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1
Tasligedik, Ali Sahin. "Lap Splice Behavior And Strength Of Cfrp Rolls." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609694/index.pdf.
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Behavior of lap splices formed by CFRP rolls has been studied. CFRP rolls have been prepared by using CFRP sheets of a certain width. Strengthening methods that use CFRP rolls as reinforcement may require an epoxy anchored lap splice due to the conditions at the strengthening regions. It may not always be possible to strengthen the region by using only one roll fan anchored at both ends, but using two rolls from opposite faces of the member and lap splicing them at the middle so that they act as a single roll. Lap splice behavior can be studied best by using flexural beam bond specimens if the reinforcing material is steel. Therefore, it has initially been suggested that flexural beam specimens reinforced for flexure with CFRP rolls as tension reinforcement can be used in studying the lap splice behavior. However, due to the difficulties encountered in the beam tests, another type of test specimen was introduced, which was a direct pull-out specimen. In this type of test specimen, lap spliced CFRP rolls have been tested under direct tension, in which the tension has been applied by making use of concrete end blocks that transfer the tension to the rolls. Eleven tests have been made in total. Full material capacity of the rolls could not be achieved due to premature failures. However, important conclusions and recommendations have been made for future studies.
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Bozalioglu, Dogu. "Evaluation Of Minimum Requirements For Lap Splice Design." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608284/index.pdf.
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Minimum requirements for lap splices in reinforced concrete members, stated in
building codes of TS-500 and ACI-318, have a certain factor of safety. These
standards have been prepared according to research results conducted previously and
they are being updated according to results of recent studies. However the reliability
of lap splices for minimum requirements needs to be investigated. For this purpose, 6
beam specimens were prepared according to minimum provisions of these standards.
The test results were investigated by analytical procedures and also a parametric
study was done to compare two standards. For smaller diameter bars both standards
give safe results. Results showed that the minimum clear cover given in TS500 is
insufficient for lap spliced bars greater than or equal to 26 mm diameter.
3
Grant, James Philip. "Non-Contact Lap Splices in Dissimilar Concretes." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/56585.
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Non-contact lap splices placed within a single concrete placement are often used and have been studied in previous research projects. However, non-contact lap splices used with each bar in a different concrete placement such that there is a cold joint between the bars, have not been investigated. This situation is found in the repair of adjacent box beam bridges and in the construction of inverted T-beam systems, among others. It is vital to understand whether the same mechanisms are present across a cold joint with two different types of concrete as are present in traditional non-contact lap splices.
In this research, eight T-beam specimens with non-contact lap splices were tested. The spacing between the bars, the splice bar blockout length, and presence of transverse bars were varied to study the effectiveness of the splices. The beams were tested in four point bending so that the splice region was under constant moment and the tension forces in the spliced bars were constant. End and midspan deflections were measured along with surface strain measurements at midspan and at the quarter span points, top and bottom. Gap openings were also measured at the ends of the blockouts.
The main conclusions found from this research are that beams containing non-contact lap splices were able to develop nominal capacity with the bar spacing less than or equal to 4 in. and the blockout between 17 and 20 in. long. Extending the blockouts and adding transverse bars underneath the splices did not add to the capacity.<br>Master of Science
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Bowdey, Thomas S. "Lap Splice Development Length of Rebar in Stabilized Hollow Interlocking Compressed Earth Blocks." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1720.
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This thesis investigates the tensile performance of unconfined lap splices in specimens constructed from interlocking compressed earth block (ICEB) units. All lap splice specimens were constructed from hollow ICEB half units with one side grouting channel. ICEB units used in this research were exclusively produced from the Soeng Thai Model BP6 block press. The BP6 block press is currently manufactured in Thailand under the guidance and direction of the Center of Vocational Building Technologies (CVBT). All ICEB units and grout constructed for this research were created from mix proportions of soil, sand, cement, and water. Rebar bar sizes were restricted to M10 (#3) and M13 (#4) for all lap splice specimens due to the limited area of the hollow 2-inch diameter rebar cavity of the ICEB unit. The limited size and strength of the ICEB units also made the use of larger bar diameters impractical. Three ICEB unit types of varying strengths (3.78 MPa, 7.81 MPa, and 11.38 MPa) and three grout types of varying strengths (1.35 MPa, 7.47 MPa, and 15.50 MPa) were developed and used to construct all specimens. The measured ICEB lap splice specimen strengths were compared against the predicted strength calculated from the Masonry Standards Joint Committee (MSJC). Findings suggested that the MSJC design equation did not adequately predict the lap splice strength of specimens, particularly for specimens constructed from weaker materials. The measured ICEB lap splice results were used to create a new ICEB lap splice design equation. This paper also investigates the compressive performance of fully grouted ICEB prisms constructed from the range of ICEB unit and grout strengths stated above. Findings suggested that the compressive strength of fully grouted ICEB prisms were exclusively controlled by the compressive strength of the ICEB units used to construct the prism. The strength of the grout had no discernable effect on the strength of the fully grouted prism. A design equation was proposed to calculate prism strengths based on measured strength results of ICEB units.
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Ghasabeh, Mehran. "Bond Of Lap-spliced Bars In Self-compacting Concrete." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615530/index.pdf.
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Self-compacting concrete is an innovative construction material<br>its priority to normal vibrated concrete is that there is not any vibration requirement. Bond strength of reinforcement is one of the key factors that ensures the usefulness of any reinforced concrete structure. In this study, 6 full-scale concrete beams spliced at the mid-span were tested under two-point symmetrical loading. Test variables were bottom cover, side cover, free spacing between longitudinal reinforcement, lap-splice length and presence of transverse reinforcements within the lap-splice region.
Specimen SC_22_44_88_800 had cover dimensions close to the code limits and had 36db lap splice length. This specimen showed flexural failure. Specimen SC_44_44_44_710 had 32db lap splice and cover dimensions greater than code minimums. This specimen showed yielding primarily. With the increasing loading, however, bond failure occurred with side splitting.
ACI 408 descriptive equation for normal vibrated concrete predicted bar stresses of the unconfined specimens produced with self-compacting concrete acceptably well. The predicted values were lower than the measured values to be on the safe side. The error varied between 3.4% and 6.5%.
All predictions of the ACI408 descriptive equation was higher than the measured bar stresses of the confined specimens produced with SCC. All the calculated values were unsafe. The error varied between 10.6% and 34.5%.
Specimen SC_44_22_22_530_T4 with 24db lap splice length had side cover and spacing between bars 63.3% and 56.7% less than the ACI 318 limits. The calculated bar stress was 21.6% higher than the measured value. The main reason of the deviation was inadequate cover dimensions.
In specimen SC_44_22_22_530_T6, number transverse reinforcement was increased to 6 stirrups to overcome the small cover and spacing problem. However, increased number of stirrups inside a small side and face cover caused weak plane and measured bar stress decreased.
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Lin, Wesley Wei-chih. "Modelling Effects Of Insufficient Lap Splices On A Deficient Reinforced Concrete Frame." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615584/index.pdf.
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assessed and strengthened. Performance evaluation of deficient buildings has become a major concern due to devastating earthquakes in the past. In order to justify new provisions in design and assessment codes, experiments and analyses are inherently necessary.
In this thesis study, investigations into the behaviour of two deficient reinforced concrete frames built at Middle East Technical University&rsquo<br>s Structural and Earthquake Laboratory and tested via pseudo-dynamic tests were made. These frames were modelled on the OpenSees platform by following methods of analyses outlined in the Turkish Earthquake Code of 2007 (TEC 2007) and ASCE/SEI-41-06. Both deficient frames were essentially the same, with the only difference being the presence of insufficient lap splices, which was the focus of the study.
Time history performance assessments were conducted in accordance to TEC 2007&rsquo<br>s damage state limits and ASCE/SEI 41-06&rsquo<br>s performance limits. The damages observed matched the performance levels estimated through the procedure outlined in TEC 2007 rather well. Specific to the specimen with lap splice deficiencies, ASCE/SEI 41-06 was overly conservative in its assessments.
TEC 2007&rsquo<br>s requirements for lap splice lengths were found to be conservative in the laboratory and are able to tolerate deficiencies up to 25% of the required length.
With respect to mathematical models, accounting for materials in deficient systems by using nominal but reduced strength properties is not very efficient and unless joint deformations are explicitly accounted for, local deformations cannot be captured.
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Adkins, Keith A. "A Model for Prediction of Fracture Initiation in Finite Element Analyses of Welded Steel Connections." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1399624062.
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Wright, Timothy R. "Full-scale seismic testing of a reinforced concrete moment frame using mobile shakers." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54414.
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A prototype reinforced concrete moment frame representative of low-rise office buildings in the Central and Eastern United States from the 1950s-1970s was designed and selected for evaluation under seismic loads. A plane frame specimen from the prototype was incorporated into the design of a test-bed of four full-scale, side-by-side nominally identical structures that could be evaluated independently. The testing of the first frame serves as the topic of this dissertation. The specimen was two bays x two stories x 9-ft. wide. A new method for testing full-scale structures under seismic loads was proposed that used a hydraulic linear inertial shaker (LIS) to impart seismic loads. The response of the structure was monitored using 155 strain gages, 38 linear variable differential transformers, six string potentiometers, and 42 accelerometers. The response of the frame to a series of 25 load histories using the nees@UCLA LIS was marked by gradual structural softening and minimal yielding of the steel reinforcing throughout the structure. At a first interstory drift of 1.5% some yielding of the reinforcing bars was measured. Between 1.5% and 2% first interstory drift, a global sway mechanism formed when the failure of a splice at the base of the first story west column led to a cascading set of failures within other first-story column splices. The experimental behavior suggests previous scaled testing of similar structures may have inadequately represented the vulnerability column splices. The design of the test-bed, response of the structure to seismic loads, qualitative evaluation of the test method, and implications on future research are discussed.
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Cintra, Danielli Cristina Borelli. "Análise experimental de emenda em armadura longitudinal de pilares curtos de concreto." Universidade Federal do Espírito Santo, 2013. http://repositorio.ufes.br/handle/10/6182.
