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Zheng, Hang. "Tempcore reinforcing steel : microstructure and mechanical properties." Phd thesis, Department of Civil Engineering, 1998. http://hdl.handle.net/2123/8671.
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Wang, X., S. Dong, Ashraf F. Ashour, S. Ding, and B. Han. "Bond behaviors between nano-engineered concrete and steel bars." Elsevier, 2021. http://hdl.handle.net/10454/18564.
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YesThis paper investigated the bond characteristics between eight types of nanofillers modified reactive powder concrete (RPC) and plain steel bars, aiming to explore the modifying mechanisms and establish a bond-slip relationship model for nanofillers modified RPC and steel bar interface. The experimental results indicated that the incorporation of nanofillers can increase the bond strength and reduce the slip between RPC and plain steel bars. It was shown that a 2.15 MPa/20.5% of absolute/relative increase in cracking bond strength, a 1.25 MPa/10.3% of absolute/relative increase in ultimate bond strength, a 2.35 MPa/22.4% of absolute/relative increase in residual bond strength, a 0.592 mm/56.5% of absolute/relative reduction in ultimate bond slip, and a 1.779 mm/52.1% of absolute/relative reduction in residual bond slip were the best achieved due to the addition of various nanofillers. The enhancement of nanofillers on RPC-steel bar interface has been mainly attributed to RPC microstructure improvement, optimization of intrinsic compositions, and elimination of defects in the interface, especially the underside near steel bar, due to the nano-core effect of nanofillers enriched in the interface. In addition, the bond-slip relationship of nanofillers modified RPC-steel bar interface can be accurately described by the proposed model considering an initial branch.
The authors would like to thank the funding offered by the National Science Foundation of China (51978127 and 51908103), and the Fundamental Research Funds for the Central Universities (DUT21RC(3)039).
The full-text of this article will be released for public view at the end of the publisher embargo on 22 Jul 2022.
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García, Taengua Emilio José. "Bond of Reinforcing Bars to Steel Fiber Reinforced Concrete (SFRC)." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/32952.
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The use of steel fiber reinforced concrete (SFRC hereafter) is becoming more and more
common. Building codes and recommendations are gradually including the positive effect of
fibers on mechanical properties of concrete. How to take advantage of the higher ductility
and energy absorption capacity of SFRC to reduce anchorage lengths when using fibers is
not a straightforward issue.
Fibers improve bond performance because they confine reinforcement (playing a similar
role to that of transverse reinforcement). Their impact on bond performance of concrete is
really important in terms of toughness/ductility.
The study of previous literature has revealed important points of ongoing discussion
regarding different issues, especially the following: a) whether the effect of fibers on bond
strength is negligible or not, b) whether the effect of fibers on bond strength is dependent
on any other factors such as concrete compressive strength or concrete cover, c)
quantifying the effect of fibers on the ductility of bond failure (bond toughness). These
issues have defined the objectives of this thesis.
A modified version of the Pull Out Test (POT hereafter) has been selected as the most
appropriate test for the purposes of this research. The effect of a number of factors on bond
stress¿slip curves has been analyzed. The factors considered are: concrete compressive
strength (between 30 MPa and 50 MPa), rebar diameter (between 8 mm and 20 mm),
concrete cover (between 30 mm and 5 times rebar diameter), fiber content (up to 70
kg/m3), and fiber slenderness and length.
The experimental program has been designed relying on the principles of statistical Design
Of Experiments. This has allowed to select a reduced number of combinations to be tested
without any bias or loss of accuracy. A total of 81 POT specimens have been produced and
tested.
An accurate model for predicting the mode of bond failure has been developed. It relates
splitting probability to the factors considered. It has been proved that increasing fiber
content restrains the risk of splitting failure. The favorable effect of fibers when preventing
splitting failures has been revealed to be more important for higher concrete compressive
strength values. Higher compressive strength values require higher concrete
cover/diameter ratios for splitting failure to be prevented. Fiber slenderness and fiber
length modify the effect of fiber content on splitting probability and therefore on minimum
cover/diameter ratios required to prevent splitting failures. Two charts have been
developed for estimating the minimum cover/ diameter ratio required to prevent splitting.
