to modify the design and detailing rules to make the traditional systems perform better at multi-level hazards.This research introduces two new structural steel systems: hybrid Buckling Restrained Braced Frames (BRBF) and hybrid steel Moment Frames (MF). The "hybrid" term for the BRBF system comes from the use of different steel material including carbon steel (A36), high-performance steel (HPS) and low yield point (LYP) steel. The hybridity of the moment frames is related to the sequence in the plastification of the system which is provided by using weaker and stronger girder sections. Alternative moment frame connections incorporating the use of LYP steel plates are also investigated.
The hybrid BRBF approach was evaluated on seventeen regular (standard) frames with different story heights, seismic design categories and building plans. By varying the steel areas and materials in the BRB cores, three hybrid BRBFs were developed for each regular (standard) frame and their behavior was compared against each other through pushover and incremental dynamic analyses. The benefits of the hybridity were presented using different damage measures such as story accelerations, interstory drifts, and residual displacements. Collapse performance evaluation was also provided.
The performance of hybrid moment frames was investigated on a design space including forty-two moment frame archetypes. Two different hybrid combinations were implemented in the designs with different column sections and different strong column-weak beam (SC/WB) ratios. The efficiency of the hybrid moment frame in which only the girder sizes were changed to control the plastification was compared with regular moment frame designs with higher SC/WB ratios. As side studies, the effect of shallow and deep column sections and SC/WB ratios on the moment frame behavior were also investigated.
In order to provide adequate ductility in the reduced capacity bays with special detailing, alternative hybrid moment frame connections adapting the use of low strength steel were also studied.
PhD
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Oetterli, Linn. "The Battle of Steel - Impact of U.S. steel tariffs on Swedish steel exports : A synthetic control group approach." Thesis, Uppsala universitet, Nationalekonomiska institutionen, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-434749.
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The aim of this study is to examine whether the 2018 U.S. steel tariffs have negatively impacted Swedish steel exports to the U.S, given that the U.S. is Swedish steel industry’s second most important foreign market and the majority of Swedish steel exports to the U.S. are subject to the tariffs. The theoretical foundation for this study is the standard trade model, which predicts a decline in quantity traded due to tariffs. With monthly export value data for January 2015 to January 2020, the synthetic control method (SCM) is used to create a counterfactual to the steel products subject to tariffs. The study encountered several data limitations which complicated the use of the SCM, but the overall results suggest that in the absence of tariffs, Swedish monthly export value for steel to the U.S. would have higher than it has been with the tariffs.
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Morris, Andrew Weldon. "The second age of steel : the era of alloy steels, 1858-1914." Thesis, University of Exeter, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444455.
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Orto, Julie M. "From Steel Cities to Steal Cities: Is Rusty Risky for High Crime?" Youngstown State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1390337303.
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Ho, Ho-chuen Federick. "Ferrous metal balance of Hong Kong : consumption, waste generation, recycling and disposal /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18734893.
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Yu, Guowang. "Cold-formed Steel Framed Shear Wall Sheathed with Corrugated Sheet Steel." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271921/.
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Incombustibility is one important advantage of the sheet steel sheathed shear wall over wood panel sheathed shear wall. Compared to shear wall sheathed with plywood and OSB panel, shear wall sheathed with flat sheet steel behaved lower shear strength. Although shear wall sheathed with corrugated sheet steel exhibited high nominal strength and high stiffness, the shear wall usually behaved lower ductility resulting from brittle failure at the connection between the sheathing to frames. This research is aimed at developing modifications on the corrugated sheathing to improve the ductility of the shear wall as well as derive practical response modification factor by establishing correct relationship between ductility factor ? and response modification factor R. Totally 21 monotonic and cyclic full-scale shear wall tests were conducted during the winter break in 2012 by the author in NUCONSTEEL Materials Testing Laboratory in the University of North Texas. The research investigated nineteen 8 ft. × 4 ft. shear walls with 68 mil frames and 27 mil corrugation sheet steel in 11 configurations and two more shear walls sheathed with 6/17-in.OSB and 15/32-in. plywood respectively for comparison. The shear walls, which were in some special cutting arrangement patterns, performed better under lateral load conditions according to the behavior of ductility and shear strength and could be used as lateral system in construction.
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Wells, James E. "Interaction of stainless steel threaded fasteners with stainless steel locking inserts." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01102009-063308/.