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Previous issue date: 2013-11-28<br>The lap splice of the longitudinal reinforcement of columns positioned at the base, widely used in the execution of multiple floors structures in reinforced concrete floors, is the most vulnerable point in the pathological manifestations columns of buildings, compromising the structural performance and durability of the building. This region suffers from the stage of concrete, the high concentration of bars and high altitude release of concrete that promote segregation of the aggregate, and hinder access to the consolidation. During the life of the structure, is a region of high concentration of efforts, especially in columns bracing and often exposed to aggressive agents, such as the accumulation of waste chemicals, cleaning and humidity. The present work is an experimental and statistical study of the behavior at break of 31 short columns reinforced concrete subjected to concentric compression. All columns possessed cross section of 19cm x 19cm, height 170cm, concrete strength around 30MPa and longitudinal geometric rate of 0.88%. Varied only the position and the length of the lap splice to analyze the influence of these two factors and the interaction between them in the capacity of the columns. Are analyzed qualitatively manufacturing procedures samples of columns, which were close to the conditions of execution of the columns in the works. We used a factorial design to statistically analyze the experimental results, which confirmed the hypothesis that none of the factors applied, even the interaction between them, would be significant for the load capacity of the columns<br>A emenda por traspasse de armadura longitudinal posicionada na base de pilares, largamente utilizada na execução de estruturas de múltiplos pavimentos em concreto armado, consiste num dos pontos mais vulneráveis às manifestações patológicas em pilares de edifícios, comprometendo o desempenho estrutural e durabilidade da edificação. Tal região é prejudicada, desde a etapa de concretagem, pela alta concentração de armadura e pela altura elevada de lançamento do concreto, que promovem a segregação do agregado, além de dificultarem o acesso para o adensamento. Durante a vida útil da estrutura, é uma região de alta concentração de esforços e geralmente exposta a agentes agressivos, como o acúmulo de resíduos de produtos químicos, de limpeza e umidade. O presente trabalho trata-se de um estudo experimental e estatístico do comportamento até a ruptura de 31 pilares curtos de concreto armado, submetidos à compressão centrada. Todos os pilares possuíam seção transversal de 19cm x 19cm, altura de 170cm, resistência do concreto em torno de 30MPa e taxa geométrica de armadura longitudinal de 0,88%. Variou-se apenas a posição da emenda e o comprimento de traspasse da armadura longitudinal para analisar a influência desses dois fatores e da interação entre eles na capacidade de carga dos pilares. São analisados qualitativamente os procedimentos de fabricação das amostras de pilares, que foram próximos às condições de execução de pilares em obras. Utilizou-se um planejamento fatorial para analisar estatisticamente os resultados experimentais, que confirmou as hipóteses de que nenhum dos fatores adotados, nem mesmo a interação entre eles, seriam significativos para a capacidade de carga dos pilares
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Wallace, J. L. "Behaviour of beam lap splices under seismic loading." Thesis, University of Canterbury. Civil Engineering, 1996. http://hdl.handle.net/10092/9638.
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The results of an investigation into the performance of reinforced concrete beam-column subassemblages containing lap spliced reinforcement in the potential plastic hinge region of a beam are presented. Two specimens were tested with simulated seismic loading. One specimen complied with the New Zealand Concrete Design Code, NZS 3101:1982, except for the placement of the lap splices. The second specimen contained beam reinforcement details from a building constructed in the early 1960s. Current concrete design codes specify lap splices should not be placed in beam potential plastic hinge regions where inelastic reversing stresses are possible during seismic events. During testing the transverse steel specified for the confinement of the lap splices was unable to prevent bond deterioration between the spliced bars once inelastic bar strains had developed at one end of the splice. The failure of the lap splices led to a loss of lateral load capacity and a low level of ductility from the specimen.
Reinforced concrete buildings designed to pre-1970s codes may be considered inadequate when viewed in light of the provisions in current codes for seismic design. The testing of beam details taken from one such building indicates insufficient anchorage existed for the plain longitudinal beam bars in the joint. The loss of bond for the plain bars began in the initial load cycles of the test and led to a lack of specimen stiffness and lateral load capacity. The presence of the lap splices is considered to have accelerated the loss of bond from the bars.
Testing investigating the performance available from plain bar reinforced subassemblages should use anchorage for the bars that represent the conditions in the existing structure. The rapid loss of bond from the bars during cyclic loading can lead to the member end connections influencing the test results.
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De, Vial Christophe. "Performance of reinforcement lap splices in concrete masonry." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/C_de-Vial_11024236.pdf.
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Thesis (M.S. in in civil engineering)--Washington State University, December 2009.<br>Title from PDF title page (viewed on Jan. 26, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 42).
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Mjelde, Jon Zachery. "Performance of lap splices in concrete masonry shear walls." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Spring2008/Jon_Mjelde.042508.pdf.
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Wakeman, R. Brett (Robert Brett) Carleton University Dissertation Engineering Mechanical and Aerospace. "Interaction of multiple site fatigue damage and corrosion in fuselage lap splices." Ottawa, 1996.
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Aly, Ragi Sayed Mohamed. "Experimental and analytical studies on bond behaviour of tensile lap spliced FRP reinforcing bars in concrete." Thèse, Université de Sherbrooke, 2005. http://savoirs.usherbrooke.ca/handle/11143/1767.
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There are very limited studies on the bond of spliced fibre reinforced polymer (FRP) reinforcing bars. Spliced bars are necessary for the limitation of the available bar lengths (standard manufactured length of reinforcing bar). In addition, this type of splice is required at the construction joints. Furthermore, bundled bars are required instead of spaced bars in case of heavily reinforced concrete structures. By using bundled bars, the congestion of reinforcement can be avoided.The current standards for steel reinforcement (such as CSA A23.3 and ACI 318) cannot be used for the FRP bars due to the inherent differences in their mechanical properties and surface configurations. There are no design recommendations available regarding the use of spliced bundled FRP bars.The results of this research project will fill this gap. In this context, 33 large-scale concrete beams reinforced with single or bundled tensile spliced FRP bars were subjected to a four-point flexural test until failure. Two types of FRP bars were used, namely glass FRP and carbon FRP bars.The effects of the bar diameter, splice length, number of bundled bars, confinement by stirrups, and thickness of the concrete cover on the bond strength, bond stress distribution, cracking behaviour and mode of failure of the spliced FRP bars in concrete were investigated. Furthermore, the research presented herein evaluates the existing recommendations for the spliced FRP bars (CAN/CSA-S6-00, ISIS-M03-01, CAN/CSA-S806-02, and ACI 440.1R-03). In addition, the average bond stresses and the critical splice lengths for the FRP bars with different diameters were investigated.The flexural test results indicated that the FRP stress limit is directly proportional to the splice length. Moreover, the ultimate strength analysis method can be used to predict the maximum stress in the spliced FRP bars.The results of these experiments show that the transverse reinforcement (steel stirrups in this case) is effective at increasing the bond strength. An objective of this research work was to develop an equation to predict the maximum average bond stress of the tensile lap-splice of FRP bars embedded in concrete.The proposed equation, which relates the average bond stress to the thickness of the concrete cover, the FRP bar diameter, the splice length, the concrete compressive strength, and the transverse reinforcement ratio, agrees well with the test data.--Résumé abrégé par UMI.
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Corbett, Brandon Richard. "A Pilot Study to Determine the Performance of Tension Lap Splices in Reinforced Masonry Made with Light-Weight Grout." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5661.
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The use of light-weight building materials in modern construction has resulted in efficient designs and considerable cost savings by reducing structural weight and supporting sections. This has only been possible because of many years of research to better understand the properties of the light-weight material, and its structural behaviors. However, light-weight grout is a relatively new building material in reinforced masonry construction and little is known about its structural properties. The main objective of this study was to determine if the use of light-weight grout would impact the performance of reinforcing steel, specifically development length, in masonry construction.The research included testing masonry wallettes made with normal and light-weight grout containing No. 4 (12 mm) bars with splice lengths as prescribed by the current design equation as well as splices with a modification factor. The modification factor was based on preliminary grout testing, using the procedure given in the concrete building code. The wallettes were tested in a tension test to determine if the splices were of sufficient length to fully develop the yield stress of the reinforcement.For small bar sizes, No. 4 or smaller, it is not necessary to include a modification factor when calculating development length. The minimum length of lap of 12 in. governs when No. 4 or smaller bars are used, and provides sufficient length to fully develop the yield stress of the reinforcement both for normal and light-weight grout types.
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Jawdhari, Akram Rasheed. "BEHAVIOR OF RC BEAMS STRENGTHENED IN FLEXURE WITH SPLICED CFRP ROD PANELS." UKnowledge, 2016. http://uknowledge.uky.edu/ce_etds/37.
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FRP laminates and fabrics, used as an externally bonded reinforcement (EBR) to strengthen or repair concrete members, have proven to be an economical retrofitting method. However, when used to strengthen long-span members or members with limited access, the labor and equipment demands may negate the benefits of using continuous EBR FRP. Recently, CFRP rod panels (CRPs) have been developed and deployed to overcome the aforementioned limitations. Each CRP is made of several small diameter CFRP rods placed at discrete spacing. To fulfill the strengthening length, CRP’s are spliced together and made continuous by means of overlaps (or finger joints).
In this doctoral dissertation, the effectiveness of spliced CRPs as flexural strengthening reinforcement for RC members was investigated by experimental, analytical and numerical methods. The experimental research includes laboratory tests on (1) RC beams under four-point bending and (2) double-lap shear concrete specimens. The first set of tests examines the behavior of concrete members strengthened with spliced CRPs. Several beams were fabricated and tested, including: (a) unstrengthened, (b) strengthened with spliced CRPs, (c) strengthened with full-length CRPs, and (d) strengthened with full-length and spliced CFRP laminates. The double-lap shear tests serve to characterize the development length and bond strength of two commonly used CRPs. Several small-scale CRPs, with variable bond lengths, were tested to arrive to an accurate estimation of development length and bond strength. Several other specimens were additionally tested to preliminarily examine the effects of bond width and rod spacing.
A 3D nonlinear finite element simulation was utilized to further study the response of CRP strengthened RC beams, by extracting essential data, that couldn’t be measured in the experimental tests. Additionally, analytical tools were added to investigate the behavior of tested bond and beam specimens. The first tool complements the double-lap shear tests, and provides mathematical terms for important characteristics of the CRP/concrete bond interface. The second tool investigates concrete cover separation failure, which was observed in the beam testing, for RC beams strengthened with full-length and spliced CRPs.
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Valverde, Montoro Johnny Mosisés. "Splines en la solución numérica de las ecuaciones diferenciales con retardo." Universidad Nacional de Ingeniería. Programa Cybertesis PERÚ, 2012. http://cybertesis.uni.edu.pe/uni/2012/valverde_mj/html/index-frames.html.
