Dissertations / Theses on the topic 'Crack width'
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Piyasena, Ratnamudigedara, and n/a. "Crack Spacing, Crack Width and Tension Stiffening Effect in Reinforced Concrete Beams and One-Way Slabs." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030606.165418.
Full textPiyasena, Ratnamudigedara. "Crack Spacing, Crack Width and Tension Stiffening Effect in Reinforced Concrete Beams and One-Way Slabs." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/366060.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Engineering
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Yang, Shangtong. "Concrete crack width under combined reinforcement corrosion and applied load." Thesis, University of Greenwich, 2010. http://gala.gre.ac.uk/7145/.
Full textKUNIEDA, Minoru, Keisuke KAWAMURA, Hikaru NAKAMURA, and Khoa K. TRAN. "QUANTITATIVELY EVALUATION OF CRACK PROPAGATION DUE TO REBAR CORROSION." 日本コンクリート工学会, 2010. http://hdl.handle.net/2237/20926.
Full textFredericks, Brandon. "Examination of flexural crack width prediction in concrete: comparison of analytical and numerical models." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/32675.
Full textMalm, Richard. "Predicting shear type crack initiation and growth in concrete with non-linear finite element method." Doctoral thesis, KTH, Bro- och stålbyggnad, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10156.
Full textQC 20100730
Ledvoňová, Monika. "Monitorování staveb v souvislosti s okolní stavební činností." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225735.
Full textBowen, Galo Emilio. "Service and Ultimate Limit State Flexural Behavior of One-Way Concrete Slabs Reinforced with Corrosion-Resistant Reinforcing Bars." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23205.
Full textDeformability of the concrete slab-strip specimens was defined with ultimate-to-service level ratios of midspan deflection and curvature. The MMFX2 and Enduramet 32 one-to-one replacement specimens had deformability consistent with the Grade 60 controls, demonstrating that bridge deck slabs employing high strength reinforcement without a defined yield plateau can still provide sufficient ductility at an ultimate limit state. A reduction in bar quantity and cover provided acceptable levels of ductility for the 2304 specimens and MMFX2 reinforced slabs.
Master of Science
Tang, Denglei, and Denglei Tang@gmail com. "Influence of Chloride-induced corrosion cracks on the strength of reinforced concrete." RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080530.091350.
Full textFeizi, Sedige, and Fateha Yasmin Khan. "Study of crack width within a suspended concrete slab with different amount of cement clinker considering lower climate impact." Thesis, KTH, Betongbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-222024.
Full textExamensarbetet undersöker möjligheten att använda ett betongrecept med endast 70 % cementklinker för ett husbyggnadsprojekt kallat Gretas Glänta med hänsyn till krav på sprickbildning i en fribärande platta. Kravet som ska uppfyllas är en sprickvidd på max 0.2 mm med hänsyn till krympning och långtidsbelastning. Syftet med att använda en lägre andel cementklinker i betongblandningen är att minska klimatpåverkan från betongen. Examensarbetet består av materialförsök och konstruktionsteknisk modellering för olika betongrecept, där andelen cementklinker varieras. Flygaska användes som alternativt bindemedel. Totalt undersöktes fem betongmixer. En mix med 100 % cementklinker jämfördes genom laboratorietestning med motsvarigheter med 85 % och 70 % cementklinkerinnehåll. Ett betongrecept med 50 % cementklinker undersöktes också i detta examensarbete, trots att detta idag inte tillåts enligt betongstandarderna, men inkluderades i studien för att testa olika materialegenskaper i färskt och hårdnat tillstånd. Alla betongmixerna testades med effektivitetsfaktorn 1 förutom receptet med 70 % cementklinkerandel som testades för både 1 och 0.4 i effektivitetsfaktor. Den genomförda studien visade att betongmix 4 med 70 % cementklinker och med effektiviseringsfaktor 0.4 uppnådde hållfasthetsklass C35/45 efter 28 dagar och uppfyllde också angivet krav på maximal sprickbredd 0,2 mm med hänsyn till krympning och långtidslast. Vattenpermeabilitetstest visade att betongmixen med 70 % cementklinker och effektiviseringsfaktor 0.4 var vattentätt. Betongmix 3 med 70 % cementklinker och effektivitetsfaktor 1 uppnådde hållfasthetsklass C30/37. Betongmix 1 med 100 % cementklinker erhöll den högsta hållfasthetsklassen C50/60 och betongmix 2 med 85 % cementklinker gav hållfasthetsklass C45/55. Betongmix 5 med 50 % cementklinker uppnådde hållfasthetsklass C20/25 vilket var den lägsta av de testade betongrecepten. Alla betongrecepten verkade ge vattentät betong enligt vattenpermeabilitetstest. En bakgrundsbeskrivning av koldioxidutsläpp från betong- och cementproduktion genomförs i rapporten. Forskning om pågående metoder för att minimera utsläppen från betong- och cementindustrin sammanfattas också. FE-modellering med programmet FEM-design och analytiska beräkningar utfördes för att undersöka sprickbredden med hänsyn till krympning och långtidslast för betongplattan för betongmix 2 med 85 % cementklinker och effektiviseringsfaktor 1 och betongmixerna 3 och 4 med 70 % cementklinker och effektiviseringsfaktorerna 1 och 0.4. Egenskaperna som erhölls i laboratorietesterna användes i modellerings och de analytiska beräkningarna. Resultat från FEM-design och analytiska beräkningarna visade att betongmixerna 3 och 4 med 70 % cementklinker med effektiviseringsfaktorerna 1 och 0.4 och betongmix 2 med 85 % cementklinker och effektiviseringsfaktor 1 uppfyllde kravet på sprickbredd. Beräkningen utfördes inte för betongmixerna 1 och 5 med 100 % cementklinker och 50 % cementklinker då de inte var aktuella för att användas i bostadsprojektet. Resultaten från den genomförda studien visade att betongmix 4 med 70% cementklinker och med en effektivitetsfaktor 0.4 kan användas i husbyggnadsprojektet Gretas Glänta för att sänka klimatpåverkan från betongen.