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Prasannavenkatesan, Rajesh. "Microstructure-sensitive fatigue modeling of heat treated and shot peened martensitic gear steels." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31713.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Chair: David L. McDowell; Committee Member: G. B. Olson; Committee Member: K. A. Gall; Committee Member: Min Zhou; Committee Member: R. W. Neu. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hussain, I. "A comparison of the cleanliness of steels treated with calcium-silicon and magnesium." Thesis, University of Wolverhampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234259.
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King, Benjamin. "Welding and post weld heat treatment of 2.25%Cr-1%Mo steel." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060404.095844/index.html.
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Jansson, Sune. "A study on molten steel/slag/refractory reactions during ladle steel refining." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-312.
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Vijayakumar, Sujaya Jairam. "Mapping and analysis of the steel matrix across the Steel/WC- Composite." Thesis, KTH, Tillämpad processmetallurgi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157349.
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Deng, Zhiyin. "Study on the Interaction between Refractory and Liquid Steel Regarding Steel Cleanliness." Doctoral thesis, KTH, Mikro-modellering, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190071.
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The present thesis focuses on the interaction between refractory and liquid steel. The aim of this work is to understand the interaction behavior between refractory and liquid steel regarding steel cleanliness. The effect of different refractories on different inclusions in Al-killed steel was studied in a furnace. The sintering mechanism of filler sand were also investigated in laboratory. In the industrial trials, the attachments of different oxides on the walls of submerged entry nozzle (SEN) were discussed in the cases of high strength low alloy steel (HSLA) and ultra-low carbon steel (ULC). It is found that the effect of alumina and spinel refractory on all the three types of inclusions is very little, while MgO refractory influences the inclusions depending on the activity of dissolved oxygen in liquid steel. At low oxygen level, alumina inclusions could transform into spinel inclusions with the help of MgO refractory, while the effect on spinel and calcium aluminate inclusions is not evident. On the other hand, when the activity of dissolved oxygen is high enough, the evolution of spinel inclusions from alumina inclusions could not be seen. The reaction between chromite and silica grains leading to liquid formation is the main mechanism for the sintering of filler sand. The factors viz. steel composition, silica size and content, operation temperature and process holding time have a strong influence on the sintering of the filler sand. Smaller size and higher content of silica in sand, steel grades containing higher Mn and Al contents, higher temperature and longer holding time would result in serious sintering. The choice of the sand needs to take those factors into account. The results show that solid alumina particles are always agglomerated on the inner wall of SEN in the case of ULC steel. The top slag with high FeO and MnO contents is considered as the main reason of this kind of attachments. The removal of slag might be a good method to avoid the attachments. In the case of HSLA steel, liquid calcium aluminate inclusions could attach on the inner wall of SEN as well. The smoothness of the inner wall of the SEN holds the key of liquid attachments. In addition, the attachment situation on the outer wall of SEN depends on the operations. The oxygen entrainment through the mold powder would result in the formation of plate-like alumina attachments. The control of reoxidation due to oxygen entrainment would help to avoid this situation.QC 20160816
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Corner, Sebastien Marc William. "Screw-Fastened Cold-Formed Steel-to-Steel Shear Connection Behavior and Models." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/78073.
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This research introduces a proposed model for predicting tilting angle and limit states of single-fastened cold-formed steel-to-steel shear connections. Predictions are validated through an experimental study considering ply configuration and a single Hex #10 -washer head fastener, centered in a 102 mm by 102 mm three boundary window. The fastener tilting angle is captured using an automated, optical non-contact measurement procedure. The results are used to identify cold-formed steel shear connection deformation as load progresses, including tilting, bearing, and combined tilting bearing at the plies and thread tension, shear and bearing fastener failure. Results shows that fastener tilting plays a kinematic affect for the connection. Fastener tilting is predicted in function of ply thickness and fastener pitch. Local ply bending deformation is reported to be the main deformation of the connection during fastener tilting. While fastener bending and shear failure occurred if the fastener does not tilt.Master of Science
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Xiao, Bin. "Multipass laboratory simulations of steel plate hot rolling for improved steel productivity." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/5072/.
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Besgul, Ozge. "Design And Production Of Steel Buildings: A Case Study In Ankara." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607871/index.pdf.
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It is vital that Turkey keep abreast of developments in the world and build up its technology to become a developed country. Steel construction is one of these areas. In this context, the main purpose of this study was to define, analyze and evaluate the general characteristics of structural steel and steel construction with the purpose of throwing new light on its advantages and disadvantages.
