Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Plates, Iron and steel Testing.
Дисертації з теми "Plates, Iron and steel Testing"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-32 дисертацій для дослідження на тему "Plates, Iron and steel Testing".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Yin, Maggie Huaying Materials Science & Engineering Faculty of Science UNSW. "Metal dusting of iron and low alloy steel." Awarded by:University of New South Wales. School of Materials Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/25188.
Повний текст джерелаАнотація:
Metal dusting is a kind of catastrophic corrosion phenomenon that can be observed in several of petrochemical processes. It occurs on iron-, nickel- and cobalt-base metals in carbonaceous atmospheres at high temperature when gaseous carbon activity is higher than one. The process is particularly rapid for ferritic alloys The aim of this project was to compare the dusting kinetics of pure iron and a 2.25Cr-1Mo alloy steel under CO-H2-H2O atmosphere at 650??C. Polished (3??m) samples of iron and the steel were exposed to flowing CO-H2-H2O gas atmospheres at 650??C, when the gases were supersaturated with respect to graphite. The partial pressure of CO was varied between 0.25 and 0.9 atm, and the carbon activity was varied from 2.35 to 16, in order to obtain a series of experimental conditions. In most experiments, pO2 was less than 7.37E-24 atm, and no iron oxide could form. However, Cr2O3 would always have been stable. When exposed to these gases, both iron and steel developed a surface scale of Fe3C which was buried beneath a deposit of carbon, containing iron-rich nanoparticles (the dust). Examination by Scanning Electron Microscopy allowed the observation of fine and coarse carbon nanotubes, and also spiral filaments. However, the morphology of the graphitic carbon was not sensitive to pCO and aC. Moreover, the carbon deposit was gas permeable, allowing continuing gas access to the underlying metal. At a fixed=4.5, the carburizing rate clearly increased with CO content from 0.25 to 0.68 atm. However, increasing the CO content to higher value led to decreased rates, indicating that carburizing rate reaches a maximum value at pCO=0.68 atm. When pCO was fixed at 0.25 atm and 0.68 atm, and carbon activity was varied. The induction period was extended by the formation of protective oxide layers at low values of carbon activity (aC= 2.35 and 2.55) where pO2 exceed the iron oxide formation value. For other reaction conditions, the carbon uptake rate for iron and steel did not increase with aC. The present work showed that the carbon deposition rates were not proportional to pCO or pCOpH2. Instead, the rate was affected by the partial pressure of all three reaction gases, and the carbon uptake rate for both materials could be expressed at r=k1pCOpH2+k2pCO2+k3pH22 and the rate constant k3 has a negative value, corresponding to coke gasification. From XRD analyses, it was found that cementite was the only iron-containing phase in the dusting product. The cementite particles acted as catalysts for carbon deposition from the gas. The same deposition process at the surface of the cementite layer led to its disintegration, thereby producing the particles. This disintegration process was faster on the steel than on pure iron. Consequently, the rates of both metal wastage and coke accumulation were faster for the steel. It is concluded that chromium and molybdenum do not stabilize the carbide but accelerate its disintegration process. It is suggested that Cr2O3 fine particles in the cementite layers provide more nucleation sites in the cementite layer on steel, explaining its more rapid dusting kinetics. However, appropriate methods of proving this assumption, such as TEM and FIB, are required.
2
Underwood, Nicholas. "Pulse pressure testing and analysis of steel plates with openings." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/15273/.