Chowdhury, Sanaul. "Damping Characteristics of Reinforced and Partially Prestressed Concrete Beams." Thesis, Griffith University, 1999. http://hdl.handle.net/10072/367400.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Engineering
Science, Environment, Engineering and Technology
Full Text
Kanjee, Janina Prakash. "Assessing the influence of crack width on the durability potential of cracked concrete using the durability index approach." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24308.
Full textMalm, Richard. "Shear cracks in concrete structures subjected to in-plane stresses." Licentiate thesis, KTH, Civil and Architectural Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4215.
Full textAfter only two years of service, extensive cracking was found in the webs of two light-rail commuter line bridges in Stockholm, the Gröndal and Alvik bridges. Due to this incident it was found necessary to study the means available for analysing shear cracking in concrete structures subjected to in-plane stresses. The aim of this PhD project is to study shear cracking with these two bridges as reference. In this thesis, the first part aims to study the possibility of using finite element analysis as a tool for predicting shear cracking for plane state stresses. The second part is concerning how the shear cracks are treated in the concrete design standards.
Shear cracking in reinforced beams has been studied with non-linear finite element analyses. In these analyses the shear cracking behaviour was compared to experiments conducted to analyse the shear failure behaviour. Finite element analyses were performed with two different FE programs Abaqus and Atena. The material model used in Atena is a smeared crack model based on damage and fracture theory with either fixed or rotated crack direction. The material model used in Abaqus is based on plasticity and damage theory. The fixed crack model in Atena and the model in Abaqus gave good results for all studied beams. For the two studied deep beams with flanges the results from the rotated crack model were almost the same as obtained with the fixed crack model. The rotated crack model in Atena gave though for some beams a rather poor estimation of the behaviour.
The calculation of crack widths of shear cracks has been studied for the long-term load case in the serviceability state for the Gröndal and Alvik bridges, with the means available in the design standards. The methods based on the crack direction corresponding to the principal stress and do not include the effect of aggregate interlocking seems to be too conservative. Two of the studied methods included the effect of aggregate interlocking, it was made either by introducing stresses in the crack plane or implicitly by changing the direction of the crack so that it no longer coincide with the direction of principal stress. For calculations based on probable load conditions, these methods gave estimations of the crack widths that were close to the ones observed at the bridges. Continuous measurements of cracks at the Gröndal and the Alvik bridges have also been included. Monitoring revealed that the strengthening work with post-tensioned tendons has, so far, been successful. It also revealed that the crack width variations after strengthening are mainly temperature dependent where the daily temperature variation creates movements ten times greater than those from a passing light-rail vehicle. Monitoring a crack between the top flange and the webs on the Gröndal Bridge showed that the top flange was moving in a longitudinal direction relative to the web until the strengthening was completed. The crack widths in the sections strengthened solely by carbon fibre laminates seem to increase due to long-term effects.
Someshwara, Korachar Eshwari. "A Numerical Based Determination of Stress Intensity Factors for Partially Cracked Flexural I-shaped Cross-sections." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/89068.
Full textMaster of Science
Steel is one of the fundamental materials used in the construction of bridge structures, and steel girder bridges are one of the most common types of bridge structures seen in the United States. Past bridge failures have helped engineers to understand shortcomings in design specifications, and AASHTO codes have been developed and revised over the years to reflect an improved understanding and evolution of engineering behavior. Engineers must make sure that a design is robust enough for functional use of the component during its service life. It is also equally important to understand the potential chances of failure and make the structure strong enough to overcome any failure mechanisms. Fracture is one structural failure mode which occurs with little to no warning and hence is very dangerous. One efficient way to quantify the stress field in the vicinity of a crack tip is by calculating the Stress Intensity Factor (SIF) around a crack tip. Fracture literature is available which describes different methods of determining SIFs for cracked members. However, there are no solutions available to find a SIF of a partially cracked flexural I-shaped members. This research was focused on determining Stress Intensity Factors and studying the fracture behavior of partially cracked I-sections using Finite Element Analysis. The resulting SIF solutions were further used to study the fracture behavior and stress redistribution in partially cracked flexural I-shaped members.