Within this framework, a literature survey was conducted on structural steel components and structuresand on steel construction in Turkey. Additionally, a case study was carried out on a steel office building in Ankara. In this, the Tü
rkiye Esnaf ve Sanatkar Kredi Kefalet Kooperatifleri Merkez Birligi (TESKOMB) Building was investigated in terms of the design and production criteria for steel structures and to determine problems faced during these processes. As a result of this study, the existing condition of the construction sector and the means to improve use of structural steel in Turkey were discussed more realistically.
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Khoo, Heng Aik. "Ductile fracture of steel." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0014/NQ59610.pdf.
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Ahn, ByeoungSoo 1959. "Hydrogen in enameling steel." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33320.
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Enameling steel, used in a vast range of applications, can suffer from a surface defect resembling fish scale. In this study, the effects of several microstructural, physical and coating factors on the hydrogen diffusion in low carbon steel were investigated using an electrochemical permeation apparatus, to find out the way to prevent the surface defects on the enamel coatings.A new mechanism explaining the formation of the surface defects on the enameling steel was proposed after summarizing the experimental results. Then, the effects of porosity, dislocation density, the surface roughness of a steel substrate, oxide passive layer and Pd coating on the hydrogen diffusion coefficient, hydrogen concentration and hydrogen flux were investigated.
The variations of hydrogen diffusion coefficient, hydrogen concentration in steel and hydrogen flux caused by all factors listed previously were calculated in order to understand the effect of these factors on hydrogen diffusion.
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Berryman, Eleanor. "Carbonation of steel slag." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110434.
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Iron and steel production is a rapidly growing industry with global outputs increasing 65% over the last ten years (World Steel Association, 2012). Unfortunately, it is also the largest industrial source of atmospheric CO2, accounting for a quarter of the CO2 emissions from industrial sources (International Energy Agency (IEA), 2007).Mineral carbonation provides a robust method for permanent sequestration of CO2 that is environmentally inert. Larnite (Ca2SiO4), the major constituent of steel slag, reacts readily with aqueous CO2 (Santos et al., 2009). Consequently, its carbonation offers an important opportunity to reduce CO2 emissions at source. A potential added benefit is that this treatment may render steel slag suitable for recycling. This study investigates the impact of temperature, fluid flux and reaction gradient on the dissolution and carbonation of steel slag, and is part of a larger study designed to determine the conditions under which conversion of larnite, and other calcium silicates, to calcite is optimized. Experiments were conducted on 2 – 3 mm diameter steel slag grains supplied by Tata Steel RD&T. A CO2-H2O mixture was pumped through a steel flow-through reactor containing these grains. For a given experiment, temperature was fixed at a value between 120°C and 200°C, pressure was 250 bar, and the fluid flux was fixed at 0.8 mL/cm2min or 6 mL/cm2min. Reactions were also carried out in a batch reactor at 180°C and 250 bar, corresponding to a condition of zero flux. The duration of experiments ranged from 3 to 7 days. The CO2-H2O fluid reacted with the steel slag grains to form phosphorus-bearing Ca-carbonate phases. At high fluid flux, 6 mL/cm2min, these phases dissolved at the edges of slag grains, leaving behind a porous rind of aluminum and iron oxides. Increasing temperature increased the rate of this reaction. At low fluid flux, 0.8 mL/cm2min, the extent of carbonation was increased. At the edge of grains, instead of being transformed to porous rinds, primary Ca minerals were replaced by phosphorus-bearing Ca-carbonate phases. As a result of the greater length of reactor used in these experiments, a reaction gradient was observed along which the fluid remained supersaturated with respect to the calcium carbonate, coating the surfaces of the slag grains. Steel slag exposed to the CO2-H2O fluid in the batch reactor was less carbonated; incongruent dissolution of the slag followed by surface coating of the grains by calcium carbonate inhibited further interaction of the slag with the fluid, limiting the extent of possible carbonation.The results of this study show that carbonation of steel slag by aqueous CO2 is feasible using relatively large grains, and that it can be optimised by varying fluid flux. Experiments of the type described above will contribute to the eventual global reduction of industrial CO2 emissions.L'industrie du fer et de l'acier est en pleine croissance et sa production mondiale a augmenté de 65% au cours des dix dernières années (World Steel Association, 2012). Malheureusement, elle est également responsable d'un quart des émissions industrielles de CO2 ce qui