Повний текст джерелаАнотація:
Steel plates are widely used in a variety of civil engineering applications for load bearing structural components, due to their favourable strength to weight ratio. Many of these plates have openings that are commonly used for reducing weight, access for utilities or for inspection in shipping and offshore installations. However the influence of these openings to the structural component’s robustness and resilience against blast loading is relatively unknown, with limited research conducted in this subject to date. Due to the high costs associated with offshore facilities they are typically very congested. This coupled with the producing, processing, storing and transporting of hydrocarbon materials means that explosions and subsequent fires are major hazards with severe consequences. In the event of an explosion, the blast load will initially impact the secondary structure (large spanning plated sections) and then transfer through to the primary structure, highlighting their critical consideration in safety assessments. Plated structures are also known to cause confinement, which in turn will results in higher overpressures, making the consequences of an event more severe. The aim of this research was to investigate the combined influence that openings have on the overpressure and the structural response of thin ductile plates subjected to extreme dynamic transverse loads. This was achieved by conducting a set of well-defined experiments investigating the response of 1/8 scale (0.5 m square) mild steel plates with openings subjected to pulse pressure loading. Six central (scaled) openings were considered; circular (50, 75 and 100 mm) and extended circular (50 by 75, 75 by 100 and 100 by 125 mm) representative of typical offshore and shipping applications. Each plate design was assessed with two boundary conditions (restrained and non-restrained) and two nominal loading conditions. The boundary conditions adopted in this study allowed the response to be bounded, and enabled them to be practicably modelled in FEA-analyses and in the simplified analytical approaches. A pulse pressure test facility was used to generate nominal pulse pressure loads (25 and 50 psi) applied over a time (100 to 200+ ms load duration) representative of extreme explosion loading conditions offshore. All plates exhibited a mode I type failure (large inelastic deformation) highlighting the large reserve strength in such members. The work has shown that the inclusion of an opening (<5% of the exposed panel area) does not significantly degrade the structural resistance when damage is restricted to large inelastic deformation. The reduction in stiffness due to the hole is compensated by the reduced area to which the load is applied. The data generated in the laboratory tests was used to develop and validate finite element models. In general, excellent correlation was observed between the experimental failure modes and the permanent displacements, within an average difference of 12% and 15% for the restrained and non-restrained plates respectively. The finite element models also provided a useful insight into the various failure processes and transient behaviour which could not be observed experimentally. A simplified analytical model was developed to predict the response of the plates and was validated against the experimental data. The results for the permanent displacements compared favourably with the restrained plates at the two nominal pressures (6.5% at 25 psi and 7% at 50 psi), but correlated less well with the non- restrained ones (10% at 25 psi and 3% at 50 psi). Correct definition of support conditions along with a detailed description of the development of plasticity, as shown in the finite element models was fundamental in accurately predicting response of the non-restrained plates. The simplified techniques developed are cost effective compared with more sophisticated finite element methods making them suitable for preliminary engineering design studies. Ultimately this study provides evidence to suggest that small (circular or extended circular) openings positioned away from areas of high stress, could be used as a passive system to mitigate the influences of an explosion event offshore. This has many benefits in the form of reducing weight, reducing confinement (thus lowering overpressures) and reducing the loading applied to these members, and subsequently reducing the loading transferred through to the primary structure.
3
Osman, Mahmoud Yassin. "Analysis of rectangular composite plates under static lateral loading." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305779.
Повний текст джерела
4
Bienias, Grzegorz. "An experimental investigation of the shear plate connections." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26682.
Повний текст джерелаАнотація:
In Limit States Design for steel structures, single plate connections are designed to transfer beam shear to supporting member. These connections, with the connection plate shop-welded to the supporting member and field-bolted to the supported beam are becoming increasingly popular due to their economy and ease of fabrication. Single plate connections are very suitable for cases where speed of erection is a primary consideration. They are particularly superior for skewed connections. Traditional design methods which deal with connection problems generally give over-conservative solutions to this complex problem.
Two series of experimental investigations of single plate connections for beam-to-girder webs were conducted. A variety of connections were tested to demonstrate their feasibility and to collect data for analytical correlation studies. The ultimate goal of these tests and studies is to devise a rational basis for the design of these connections. This work is part of a comprehensive research project and the reader is referred to other papers (References 1 and 2) for completeness.
Based on experimental results and theoretical correlation studies, a modified design formula is proposed in order to predict the ultimate capacity of single plate connections. The formula tries to incorporate the influences of applied loads (shear force, torsional moment, and bending moment), resistance of the single plate connection, skew angle of the connection plate and type of holes (slotted and standard) used in the connection.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
5
Kasonde, Maweja. "Optimising the mechanical properties and microstructure of armoured steel plate in the quenched and tempered condition." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-11022006-192139.
Повний текст джерела
6
Awang, Mokhtar. "The effects of process parameters on steel welding response in curved plates." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2682.
Повний текст джерелаАнотація:
Thesis (M.S.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains xiv, 133 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 83-85).
7
Banerjee, Gautam. "Classification of end plate connections with application to gable frames." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040618/.
Повний текст джерела
8
Gentry, T. Russell. "The use of elastic finite elements in the design of reinforced concrete flat plates." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/21439.
Повний текст джерела
9
Alsaket, Yahya. "Benchmark solutions for advanced analysis of steel frames." Thesis, Queensland University of Technology, 1999. https://eprints.qut.edu.au/36105/1/36105_Alsaket_1999.pdf.