Nurro, Matti, and Emanuel Jönsson. "Minimiarmering i grundplattor : En studie om hur konstruktörsföretag väljer armering och hur valet påverkar den färdiga konstruktionen." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Byggnadsteknik och belysningsvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-45317.
Full textAhmed, Lamis. "Models for analysis of young cast and sprayed concrete subjected to impact-type loads." Doctoral thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168211.
Full textQC 20150529
Ge, W., K. Chen, Z. Guan, Ashraf F. Ashour, W. Lu, and D. Cao. "Eccentric compression behaviour of concrete columns reinforced with steel-FRP composite bars." Elsevier, 2021. http://hdl.handle.net/10454/18412.
Full textEccentric compression behaviour of reinforced concrete (RC) columns reinforced by steel-FRP composite bars (SFCBs) was investigated through experimental work and theoretical analyses. The tension and compression test results show that SFCBs demonstrate a stable post-yield stiffness. The mechanical properties of the composite reinforcement have a significant influence on eccentric compression behaviour of the reinforced concrete columns, in terms of failure mode, crack width, deformation and bearing capacity. Formulae were also developed to discriminate failure mode and to determine moment magnification factor, bearing capacity and crack width of the columns studied, with the theoretical predictions being in a good agreement with the experimental results. In addition, parametric studies were conducted to evaluate the effects of mechanical properties of reinforcement, reinforcement ratio, eccentricity, slenderness ratio, types of reinforcement and concrete on the eccentric compression behaviour of RC columns. The results show that the compressive performance is significantly improved by using the high performance concrete, i.e. reactive powder concrete (RPC) and engineered cementious composites (ECC).
financial supports of the work by the National Natural Science Foundation of China (51678514), the Natural Science Foundation of Jiangsu Province, China (BK20201436), the China Postdoctoral Science Foundation (2018M642335), the Science and Technology Project of Jiangsu Construction System (2018ZD047), the Deputy General Manager Science and Technology Project of Jiangsu Province (FZ20200869), the Cooperative Education Project of Ministry of Education, China (201901273053), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province (2020), the Six Talent Peaks Project of Jiangsu Province (JZ-038, 2016), the Yangzhou University Top Talents Support Project and the Jiangsu Government Scholarship for Overseas Studies.
The full-text of this article will be released for public view at the end of the publisher embargo on 3 Apr 2022.
Ewang, Bruce Ekane. "Estudo de fissuração em concreto armado com fibras e armadura convencional." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-06122017-154223/.
Full textDue to the brittleness of concrete, the control and prevention of cracking in reinforced concrete structures are of prime importance. One way of improving the tensile properties of concrete is by the addition of fibres. The present research is a trial to provide guidelines for the design of fibre reinforced concrete structures under service loads. First of all, a study of the tensile behaviour of the composite material is presented. A probabilistic/fracture mechanics based micromechanical model, capable of predicting the poscracking behaviour of the material is presented. The model predicts the tensile stress-crack width relationship, accounting for the following micromechanisms: fibre and aggregate bridging, fibre rupture, local snubbing, matrix spalling, the Cook-Gordon interface effect, and fibre prestressing. At the structural level, two macromechanical models are presented. One is founded on the classical theory of cracking, while the other, a shear lag model, is founded on the continuum damage mechanics. The first model is adjusted for application to the prevision of crack width and crack spacing in fibre reinforced concrete structures with short discrete and randomly dispersed fibres. It is shown that the micromechanical model fits very well in the macrostructural model. Tensile tests with mortar specimens reinforced with continuous steel wires or meshes and PVA or polypropylene fibres were carried out. The theoretical results predicted by the model were compared with results obtained from the experimental program, and show very good agreement, confirming the validity of the theoretical model.
Mlynář, Bronislav. "Základová vana z vodonepropustného betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265561.
Full textBrattström, Niels, and Oliver Hagman. "Reinforced Concrete Subjected To Restraint Forces : A comparison with non-linear numerical analyses." Thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209122.