Predictive equations have been obtained for estimating bond strength and areas under the
bond stress¿slip curve as a function of the factors considered. Increasing fiber content has a
slightly positive impact on bond strength, which is mainly determined by concrete
compressive strength. On the contrary, fibers have a very important effect on the ductility of
bond failure, just as well as concrete cover, as long as no splitting occurs.
Multivariate analysis has proved that bond stress corresponding to the onset of slippage
behaves independently from the rest of the bond stress¿slip curve. The effect of fibers and
concrete compressive strength on bond stress values corresponding to the onset of slips is
mainly attributable to their influence on the material mechanical properties. On the
contrary, the effect of fibers and concrete cover on the rest of the bond stress¿slip curve is
due to their structural role.García Taengua, EJ. (2013). Bond of Reinforcing Bars to Steel Fiber Reinforced Concrete (SFRC) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/32952
TESIS
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Mbewe, Peter Binali Kamowa. "Development of analytical flexural models for steel fibre-reinforced concrete beams with and without steel bars." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18088.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: There is an increasing demand for the development and use of innovative materials with reduced cost of construction while offering improved structural properties. Steel fibre reinforced concrete (SFRC) can be used as a structural material to substitute the conventional reinforcing bars partially or fully. However, there is little or no codified approach on the design procedures for SFRC members in the latest guidelines outlined in the draft 2010 Model code. It is against this background that analytical methods are derived in this study for the determination of the flexural capacity of strain-softening, deflection-hardening SFRC with and without steel reinforcing bars. Models used for the determination of the flexural capacity of SFRC rectangular sections are based on equivalent stress blocks for both compression and tensile stresses. These are derived from an elastic-perfect plastic model for compression and either an elastic-constant post-peak response or Rilem’s multi-linear model for tension, in which strain compatibility and force equilibrium theories are used. By employing the equivalent stress blocks for both tensile and compressive stress states, parameters are defined by converting the actual stress-strain distribution to an equivalent stress block, depending on the ratio of yield (or cracking) strain and post-yield (post-cracking) strains. Due to the simplicity of a drop-down tensile model and a bilinear compression model, these material models are used for the subsequent derivation of the flexural models for both SFRC with and without steel reinforcing bars. An experimental program is designed and executed for model verification. This includes material characterisation experiments for the determination of material model input parameters, and main beam flexural experiments for the determination of the beam bending capacity. An indirect tensile test is used for the characterisation of the tensile behaviour while a four-point bending test is used for beam bending behaviour. Both flexural models for SFRC with and without reinforcing bars have been verified to fairly predict the flexural capacity of the beams. However, the flexural model for SFRC with steel bars offers some challenges as to whether the synergetic effect of using both steel bars and steel fibres should be incorporated at the low fibre volumes as used in the verification exercise. Furthermore, the use of indirect methods to characterise tensile behaviour added some uncertainties in the material model parameters and hence may have affected the predictability of the model. More research on the verification of the models is required to enable the use of a wider concrete strength spectrum for the verification and possible modification of the models. Studies on the model uncertainty may also help determine the reliable safety factor for the use of the model in predicting design strength of beam sections at a prescribed reliability index.