Повний текст джерелаАнотація:
During the past ten years, considerable research has been conducted with the aim of
developing, implementing and verifying "advanced analysis" techniques suitable for the
non-linear analysis and design of steel framed structures. With the use of one of these
methods, the simplified concentrated methods, comprehensive assessment of the actual
failure modes and ultimate strengths of framing systems is now possible in practical
design situations, without resort to conventional elastic methods of analysis and semiempirical
specification equations. This research has the potential to extend the
creativity of the structural engineer and simplify the design process, while ensuring
greater economy and more uniform safety in certain design situations. However, the
application of concentrated plasticity methods is currently restricted to two
dimensional steel frame structures that are fully laterally restrained and constructed
from compact sections (i.e. sections not subject to local and/or lateral buckling
effects). Unfortunately this precludes the use of advanced analysis from the design of
frames consisting of cold-formed sections and a significant proportion of hot-rolled
universal beam sections. Therefore research is currently under way to develop
concentrated plasticity methods of analysis for steel frame structures subject to local
and/or lateral buckling effects. This thesis was aimed at developing appropriate
benchmark solutions that are needed to validate these simplified methods of analysis.
Finite element analyses and five large scale experiments were conducted in order to
study the ultimate strength behaviour of two-dimensional single bay single storey steel
frames subjected to local and/or lateral buckling effects. The frames comprised of
cold-formed rectangular hollow sections and hot-rolled I-sections. A good agreement
between the results from finite element analyses and experiments validated the
accuracy of the finite element model used. The finite element model was then used to
develop benchmark solutions for two-dimensional single storey, single bay steel frames
comprising cold-formed rectangular hollow sections and hot-rolled I-sections subjected
to local and/or lateral buckling effects. This thesis presents the details of finite element analyses and large scale experiments
and their results, and a series of analytical benchmark solutions that can be used for the
verification of simplified concentrated plasticity methods of analysis.
10
Oesch, Everett Ralph. "Strength and performance field testing of hybrid HPS bridge A6101 /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418053.
Повний текст джерела
11
Kay, Thomas Sidney. "Numerical Modeling and Analyses of Steel Bridge Gusset Plate Connections." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/84.
Повний текст джерелаАнотація:
Gusset plate connections are commonly used in steel truss bridges to connect individual members together at a node. Many of these bridges are classified as non-load-path-redundant bridges, meaning a failure of a single truss member or connection could lead to collapse. Current gusset plated design philosophy is based upon experimental work from simplified, small-scale connections which are seldom representative of bridge connections. This makes development of a refined methodology for conducting high-fidelity strength capacity evaluations for existing bridge connections a highly desirable goal. The primary goal of this research effort is to develop an analytical model capable of evaluating gusset plate stresses and ultimate strength limit states. A connection-level gusset connection model was developed in parallel with an experimental testing program at Oregon State University. Data was collected on elastic stress distributions and ultimate buckling capacity. The analytical model compared different bolt modeling techniques on their effectiveness in predicting buckling loads and stress distributions. Analytical tensile capacity was compared to the current bridge gusset plate design equations for block shear. Results from the elastic stress analysis showed no significant differences between the bolt modeling techniques examined, and moderate correlation between analytical and experimental values. Results from the analytical model predicted experimental buckling capacity within 10% for most of the bolt modeling techniques examined. Tensile capacity was within 7% of the calculated tensile nominal capacity for all bolt modeling techniques examined. A preliminary parametric study was conducted to investigate the effects of member flexural stiffness and length on gusset plate buckling capacity, and showed an increase in member length or decrease in member flexural stiffness resulted in diminished gusset plate buckling capacity.
12
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.
Повний текст джерела
13
De, Bruin P. D. (Peter Douglas). "Experimental determination of the effective elastic constants of thin perforated plates." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/66862.
Повний текст джерела
14
Chen, Yujie. "Nominal Shear Strength and Seismic Detailing of Cold-formed Steel Shear Walls using Steel Sheet Sheathing." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc30444/.