Full textI Sverige är det Eurokod 2 som används som basis för dimensionering av betongkonstruktioner, i vilken metoder som beskriver sprickkontroll i bruksgränsstadiet för betong utsatt för tvångskrafter återfinns. Både detaljerade handberäkningsmetoder och förenklade metoder beskrivs. I olika koder och rapporter återfinns ett flertal förslag till hur detta problem ska hanteras. Vissa påstår att metoderna som anges i Eurokod 2 är på osäkra sidan då dessa förlitar sig på stabiliserad sprickbildning, medan andra menar att Eurokod 2 är för konservativ då inspänningen kommer förhindra att sprickorna öppnar sig. Då metoderna analyseras noggrannare och testas framgår det att alla genererar olika resultat under samma antaganden. De flesta ligger inom samma spann och skillnaderna uppkommer då de olika metoderna beaktar olika aspekter. En metod genererar dock ett resultat som är högre än alla andra, som i denna rapport benämns som Chalmersmetoden. Då denna metod lärs ut på Göteborgs tekniska universitet (Chalmers) så har de utstickande resultatet skapat en viss förvirring bland konstruktörer i Sverige. Då metoderna jämförs med numeriska analyser framgår det att Eurokod 2 förutspår en rimlig sprickvidd för låga töjningsgrader, medan den verkar vara överkonservativ för höga töjningsgrader. Chalmersmetoden verkar underestimera antalet sprickor som uppkommer i konstruktionen, vilket resulterar i de utstickande resultaten. Fortsättningsvis fastslås det att i relation till en mer detaljerad handberäkning så är den förenklade metoden i Eurokod 2 inte alltid på säkra sidan. Metoden är endast giltig inom ett visst spann, vilket kan överskridas beroende på den egentliga töjningens storlek och valet av dimensioneringsparametrar. Krypningens effekt på fastinspända betongkonstruktioner då de utsätts för långtidslaster så som krympning har också diskuterats och analyserats numeriskt. Olika handberäkningsmetoder antyder att krypningen har en positiv effekt på så sätt att sprickvidden minskar. Även de numeriska resultaten indikeratar att så är fallet, dock anses osäkerheten i dessa analyser vara stor i förhållande till analyser av korttidslaster.
Güngör, Güven. "Biaxial Load Effects on Fatigue Properties." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19079/.
Full textElgabbas, Fareed Mahmoud. "Development and structural testing of new basalt fiber-reinforced-polymer (BFRP) bars in RC beams and bridge-deck slabs." Thèse, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8734.
Full textAbstract: The advances in fiber-reinforced-polymer (FRP) technology have spurred interest in introducing new fibers, such as basalt FRP (BFRP), which has the potential to offer an efficient solution when implemented in concrete structure, such as corrosion resistant, durable and cost-effective. Furthermore, the available design codes and guides do not provide any recommendations for the use of BFRP bars since fundamental studies and relevant applications are still limited. Therefore, investigations are needed to characterize and understand the behavior of BFRP bars in concrete members. Consequently, the main objectives of this experimental investigation are to evaluate the short- and long-term characteristics of newly developed BFRP bars, as well as evaluate the structural performance of these new bars as internal reinforcement for concrete beams and bridge-deck slabs to introduce these new reinforcing bars to the design codes and guides. The experimental tests were completed through three parts. The first part was conducted on three newly developed BFRP bars and tendons to investigate their physical and mechanical properties. Durability and long-term performance were assessed by conditioning the BFRP bars in an alkaline solution simulating the moist concrete environment to determine their suitability as internal reinforcement for concrete elements. Thereafter, the properties were assessed and compared with the unconditioned (reference) values. The second part of this study was conducted on seven full-scale edge-restrained concrete bridge-deck slabs simulating actual slab-on-girder bridge-deck that is commonly used in North America to evaluate the performance of concrete bridge-deck slabs reinforced with BFRP and steel bars. The deck slabs measured 3000 mm long × 2500 mm wide × 200 mm deep. The slabs were tested up to failure under single concentrated load acting on the center of each slab simulating the footprint of sustained truck wheel load. The punching shear capacities were predicted using the available provisions, and compared with the experimental results. The third part of this study included testing of fourteen concrete beams of 3100 mm long × 200 mm wide × 300 mm deep to investigate the flexural behavior and serviceability performance of sand-coated and ribbed BFRP bars in concrete beams. The beams were tested under four-point bending over a clear span of 2700 mm until failure. The results are introduced and discussed in terms of cracking behavior, deflection, flexure capacity, and failure modes. In addition, the bond-dependent coefficient (kb) of the BFRP bars was determined and compared with the recommendations of the current FRP design codes and guides. The findings of this study concluded the feasibility of producing BFRP bars meet the requirements of the current FRP standards. Also, the test results revealed that the BFRP bars had good mechanical behavior and could be placed in the same category as grade II and grade III GFRP bars. Moreover, the behavior of the concrete bridge-deck slabs and beams reinforced with BFRP bars was quite similar to the counterparts reinforced with glass- and carbon-FRP bars and the available FRP provisions are applicable for BFRP bars. The beam test results yielded an average bond-dependent coefficient (kb) of 0.76±0.03 and 0.83±0.03 for the sand-coated and ribbed BFRP bars, respectively.
CORBANI, SILVIA. "CRACK GROWTH WITH PARTIAL BENDING-INDUCED CRACK CLOSURE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23847@1.