AFRIKAANSE OPSOMMING: Daar is ‘n groeiende aanvraag na die ontwikkeling en gebruik van innoverende materiale met verminderde konstruksiekoste maar verbeterde strukturele eienskappe. Staalvesel-gewapende beton (SVGB) kan gebruik word as strukturele materiaal om die konvensionele wapeningstawe gedeeltelik of ten volle te vervang. Daar is egter min of geen gekodifiseerde benaderings tot die ontwerpprosedures vir SVGB-dele in die nuutste riglyne uitgestippel in die konsepweergawe van die 2010 Modelkode nie. Dit is teen hierdie agtergrond dat in hierdie studie analitiese metodes afgelei is vir die bepaling van die buigkapasiteit van spanning-versagtende, defleksie-verhardende SVGB met en sonder staalbewapeningstawe. Modelle wat gebruik is vir die bepaling van die buigkapasiteit van SVGB reghoekige snitte is gebaseer op ekwivalente spanningsblokke vir beide druk- en trekspannings. Hierdie is afgelei van ‘n elasties-perfekte plastiese model vir druk en óf ‘n elasties-konstante post-piek respons óf Rilem se multi-lineêre model vir spanning, waarin teorieë vir drukkapasiteit en krag-ewewig gebruik is. Deur die ekwivalente spanningsblokke vir beide trek- en drukspanningstoestande te implementeer, is parameters bepaal deur die werklike verspreiding van spanningsdruk om te wissel na ‘n ekwivalente spanningsblok, afhangend van die verhouding van swig- (of kraak-)spanning en post-swig (post-kraak) spannings. Te wyte aan die eenvoud van ‘n aftrek trekmodel en ‘n bilineêre kompressiemodel, is hierdie materiaalmodelle gebruik vir die daaropvolgende afleiding van die buigingsmodelle vir beide SVGB met en sonder staalbewapeningstawe. ‘n Eksperimentele program vir modelkontrolering is ontwerp en uitgevoer. Dit sluit eksperimente in vir materiaalbeskrywing, om invoerparameters van materiaalmodelle te bepaal, asook eksperimente vir hoofbalkbuigings, om balkbuigingskapasiteit te bepaal. ‘n Indirekte trektoets is gebruik vir die beskrywing van die trekgedrag, terwyl ‘n vierpuntbuigingstoets gebruik is vir balkbuiggedrag. Dit is bewys dat beide buigingsmodelle vir SVGB met en sonder staalbewapeningstawe die buigingskapasiteit van die balke redelik akkuraat kan voorspel. Nietemin, bied die buigingsmodel vir SVGB met staalbewapeningstawe sekere uitdagings: die vraag ontstaan rondom die insluiting van die sinergetiese effek van die gebruik van beide staalstawe en staalvesels met die lae veselvolumes soos gebruik in die kontroleringsoefening. Verder het die gebruik van indirekte metodes om die buigingsgedrag te bepaal, onsekerhede gevoeg by die materiaalmodelparameters en dit mag dus as sulks die voorspelbaarheid van die model beïnvloed. Meer navorsing moet uitgevoer word oor die kontrolering van die modelle sodat ‘n wyer spektrum van betonsterkte gebruik kan word vir die verifikasie en moontlike aanpassing van die modelle. Navorsing oor die wisselvalligheid van die modelle mag ook help om die betroubare veiligheidsfaktor te bepaal vir die model se gebruik in die berekening van ontwerpkrag van balkdele teen ‘n voorgeskrewe betroubaarheidsindeks.
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Nachiappan, Vijayakumar. "Corrosion of high-chromium and conventional steels embedded in concrete." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3195.
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Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains ix, 56 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-52).
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Wuertz, Augustine F. "Strengthening rectangular beams with NSM steel bars and externally bonded GFRP." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/15624.
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Master of ScienceDepartment of Civil Engineering
Hayder Rasheed
The technology of FRP strengthening has matured to a great extent. However, there is always room for performance improvements. In this study, external bonding of GFRP and near surface mounting (NSM) of regular steel bars is combined to improve the behavior, delay the failure, and enhance the economy of the strengthening. E-Glass FRP is selected due to its inexpensive cost and non-conductive properties to shield the NSM steel bars from corrosion. On the other hand, the use of NSM bars gives redundancy against vandalism and environmental deterioration of the GFRP. An experimental program is conducted in which four rectangular cross-section beams are designed, built, and tested in four-point bending. The first beam is tested as a control beam failing at about 12.24 kips. The second beam is strengthened using two #5 steel NSM bars and 1 layer of GFRP, both extending to the support. This beam failed at 31.6 kips. The third beam is strengthened with the same system used for the second beam. However, the NSM steel bars were cut short covering 26% of the shear-span only while the GFRP was extended to the support. This beam failed at 30.7 kips due to reaching the full flexural capacity of the section at the NSM bars cut off point and the shear stress concentration at the steel bar cut off point. The fourth beam was strengthened with same system as the third beam but then submerged in a highly concentrated saline solution for six months and then tested. This beam failed at a maximum applied load of 29.8 kips, which shows that the GFRP sheet provided good corrosion resistance from the saline solution.
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Araba, Almahdi M. A. A. "Behaviour of continuous concrete beams reinforced with hybrid GFRP/steel bars." Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/16920.
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Song, Mengli. "Effectiveness of steel bars in reinforced masonry walls under concentric compression." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/132724/1/Mengli_Song_Thesis.pdf.