Повний текст джерелаАнотація:
In this research, monotonic and cyclic tests on cold-formed steel shear walls sheathed with steel sheets on one side were conducted to (1) verify the published nominal shear strength for 18-mil and 27-mil steel sheets; and (2) investigate the behavior of 6-ft. wide shear walls with multiple steel sheets. In objective 1: this research confirms the discrepancy existed in the published nominal strength of 27-mil sheets discovered by the previous project and verified the published nominal strength of 18 mil sheet for the wind design in AISI S213. The project also finds disagreement on the nominal strength of 18-mil sheets for seismic design, which is 29.0% higher than the published values. The research investigated 6-ft. wide shear wall with four framing and sheathing configurations. Configuration C, which used detailing, could provide the highest shear strength, compared to Configurations A and B. Meanwhile, the shear strength and stiffness of 2-ft. wide and 4-ft. wide wall can be improved by using the seismic detailing.
15
Hartnagel, Bryan A. "Inelastic design and experimental testing of compact and noncompact steel girder bridges /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841147.
Повний текст джерела
16
Hedric, Andrew C. "Dynamic Behaviors of Historical Wrought Iron Truss Bridges – a Field Testing Case Study." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822751/.
Повний текст джерелаАнотація:
Civil infrastructure throughout the world serves as main arteries for commerce and transportation, commonly forming the backbone of many societies. Bridges have been and remain a crucial part of the success of these civil networks. However, the crucial elements have been built over centuries and have been subject to generations of use. Many current bridges have outlived their intended service life or have been retrofitted to carry additional loads over their original design. A large number of these historic bridges are still in everyday use and their condition needs to be monitored for public safety. Transportation infrastructure authorities have implemented various inspection and management programs throughout the world, mainly visual inspections. However, careful visual inspections can provide valuable information but it has limitations in that it provides no actual stress-strain information to determine structural soundness. Structural Health Monitoring (SHM) has been a growing area of research as officials need to asses and triage the aging infrastructure with methods that provide measurable response information to determine the health of the structure. A rapid improvement in technology has allowed researchers to start using new sensors and algorithms to understand the structural parameters of tested structures due to known and unknown loading scenarios. One of the most promising methods involves the use of wireless sensor nodes to measure structural responses to loads in real time. The structural responses can be processed to help understand the modal parameters, determine the health of the structure, and potentially identify damage. For example, modal parameters of structures are typically used when designing the lateral system of a structure. A better understanding of these parameters can lead to better and more efficient designs. Usually engineers rely on a finite element analysis to identify these parameters. By observing the actual parameters displayed during field testing, the theoretical FE models can be validated for accuracy. This paper will present the field testing of a historic wrought iron truss bridge, in a case study, to establish a repeatable procedure to be used as reference for the testing of other similar structures.
17
Jiao, Hui 1963. "The behaviour of very high strength (VHS) members and welded connections." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9417.
Повний текст джерела
18
Carballo, Manuel. "Strength of z-purlin supported standing seam roof systems under gravity loading." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/45952.
Повний текст джерелаАнотація:
The objective of the Standing Seam Roof Systems Research Project at the Virginia Polytechnic Institute and State University is to develop a design procedure for the strength of Z-purlin supported standing seam roof systems under gravity leading. Various approaches were taken to calculate the strength of systems with either torsional restraint, third point span restraint, or midspan restraint. Since few test results are available for single and three span continuous, two purlin line systems, the primary focus of this research is analytical. Even though the test setup used for these tests does not represent actual field conditions, the data obtained will be extremely useful in the development of analytical models to predict system strength. However, at least four multiple purlin line tests will be required to verify the accuracy of the design procedure. The analytical formulation will include the effects of sliding friction in the clips and "drape" restraint effects of the standing seam deck.
Master of Science
19
Vora, Hitesh. "Shear Wall Tests and Finite Element Analysis of Cold-Formed Steel Structural Members." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9726/.
Повний текст джерелаАнотація:
The research was focused on the three major structural elements of a typical cold-formed steel building - shear wall, floor joist, and column. Part 1 of the thesis explored wider options in the steel sheet sheathing for shear walls. An experimental research was conducted on 0.030 in and 0.033 in. (2:1 and 4:1 aspect ratios) and 0.027 in. (2:1 aspect ratio) steel sheet shear walls and the results provided nominal shear strengths for the American Iron and Steel Institute Lateral Design Standard. Part 2 of this thesis optimized the web hole profile for a new generation C-joist, and the web crippling strength was analyzed by finite element analysis. The results indicated an average 43% increase of web crippling strength for the new C-joist compared to the normal C-joist without web hole. To improve the structural efficiency of a cold-formed steel column, a new generation sigma (NGS) shaped column section was developed in Part 3 of this thesis. The geometry of NGS was optimized by the elastic and inelastic analysis using finite strip and finite element analysis. The results showed an average increment in axial compression strength for a single NGS section over a C-section was 117% for a 2 ft. long section and 135% for an 8 ft. long section; and for a double NGS section over a C-section was 75% for a 2 ft. long section and 103% for an 8 ft. long section.