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El objetivo de este trabajo es el estudio de la estructura fina de grupo de los objetos conocidos como curvas elípticas. Una curva elíptica proviene de una ecuación cúbica en la forma de Weierstrass no singular. En este caso, el conjunto de puntos racionales, esto es los puntos (x,y) E Q x Q que satisfacen la ecuación y2 + aixy + a^y = x3 + a^x2 + a^x + a6 mas un punto que denotamos O, y que proviene de la forma proyectiva original de la curva, constituyen un grupo abeliano con una operación de intersección de curvas, vía el teorema de Bézout en el plano proyectivo. Demostramos que este conjunto es finitamente generado, resultado conocido como el teorema de Mordell-Weil. Más precisamente -E(Q) = -E(Q)tors © ^r donde -E(Q)tors es el subgrupo de torsión (los puntos de orden finito) y Zr es la parte libre. Para determinar el subgrupo de torsión se utiliza el teorema de Lutz-Nagell, que proporciona un algoritmo para descartar los puntos de orden finito; esto sumado a un teorema de Mazur, que clasifica los grupos que se pueden obtener implica que el cálculo del subgrupo de torsión de una curva dada es siempre factible. Por otro lado, el número r en el teorema de Mordell se llama el rango de la curva elíptica. El rango de una curva elíptica sobre Q elegida al azar casi siempre es pequeño, y no es sencillo generar curvas elípticas sobre Q de rango moderadamente alto. Sin embargo, se conjetura que existen curvas elípticas sobre los racionales de rango arbitrariamente grande. Para los cálculos, usamos la forma bilineal de Nerón - Tate, que permite determinar si una cantidad finita de puntos de la curva son Z-independientes, y la conjetura de Birch Swinnerton-Dyer, que nos dice que la función L de Hasse-Weil de una curva elíptica es holomorfa en s = 1 y el orden de anulación en s = 1 es igual al rango de la curva elíptica. Esto nos da una estimación del rango que siempre logramos verificar. En el presente trabajo, revisamos la teoría circundante y, con ayuda del sistema de cálculo PARI/GP, revisamos los record de curvas elípticas de rango alto logrados hasta hoy<br>IThe objective of this work is the study of the fine group structure of the objects known as elliptic curves. An elliptic curve is given by a cubic equation in a non-singular Weierstrass form. In this case, the set of rational points, meaning the points (x,y) E Q x Q that satisfy the equation y2 + aixy + a^y = x3 + a^x2 + a^x + a6 plus a point that we denote by O, and that comes from the original projective form of the curve, constitute an abelian group with an operation defined from intersection of curves, via Bezout's theorem on the projective plañe. We prove that this set is finitely generated, result known as Mordell-WeiPs theorem. More precisely, -E(Q) ~ £-(Q)tors ©^r, where -E(Q)tors is the subgroup of torsión (the points of finite order) and Zr is the free part. To determine the torsión subgroup we use the Lutz-NagelPs theorem, which provides an algorithm to determine the points with finite order; this added to a Mazur's theorem, which classifies the groups that can be obtained, imply that the calculation of the torsión subgroup of a given curve is always feasible. On the other hand, the number r in MordelPs theorem is called the rank of the elliptic curve. The rank of a randomly chosen elliptic curve over Q is small, and it's not easy to genérate elliptic curves over Q with moderately high rank. However, it is conjectured that there exist elliptic curves over Q with arbitrarily high rank. For calculations we use Nerón- Tate's bilinear form, which allows to determine if a finite number of points on the curve are Z-independent, and the Birch Swinnerton-Dyer's conjecture, which tells us that the Hasse-Weil function L of an elliptic curve is holomorfic in s = 1 and the order of the zeros at s = 1 is equal to the rank of the elliptic curve. This gives us an estimate of the rank which we can always verify. In the present work, we review the surrounding theory and, with the help of the calculation system PARI/GP, we review the records of high rank elliptic curves achieved until today
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Bournas, Dionysios A., Thanasis C. Triantafillou, and Catherine G. Papanicolaou. "Retrofit of Seismically Deficient RC Columns with Textile- Reinforced Mortar (TRM) Jackets." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244049636138-65944.
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The effectiveness of a new structural material, namely textilereinforced mortar (TRM), was investigated experimentally in this study as a means of confining old-type reinforced concrete columns with limited capacity due to bar buckling or due to bond failure at lap splice regions. Comparisons with equal stiffness and strength fiber-reinforced polymer (FRP) jackets allow for the evaluation of the effectiveness of TRM versus FRP. Tests were carried out on full scale non-seismically detailed RC columns subjected to cyclic uniaxial flexure under constant axial load. Thirteen cantilever-type specimens with either continuous longitudinal reinforcement (smooth or deformed) or lap splicing of longitudinal bars at the floor level were constructed and tested. Experimental results indicated that TRM jacketing is quite effective as a means of increasing the cyclic deformation capacity of old-type RC columns with poor detailing, by delaying bar buckling and by preventing splitting bond failures in columns with lap spliced bars. Compared with their FRP counterparts, TRM jackets used in this study were found to be equally effective in terms of increasing both the strength and deformation capacity of the retrofitted columns. From the response of specimens tested in this study, it can be concluded that TRM jacketing is an extremely promising solution for the confinement of reinforced concrete columns, including poorly detailed ones with or without lap splices in seismic regions.
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Quttineh, Yousef. "Transfer Pricing Profit Split Methods : A Practical Solution?" Thesis, Jönköping University, JIBS, Commercial Law, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-11107.
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<p>The purpose of this master’s thesis is to explain and analyze whether today’s existing regulations provide sufficient guidance on how to apply the Profit Split Method (PSM) in practice. Since the enterprises’ profits arising from intra-group transactions increases, the tax base for any government also becomes larger and more important. This issue will likely become even more problematic as the globalization branches out and the majority of the global trade is undertaken between associated enterprises.</p><p>In order to satisfy all parts and serve the dual objective of securing an appropriate tax base in each jurisdiction and avoiding double taxation, one ambition of the OECD is to harmonize the transfer pricing rules and make them become more uniform. An area in which this goal can be accomplish is at an international level such as the OECD; an important developer in the field of transfer pricing. Different transfer pricing methods has been developed which can be applied by both taxpayers and tax authorities to determine a correct transfer price. Six of these methods has gained international acceptance, although to a more or less extent among various countries, and one of these methods is the PSM. In the years between 1979 and 1995, the OECD had a reluctant standpoint of accepting the application of any transfer pricing method based on profits, such as the PSM. This hesitant viewpoint changed in the existing TPG which explicitly stipulates that the PSM could provide a transfer pricing estimation in accordance with the ALP, which should be accepted in exceptional cases.</p><p>There are certain situations where a PSM possibly will provide the most appropriate arm’s length result. Since the principle of economics can create complex business environments of both vertical and horizontal integration, contributions of valuable intangibles on both sides of the cross-border transaction, the PSM might be the only method which can be employed. A relevant issue which need to be enlightened is whether the existing guidance provided by the OECD and USA is sufficient from a practitioners and tax administration point of view, or is more guidance needed to better understand the issues surrounding the concept of the PSM. The fact that OECD insist of using comparables to the highest extent as possible when employing the PSM entails practical problems, since it is rather a rule than an exception that reliable comparables cannot be found when valuable intangibles are involved.</p><p>The Arthur of this master’s thesis has identified three key conclusions which might facilitate how PSM issues can be handled in the future and improve the existing PSM guidance. These conclusions are the need for a uniform PSM interpretation, the need for additional flexibility and acceptance, and the need for additional TPG guidance.</p>
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Abdulwanis, Mohamed Sana Mohamed. "Split delta shocks and applications to conservation law systems." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=112666&source=NDLTD&language=en.
Full textAbstract:
There are many real models in which unbounded solution to conservation law system occur. Most often we have some kind of delta function in the solution as a result of the accumulation of mass or some other variable. There is no general method of approachingsuch problems with nonlinearities. This dissertation provides solutions to conservation law systems that contain division by a dependent variable, which is a problematic part when working with measures. For example, a basic model of chromatography and similar chemical processes has a division with a variable that is unbounded in some cases. The denition of the split delta shock and the general method of using it in such systems is given. Finally, the solution for the singular chromatography model is given. <br>Postoji mnogo realnih modela u kojima se javljaju neoranicena resenja zakona odrzanja. Najcesce imamo neku vrstu delta funkcije u resenju kao posledicu nagomilavanja mase ili neke druge velicine. Ne postoji opsti metod prilaza takvim problemima sa nelinearnostima. U ovoj disertaciji su data resenja problema zakona odrzanja koja sadrze delenje zavisnom promenljivom, sto je problematican deo kod rada sa merama. Na primer, osnovni model hromatograje i slicnih hemijskih procesa ima delenje promenljivom koja je neogranicena u nekim slucajevima. Data je denicija inverza delenjog delta udarnog talasa i opsti metod primene u takvim sistemima. Na kraju je dato resenje kod modela singularne hromatograje.
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Aguilà, Moliner Pau. "Estudio de las propiedades de radiación de partículas resonantes con aplicaciones en sistemas de comunicaciones." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/402268.
Full textAbstract:
El sector de las radiocomunicaciones ha experimentado un drástico desarrollo estos últimos años. Entre ellos, los sistemas de comunicaciones inalámbricos han sufrido un gran crecimiento en la sociedad moderna motivado por el elevado número de servicios en que se pueden aplicar (por ejemplo radiodifusión, telefonía móvil, posicionamiento por satélite o bien identificación por radiofrecuencia). Esto ha motivado la investigación de nuevos dispositivos de microondas con diferentes y mejores prestaciones. La tendencia más extendida actualmente consiste en utilizar tecnologías planares para la realización de los elementos radiantes (típicamente parches metálicos o dipolos de media longitud de onda), lo que permite obtener diseños de bajo coste y fácilmente integrables con el resto de circuitería impresa. Puesto que estos dispositivos son progresivamente más compactos, un aspecto clave también es la búsqueda de técnicas para reducir las dimensiones finales de las antenas así como mejorar su funcionalidad. Una metodología aplicada ampliamente con anterioridad consiste en cargar las antenas impresas con estructuras resonantes (provenientes del campo de los metamateriales) para reducir su frecuencia de operación así como lograr un funcionamiento multifrecuencia. Recientemente, sin embargo, se ha presentado otra alternativa basada en utilizar un resonador Split Ring Resonator trabajando a la segunda resonancia como elemento radiante puesto que muestra unas propiedades de radiación interesantes en términos de eficiencia de radiación e impedancia de entrada.