en fait la plus importante source industrielle de CO2 atmosphérique (International Energy Agency (IEA), 2007).La carbonatation minérale fournit une méthode robuste pour la séquestration permanente du CO2 sous une forme écologiquement inerte. La larnite (Ca2SiO4), constituant principal des scories d'acier, réagit aisément avec le CO2 aqueux (Santos et al., 2009). Par conséquent, sa carbonatation offre une importante occasion de réduire à la source les émissions de CO2. Un avantage potentiel supplémentaire de ce traitement est de rendre les scories d'acier convenables pour le recyclage. Cette étude examine l'impact de la température, le flux molaire surfacique du fluide carbonaté, et d'un gradient de réaction sur la dissolution et la carbonatation des scories d'acier. Elle s'inscrit dans une étude plus large visant à déterminer les conditions optimisant la conversion de la larnite, et d'autres silicates de calcium, à la calcite.Des expériences ont été menées sur des grains de scories d'acier d'un diamètre de 2 à 3 mm fournis par Tata Steel RD&T. Un mélange de CO2-H2O a été pompé à travers un réacteur continu contenant ces grains et maintenu à une température entre 120°C et 200°C, une pression de 250 bar et à des flux molaires surfaciques de 0.8 à 6 mmol/cm2min. Chaque expérience a duré de 3 à 7 jours. Le fluide CO2-H2O a réagi avec les grains de scories d'acier et a formé des minéraux de carbonate de calcium contenant du phosphore. À flux molaire surfacique élevé, soit 6 mL/cm2min, ces phases sont dissoutes aux bords des grains, laissant place à une bordure poreuse d'oxydes d'aluminum et de fer. Une augmentation de la température a augmenté la vitesse de cette réaction. A valeur intermédaire de flux molaire surfacique, 0.8 mL/cm2min, le degré de carbonatation a augmenté. Au lieu laisser des bordures poreuses d'oxydes, les minéraux de calcium primaires en marge des grains ont plutôt été remplacés par des phases de calcium carbonate contenant du phosphore. En plus, l'usage d'un réacteur plus long a créé un gradient de réaction et maintenu la supersaturation du fluide relative au carbonate de calcium qui a enrobé les grains. Les scories d'acier exposées au fluide dans un réacteur discontinu (sans flux de fluide) ont été moins carbonatées; la dissolution non-congruente de la scorie a pris place suivie par l'enrobage des grains de scories par le carbonate, et ce dernier a réduit la surface de réaction de la scorie avec le fluide.Les résultats de cette étude démontrent que la carbonatation par le CO2 aqueux des scories d'acier à granulométrie relativement grossière est possible et qu'elle peut être optimisée en variant le flux molaire surfacique du fluide. Les expériences de ce type contribueront à la réduction éventuelle des émissions industrielles globales de CO2.
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Pickering, Edward John. "Macrosegregation in steel ingots." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708651.
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Nhamoinesu, Shelton. "Steel-glass composite panels." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708845.
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Strömbom, Johannes. "Natural Fingerprinting of Steel." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85531.
Full textAbstract:
A cornerstone in the industry's ongoing digital revolution, which is sometimes referred to as Industry 4.0, is the ability to trace products not only within the own production line but also throughout the remaining lifetime of the products. Traditionally, this is done by labeling products with, for instance, bar codes or radio-frequency identification (RFID) tags. In recent years, using the structure of the product itself as a unique identifier, a "fingerprint", has become a popular area of research. The purpose of this work was to develop software for an identification system using laser speckles as a unique identifier of steel components. Laser speckles, or simply speckles, are generated by illuminating a rough surface with coherent light, typically laser light. As the light is reflected, the granular pattern known as speckles can be seen by an observer. The complex nature of a speckle pattern together with its sensitivity to changes in the setup makes it robust against false-positive identifications and almost impossible to counterfeit. Because of this, speckles are suitable to be used as unique identifiers. In this work, three different identification algorithms have been tested in both simulations and experiments. The tested algorithms included one correlation-based, one method based on local feature extraction, and one method based on global feature extraction. The results showed that the correlation-based identification is most robust against speckle decorrelation, i.e changes in the speckle pattern, while being quite computationally expensive. The local feature-based method was shown to be unfit for this current application due to its sensitivity to speckle decorrelation and erroneous results. The global feature extraction method achieved high accuracy and fast computational speed when combined with a clustering method based on overlapping speckle patterns and a k-nearest neighbours (k-NN) search. In all the investigated methods, parallel calculations can be utilized to increase the computational speed.