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This PhD thesis aims at developing an economical and safe reinforced masonry structural walling system suitable for usage in the heavily loaded lower stories of the multi-storeyed residential or commercial buildings. Through a systematic experimental investigation of more than 50 walls and a finite element modelling incorporating material and geometric nonlinearities, design formulae have been developed and incorporated in the Australian Masonry Design Standard AS3700 (2018). With this significant contribution, the outcomes of this PhD thesis can address some of the recent problems of huge societal costs involving cracked walls in several residential apartments in Australia.
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Abosrra, L. R. "Corrosion of steel reinforcement in concrete : corrosion of mild steel bars in concrete and its effect on steel-concrete bond strength." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5417.
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This thesis reports on the research outcome of corrosion mechanism and corrosion rate of mild steel in different environments (saline, alkaline solutions and concrete media) using potentiodynamic polarization technique. The study also included the effect of corrosion on bond strength between reinforcing steel and concrete using pull-out test. Corrosion of mild steel and 316L stainless steel with different surface conditions in 1, 3 and 5% saline (NaCl + Distilled water) was investigated. Specimens ground with 200 and 600 grit silicon carbide grinding paper as well as 1μm surface finish (polished with 1μm diamond paste) were tested. In case of mild steel specimens, reduction in surface roughness caused increase in corrosion rate, while in 316L stainless steel corrosion rate decreased as the surface roughness improved. Metallographic examination of corroded specimens confirmed breakdown of passive region due to pitting corrosion. Corrosion of mild steel was also investigated in alkaline solution (saturated calcium hydroxide, pH =12.5) contaminated with 1, 3 and 5% saline. A series of corrosion experiments were also conducted to examine the efficiency of various concentrations of calcium nitrite (CN) on corrosion behaviour of both as-received and polished mild steel in alkaline solution containing 3% saline after 1 hour and 28 days of exposure. Corrosion rate was higher for the as-received than polished mild steel surface under the same testing conditions in NaCl alkaline solution with and without nitrites due to the effect of surface roughness. Morphology investigation of mild steel specimens in alkaline solution ii containing chlorides and nitrites showed localized pits even at nitrite concentration equal to chloride concentration. Corrosion of steel bars embedded in concrete having compressive strengths of 20, 30 and 46MPa was also investigated. The effect of 2 and 4% CN by weight of cement on corrosion behaviour of steel bar in low and high concrete strengths specimens were also studied. All reinforced concrete specimens were immersed in 3% saline solution for three different periods of 1, 7 and 15 days. In order to accelerate the chemical reactions, an external current of 0.4A was applied. Corrosion rate was measured by retrieving electrochemical information from polarization tests. Pull-out tests of reinforced concrete specimens were then conducted to assess the corroded steel/concrete bond characteristics. Experimental results showed that corrosion rate of steel bars and bond strength were dependent on concrete strength, amount of CN and acceleration corrosion period. As concrete strength increased from 20 to 46MPa, corrosion rate of embedded steel decreased. First day of corrosion acceleration showed a slight increase in steel/concrete bond strength, whereas severe corrosion due to 7 and 15 days corrosion acceleration significantly reduced steel/concrete bond strength. Addition of only 2% CN did not give corrosion protection for steel reinforcement in concrete with 20MPa strength at long time of exposure. However, the combination of good quality concrete and addition of CN appear to be a desirable approach to reduce the effect of chloride induced corrosion of steel reinforcement. At less time of exposure, specimens without CN showed higher bond strength in both concrete mixes than those with CN. After 7 days of corrosion acceleration, the higher concentration of CN gave higher bond strength in both concrete mixes. The same trend was observed at 15 days of corrosion acceleration except for the specimen with 20MPa compressive strength and 2% CN which recorded the highest deterioration in bond strength.
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Hayford, Frank. "CLEANLINESS ASSESSMENT OF STEEL BARS PRODUCED FROM A HIGH FREQUENCY INDUCTION FURNACE." Thesis, KTH, Tillämpad processmetallurgi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-125018.