El objetivo principal de esta tesis ha sido, por tanto, explotar el comportamiento de esta partícula (y otras configuraciones derivadas) a la segunda frecuencia de resonancia como radiador para mejorar las prestaciones de las antenas planares convencionales en una variedad de aplicaciones. Esto abarca las antenas microstrip, las agrupaciones de antenas y, en último término, las superficies polarizadoras.<br>The radiocommunication sector has suffered a rapid development in recent years. Among them, wireless communications systems have shown a great growth in modern society due to the high number of services in which they can be applied (e.g. radio broadcasting, mobile telecommunications, satellite navigation or radio frequency identification). This has motivated a research of new microwave devices with different and improved features. The current trend is to use planar technologies for the realization of radiating elements (typically metallic patches or half-wavelength dipoles), which allows to obtain low cost designs that can be easily integrated with all the printed circuitry. Since these devices are more and more compact, a key point is also the search for techniques to reduce the final dimensions of the antennas as well as to improve their functionality. A widely applied methodology is to load the printed antennas with resonant structures (coming from the field of metamaterials) to reduce their operating frequency as well as to achieve multifrequency operation. Recently, however, another alternative has been proposed based on using a Split Ring Resonator working at the second resonance as a radiator since it shows interesting radiation properties in terms of its radiation efficiency and input impedance.
Therefore the main objective of this thesis has been to exploit the behavior of this resonant particle (and other derived configurations) at the second resonant frequency as a radiating element to improve the performance of conventional planar antennas in a variety of applications. This includes microstrip antennas, antenna arrays and, moreover, polarizer sheets.
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Vallgren, Isak. "Att dela på notan - Om expertskatten, beloppsregeln och EU-rättens fyra friheter." Thesis, Umeå universitet, Juridiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-145479.
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Radeschnig, Jessica. "Heterogeneous Optimality of Lifetime Consumption and Asset Allocation : Growing Old in Sweden." Thesis, Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-36119.
Full textAbstract:
This thesis covers a utility optimizing model designed and calibrated for agents of the Swedish economy. The main ingredient providing for this specific country is the modeling of the pension accumulation and pension benefits, which closely mimics the Swedish system. This characteristic is important since it measures one of the only two diversities between genders, that is, the income. The second characteristic is the survival probability. Except for these differences in national statistics, men and women are equal. The reminding model parameters are realistically set estimates from the surrounding economy. When using the model, firstly a baseline agent representing the entire labor force is under the microscope for evaluating the model itself. Next, one representative woman and one representative man from the private and public sectors respectively, composes a set of four samples for investigation of heterogeneity in optimality. The optimum level of consumption and risk-proportion of liquid wealth are solved by maximizing an Epstein-Zin utility function using the method of dynamic programming. The results suggests that both genders benefit from adapting the customized solutions to the problem.
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Saucez, Manuel. "Résolution des qualités de vol de l'aile volante Airbus." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0026/document.
Full textAbstract:
L'objectif de cette étude est de résoudre les qualités de vol d'une aile volante long courrier, au stade de la conception avion. Le concept d'aile volante promet un gain important en terme de performances et de niveau de finesse par rapport aux configurations classiques. Ce gain est obtenu par l'intégration des quatre fonctions principales de l'avion (portance, contrôle, propulsion, transport) dans un seul corps. Ces choix de configuration entraînent des challenges à relever, dont l'obtention de qualités de vol respectant la certification. La configuration initiale étudiée présente de fortes instabilités longitudinales et latérales, une faible autorité en roulis, et des difficultés à effectuer la manœuvre de rotation au décollage. Dans cette étude sont proposées des solutions, combinant des surfaces de contrôle innovantes et des degrés de libertés originaux, qui tirent profit des avantages de la configuration. Les qualités de vols sont résolues dans un processus de résolution avec aussi peu de boucles que possible, et l'impact sur les performances est minimisé. En sortie de ce processus se trouve l'architecture de surface de contrôle optimisée, qui minimise l'impact des qualités de vol sur le coût de la mission<br>The aim of this study is to solve the handling qualities problems of a long range blended wing body, at the conceptual design phase. That concept, also named flying wing in this report, is an aircraft which integrates the four aircraft functions (lift, control, propulsion, passengers transportation) in one single body. That configuration presents a benefit in cruise lift-over-drag ratio, as well as in noise emissions, due to the shielding effect provided by the inner wing to mask the engine noise.That configuration choice leads also to challenges. One of them is the handling qualities. The baseline studied flying wing presents initially longitudinal and lateral instabilities, as well as lack of roll manoeuvrability and difficulty to do the rotation at takeoff. In this report are proposed solutions, combining innovative control surfaces and original drivers, which are adapted to the configuration advantages. The handling qualitiesare solved in a resolution process with as few loops as possible, and the impact on the performances is minimized. The output of that process is the best control surfaces architecture and airfoils design which minimizes the impact of the handling qualities resolution on the cost of the mission
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Bosch, Roig Ignacio. "Algoritmos de detección distribuida en sistemas monosensor." Doctoral thesis, Universitat Politècnica de València, 2008. http://hdl.handle.net/10251/1898.
Full textAbstract:
La presente tesis aborda la elaboración de algoritmos de detección distribuida en sistemas monosensor. Tradicionalmente, la detección distribuida se ha aplicado a la fusión de decisiones tomadas por sensores espacialmente dispersos. No obstante, puede ser de utilidad en la implementación de detectores que tratan de explotar diferentes tipos de información sobre las diferencias existentes entre las dos hipótesis sobre las que decidir. El objetivo es sustituir un único detector complejo, cuando no inabordable, por una combinación de detectores más sencillos, implementables a partir de la teoría de detección óptima.
Frente a la posibilidad de un enfoque general, se ha preferido focalizar la tesis en dos aplicaciones de especial interés para el grupo de investigación, en cuyo seno se ha desarrollado esta tesis: detección de incendios forestales a partir de señales infrarrojas y detección de ecos en ruido de fondo granular, en ensayos no destructivos por ultrasonidos.
En cuanto a la detección de incendios forestales se ha propuesto un esquema de detección que fusiona dos tipos de detectores que hemos denominado detector de persistencia y detector de crecimiento. La idea subyacente es tratar de explotar la misma información que utiliza el propio vigilante humano, al que se trata de reemplazar. El detector de persistencia se basa a su vez en la fusión de decisiones correspondientes a pequeños intervalos de observación consecutivos. En cada intervalo se implementa un detector de filtro adaptado en subespacio que trata de explotar el comportamiento de persistencia en tiempo a corto plazo de un fuego, frente a otros efectos de carácter impulsivo que también pueden producir incrementos de temperatura esporádicos en la celda bajo vigilancia (coches, personas, sol, ). Por su parte el detector de crecimiento trata de explotar mediante un filtro adaptado a un crecimiento de tipo lineal, el esperado crecimiento en temperatura que, a medio y largo plazo, debe producir un fuego des<br>Bosch Roig, I. (2005). Algoritmos de detección distribuida en sistemas monosensor [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1898<br>Palancia
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Hakala, Tim. "Settling-Time Improvements in Positioning Machines Subject to Nonlinear Friction Using Adaptive Impulse Control." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1061.
Full textAbstract:
A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These displacements are achieved through the application of short duration, high intensity pulses. The relationship between pulse duration and displacement is seldom a simple function. The most dependable practical methods for control are self-tuning; they learn from online experience by adapting an internal control parameter until precise position control is achieved. To date, the best known adaptive pulse control methods adapt a single control parameter. While effective, the single parameter methods suffer from sub-optimal settling times and poor parameter convergence. To improve performance while maintaining the capacity for ultimate precision, a new control method referred to as Adaptive Impulse Control (AIC) has been developed. To better fit the nonlinear relationship between pulses and displacements, AIC adaptively tunes a set of parameters. Each parameter affects a different range of displacements. Online updates depend on the residual control error following each pulse, an estimate of pulse sensitivity, and a learning gain. After an update is calculated, it is distributed among the parameters that were used to calculate the most recent pulse. As the stored relationship converges to the actual relationship of the machine, pulses become more accurate and fewer pulses are needed to reach each desired destination. When fewer pulses are needed, settling time improves and efficiency increases. AIC is experimentally compared to conventional PID control and other adaptive pulse control methods on a rotary system with a position measurement resolution of 16000 encoder counts per revolution of the load wheel. The friction in the test system is nonlinear and irregular with a position dependent break-away torque that varies by a factor of more than 1.8 to 1. AIC is shown to improve settling times by as much as a factor of two when compared to other adaptive pulse control methods while maintaining precise control tolerances.
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(10709154), William G. Pollalis. "Drift Capacity of Reinforced Concrete Walls with Lap Splices." Thesis, 2021.
Find full textAbstract:
<p>Twelve large-scale reinforced concrete (RC) specimens
were tested at Purdue University’s Bowen Laboratory to evaluate the
deformability of structural walls with longitudinal lap splices at their bases.
Eight specimens were tested under four-point bending and four specimens were
tested as cantilevers under constant axial force and cyclic reversals of
lateral displacement. All specimens failed abruptly by disintegration of the
lap splice, irrespective of what loading method was used or what splice details
were chosen. Previous work on lap splices has focused mainly on splice
strength. But, in consideration of demands requiring structural toughness (e.g.
blast, earthquake, differential settlement), deformability is arguably more
important than strength. </p>
<p>Approximations of wall
drift-strain relationships are presented in combination with estimates of
splice strength and deformability to provide lower-bound drift capacity
estimates for RC walls with lap splices at their bases. Deformations in slender
structural walls (with aspect ratios larger than 3) are controlled by flexure.
Shear deformations must be considered for walls with smaller aspect ratios. For
slender walls with lap splices comparable to those tested, the observations
collected suggest that drift capacities can be as low as 0.5%. That is: splices
with minimum concrete cover, minimum transverse reinforcement (0.25% transverse
reinforcement ratio) terminating in hooks, and lap splice lengths selected to
reach yielding in the spliced bars (approximately 60 bar diameters for splices
of Grade-60 reinforcement) can fail as yield is reached or soon after. For
splices of the same length, doubling the amount of hooked transverse
reinforcement increases deformation capacity by nearly 50%. By maintaining the
same transverse reinforcement ratio but confining splices with closed hoops
(instead of hooks), deformation capacity nearly doubles. Increasing splice
length increases the expected splice strength but also increases the strain
required to reach the same drift ratio. </p>
<p>Evidence from this and
similar experimental programs suggests that lap splices with minimum cover and
confined only by minimum transverse reinforcement terminating in hooks should
not be used in critical sections of structural walls when toughness is
required. To prevent abrupt failure during events that demand structural
toughness, it is recommended that lap splices be shifted away from locations
where yielding in structural walls is expected.</p>
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"The Effect of Splice Length and Distance between Lapped Reinforcing Bars in Concrete Block Specimens." Thesis, 2014. http://hdl.handle.net/10388/ETD-2014-04-1529.