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Carolan, Matthew. "Voices of Bethlehem Steel." Thesis, Lehigh University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10275483.
Full textAbstract:
This research and documentary film attempts to articulate the story of the worker at Bethlehem Steel formally located in Bethlehem, Pennsylvania. In part, this is an examination of the labor unions at Bethlehem Steel and though they remain always in the background the film delves more deeply into the evolution of the worker at the plant from the early strikes for labor recognition to the closing of the plant. There are three chapters in the film; the 1941 Bethlehem Steel strike, the unions after their recognition, and the closing of the Bethlehem plant. The workers stories and analysis form the central component of the film and the methodology for selecting what would be included. Workers provide most of the analysis whereas the narration and multi-media selected serve to facilitate their story. What the documentary finds is a wealth of information on Bethlehem Steel as told by their workers coupled with the human emotion that accompanies their struggle. This documentary film explores workers at Bethlehem Steel, their initiation into labor unions, their evolution through the decades, and finally their lives through the closing.
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Abosrra, L. R. "Corrosion of steel reinforcement in concrete : corrosion of mild steel bars in concrete and its effect on steel-concrete bond strength." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5417.
Full textAbstract:
This thesis reports on the research outcome of corrosion mechanism and corrosion rate of mild steel in different environments (saline, alkaline solutions and concrete media) using potentiodynamic polarization technique. The study also included the effect of corrosion on bond strength between reinforcing steel and concrete using pull-out test. Corrosion of mild steel and 316L stainless steel with different surface conditions in 1, 3 and 5% saline (NaCl + Distilled water) was investigated. Specimens ground with 200 and 600 grit silicon carbide grinding paper as well as 1μm surface finish (polished with 1μm diamond paste) were tested. In case of mild steel specimens, reduction in surface roughness caused increase in corrosion rate, while in 316L stainless steel corrosion rate decreased as the surface roughness improved. Metallographic examination of corroded specimens confirmed breakdown of passive region due to pitting corrosion. Corrosion of mild steel was also investigated in alkaline solution (saturated calcium hydroxide, pH =12.5) contaminated with 1, 3 and 5% saline. A series of corrosion experiments were also conducted to examine the efficiency of various concentrations of calcium nitrite (CN) on corrosion behaviour of both as-received and polished mild steel in alkaline solution containing 3% saline after 1 hour and 28 days of exposure. Corrosion rate was higher for the as-received than polished mild steel surface under the same testing conditions in NaCl alkaline solution with and without nitrites due to the effect of surface roughness. Morphology investigation of mild steel specimens in alkaline solution ii containing chlorides and nitrites showed localized pits even at nitrite concentration equal to chloride concentration. Corrosion of steel bars embedded in concrete having compressive strengths of 20, 30 and 46MPa was also investigated. The effect of 2 and 4% CN by weight of cement on corrosion behaviour of steel bar in low and high concrete strengths specimens were also studied. All reinforced concrete specimens were immersed in 3% saline solution for three different periods of 1, 7 and 15 days. In order to accelerate the chemical reactions, an external current of 0.4A was applied. Corrosion rate was measured by retrieving electrochemical information from polarization tests. Pull-out tests of reinforced concrete specimens were then conducted to assess the corroded steel/concrete bond characteristics. Experimental results showed that corrosion rate of steel bars and bond strength were dependent on concrete strength, amount of CN and acceleration corrosion period. As concrete strength increased from 20 to 46MPa, corrosion rate of embedded steel decreased. First day of corrosion acceleration showed a slight increase in steel/concrete bond strength, whereas severe corrosion due to 7 and 15 days corrosion acceleration significantly reduced steel/concrete bond strength. Addition of only 2% CN did not give corrosion protection for steel reinforcement in concrete with 20MPa strength at long time of exposure. However, the combination of good quality concrete and addition of CN appear to be a desirable approach to reduce the effect of chloride induced corrosion of steel reinforcement. At less time of exposure, specimens without CN showed higher bond strength in both concrete mixes than those with CN. After 7 days of corrosion acceleration, the higher concentration of CN gave higher bond strength in both concrete mixes. The same trend was observed at 15 days of corrosion acceleration except for the specimen with 20MPa compressive strength and 2% CN which recorded the highest deterioration in bond strength.