Full textCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Neste trabalho são investigadas experimentalmente e numericamente as mudanças de geometria em trincas inicialmente passantes submetidas a carregamento remoto de flexão pura induzindo fechamento parcial das faces da trinca. Esse crescimento de trinca pode ocorrer numa variedade de estruturas com defeitos pré-existentes, tais como fuselagens de aviões, cascos de navios, vasos de pressões e pontes metálicas. O carregamento de flexão pura ocasiona regiões de tração e compressão na frente da trinca. É inquestionável que parte das faces da trinca sob compressão fecha independentemente de qualquer mecanismo de fechamento; e outra parte das faces da trinca, por outro lado, sob tração cresce mudando gradualmente de geometria. Após realizar ensaios em corpos-de-prova de aço ASTM A-36, foi observado que tais carregamentos geram uma quina na frente da trinca, que é a transição de uma geometria parcialmente passante e um trecho remanescente da geometria inicial. Para entender a distribuição do fator de intensidade de tensão em tais frentes de trinca, suas geometrias foram reproduzidas em um modelador tridimensional de mecânica da fratura linear elástica, o FRANC3D, acoplado a um programa de análise de elementos finitos (ABAQUS). Com este sistema acoplado, foram executadas análises considerando efeitos não lineares causados pelo contato das faces da trinca sob compressão. Verificou-se a necessidade de propor metodologias para tratamento dos resultados numéricos na quina, obtendo-se predições eficientes das mudanças na geometria da trinca. Contudo, a estimativa de vida, quando se compara taxas de crescimento da trinca obtidas em um corpo-de-prova sob tração cíclica e as taxas em um corpo-de-prova sob flexão com fechamento parcial da trinca, foi melhor reproduzida usando um fator de correção de fechamento da trinca. Adicionalmente, uma série de expressões empíricas normalizadas para geometrias da trinca e fatores de intensidade de tensão são propostas.
This work investigates experimentally and numerically how the front of initially through edge cracks in plate changes after they pass to be remotely fatigue loaded under pure bending to induce partial closure of the crack faces. This type of crack growth problem can occur in a variety of structures with preexisting defects, such as aircraft fuselages, ship hulls, pressure vessels components, and steel bridges. The bending loads induce tension and compression regions along the crack front, with the part of the crack faces that work under compression undoubtedly closed by the load, independently of any other closure mechanism. The part of the crack faces that work under tension; on the other hand, crack grows by fatigue gradually changing its shape. After performing tests on ASTM A36 steel specimens, it was observed that the bending load induces a kink on the crack front, in the transition between the part through crack created on the tension side and initial crack geometry. To understand the distribution of the stress intensity factor along such crack fronts, the measured crack shapes were reproduced in a three-dimensional fracture mechanics modeler (FRANC3D) coupled to a finite element analysis program (ABAQUS). With this coupled system, linear elastic stress analysis simulations were performed considering the nonlinear effects caused by the crack face contact in the compressed region. In particular, methods had to be proposed to treat numerical noise around the kink. The proposed methodology efficiently predicts the observed crack front shape changes; although the observed fatigue lives were better reproduced using a crackclosure correction factor when compared to crack growth data obtained from standard compact tension specimens. In addition, a series of normalized empiric expressions for both crack front shapes and stress intensity factors are proposed.
Eckfeldt, Lars. "Möglichkeiten und Grenzen der Berechnung von Rissbreiten in veränderlichen Verbundsituationen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1138179912681-09751.
Full textThe doctoral thesis reflects the recent discussion on the finding of suitable verification models for crack width control. It tries to assemble criteria for the comparison in order to draw conclusions from the outcome. In the very beginning stands a widespread analysis of the bond mechanisms between the reinforcing steel and the concrete. Starting from own testing on short embedment lengths in HPC, opportunities are researched for the prediction of a sliding or splitting failure of the surrounding concrete during bar pull-out. An improved test setup is developed by the Author to verify the splitting failure mechanism that finally leads to longitudinal cover cracking. It enables to obtain better indications for the inner strain development in the later failure plane, showing the development of the bond resistance during loading. Although progress were made in the quality of analysis, it turned out that, a direct implementation of obtained bond laws is less successful to take care of the apparent problem of long embedment lengths. The description of that problem is essential within the crack width verification. Differently, a method is suggested to simulate a probable longitudinal splitting plane and its potential to resist an applied longitudinal load. In that method, the possible reaction of interlinked concrete tension rings around a steel bar is thought to form a growing global resistance with every added resistance ring in a sequential chain that are decreasingly loaded if the distance to the load application increases. The segmentation follows an approximation of the possibly development of local bond cracks acc. to Goto. In this, the application of the tension ring theory from Tepfers were successfully overtaken to the problem of long embedment lengths. It enables for simulations close to the original theory of tensile rings formed by concrete around the reinforcing steel. Comparing the results with MC 90, the simulation of long embedment lengths were performed using imaginary cylindrical test-specimen, enabling the verification of single and stabilized cracking. Simplified methods were developed in order to implement time-dependent influences like restraint from creep and shrinkage.An extensive evaluation of the normative methods (MC 90/ DIN 1045-1 and EN 1992-1-1) for verifications of a characteristic crack width stands at the end of the studies. A key position within the models is held by the realistic prognosis of the accountable crack distance. Using a newly compiled dataset and already existing data for comparison, the performances of current models were verified for predicting crack widths or distances. Complicated fields of its application could be marked and isolated. It was concluded that, the approaches for the determination of the effective reinforcement ratio and the bond stress should be improved. The developed alternative for calculation is assembled with an added safety feature and a variable minimum for the crack distance. It can lead to a more reliable prognosis for crack distances and the depending crack widths in order to design a more efficient reinforcement detailing. The requirements on the performance of a determined characteristic crack width wk are extended by the application of a criteria of effectiveness for the calculated crack distance srk. The reliability of the MC 90 -approach and the DIN-approach for minimum reinforcement has also been checked. Extensive compilations of data, examples and parameter studies are added to the appendix in order to backup the theoretical results and to invite others to compare. Two calculation flow charts and helptools are integrated to ensure the quality of crack width calculations also in cases where smaller crack widths must be verified, using informative and normative methods in MC 90/ DIN 1045-1
Potirniche, Gabriel Petru. "FINITE ELEMENT MODELING OF CRACK TIP PLASTIC ANISOTROPY WITH APPLICATION TO SMALL FATIGUE CRACKS AND TEXTURED ALUMINUM ALLOYS." MSSTATE, 2003. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06242003-220551/.