Full textAbstract:
The tensile resistance of No. 15 lap spliced reinforcing bars with varying transverse spacing and lap splice length was evaluated in full-scale concrete block wall splice specimens. The range of the transverse spacing between bars was limited to that which allowed the bars to remain within the same cell, and included the evaluation of tied spliced bars in contact. Two-and-a-half block wide by three course tall double pullout specimens reinforced with contact lap splices were initially used to determine the range of lap splice length values to be tested in the wall splice specimens such that bond failure of the reinforcement occurred. The double pullout specimens were tested in direct tension with six replicates per arrangement. Three values of lap splice length: 150, 200, and 250 mm, were selected from the testing of the double pullout specimens and tested in the wall splice specimens in combination with three values of transverse spacing: 0, 25, and 50 mm, with three replicates per configuration. A total of twenty-seven two-and-a-half block wide by thirteen course tall wall splice specimens reinforced with two lap splices were tested in four-point loading. Both the double pullout and the wall splice specimens were constructed in running bond with all cells fully grouted.
The tensile resistance of the lap spliced bars in the double pullout specimens was measured directly. The contact lap splices with a 150, 200, and 250 mm lap splice length developed approximately 38, 35 and 29% of the theoretical yield load of the reinforcement, respectively. The difference between the mean tensile resistances of the three reinforcement configurations tested in the double pullout specimens was found to be statistically significant at the 95% confidence level. Different than expected, the tensile resistance of the lap spliced reinforcing bars in the double pullout specimens was inversely proportional to the lap splice length provided. For the short lap splice lengths used in this investigation, the linear but not proportional relationship between bond force and lap splice length known from reinforced concrete is believed to have caused this phenomenon.
An iterative sectional analysis using moment-curvature response was used to calculate the tensile resistance of the lap spliced reinforcement in the wall splice specimens. The calculated mean tensile resistance of the reinforcement increased with increasing lap splice length, and was greater when the bars were in contact. Securing the bars in contact may have influenced the tensile capacity of the contact lap splices as higher stresses are likely to develop as a result of the bar ribs riding over each other with increasing slip. Results of the data analysis suggest that the tensile resistance of non-contact lap splices within the same cell is generally independent of the spacing between the bars. A comparison of the experimental results for the wall splice specimens with the development and splice length provisions in CSA S304.1-04 and TMS 402-11 indicate that both the Canadian and U.S. design standards are appropriate for both contact and non-contact lap splices located within the same cell given the limited test database included in this investigation.
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Miao-I, Kuo, and 郭苗宜. "Seismic Retrofit of Existing RC Bridge Columns─Sheer Strength and Lap-Splice Retrofit." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/94991414115500851153.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>營建工程系<br>88<br>The seismic resistantance of the existing bridge columns may be questionable due to the un-desired design details. Among others,the weakness of the column details of particular interest in this study includes short column problems and the lap-splices of main reinforcements at the plastic hinge zone.This experimental study has focused on the performance evaluation of a few scaled-down models of bridge columns with the aforementioned weakness. Retrofitting strategies including the steel jacketing and FRP jacketing are applied to enhance the seismic performance of the column models.
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"Performance of large size reinforced concrete beams containing a lap splice subjected to fatigue loads." Thesis, 1990. http://hdl.handle.net/10388/etd-01152013-125036.
Full textAbstract:
Extensive research has been conducted into the areas of
low cycle high stress loading (seismic loading) and static
loading of reinforced concrete beams containing lap splices.
The knowledge acquired from this research has led to
recommendations for changes in how seismic and static
loading of lap splices are handled.
For splices subjected to high cycle low stress load
patterns (fatigue loading) current design of lap splices is
very similar to that used for statically loaded splices,
even though little research information is available on
performance of lap splices under high cycle fatigue,
particularly for larger size bars and members. With this in
mind a testing programme was initiated to determine the
effects of fatigue on the performance of lap splices
proportioned and confined with transverse reinforcing steel
according to the ACI Committee 408 recommendations for
tensile static loading. In the test programme described in
this report, only short lap lengths with heavy transverse
confinement were investigated.
Specimens used in this study were 7 m long with a 330
mm x 508 mm cross-section. Equal loading is applied at two
points symmetrically placed two meters apart on the simply
supported beam. Reinforcement consists of 2 - No. 30 Grade
400 tension reinforcement with either 2 - No. 30 or 3 - No.
25 Grade 400 compression reinforcement. Both tension bars
contain 900 mm lap splices confined with 7 - No. 10 Grade
300 stirrups. The splices are located at mid-span in the
constant moment, zero-shear region. Shear reinforcement
consists of No. 10 Grade 300 stirrups placed at 150 mm on
centre.
Eight specimens were constructed and subjected to
either cyclic loads or monotonically increasing loads
(static loads) until failure. Cyclic loads were applied to
seven specimens with a monotonically increasing load applied
to the eighth. Different load ranges were used in the
fatigue testing, but stress reversal was not applied. Six
of seven cyclically loaded specimens failed when one or both
of the main tension bars ruptured, while the seventh
specimen failed when the compression zone crushed after the
cyclic test was terminated at 3 million cycles and a
monotonically increasing load was applied. The one beam
subjected to a static load until failure exhibited a bond
failure in the splice region.
The tests showed that heavily confined splices
proportioned according to the guidelines set out in ACI
Committee 408 recommendations for static loading are
adequate for cyclic fatigue loading, and the splice does not
appear to influence the fatigue life of the specimen.
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(9029597), Rebeca P. Orellana Montano. "Case Study To Evaluate Drift Estimation In Non-Ductile Reinforced Concrete Buildings With Foundation Lap-Splices: Numerical Simulation Work." Thesis, 2020.
Find full textAbstract:
<p>Past earthquake damage
assessments have shown the seismic vulnerability of older non-ductile reinforced
concrete buildings. The life safety-risk these buildings pose has motivated
researchers to study, develop, and improve modeling techniques to better simulate
their behavior with the aim to prioritize retrofits.</p><p><br></p>
<p>This study focuses on the lap
splice detailing at the base of the building in columns, shorter than those
recommended by modern codes which consider seismic effects. Current modeling efforts
in non-ductile reinforced concrete frame structures have considered the
connection at the foundation fixed. This study models the influence of the performance
of short lap splices on the simulation of response of an instrumented perimeter-frame-non-ductile
building located in Van Nuys, California, and to compare results with those of
previous studies of the same building.</p><p><br></p>
<p>The methodology consisted of evaluating
the response of a non-ductile concrete building subjected to a suite of ground
motions through the comparison of three base connections: fixed, pinned, and a
rotational spring modeling the short lap splice. Comparison and performance
evaluation are done on the basis of drift as the main performance metric. In
the building response evaluation flexure and shear forces in frame elements
were also compared using the different base conditions. </p><p><br></p>
<p>The models consist of two-dimensional
frames in orthogonal direction, including interior and exterior frames,
totaling into 4 frames. The dynamic analysis was performed using SAP2000
analysis software. The proposed rotational spring at the base was defined using
the Harajli & Mabsout (2002) bond stress – slip relationship and moment –
curvature sectional analysis, applied to 24d<sub>b</sub> and 36d<sub>b</sub>
lap splices. Deformation considered flexure and slip. Adequacy of shear strength
was checked prior to the analysis to verify that shear failure did not occur
prior to either reaching first yield of the column reinforcement or splice
capacity. </p><p><br></p>
In this study, the response of the frames using the
proposed rotational spring model was found to be between the fixed and pinned
base conditions with regard to roof displacement and interstory drift ratio,
also termed as story drift ratio. The behavior of the frames changed depending
on the yielding of the longitudinal reinforcement, as depicted by the
interstory drift ratio and displacement. The performance of the building frames
also depended on the ground motion. The N-S and E-W direction frame
computational models considered three and four earthquakes, respectively,
totaling to 14 computational models per base condition. Three computational
models out of the 14 with the proposed rotational spring base condition simulated
recorded roof displacement results with accuracy. In the frame simulations
where yielding of most of the column longitudinal bars was not calculated, the
maximum interstory drift occurred in the upper stories, matching column damage
observations during the event. The findings of the study showed that short lap
splice increases the drift and displacement compared to the fixed base supporting
its effect, i.e. the behavior of a non-ductile reinforced concrete case study
building to an earthquake.
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Naqvi, Syed. "Lap splice in glass fiber reinforced polymer‐reinforced concrete rectangular columns subjected to cyclic‐reversed loads." 2016. http://hdl.handle.net/1993/31906.
Full textAbstract:
This study presents the experimental results of nine full-scale lap spliced glass-fiber reinforced polymer (GFRP) reinforced concrete (RC) columns, and one additional reference steel-RC column with lap splices, under axial and cyclic-reversed loads. The test parameters included type of reinforcement, lap splice length of longitudinal reinforcement, transverse reinforcement spacing, and the effect of using steel fiber-reinforced concrete (SFRC). Test results indicated that a splice length of 60 times the diameter of the longitudinal column bar was adequate in transferring the full bond forces along the splice length and were able to maintain the lateral load carrying capacity when subjected to higher levels of axial loads and drift ratios. In addition, lap spliced GFRP-RC columns with closely spaced transverse reinforcement achieved high levels of deformability. Furthermore, the use of SFRC in columns with inadequate splice increased the peak lateral strength and the energy dissipation of the specimens.<br>February 2017
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Lee, Chung-Lung, and 李宗龍. "A Study on Testing Interface Strength of CFRP sheets and the Confining Effect with a Lap Splice." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/f4nwe3.
Full textAbstract:
碩士<br>國立臺北科技大學<br>土木與防災研究所<br>100<br>After the 921 earthquake, the reinforcement of the reinforced concrete structure needs grow with each passing day, the carbon fiber polymer composites with high strength, simple construction and resistant to corrosion and other advantages of the structural reinforcement materials applied to the RC beam shear reinforcing RC columns, shear and confinement reinforcement of behavior has been extensively studied and discussed; past studies confirm, and carbon fiber reinforcement effect is often affected by the carbon fiber interface strength of the design criteria (ACI 440.2R) the proposed design, in accordance with the strength of concrete , the amount of carbon fiber reinforcement in the form of conditions to calculate the carbon fiber to effectively design strain, as have the security and rational reinforcement design.