20
Kahle, Matthew Gilbert. "Partially restrained composite connections : design and analysis of a prototype structure." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/20830.
Повний текст джерела
21
Moreland, Andrew. "Experimental and numerical investigation of a deeply buried corrugated steel multi plate pipe." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176922845.
Повний текст джерела
22
Nassiri, Esmail. "Modelling nonlinear behaviour of two-dimensional steel structures subjected to cyclic loading." Thesis, Queensland University of Technology, 1998.
Знайти повний текст джерела
23
Huegler, Peter A. "Fulfilling customer orders for steel plates from existing inventory /." Diss., 2003. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3086949.
Повний текст джерела
24
Wei, Ber-Lin. "The static in-plane strength of welded steel plate I-girders under bending /." Diss., 1998. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9914252.
Повний текст джерела
25
Chung, Hsin-yang. "Fatigue reliability and optimal inspection strategies for steel bridges." Thesis, 2004. http://hdl.handle.net/2152/28503.
Повний текст джерелаАнотація:
Structural reliability techniques can be employed to evaluate the fatigue performance of fracture-critical members in steel bridges. In this dissertation, two fatigue reliability formulations that can be applied for most details in steel bridges are developed. For details classified according to AASHTO fatigue categories, a limit state function related to the number of stress cycles leading to failure based on Miner’s rule is used; for details not classified according to AASHTO fatigue categories, a limit state function based on linear elastic fracture mechanics and expressed in terms of crack size and growth rate is employed. With the application of fatigue reliability analysis, a procedure for inspection scheduling of steel bridges is developed to yield the optimal (most economical) inspection strategy that meets an acceptable safety level through the planned service life. This inspection scheduling problem is modeled as an optimization problem with an objective function that includes the total expected cost of inspection, repair, and failure formulated using an event tree approach, with appropriate constraints on the interval between inspections, and a specified minimum acceptable (target) safety level. With the help of several illustrations, it is shown that an optimal inspection scheduling plan can thus be developed for any specified fatigue details or fracture-critical sections in steel bridges. A second optimal inspection scheduling procedure is formulated that takes into consideration crack detectability (or quality) of alternative nondestructive inspection techniques. This procedure based on Monte Carlo simulation of crack growth curves yields an optimal inspection technique and associated schedule for a given fracture-critical member in a steel bridge for minimum cost and a target safety level while also taking into account probability of detection (POD) data for candidate nondestructive inspection techniques. Comparisons between the reliability-based procedure and the POD-based procedure for optimal inspection scheduling are discussed. Both scheduling strategies, when contrasted with ad hoc periodic inspection programs for steel bridges, are recommended because they are rational approaches that consider the actual fatigue reliability of the bridge member and account for economy as well as safety.text
26
Higgins, Christopher C. "Full-scale real-time testing and analysis of a viscoelastically damped steel frame /." Diss., 1997. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9734880.
Повний текст джерела
27
DePiero, Anthony H. "High cycle fatigue modeling and analysis for deck floor truss connection details." Thesis, 1997. http://hdl.handle.net/1957/33707.
Повний текст джерелаАнотація:
The Oregon Department of Transportation is responsible for many steel deck truss bridges containing connection details that are fatigue prone. A typical bridge, the Winchester Bridge in Roseburg, Oregon, was analyzed to assess the loading conditions, stress levels, and fatigue life of the connection details. The analysis included linear-elastic beam analysis, 2D and 3D finite element modeling, and fatigue modeling. A field identification methodology was developed to expand the analysis to other steel deck truss bridges. Five retrofit strategies were investigated to determine their effectiveness in reducing the stress ranges developed in the connection details.Graduation date: 1998
28
Chen, Quan 1977. "Effects of thermal loads on Texas steel bridges." 2008. http://hdl.handle.net/2152/17802.