Full textTeklemariam, Daniel Mekonnen, and Bennie Hamunzala. "Design of Thick Concrete Beams : Using Non-Linear FEM." Thesis, KTH, Bro- och stålbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189141.
Full textDe experimentella studier som utförts på tjocka betongbalkar som utsätts för statisk last har visat att skjuvning spelar en viktig roll i brottmekanismen. Syftet med detta examensarbete är att rekommendera lämpliga dimensioneringsmetoder för tjock betongbalkar utsatt for statisk koncentrerad last enligt Eurokod 2 med hjälp av ickelinjära finita element metod. Abaqus/Explicit användes genom att utnyttja konstitutiva materialmodeller för att fånga materialens icke-linjäritet och minskad styvhet. Tre dilatationsvinklar (30°, 38° och 45°) och två brottenergi från FIB 1990 (76 N/m) och FIB 2010 (142 N/m) tillämpas för att kontrollera deras inverkan på FE-modellerna. Dilatationsvinkel med 38° och FIB 2010 med högre brottenergi valdes i de icke-linjära finita elementanalyserna. Kontroll av FE-modellerna är baserad på ”American Concret Institutes” experimentella resultat på de tjocka betongbalkarna. Handberäkningar av tjocka betongbalkar har utförts i brott- och bruksgränstillstånd med tre dimensioneringsmetoder i Eurokod 2 nämligen balk metoden, fackverksmetoden och linjära-FE skalelementmetoden. Jämförelse har gjorts för de olika dimensioneringsmetoderna, genom att använda de armeringsdetaljer av handberäkningar i de verifierade och kalibrerade icke linjära FE-modellerna i Abaqus/Explicit. Resultaten i fråga är last för 0.3 mm handberäknad sprikvidd, FE-last för 0.3 mm sprikvidd, armeringsmängd och FE-brottlast. Jämförelse av resultaten mellan de tre dimensioneringsmetoder (balkmetod, fackverksmetod och skalelementmetod) visar att fackverksmetod är bättre design metod, eftersom det är relativt ekonomiskt med avseende på armeringsmängd, har högre lastkapacitet och last på 0.3 mm sprickvidd.
Kapanadze, David, and Bert-Wolfgang Schulze. "Pseudo-differential crack theory." Universität Potsdam, 2000. http://opus.kobv.de/ubp/volltexte/2008/2575/.
Full textSjoberg, Brian David. "Crack widths in reinforced concrete." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ38642.pdf.
Full textLekesiz, Huseyin. "Stress Intensity Factors and Effective Spring Stiffness for Interfaces with Two and Three Dimensional Cracks at the Interface between Two Dissimilar Materials." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1293574318.
Full textEckfeldt, Lars. "Möglichkeiten und Grenzen der Berechnung von Rissbreiten in veränderlichen Verbundsituationen." Doctoral thesis, Technische Universität Dresden, 2004. https://tud.qucosa.de/id/qucosa%3A24631.