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Wibbenmeyer, Kaye Dee. "Determining the R values for 12 inch deep Z-purlins and girts with through-fastened panels under suction loading." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2010. http://scholarsmine.mst.edu/thesis/pdf/Wibbenmeyer_09007dcc807d5580.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2010.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed July 26, 2010) Includes bibliographical references (p. 58-59).
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Jaramillo, Fulvio E. "Axially loaded stainless steel compression members." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07102006-144943/.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007.Leroy Z. Emkin, Committee Member ; Lawrence F. Kahn, Committee Member ; Abdul-Hamid Zureick, Committee Chair.
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Soltani, Maryam. "Image-based analysis of steel sheathed cold-formed steel shear wall buckling behavior." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
The high lateral force resisting feature of the cold-formed steel structure, make it an attractive design choice in seismic zones. The shear strength of these systems controls by two critical factors, the characteristic of the sheathed and the sheathing-to-frame connections. There are many challenges associated with testing different configurations of these thin-wall structures (size, layout, sheathed material). Despite the huge growth of such constructions, the design procedure and the numerical calculation developed by the American Iron and Steel Institute provision AISI S240 (2015) and AISI S400 (2015), didn’t provide a proper standard for the various possible design of the CFS shear walls. This thesis proposes a study aiming to expose the gap across the theory to the practical issue by comparing the equation-based analysis and the image-based analysis of the shear strength of the shear walls.
Two large-scale CFS shear walls infilled with gravity wall were tested under the quasi-static reversed cyclic protocol at the laboratory of the University of California San Diego. These innovative specimens were built with the thicker framing members than the listed ones in the AISI standard and assembled in the specific framing layout. The sheathing-to-frame connections and sheathing parameters like screw spacing, screw size, and thickness of the sheet was the same in both walls.
The shear strength of these walls computed through the effective Strip width method in the provisions of the AISI S400 (2015) by selecting the minimum value between the shear capacity of the connections which bar the shear force in the tension field and the shear strength of the sheathed. Surprisingly the calculated result was one-third of the test results.
This experiment shows how imperfect is the provided equation-based shear strength method by the AISI standard design for CFS Structures.
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Rodrigues, Pardal Goncalo Nuno. "Joining of steel to aluminium and stainless steel to titanium for engineering applications." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/10007.
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Dissimilar welding has been subject of several investigations due to its potential importance in various industrial fields such as transportation, energy generation and management. Dissimilar welding can increase the design efficiency, by the use of complementary alloys with different properties, cost cutting and light weighting structures. The use of different materials within a component or structure to best suit a particular task, requirement or increase its life and performance has always been an ambition of several designers and engineers. This project investigated the joining steel and aluminium for the automotive industry and also stainless steel and titanium to be applied in the civil nuclear energy generation industry. These dissimilar metallic combinations are metallurgically incompatible and the formation of brittle intermetallic phases (IMC) need to be controlled or eliminated. To join steel to Al, laser spot welding process was selected, to avoid the bulk melting of steel and Al at the joint interface that enhance the formation of brittle IMC. This part of the work was focused in controlling the joining process to control the IMC formation of galvanized and uncoated steel to Al and verify if it was possible to have a sound and reliable joint in the presence of an IMC layer. In the second part of this study, stainless steel to titanium joining, a different approach was taken with the application of weld metal engineering to modify or eliminate the IMC formation. Several metals were evaluated as potential interlayers to use and laser welding with a Ni interlayer was evaluated with moderate success, due to the modified IMC with improved mechanical properties and the good compatibility between Ni and the stainless steel. A further improvement was achieved when Cu was brazed between stainless steel and Ti using CMT (Cold Metal Transfer) a low heat input MIG process. The final attempt was to use a different interlayer that was 3D printed and deposited in several layers. This interlayer was composed Cu and Nb that were selected as candidates to avoid the IMC formation between the stainless steel and Ti. With this approach it was possible to build an IMC free component and possibly improve and avoid IMC formation in several other dissimilar metallic combinations.
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Jeyarupalingam, Nadarajah. "Steel, steel/concrete composite and reinforced concrete beams and columns exposed to fire." Thesis, City University London, 1996. http://openaccess.city.ac.uk/7766/.