Reference design this study to explore the overlap between the carbon fiber patch strength in order to quantify the experimental results; carbon fiber confinement reinforcement RC column to column confinement to enhance the axial compression strength and the axis of the finale of toughness, however, literature and design criteria overlap length between the requirements and recommendations in the confined carbon fiber is more lacking in this study to design a series of overlap between the specimen test carbon fiber strength, seek to quantify the strength test results for the variable to the length and width of the lap, while planning the concrete the cylindrical specimens confined test, using the mathematical model to verify the equivalent confinement of confinement reinforcement, carbon fiber lap premises.
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Forero, Henao Miguel. "Autoclaved aerated concrete (AAC) masonry : lap-splice provisions and nominal capacity for interface shear transfer between grout and AAC." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2063.
Full textAbstract:
Design of autoclaved aerated concrete (AAC) masonry in the United States is currently based on Appendix A of the 2008 Masonry Standards Joint Committee (MSJC) Code. Those provisions include the design of lap splices, and equations for the nominal capacity in interface shear transfer between grout and AAC. The provisions for lap splices are an extension of the provisions for concrete or clay masonry, modified to neglect the contribution of AAC to splice capacity. This thesis describes a testing program aimed at verifying the current provisions using tests of lap splices in grouted AAC masonry. Based on the results of those tests, the provisions are shown to be appropriate. The provisions on interface shear transfer between grout and AAC require that the transferred shear be checked against a nominal capacity based on limited test results. This thesis describes a testing program aimed at verifying and refining this nominal capacity using pullout tests of grout cores in AAC masonry units. Based on the results of those tests, the currently used nominal capacity is shown to be conservative, and a recommendation is made to increase it.<br>text
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(5930642), Rebecca L. Glucksman. "Bond Strength of ASTM A615 Grade 100 Reinforcement for Beams." Thesis, 2019.
Find full textAbstract:
<div>In the past decade, high-strength reinforcement (fy > 60 ksi) has become more prevalent and more widely accepted. Building codes such as ACI 318-14 do not address the use of highstrength reinforcement for proper development and splicing of reinforcement. Furthermore, research on development of high-strength reinforcement is limited. The objective of the study is to develop a suitable expression for the development and splicing of high-strength reinforcement.</div><div>Of particular interest is evaluating the influence of splice length and confinement on bond strength as well as evaluating the effectiveness of high-strength transverse reinforcement on bond strength. The study tested 22 large-scale concrete beams reinforced with ASTM A615</div><div>Grade 100 deformed steel bars: 11 specimens without transverse reinforcement within the splice region (unconfined) and 11 specimens with transverse reinforcement within the splice region (confined). Splice lengths varied from 40 bar diameters to 120 bar diameters, which are some of the largest ever tested. The effect of the test variables which were systematically studied, found</div><div>that splice strength is nonlinearly related with splice length and can be represented by a power equation. Furthermore, it was found that high-strength transverse reinforcement does not improve bond strength compared with the use of Grade 60 transverse reinforcement. Considering the test results and review of historical test results, an analytical investigation was conducted which developed a simple expression for estimating the capacity of both unconfined</div><div>and confined beams. The results are compared with the current building code design expressions as well as other proposed bond strength equations. The research conducted here provides the basis for development of a design expression that will allow for the incorporation of highstrength reinforcement in future building codes.</div>
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Eck, Mary. "Effects from Alkali-Silica Reacton and Delayed Ettringite Formation on Reinforced Concrete Column Lap Splices." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10747.
Full textAbstract:
Reinforced concrete bridge columns can deteriorate prematurely due to the alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF), causing internal expansion and cracking on the surface of the concrete. The performance of the longitudinal reinforcement lap splice in deteriorated concrete columns is the focus in this research.
This thesis presents the results from the deterioration of large-scale specimens constructed and placed in an environment susceptible to ASR/DEF deterioration, the experimental results from four-point and three-point structural load tests, and an analytical model based on bending theory characterizing the specimen behavior during the structural load tests.
Fourteen large-scale specimens were constructed, placed in an environment to accelerate the ASR/DEF deterioration mechanisms, and instrumented both internally and externally to measure the internal concrete expansions, and surface expansions and crack widths. In addition, two control specimens were constructed and kept in a laboratory, preventing ASR/DEF deterioration. Post-tensioning was used to simulate axial load on a bridge column. Structural load tests were performed on eight specimens with no ASR/DEF damage to late stage ASR and minimal DEF damage. Comparing the specimen behaviors during the loading testing, it was found that the yield strength increased about 5-15%, and post-cracking stiffness up to first yielding of the deteriorated specimens was about 25-35% stiffer than the control specimens. The increased specimen strength and stiffness likely occurred from volumetric expansion due to ASR/DEF damage which engaged the reinforcement, further confining the concrete and causing a beneficial increase in the axial post-tensioning load. The analytical model matched the control specimens well and matched the non-control specimens when the axial load was increased.
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(6611555), Eric Fleet. "Effective Confinement and Bond Strength of Grade 100 Reinforcement." Thesis, 2019.
Find full textAbstract:
The primary reinforcement used for construction of structural concrete members has a yield strength of 60 ksi. This reinforcement grade was incorporated into construction over 50 years ago and remains the standard. Recent advances in material technology have led to the development of commercially available reinforcing steel with yield strengths of 100 ksi. While greater yield strengths can be utilized in design, it is essential that the bars can be properly anchored and spliced to fully develop their strength. Although design expressions are available for this purpose, they were established considering 60 ksi reinforcement. Therefore, the objective of this research program is to evaluate the development of high-strength reinforcing steel and establish a design expression for the development and splicing of this steel. Two phases of experimental tests were conducted. Phase I was performed by Glucksman (2018) and investigated the influence of splice length and transverse reinforcement on bond strength over four series of beam tests. This study (Phase II) was conducted following Phase I and consisted of reinforced concrete slab and beam testing over three series. An investigation was conducted on reinforcement development with a focus on the effect of splice length, concrete compressive strength, stress-strain relationships of the steel (ASTM A615 vs. ASTM A1035), and transverse reinforcement. Based on the results, the influences of test variables were identified, and a new confinement model was developed that estimates the transverse reinforcement contribution to bond strength. Finally, a design expression is provided for calculating the development and splice lengths of high-strength reinforcement.
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Alberson, Ryan M. "Performance of Reinforced Concrete Column Lap Splices." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-7068.
Full textAbstract:
Cantilevered reinforced concrete columns with a lap splice of the longitudinal
reinforcement near the base can induce high moment demands on the splice region when
lateral loads are present on the structure. Code design specifications typically require a
conservative splice length to account for these high moment demands and their
consequences of bond failure. The required splice length is calculated as a function of
required development length, which is a function of the bond between the reinforcement
and the surrounding concrete, and a factor depending on the section detailing. However,
the effects of concrete deterioration due to alkali silica reaction (ASR) and/or delayed
ettringite formation (DEF) may weaken the bond of the splice region enough to
overcome the conservative splice length, potentially resulting in brittle failure of the
column during lateral loading.
This thesis presents the following results obtained from an experimental and analytical
program.
* Fabrication of large-scale specimens of typical column splice regions with
concrete that is susceptible to ASR/DEF deterioration
* Measurement of the large-scale specimen deterioration due to ASR/DEF
accelerated deterioration
* Analytical model of the column splice region based on flexure theory as a
function of the development length of the reinforcement and a factor to account
for deterioration of the bond due to ASR/DEF
* Experimental behavior of two large-scale specimens that are not influenced by
premature concrete deterioration due to ASR/DEF (control specimens). This
experimental data is also used to calibrate the analytical model.
The conclusions of the research are that the analytical model correlates well with the
experimental behavior of the large-scale control specimens not influenced by ASR/DEF.
The lap splice region behaved as expected and an over-strength in the splice region is
evident. To account for ASR/DEF damage, the analytical model proposes a reduction
factor to decrease the bond strength of the splice region to predict ultimate performance
of the region with different levels of premature concrete deterioration.
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Pereira, Tiago Miguel Nico. "Experimental Campaign Addressing Lap-Splices under Cyclic Loading." Master's thesis, 2017. http://hdl.handle.net/10362/27891.
Full textAbstract:
Many existing bridges were built before modern seismic design guidelines were written. This means that particularly in countries with moderate seismicity where another type of loads such as gravity, wind or snow are more demanding, the seismic hazard may have been underestimated in the past years. Past experience shows that critical details, including lap-splices on the potential plastic hinge region above the foundation and low transverse reinforcements ratios, can lead to a small deformation capacity of the existing bridge piers and therefore to a possible major structural damage.
The performance of RC members featuring lap splices was extensively studied in the past. However, a large number of authors focused on the force capacity of lap splices while their deformation capacity was rather neglected. This topic has become a target of interest only recently.
This dissertation represents the first part of a research project developed at École Polytechnique Fédérale de Lausanne that has the final goal of presenting a constitutive law capable of predicting the lap splice behavior, in particular its deformation capacity. The dissertation presents an experimental campaign regarding the lap splice performance under cyclic loading.
This experimental campaign gives continuity to the experimental campaigns presented by Bimschas (2010) and Hannewald et al. (2013), where three large-scale piers featuring lap splices near the foundation were tested. Three specimens representing a boundary region of the previously specimens are presented in this dissertation.
The test specimens subjected to the same cyclic load history only differ regarding the transversal reinforcement. Particular attention is given to the slippage between the rebars and the steel strains in the lap splice zone.
These tests along with the results of future specimens intend to create a database that will allow to validate the future expression mentioned above.
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Shihata, Ayman. "CFRP strengthening of RC beams with corroded lap spliced steel bars." Thesis, 2011. http://hdl.handle.net/10012/6185.
Full textAbstract:
Corrosion is the number one deterioration mechanism that decreases the service life of the concrete structures. Many structures in severe environments have experienced an unacceptable loss in serviceability earlier than anticipated due to corrosion.
Advanced composite materials in the form of externally bonded fiber reinforcing polymer (FRP) sheets have been successfully used for rehabilitation and strengthening of infrastructure in lieu of traditional repair techniques such as steel plates bonding. FRPs are used because of their light weight, ease of application, non-corrosiveness material, and high strength.
The current study comprised of testing eighteen reinforced concrete beams to investigate the confinement provided by carbon fiber-reinforced polymer (CFRP) sheets on the bond strength of corroded tension lap splices under static loading. The beams were 200mm wide by 300mm high by 2000mm. Each beam was reinforced on the tension side with two steel bars (2 M 15 or 2 M20 steel bars) spliced at mid span in the constant moment region. The nominal concrete strength was 43 MPa and the yield stress of the steel reinforcement was 400MPa. The test variables were the concrete cover to bar diameter ratio (c/d) which varied from 1.5 to 2.67, the level of corrosion (0% and 2.5% mass loss), and the presence or absence of transverse CFRP wrapping. The corrosion in the steel bars was induced by means of accelerated technique withan impressed current density of 150mA/cm2. The specimens were instrumented by strain gauges on the steel reinforcement, concrete, and CFRP sheets. Linear variable differential transformer (LVDT) was used to measure mid span deflection. The specimens were tested to failure in four point bending.