Full textThe doctoral thesis reflects the recent discussion on the finding of suitable verification models for crack width control. It tries to assemble criteria for the comparison in order to draw conclusions from the outcome. In the very beginning stands a widespread analysis of the bond mechanisms between the reinforcing steel and the concrete. Starting from own testing on short embedment lengths in HPC, opportunities are researched for the prediction of a sliding or splitting failure of the surrounding concrete during bar pull-out. An improved test setup is developed by the Author to verify the splitting failure mechanism that finally leads to longitudinal cover cracking. It enables to obtain better indications for the inner strain development in the later failure plane, showing the development of the bond resistance during loading. Although progress were made in the quality of analysis, it turned out that, a direct implementation of obtained bond laws is less successful to take care of the apparent problem of long embedment lengths. The description of that problem is essential within the crack width verification. Differently, a method is suggested to simulate a probable longitudinal splitting plane and its potential to resist an applied longitudinal load. In that method, the possible reaction of interlinked concrete tension rings around a steel bar is thought to form a growing global resistance with every added resistance ring in a sequential chain that are decreasingly loaded if the distance to the load application increases. The segmentation follows an approximation of the possibly development of local bond cracks acc. to Goto. In this, the application of the tension ring theory from Tepfers were successfully overtaken to the problem of long embedment lengths. It enables for simulations close to the original theory of tensile rings formed by concrete around the reinforcing steel. Comparing the results with MC 90, the simulation of long embedment lengths were performed using imaginary cylindrical test-specimen, enabling the verification of single and stabilized cracking. Simplified methods were developed in order to implement time-dependent influences like restraint from creep and shrinkage.An extensive evaluation of the normative methods (MC 90/ DIN 1045-1 and EN 1992-1-1) for verifications of a characteristic crack width stands at the end of the studies. A key position within the models is held by the realistic prognosis of the accountable crack distance. Using a newly compiled dataset and already existing data for comparison, the performances of current models were verified for predicting crack widths or distances. Complicated fields of its application could be marked and isolated. It was concluded that, the approaches for the determination of the effective reinforcement ratio and the bond stress should be improved. The developed alternative for calculation is assembled with an added safety feature and a variable minimum for the crack distance. It can lead to a more reliable prognosis for crack distances and the depending crack widths in order to design a more efficient reinforcement detailing. The requirements on the performance of a determined characteristic crack width wk are extended by the application of a criteria of effectiveness for the calculated crack distance srk. The reliability of the MC 90 -approach and the DIN-approach for minimum reinforcement has also been checked. Extensive compilations of data, examples and parameter studies are added to the appendix in order to backup the theoretical results and to invite others to compare. Two calculation flow charts and helptools are integrated to ensure the quality of crack width calculations also in cases where smaller crack widths must be verified, using informative and normative methods in MC 90/ DIN 1045-1.
Dahl, Robert, and Emelie Göransson. "Jämförelse av beräkningsprogram och handberäkningar för att minimera armeringsmängd i grundplatta." Thesis, Uppsala universitet, Institutionen för samhällsbyggnad och industriell teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413978.
Full textDetta examensarbete handlar om att analysera en grundplatta genom att hitta en balans mellan tid, arbetsmiljö och minimering av koldioxidutsläpp. Sweco presenterade utmaningen att beräkna den optimala ameringsmängden med hänsyn till dessa aspekter och erbjöd resurser för analysen. Plattan som analyseras är en del av en industribyggnad. Den är uppdelad i två delplattor som har olika förutsättningar för tjocklek och laststorlek. Ett sätt att minimera tid kan vara att använda sig av FEM-beräkningsprogram. I vissa fall är FEM-beräkningsprogram mer säkra än handberäkningar då handberäkningar approximerar. Av dessa anledningar jämförs handberäkningar med FEM-Design. Grundplattor är intressanta konstruktionsdelar som utsätts för krymp- samt krypdeformationer utöver externa laster. Dessa deformationer kan orsaka sprickbildning i armerade grundplattor. Momentfördelningen för grundplattor skiljer sig avsevärt jämfört med betongplattor som vilar på stöd. Resultaten visar att FEM-Design tar mindre tid, men utifrån avgränsningar kräver större armeringsmängd för större dimensioner av grundplattor. Större mängdarmering innebär negativ miljöpåverkan, eftersom större koldioxidutsläpp uppstår vid tillverkning. Båda metoderna klarar arbetsmiljökravet på maximalt 150 mm i centrumavstånd.
Čožík, Martin. "Monolitická nádrž ČOV." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240045.
Full textBian, Lichun, and 卞立春. "Fatigue crack growth analysis of metallic plates with an inclinedsemi-elliptical crack." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31242844.
Full textBjörnberg, Maja, and Victor Johansson. "Numeriska simuleringar av betongkonstruktioner med minimiarmering för sprickbreddsbegränsning." Thesis, KTH, Betongbyggnad, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131428.