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This thesis describes the development of a numerical method for the structural analysis of beams and columns subjected to a non-linear variation of temperatures in all three directions. The numerical method allows for analysis of a wide variety of cross sections with a number of materials and members with varying cross section along the length. The member can be subjected to any combination of axial load, end moments, lateral load and bi-axial bending. Any fire temperature characteristic can be specified. The numerical method has been validated by comparing results with a number of experimental results on steel, concrete and composite beams and columns from literature and with the experiments carried out under this research programme. Experiments were carried out on seven columns with non-uniform temperature distribution along the length and across the depth. The test rig was designed and manufactured at City University. Electrical heating elements were used to heat the specimens. To obtain a comprehensive temperature profile of the test columns several thermocouples were used. Deflection measurements were made using displacement transducers placed at different positions. Using the new method of analysis a simple design method for steel columns subjected to non-uniform temperature distribution across the depth of the section has been developed. The method has been validated with a number of results on H-section columns from numerical experiments performed using the computer programs developed in this thesis. Another parametric study has been carried out to improve the inherent fire resistance capacity of Slimflor beams. It is concluded that it is possible to design a Slimflor beam with higher fire resistance capacity than the current rating of 60 minutes by introducing steel reinforcing bars at appropriate place.
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Hatlee, Jonathan Russell. "The Viability of Steel-Concrete Composite Girder Bridges with Continuous Profiled Steel Deck." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/34208.
Full textAbstract:
The continuous permanent metal deck form system provides a quick and efficient method
of constructing short-span, simply supported composite steel girder bridges. However, because
shear studs can only be welded to the girder through the steel deck at rib locations, the number of
shear stud locations is limited to the number of ribs in the shear span while the spacing of the
shear studs is restricted to the rib spacing of the steel deck. This results in a condition where
various provisions of the AASHTO LRFD Bridge Design Specifications (2007) cannot be
satisfied, including shear stud fatigue spacing requirements and the fully composite section
requirements.The purpose of this research was to investigate whether continuous permanent metal deck form construction method can be used for bridges given the code departures. Using this method, a full scale test specimen was constructed with one half of the specimen using one stud per rib and the other half using two studs per rib and then each half was tested separately. The steel deck used in the specimen was supplied by Wheeling Corrugating. Fatigue testing was conducted to determine the fatigue resistance of the specimen at both levels of interaction, with load ranges calculated using the AASHTO LRFD shear stud fatigue equation. This was followed by static tests to failure to determine the plastic moment capacity at both levels of interaction. Results of the testing were compared to existing design models and modifications specific to this construction method are made. Investigations into whether the profiled steel deck can act as full lateral bracing to the steel girder compression flange during deck placement were also made.
Fatigue testing results showed that very little stiffness was lost over the course of testing
at both levels of composite interaction. This leads to the conclusion that the AASHTO shear
stud equation used for this design is conservative. Static testing results indicated that the
measured values for the plastic moment capacity of the specimen were less than the calculated
capacity. This leads to the conclusion that the individual shear stud strengths were overestimated
using current design equations. Recommendations for modifications to the existing design
equations are provided.
Master of Science
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Sanchez, Andrea Nathalie. "Forecasting Corrosion of Steel in Concrete Introducing Chloride Threshold Dependence on Steel Potential." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5303.
Full textAbstract:
Corrosion initiates in reinforced concrete structures exposed to marine environments when the chloride ion concentration at the surface of an embedded steel reinforcing bar exceeds the chloride corrosion threshold (CT) value. The value of CT is generally assumed to have a conservative fixed value ranging from 0.2% to - 0.5 % of chloride ions by weight of cement. However, extensive experimental investigations confirmed that CT is not a fixed value and that the value of CT depends on many variables. Among those, the potential of passive steel embedded in concrete is a key influential factor on the value of CT and has received little attention in the literature. The phenomenon of a potential-dependent threshold (PDT) permits accounting for corrosion macrocell coupling between active and passive steel assembly components in corrosion forecast models, avoiding overly conservative long-term damage projections and leading to more efficient design. The objectives of this investigation was to 1) expand by a systematic experimental assessment the knowledge and data base on how dependent the chloride threshold is on the potential of the steel embedded in concrete and 2) introduce the chloride threshold dependence on steel potential as an integral part of corrosion-related service life prediction of reinforced concrete structures. Experimental assessments on PDT were found in the literature but for a limited set of conditions. Therefore, experiments were conducted with mortar and concrete specimens and exposed to conditions more representative of the field than those previously available. The experimental results confirmed the presence of the PDT effect and provided supporting information to use a value of -550 mV per decade of Cl- for the cathodic prevention slope βCT, a critical quantitative input for implementation in a practical model. A refinement of a previous corrosion initiation-propagation model that incorporated PDT in a partially submerged reinforced concrete column in sea water was developed. Corrosion was assumed to start when the chloride corrosion threshold was reached in an active steel zone of a given size, followed by recalculating the potential distribution and update threshold values over the entire system at each time step. Notably, results of this work indicated that when PDT is ignored, as is the case in present forecasting model practice, the corrosion damage prediction can be overly conservative which could lead to structural overdesign or misguided future damage management planning. Implementation of PDT in next-generation models is therefore highly desirable. However, developing a mathematical model that forecasts the corrosion damage of an entire marine structure with a fully implemented PDT module can result in excessive computational complexity. Hence, a provisional simplified approach for incorporating the effect of PDT was developed. The approach uses a correction function to be applied to projections that have been computed using the traditional procedures.