The test results showed that all beams failed by bond splitting. The reduction in the ultimate bond strength due to a 2.5% corrosion level ranged between 16% and 25% depending on the c/d ratio. The reduction in the ultimate bond strength due to a 5.0% corrosion level ranged between 20% and 45% depending on the c/d ratio. FRP wraps were effective in confining the tension splice region. The failure in the FRP repaired beams was more ductile and more gradual although the final mode of failure was splitting of the concrete cover. A new, (Ktr,f,) accounting for the presence and amount of FRP confining tension lap-splice was proposed.
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"High cycle (fatigue) resistance of reinforced concrete beams with lap splices." Thesis, 1993. http://hdl.handle.net/10388/etd-01152013-124631.
Full textAbstract:
The development of current design standards for reinforced concrete beams containing
lap splices has been mainly aimed at preventing failures due to static (monotonic) loading,
or low cycle, high intensity (seismic) loading. However, little consideration has been
given in these standards or in previous research to the performance of lap splices when
subjected to high cycle, low intensity (fatigue) loading. Also, recently proposed design
equations for lap splices under static loading will permit shorter lap lengths. For these
reasons, a study was initiated to investigate the fatigue resistance of reinforced concrete
beams with lap splices. A principal variable in this research program was the degree of
transverse reinforcement (stirrups) which was provided along the lap splice.
The specimens used in this experimental program were seven meters in length, with a
cross section 330 mm wide and 508 mm deep, and were reinforced with two No. 30
Grade 400 bars, top and bottom. A lap splice was provided in the bottom tension bars
situated in a constant moment region created by a symmetrical two point loading system.
The lap splice length and confinement were designed according to ACI Committee 408
recommendations for static loading.
Two different lap splice configurations were provided for the test specimens. The first
used the maximum number of stirrups that were deemed to be effective for static loading,
permitting a shorter lap length. In the second configuration nominal stirrups were
provided to the splice at a spacing of one half the effective beam depth, requiring a longer
lap length. Failure of the specimens with the heavier stirrups occurred from fatigue of the
tensile reinforcing steel and showed similar fatigue resistance to beams containing
continuous reinforcement. The specimens with nominal stirrups usually resulted in a
splice failure after fewer load cycles, after splitting and delamination of the concrete
confining the lap had occurred.
Both beams had a similar static bond resistance; however, the beams with the heavier
stirrup confinement (shorter lap length) displayed a greater fatigue resistance than the
beams with lighter stirrups (longer lap length). These results are in agreement with
conclusions reached for seismic loading conditions, which found that splice confinement
provided by a high degree of transverse reinforcement is required under cyclic loading to
offset the rapid deterioration of the concrete cover confinement.
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Dhabale, Ashwin. "Impact Angle Constrained Guidance Using Cubic Splines." Thesis, 2015. http://etd.iisc.ernet.in/2005/3658.
Full textAbstract:
In this thesis the cubic spline guidance law and its variants are derived. A detailed analysis is carried out to find the initial conditions for successful interception. The results are applied to three dimensional guidance design and for solving waypoint following problems.
The basic cubic spline guidance law is derived for intercepting a stationary target at a desired impact angle in a surface-to-surface engagement scenario. The guidance law is obtained using an inverse method, from a cubic spline curve based trajectory. For overcoming the drawbacks of the basic cubic spline guidance law, it is modified by introducing an additional parameter. This modification has an interesting feature that the guidance command can be obtained using a single cubic spline polynomial even for impact angles greater than π/2, while resulting in substantial improvement in the guidance performance in terms of lateral acceleration demand and length of the trajectory. For imparting robustness to the cubic spline guidance law, in the presence of uncertainties and acceleration saturation, an explicit guidance expression is also derived.
A comprehensive capturability study of the proposed guidance law is carried out. The capturability for the cubic spline guidance law is defined in terms of the set of all feasible initial conditions for successful interception. This set is analytically derived and its dependence on various factors, such as initial engagement geometry and interceptor capability, are also established.
The basic cubic spline guidance and its variants are also derived for a three dimen- sional scenario. The novelty of the present work lies in the particular representation of the three dimensional cubic spline curve and the adoption of the analytical results available for two dimensional cubic spline guidance law. This enables selection of the boundary condition at launch for given terminal boundary condition and also in avoiding the singularities associated with the inverse method based guidance laws.
For establishing the feasibility of the guidance laws in the real world, the rigid body dynamics of the interceptor is presented as a 6 degrees-of-freedom model. Further, using a simplified model, elementary autopilots are also designed. The successful interception of the target in the presence of the rigid body dynamics proves practical applicability of the cubic spline based guidance laws.
Finally, the theory developed in the first part of the thesis is applied to solve the waypoint following problem. A smooth path is designed for transition of vehicle velocity from incoming to outgoing direction. The approach developed is similar to Dubins’ path, as it comprises line–cubic spline–line segments. The important feature of this method is that the cubic spline segments are fitted such that the path curvature is bounded by a pre-specified constrained value and the acceleration demand for following the smooth path obtained by this method, gradually increases to the maximum value and then decreases. This property is advantageous from a practical point of view.
All the results obtained are verified with the help of numerical simulations which are included in the thesis. The proposed cubic spline guidance law is conceptually simple, does not use linearised kinematic equations, is independent of time-to-go es- timates, and is also computationally inexpensive.
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Thompson, Keith. "The anchorage behavior of headed reinforcement in CCT nodes and lap splices." Thesis, 2002. http://wwwlib.umi.com/cr/utexas/fullcit?p3086715.
Full text
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"Evaluation of Mitigative Techniques for Non-Contact Lap Splices in Concrete Block Construction." Thesis, 2014. http://hdl.handle.net/10388/ETD-2014-04-1497.
Full textAbstract:
A previously completed study in the field of concrete block construction by Ahmed and Feldman (2012) indicated that, on average, the reinforcing bars in non-contact lap splices, where the lapped bars are located in adjacent cells, only develop 71% of the tensile resistance of spliced bars which are in contact. An experimental program was therefore initiated to design and evaluate remedial measures which can potentially increase the tensile resistance of non-contact lap splices to that of contact lap splice of the same lap length. Implementation of the proposed measures in various field situations was also analyzed. Six unique remedial splice details, along with standard contact and unaltered non-contact lap splices were evaluated and compared. The mitigative details included providing additional confinement, installing knock-out webs, placing splice reinforcement between the lapped bars, and combinations of these aforementioned details. Three replicates of each splice detail were constructed for a total of 24 wall splice specimens.
Each wall splice specimen was reinforced with No. 15 Grade 400 deformed steel reinforcing bars with 200 mm lap splice lengths at located the midspan. The specimens were tested in a horizontal position under a monotonic, four-point loading geometry. Load and deflection data were collected throughout testing and were subsequently used in an iterative moment-curvature analysis to calculate the maximum tensile resistance of the spliced reinforcement. This was then used to compare the structural performance of each remedial splice detail to the standard contact and non-contact lap splices.
The wall splice specimens which contained non-contact lap splices with knock-out webs, s-shaped, and transverse reinforcement in the splice region achieved similar tensile capacities as the wall splice specimens with standard contact lap splices. Industry professionals have indicated that the installation of the remedial measures evaluated in this study would not affect the constructability of masonry assemblages in field situations. The splice detail with knock-out webs confined within the lap splice length was determined to be the most viable procedure as it can be installed to increase the resistance of non-contact lap splices in almost all construction situations. This remedial procedure was able to improve the tensile resistance of the lapped reinforcement by 63% compared to the wall splice specimens with standard non-contact lap splices.
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Reyes, Olga. "Modeling of R/C columns with short lap splices subjected to earthquake loading." 1999. http://catalog.hathitrust.org/api/volumes/oclc/50200324.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1999.<br>Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 78-80).
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Wu, Sheng-Hung, and 吳聲鴻. "The influence of lap-splices of steel bars on the behavior of HSC beam-column joint." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/74956081008509084227.
Full textAbstract:
碩士<br>國立中央大學<br>土木工程學系<br>86<br>The concept of Strong-Column-Weak-Beam is adopted by
construction design code currently in which the plastic hinge
occurs on the beam-column joint. This phenomenon will induce the
decay of strength and stiffness, effect the whole earthquake
resistant behavior of intersection. Decreasing the decay of the
stiffness of intersection can be performed by the moving of the
plastic hinge from the intersection of beam-column. The purpose
of this paper is to apply the lap-splices of beam steel bars on
the beam-column joint in order to remove the plastic hinge to
decrease the damage of joint. Four full-scale beam-column joint
specimens including three specimens produced by high strength
concrete(HSC) and one by common concrete are prepared for the
investigation of the effect of the lap-splices of steel bars on
the behavior of HSC beam-column joint. From the
observation of the result of experiment, the arrangement of the
lap-splices of beam steel bars can remove the plastic hinge from
the surface of column. The bonding force of steel bar is well
developed in HSC and it decreases the slippage of steel bar
either. If the specifications about lap-splices of code are
taken, the steel bar with larger diameter would produce high
shear stress on the joint and increase the damage of the joint
due to the longer length of lap-splice. Therefore, the length of
lap-splice is important to the behavior of whole joint. Well
confining effect of concrete of the joint is fulfilled if the
tie bar is produced by high tension steel. Furthermore, the
adoption of HSC offers positive contribution to the joint.
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Mahlawe, Anele Emanuel. "Effect of corrosion of lap-spliced steel reinforcement on the flexural strength of reinforced concrete beams." Thesis, 2020. https://hdl.handle.net/10539/31185.
Full textAbstract:
A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2020<br>The study aimed to investigate the effect of corrosion on the flexural strength of reinforced concrete (RC) beams with steel lap-splicing in the central constant moment region. A total of 24 RC 100 × 165 × 1500 mm beams were cast each for SANS10100-1 and Eurocode 2. Out of the 24 RC beams, 12 RC beams were cast for each design code (6 with lap-splicing and 6 without spliced flexural reinforcement). Accelerated chloride-induced corrosion was used to induce steel corrosion in the in the central constant moment region. Only 6 RC beams were corroded for each design code, the remaining 6 were used for reference purposes. All beams were tested for ultimate strength using a 4-point bending configuration. The applied load, mid-span deflection and mode of failure were recorded until failure load was reached. The results showed an increase in deflection and a decrease in ultimate strength in the corrosion-damaged specimens. The failure mode of non-lapped beams remained ductile, while on lap-spliced beams the failure mode changed from ductile to brittle. The corroded bars were physically measured using a Vernier Caliper for the determination of corrosion degree<br>CK2021
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(9768341), Kinsey C. Skillen. "The Effects of Transverse Reinforcement on the Strength and Deformability of Reinforced Concrete Elements." Thesis, 2020.