Повний текст джерелаАнотація:
The effects of thermal loads on steel bridges are not well understood. Although thermal effects are discussed in the AASHTO specifications, the appropriateness of the recommended thermal gradients is questionable. Thermal effects on the bridges can impact the design of the steel superstructure, the support bearings, and even the bridge piers. Previous field monitoring of steel trapezoidal box girder bridges has shown that thermal stresses on the order of ±5 ksi were not uncommon under regular daily thermal cycles. Stresses induced during annual thermal cycles may be potentially larger than those during daily thermal cycles. Recent data has shown that the bearings that are to allow the girders to expand and contract freely due to thermal movements are not frictionless. Because of the bearing friction, the supporting piers must flex to accommodate the bridge movements. In curved girder applications, questions have been raised by designers and contractors regarding the proper orientation of guided bearings. This research study includes field measurements, laboratory tests and finite element parametric analyses. The bearings of nine bridges in the Houston area have been instrumented and monitored for more than a year to measure bearing movements due to changes in temperature. Instrumentation of the steel girders on one of the Houston bridges was made utilizing thermocouples and vibrating wire strain gages to measure temperature distribution and thermal stresses. In addition, strain gages and thermal couples were applied to the steel girders and concrete bridge deck on a simple twin box girder bridge located at the Ferguson Structural Engineering Laboratory in Austin, Texas. The data from the field monitoring and laboratory tests were used to validate a finite element model. Based on this model, a detailed parametric study was conducted to investigate the effects of bridge configuration. It is found that under the given weather conditions, the most critical thermal loads are achieved under the following bridge configurations: N-S bridge orientation, shorter lengths of the concrete deck overhang, deeper steel girder webs, thinner concrete decks, and larger spacing between two box girders. To evaluate the effect of environmental conditions and obtain extreme thermal loads for design purposes, the most critical configuration of bridge sections was modeled for thermal analysis with Texas weather data from 1961 to 2005 as the input environmental conditions. Four cities were considered to bound Texas weather conditions. Based on the thermal analyses, a 45-year sample data of thermal parameters were used to describe the temperature field over a section. Extreme value analyses of the sample data were performed to obtain the relationship between thermal loads and return periods. The thermal loads with 100-year return period were compared to the ones suggested by AASHTO. The thermal loads with 100-year return period were used to investigate structural response. The effect of bearing orientation and the point of fixity were studied. A rigid body model was proposed to estimate thermal movements at the ends, which matched those obtained from field monitoring and finite element analysis. The maximum possible thermal stresses were also evaluated. Design suggestions are put forward based on the analysis.text
29
Yu, Liang. "Behavior of bolted connections during and after a fire." Thesis, 2006. http://hdl.handle.net/2152/2959.
Повний текст джерела
30
Hafner, Anthony G. "Experimental research on the behavior and strength of large-scale steel gusset plates with sway-buckling response including effects of corrosion and retrofit options." Thesis, 2012. http://hdl.handle.net/1957/28486.
Повний текст джерелаАнотація:
The collapse of the I-35W Bridge in Minneapolis, MN on August 1, 2007 brought into question the design and inspection of gusset plates in steel truss bridges. The experimental tests performed in this research study the sway-buckling strength and behavior of large-scale steel gusset plates in an isolated truss connection. Parameters studied include plate thickness,combination member loading, initial out-of-plane imperfection, diagonal compression member out-of-plane flexural stiffness, corrosion, and alternative retrofits to increase lateral stiffness. The flexural stiffness of the diagonal compression member and retrofit designs were unique to
the testing program. The variables monitored during testing include gusset plate surface stresses and strains, member axial strains, out-of-plane displacement of the gusset plate free
edge, and buckling capacity. The results were compared with previously established design models for predicting buckling capacity of gusset plates which include the Whitmore effective
width, the Modified-Thornton method, and the FHWA Load Rating Guidelines. A parametric finite element model was developed to determine the lateral stiffness of the gusset plate
connection and the additional stiffness provided by the alternative retrofit options.
The results showed interaction between the diagonal compression member and gusset plate occurs, which affects sway-buckling capacity. Combination of member loads showed evidence of detrimental effects on sway-buckling capacity. Corrosion of the gusset plates along the top edge of the bottom chord did not lead to significant reduction in sway-buckling capacity. The two retrofit designs showed increases in both lateral stiffness and buckling capacity as well as economic benefits over traditional retrofit methods. Comparison of the results to the current design guidelines showed that the current methods are conservative and
do not accurately represent the true behavior of gusset plate connections. The research concludes with two proposed models for future use in design and retrofit of gusset plates. The
first is a member-gusset plate interaction model based on a stepped column analogy that takes into account the effects of member flexural stiffness and gusset plate stiffness. The second is
a general design guideline developed for retrofit of gusset plate connections dominated by sway-buckling behavior which uses a stiffness based approach to increase the capacity of gusset plate connections.Graduation date: 2012
31
Kwon, Gun Up 1977. "Strengthening existing steel bridge girders by the use of post-installed shear connectors." 2008. http://hdl.handle.net/2152/18079.