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Sanchez, Escalera Victor M. "ENHANCING PROGRESSIVE COLLAPSE RESISTANCE OF STEEL BUILDING FRAMES USING THIN INFILL STEEL PANELS." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/499.
Full textAbstract:
Progressive collapse occurs when damage from a localized first failure spreads in a domino effect manner resulting in a total damage disproportionate to the initial failure. Recent building failures (e.g., World Trade Center twin towers) highlight the catastrophic outcome of progressive collapse. This research proposes a reliable and realistic retrofit technology which installs thin steel panels into steel building structural frames to enhance the system progressive collapse resistance.
The steel frames with simple beam-to-column connections, under different boundary conditions (i.e., sidesway uninhibited and sidesway inhibited, respectively), and the loss of one bottom story column were retrofitted using the proposed technology (i.e. installing thin steel panels in the structural frames). Performance of these frames was investigated. Two Finite Element (FE) models which require different modeling efforts were developed to capture the system behavior. The first model explicitly models the infill plates to capture the plate buckling behavior. The second model known as strip model represents the infill panels as diagonal strips. In addition to the FE models, a plastic analysis model derived from the prior research on seismically designed Steel Plate Shear Walls (SPSWs) was considered. The system progressive collapse resistance obtained from the two FE models and the plastic analysis procedure were compared and good agreements were observed. It was observed that installing infill plates to steel structural frames can be an effective approach for enhancing the system progressive collapse resistance.
Beyond the strength of the overall system, the Dynamic Increase Factor (DIF) which may be used to amplify the static force on the system to better capture the dynamic nature of progressive collapse demand was evaluated for the retrofitted system. Furthermore, the demands including axial force, shear force and bending moment on individual frame components (i.e., beams and columns) in the retrofitted system were quantified via the nonlinear FE models and a simplified procedure based on free body diagrams (FBDs). Finally, the impact of premature beam-to-column connection failures on the system performance was investigated and it was observed that the retrofitted system is able to provide stable resistance even when connection failures occur in all beams.
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Guo, Tzer-main, and 郭澤綿. "Acicular ferrite transformation in alloy-steel metals and alloy steels." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/60966943195502754404.
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"INVESTIGATION OF FRACTURE BEHAVIOR OF STEEL/STEEL LAMINATES." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604834/index.pdf.
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Espinos, A., M. L. Romero, and Dennis Lam. "Fire performance of innovative steel-concrete composite columns using high strength steels." 2016. http://hdl.handle.net/10454/8142.
Full textAbstract:
yesThis paper presents the results of a numerical investigation on strategies for enhancing the fire behaviour of concrete-filled steel tubular (CFST) columns by using inner steel profiles such as circular hollow sections (CHS), HEB profiles or embedded steel core profiles. A three-dimensional finite element model is developed for that purpose, which is capable for representing the various types of sections studied and the nonlinear behaviour of the materials at elevated temperatures. High strength steel is considered in the numerical model, as a possible way to lengthen the fire endurance. The numerical model is validated against experimental results available in the literature for various types of steel-concrete composite sections using inner steel profiles, obtaining satisfactory results. Based on the developed numerical model, parametric studies are conducted for investigating the influence of the cross-sectional geometry and the steel grade of the inner profiles on the fire performance of these composite columns, for eventually providing some practical recommendations.
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Marshall, Paul Thomas. "Steel waters." 2005. http://purl.galileo.usg.edu/uga%5Fetd/marshall%5Fpaul%5Ft%5F200512%5Fma.
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WU, Y. J., and 吳英政. "steel reserch." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/73279263252966294627.
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