Full textAfter the introduction of the Eurocodes, the minimum amount of reinforcement for crack control in concrete structures has increased. This is due to differences in themethods for calculating the minimum amount of reinforcement used in the Eurocodes and in BKR, a standard which was used in Sweden before the Eurocodes. Minimum reinforcement for crack control is used in concrete structures to redistribute the tensile stresses caused by restraint during the shrinkage. This thesis examines if the amount of minimum reinforcement can be reduced without compromising the main functions of the reinforcement. In this thesis a number of methods for calculating the minimum reinforcement has been compared to see how large the differences in the amount of reinforcement are, why they occur and what are the advantages and disadvantages of the different methods. The different methods revised in this thesis are the method in Eurocode 2, the changes made in the German National Annex to the Eurocode 2 method and a method proposed by Hallgren in a preliminary work. The results are based on simulations performed in the FEM-application Atena where different scenarios were examined. In the investigated scenarios, the strength classes of the concrete, the cross-sectional dimensions, the size of the reinforcement bars, the size of the concrete cover and the bond strength has been varied. The amount of reinforcement in each case has been varied to correspond to the required minimum amount according to the different methods for calculating minimum reinforcement. In all investigated cases, the cross section is assumed to be exposed to pure tensile load, which is the case for shrinkage. The results of the simulations showed that a larger amount of reinforcement reduces the width of the cracks, that a larger amount of small cracks are formed, and that new cracks are formed earlier at a lower shrinkage value. The differences are however in most cases small compared to when a lower amount of reinforcement is used. In other words, a lower amount of reinforcement could be used without compromising the main functions of the minimum reinforcement. The results from the simulations have also been used to obtain an alternative method for calculating the minimum reinforcement that gives a lower amount of reinforcement without compromising the main functions. The proposed change in Eurocode is a modification in the value of the coefficient k. By changing the value of the coefficient k, the amount of required minimum reinforcement is decreased significantly, especially for large crosssection heights. More numerical simulations were performed to ensure that the reinforcement amount according to the proposed change works for all scenarios considered in this thesis. The results showed that the reinforcement were capable of redistributing the tensile stresses caused by restraint. Only a small increase in the crack widths could be observed. An investigation was conducted to find an explanation to why cracks occur during the first weeks after casting of the concrete. The results show that the problem with cracks occurring during this period is neither due to the autogenous shrinkage nor the drying shrinkage. Only a small share of those types of shrinkage are achieved during the first weeks, and at the same time the concrete strength growth is relatively fast. Instead, the problems with cracks seem to be caused by other factors, such as a large heat development in the concrete during the first day, uneven drying shrinkage or an uneven temperature distribution over the cross section in combination with restraint. Cracks can develop during the first days after casting of the concrete due to the shrinkage that occur when the concrete cools off after the large heat development the first day. These cracks remain when the drying shrinkage continues. A comparison was also made between hand calculations of the characteristic crack widths according to “Betongföreningens handbok till Eurokod 2” and the crack widths read out of the results from the numerical simulations. The results showed that the method generally works well, but some minor adjustments could be made to adapt the method to smaller values of concrete shrinkage.
Schulze, Bert-Wolfgang. "Crack theory with singularties at the boundary." Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2008/2660/.
Full textLindblom, David. "Crack growth based FEM with embedded discontinuities." Thesis, KTH, Hållfasthetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298347.
Full textUnder dem senaste åren har det skett en massiv utveckling inom beräkningsmekaniken när det kommer till att modellera brottmekaniska fenomen. Det finns nu ett flertal väletablerade numeriska metoder som är implementerade i kommersiella program såsom: Phase Field Modelling, Enhanced Assumed Strain (EAS), Smeared Crack Methods, Extended Finite Element Method (XFEM) and Partition of Unity Finite Element Method (PUFEM). Detta arbete har fokuserat på (PUFEM) och det har varit av intresse att se om denna metod kan kombineras tillsammans med plastisk deformation. Anledningen till att detta har varit av intresse är på grund av att det finns ett flertal komplexa struktur - och materialfenomen såsom försprödning av stål och kompositer som uppvisar en variation i sin duktilitet. Detta medför att mer avancerade metoder behöver tillämpas för att fånga responsen av dessa strukturer och material. Analysen som har genomförts var uppdelad i tre delar. Först analyserades ett problem med linjär tetrahedriska element som ett riktmärke, detta har implementerats i tidigare applikationer. Därefter analyserades samma problem fast med tethraderiska element med kvadratisk interpolation. Slutligen så integrerades plasticitet med PUFEM, där samma geometrier analyserades som riktmärke. Den analysen som har genomfört visar att det går att kombinera plastiska deformation tillsammans med PUFEM och att denna metod har potentialen att användas i framtida applikationer.
馮錦生 and Kam-sang Fung. "Fatigue crack propagation with strain energy density approach." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31209713.
Full textFung, Kam-sang. "Fatigue crack propagation with strain energy density approach /." [Hong Kong] : University of Hong Kong, 1989. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12827204.
Full textRuber, Lukáš. "Nosná železobetonová konstrukce bytového domu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372062.
Full textMaršalová, Jiřina. "Dvorní vícepodlažní přístavba výukových prostor." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240376.
Full textTurek, Jan. "Železobetonová základová vana administrativní budovy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409781.
Full textDe, Noronha Motta Carlos Henrique. "A fatigue crack growth model with mean stress effects." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21163.pdf.
Full textSmith, Christopher Anton. "Simulation of crack propogation in shells with geophysical applications." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315649.
Full textRomeo, Alberto. "On a crack tip interacting with a bimaterial interface." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1062699982.
Full textZhongyi, Cai. "Vibration diagnosis of elastic shafts with a transverse crack." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/405.
Full textHmidan, Amer. "Crack-Dependent Response of Structural Steel Members Repaired with CFRP." Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27562.
Full textKunaporn, Chalitphan. "Probabilistic Analysis of a Thin-walled Beam with a Crack." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77072.
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Matušík, Petr. "Monolitická nádrž ČOV." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225935.
Full textMürk, Annely. "Optimization of inelastic plates with cracks /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/1226/5/murkannely.pdf.
Full textSchulze, Bert-Wolfgang, Alexander Shlapunov, and Nikolai Tarkhanov. "Green integrals on manifolds with cracks." Universität Potsdam, 2000. http://opus.kobv.de/ubp/volltexte/2008/2577/.
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