Повний текст джерелаАнотація:
A number of older bridges built before the 1970’s were constructed with floor systems consisting of a non-composite concrete slab over steel girders. Many of these bridges do not satisfy current load requirements and may require replacement or strengthening. A potentially economical means of strengthening these floor systems is to connect the existing concrete slab and steel girders to permit the development of composite action. This dissertation describes a research program investigating methods to develop composite action in existing non-composite floor systems by the use of postinstalled shear connectors. Three types of post-installed shear connection methods were investigated. These methods are referred to as the double-nut bolt, the high tension friction grip bolt, and the adhesive anchor. These post-installed shear connectors were tested under static and fatigue loading, and design equations for ultimate strength and fatigue strength were developed. These post-installed shear connectors showed significantly higher fatigue strength than conventional welded shear studs widely used for new construction. The superior fatigue strength of these post-installed shear connectors enables strengthening of existing bridge girders using partial composite design, thereby requiring significantly fewer shear connectors than possible with conventional welded shear studs. Five full-scale non-composite beams were constructed and four of these were retrofitted with post-installed shear connectors and tested under static load. The retrofitted composite beams were designed as partially composite with a 30-percent shear connection ratio. A non-composite beam was also tested as a baseline specimen. Test results of the full-scale composite beams showed that the strength and stiffness of existing non-composite bridge girders can be increased significantly. Further, excellent ductility of the strengthened partially composite girders was achieved by placing the postinstalled shear connectors near zero moment regions to reduce slip at the steel-concrete interface. Parametric studies using the finite element program ABAQUS were also conducted to investigate the effects of beam depth, span length, and shear connection ratio on the system behavior of strengthened partially composite beams. The studies showed that current simplified design approaches commonly used for partially composite beams in buildings provide good predictions of the strength and stiffness of partially composite bridge girders constructed using post-installed shear connectors.text
32
Law, J. R. "Time varying probability of failure of steel floor beams subjected to real fire." Thesis, 1997. https://vuir.vu.edu.au/18185/.
Повний текст джерелаАнотація:
A model for estimating the time-dependent reliability of steel beams under real fire
conditions has been developed. It gives a more rational basis than time of failure
modelling does for design. From risk modelling, some small resistance time from the
probabilistic distribution times of failure can be deduced, which gives an acceptably
small risk of failure. Time of failure modelling by itself can only give the mean time failure which could lead to excessive risk if the variability of time of failure is large. The model comprises submodels for fire severity, heat transfer, mechanical properties, loads,
structural analysis and reliability. Simple submodels have been adopted commensurate
with the level of accuracy of other models in fire safety engineering. The submodel for
real fire severity is Lie's. Heat transfer submodels have been adopted for three and four
sided exposure and have been taken from work by the European Regional Organisation
for Steel Construction and the French Technical Centre for Steel Construction. Three
sided arises when the beam supports a concrete slab. The mechanical properties
submodel was derived from an empirical fit to available test data. It gave better results
than the current model in AS4100. It is appropriate for the model but is too complex for
replacing the model in AS4100. The structural model four sided exposure was
developed from simple plastic theory. For three sided exposure, discrete element
analysis was adopted. The load submodels were lognormal for dead load and Weibull
arbitrary point in time values for live load. The Monte Carlo method was adopted for the
reliability submodel. The overall model was used to obtain the following sensitivities.
An increase of lOkg.m-2 in fire load density can increase the risk of failure by 40%. In
relation to the sensitivity of risk to ventilation, a reduction of the opening factor from
0.12 to 0.04 m0.5 increases the risk of failure approximately 200 times. Doubling the
insulation thickness reduces the risk of failure by a factor ten. Increasing the live load
has less effect on the risk of failure than increasing the dead load. If the load present predominantly live load, there is much less risk of failure than if the load is
predominantly live load. Four sided exposure has ten times the risk of failure compared
with three sided exposure. Accepting larger proof strains reduces the risk of failure; for
example, increasing proof strain from 0.2% to 1% reduces the risk of failure by 50%.