Find full textAbstract:
Post-earthquake examinations of reinforced concrete structures often show structural damage resulting from bond and shear failures. Such failures typically occur in reinforced concrete elements with details known to cause problems, such as widely spaced transverse reinforcement and/or lap splices located in regions of flexural yielding. These details are common in older reinforced concrete buildings (built before 1970) that have reinforced concrete columns with longitudinal reinforcement spliced just above the floor level, and transverse reinforcement spaced at a distance of d/2 or longer. This investigation focused on means to increase the deformability of existing reinforced concrete elements susceptible to bond and shear failures during a seismic event or other applications requiring toughness. The effects of confinement provided by epoxied anchors, spiral transverse reinforcement, and post-tensioned external clamps were investigated. Emphasis was placed on producing a strengthening device that can be sized, fabricated, and installed with ease because most of the existing strengthening techniques require specialized labor, tools, and materials. The observations collected support the idea that active confinement provided by post-installed and post-tensioned transverse reinforcement was the most effective method to improve structural deformability among the methods studied and within the ranges considered.
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Μπισκίνης, Διονύσιος. "Αντοχή και ικανότητα παραμόρφωσης μελών οπλισμένου σκυροδέματος, με ή χωρίς ενίσχυση". Thesis, 2007. http://nemertes.lis.upatras.gr/jspui/handle/10889/478.
Full textAbstract:
Η παρούσα διατριβή ανήκει στο γενικότερο θεματικό πεδίο της σεισμικής αποτίμησης, σχεδιασμού ή ανασχεδιασμού κατασκευών οπλισμένου σκυροδέματος με βάση τις μετακινήσεις. Οι σύγχρονες μέθοδοι αυτού του τύπου, στηρίζονται σε έλεγχο και σύγκριση της σεισμικής απαίτησης με την ικανότητα των μελών της κατασκευής σε όρους μετακινήσεων παρά σε όρους δυνάμεων. Δημιουργείται επομένως η ανάγκη για απλό και αξιόπιστο υπολογισμό της συμπεριφοράς μελών οπλισμένου σκυροδέματος σε κάμψη και διάτμηση, σε όρους μετακινήσεων.
Το αντικείμενο της παρούσης διατριβής είναι η ανάπτυξη προσομοιωμάτων για τον υπολογισμό των βασικών χαρακτηριστικών της συμπεριφοράς καμπτόμενων μελών οπλισμένου σκυροδέματος και συγκεκριμένα: της ροπής διαρροής, της παραμόρφωσης στη διαρροή, της ενεργού δυσκαμψίας, της παραμόρφωσης στην αστοχία, της διατμητικής αντοχής σε ανακυκλιζόμενη φόρτιση, της αντοχής μελών με χαμηλό λόγο διάτμησης και της συμπεριφοράς υπό διαξονική καταπόνηση. Εξετάζονται μέλη διαφόρων τύπων και διαφορετικής διατομής, μέλη με ενίσχυση μανδύα οπλισμένου σκυροδέματος ή μανδύα σύνθετων υλικών, καθώς επίσης και μέλη με μάτιση του διαμήκους οπλισμού στην περιοχή πλαστικής άρθρωσης. Για την ανάπτυξη των προσομοιωμάτων, καθώς και για τον έλεγχο άλλων παλαιότερων, αναπτύχθηκε και αξιοποιήθηκε βάση πειραματικών δεδομένων μελών οπλισμένου σκυροδέματος με περισσότερα από 2800 πειράματα από τη διεθνή βιβλιογραφία.
Για τον υπολογισμό της ροπής και της καμπυλότητας στη διαρροή, αναπτύσσονται απλές σχέσεις υπολογισμού, βασιζόμενες σε ανάλυση σε επίπεδο διατομής και καθορίζονται τα κατάλληλα κριτήρια διαρροής. Αναπτύσσονται ακολούθως σχέσεις υπολογισμού της παραμόρφωσης στη διαρροή, και συγκεκριμένα της γωνίας στροφής χορδής του μέλους στη διαρροή, θy, ως άθροισμα τριών όρων: καμπτικής παραμόρφωσης, διατμητικής παραμόρφωσης και παραμόρφωσης λόγω ολίσθησης των ράβδων διαμήκους οπλισμού από την περιοχή αγκύρωσης. Προτείνονται δε δύο εναλλακτικοί τρόποι υπολογισμού της ενεργού δυσκαμψίας, ένας θεωρητικός και ένας καθαρά εμπειρικός. Στη συνέχεια εξετάζεται η παραμόρφωση στην αστοχία και προτείνονται δύο εναλλακτικοί μέθοδοι υπολογισμού της γωνίας στροφής χορδής στην αστοχία, θu. Η 1η βασίζεται στον υπολογισμό της καμπυλότητας στην αστοχία, φu, με εφαρμογή του κατάλληλου προσομοιώματος περίσφιγξης του σκυροδέματος, και στην εφαρμογή της φu σε μήκος πλαστικής άρθρωσης ίσο με Lpl, ενώ η 2η σε καθαρά εμπειρικές εξισώσεις. Εξετάζεται ακολούθως η διατμητική αντοχή σε ανακυκλιζόμενη φόρτιση και προτείνονται προσομοιώματα για αστοχία σε διαγώνιο εφελκυσμό ή αστοχία σε λοξή θλίψη, μετά την καμπτική διαρροή. Στη συνέχεια εξετάζεται η συμπεριφορά μελών οπλισμένου σκυροδέματος υπό διαξονική καταπόνηση. Εξετάζονται επίσης μέλη με χαμηλό λόγο διάτμησης και προτείνονται νέα αντιπροσωπευτικότερα κριτήρια για τον χαρακτηρισμό ενός μέλους ως “κοντό μέλος”, καθώς και νέα μεθοδολογία υπολογισμού της αντοχής των μελών αυτών, με κατάλληλο συνδυασμό του προσομοιώματος των Shohara and Kato, 1981 και των Φαρδής και συνεργάτες 1998. Ακολούθως εξετάζονται μέλη ενισχυμένα με μανδύα σύνθετων υλικών και προτείνονται προσομοιώματα υπολογισμού της γωνίας στροφής χορδής στη διαρροή και την καμπτική αστοχία, καθώς και προσομοίωμα υπολογισμού της διατμητικής αντοχής. Στη συνέχεια εξετάζεται η συμπεριφορά μελών με μάτιση του διαμήκους οπλισμού στην περιοχή πλαστικής άρθρωσης, καθώς και η εφαρμογή μανδύα σύνθετων υλικών για την ενίσχυση της περιοχής αυτής. Τέλος εξετάζεται η συμπεριφορά στη διαρροή και στην αστοχία, μελών ενισχυμένων με μανδύα οπλισμένου σκυροδέματος. Η ανάπτυξη όλων των προτεινόμενων προσομοιωμάτων της διατριβής βασίζεται στην καλύτερη δυνατή συμφωνία με τα πειραματικά αποτελέσματα της βάσης δεδομένων, χωρίς όμως να θυσιάζεται η απλότητα και η ευχρηστία αυτών.<br>The present Thesis belongs in the general field of seismic assessment, design and redesign of concrete structures with displacement based procedures. Modern methods of this kind are based in controlling and comparing seismic demand with structural elements capacity in terms of displacements rather than forces. This leads in the need of estimating reinforced concrete elements performance under bending and shear, in terms of displacements.
The object of the Thesis is development of models for calculating the basic performance characteristics of reinforced concrete elements under bending, in particular: yield moment, deformation at yielding, effective stiffness, deformation at ultimate, shear strength under cyclic loading, maximum strength of members with low shear ratio and behavior under biaxial loading. Members with various types of section and various characteristics are included, as also members retrofitted with FRP jacket or concrete jacket and members with lap-splice of longitudinal reinforcement in plastic hinge region. In order to develop new models and check older ones, a database of more than 2800 experiments from international literature on reinforced concrete elements was created and used here.
Simple equations and procedures are suggested for calculating yield moment and corresponding curvature, based on section analysis, by specifying the appropriate yield criteria. Equations for calculating deformation at yielding, in particular chord rotation at yielding, θy as the sum of deformations due to bending, due to shear and due to slippage of longitudinal reinforcement from anchorage zone, are also developed. Calculation of effective stiffness is based on two alternative models, one theoretical and one purely empirical. Deformation at ultimate is then examined where two methods for calculating chord rotation at ultimate are suggested. 1st one is based on ultimate curvature, φu, where an appropriate concrete confinement model is used, and plastic hinge length Lpl, while 2nd one is based on purely empirical equations. Shear strength under cyclic loading is also examined and new models for calculating shear strength for shear tension and shear compression failure after flexural yield are developed. Behavior of reinforced concrete elements under biaxial loading is then examined. Elements with low shear ratio are also covered and new, more representative, criteria to characterize an element as a “short element” are suggested. A procedure based on an appropriate combination of Shohara and Kato 1981 model and Fardis et al. 1998 model is then suggested for calculating maximum strength of such “short elements”. Retrofitted members with FRP jacket are then examined and models for chord rotation at yielding and ultimate, as well as for shear strength are suggested. Behavior of members with lap-splice of longitudinal reinforcement inside plastic hinge region is then examined, including also retrofitting of this region with FRP jacket. Performance at yielding and ultimate of retrofitted members with concrete jacket is also examined. Development of all the suggested models of the Thesis is based on best fit with experimental results of the database, without sacrificing simplicity and applicability of the models.
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McCaffrey, Kiera Maureen. "Episcopal split tests faith and law." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1254.
Full textAbstract:
Upset with what they say is the increasingly heterodox stance the national leadership of The Episcopal Church, Episcopalians in Texas and throughout the country are leaving their denomination and aligning under Anglican bishops.
In a last-grasp effort to hold on to property and assert control over an often dissident flock, the leadership of The Episcopal Church is arguing Canon law in the unlikeliest of places: the secular courtroom. As parishes and even whole dioceses country break free of the hierarchy and declare themselves independent from the national church, two lawsuits in Texas are raising the stakes and asking the government not just to intervene in land disputes, but to go further and determine the organizational structure of the faith.<br>text