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To stay competitive in the steel industry, steelmakers are utilizing different production methods to reduce production cost without compromising on the quality of their products. In steelmaking, the production process plays a significant role on the steel cleanliness. Recent increasing demands on the cleanliness level therefore require optimization of production process to meet the requirement. Often, the types and distribution of non-metallic inclusions in steel determines the steel cleanliness. In order to optimize the production process, complete assessment of the non-metallic inclusions in the steel is necessary, leading to implementation of measures to control and/or remove non-metallic inclusions in the steel. The present study was performed to investigate the cleanliness level of steel bars produced from a high frequency induction furnace (HF) route at Uddeholms AB. Experimental studies were carried out and characteristics such as number, composition, size distribution and morphology of non-metallic inclusions were investigated. Total oxygen and total nitrogen content were also measured for indirect assessment. Further, the production operations at the HF were observed and evaluated to determine their influence on the inclusion characteristics. The characteristics obtained were compared with characteristics of inclusions in steel bars produced from an electric arc furnace production (EAF) route at Uddeholms AB and a competitor producer sample. The results showed that the level of cleanliness varies from different production routes and is hence dependent on the process at each production route. The number, maximum and mean size of inclusions were found to be higher in the HF route compared to the other routes. More so, there were differences in the types of oxide inclusions observed from each process route. However, sulphide inclusions exhibit similar characteristics from the different process routes. Further, the compositions of oxide inclusions observed from the HF route were found to be closely related to the steel chemistry. More importantly, the types of inclusions formed in the HF route were found to be sensitively affected by the extent of aluminium and calcium contents in the steel. Thus, the oxide inclusion types in the HF samples could be traced to the extent of different additions and operations such as deoxidation and calcium treatment that were carried out during the steelmaking process.
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Traplsi, Abdelbaset Mahmoud. "Combined NSM steel bars and externally bonded GFRP in strengthening T beams." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/15170.
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Master of ScienceDepartment of Civil Engineering
Hayder A. Rasheed
Nowadays, using the technology of FRP strengthening has become acknowledged by engineers and has reached a full acceptance. However, researchers are always looking for improvement in performance. In this study, external bonding of GFRP and near surface mounting of regular steel bars are combined to improve the behavior, delay the failure and enhance the economy of the strengthening. E-Glass FRP is selected due to its inexpensive cost and non-conductive properties to shield the NSM steel bars from corrosion. On the other hand, the use of NSM bars gives redundancy against vandalism and environmental deterioration of GFRP. An experimental program was conducted in which four full scale T beams were designed and built. All four specimens were fabricated with Grade 70 steel reinforcement and 8000 psi concrete. Only one beam was loaded beyond first cracking then exposed to highly concentrated deicing salt water to accelerate the corrosion process. All beams were tested by monotonic loading until failure. The load rate was 1 kips/min. The first specimen is tested as a control beam failing at about 15 kips. The second specimen is strengthened using two #5 steel NSM bars and 1 layer of GFRP, both extending to the support. This beam failed at 38.4 kips by GFRP debonding. The third specimen is strengthened with the same system used for the second beam. However, the NSM steel bars were cut short covering only 30% of the shear-span while the GFRP was extended to the support. This beam failed at 25.9 kips by GFRP debonding and NSM delamination due to the lack of sufficient development of the NSM steel bars and the shear stress concentration at the steel bar cut off point. Nevertheless, the fourth beam is strengthened with the same system used for the third beam. The fourth specimen was exposed to severe attack of deicing salt by immersing it in concentrated deicing salt solution for three continuous months. In order to accelerate the corrosion process, the beam was loaded beyond its cracking load before the corrosion procedure. After the completion of the three months, the beam was tested monotonically to failure. It failed at 23.2 kips indicating that some deterioration might have taken place. The failure mode was by GFRP debonding and NSM delamination like the case of Beam 3.However, it was observed after failure that the NSM bars were very well protected by the surrounding epoxy.
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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.
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YesEccentric 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.
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El-Nemr, Amr Maher. "Serviceability of concrete members reinforced with FRP bars." Thèse, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6124.
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La détérioration des infrastructures au Canada due à la corrosion des armatures est l'un des défis majeurs de l'industrie de la construction. Les progrès récents dans la technologie des polymères ont conduit au développement d'une nouvelle génération de barres d'armature à base de fibres renforcées de polymères (PRF), (en particulier les fibres de verre). Ces barres, résistant à la corrosion, ont montré un grand potentiel d'utilisation pour mieux protéger les infrastructures en béton armé contre les effets dévastateurs de la corrosion. Avec la publication du nouveau code S807-10 "Spécifications pour les polymères renforcés de fibres" et la production de barres en PRF de très haute qualité, celles-ci représentent une alternative réaliste et rentable par rapport à l'armature en acier pour les structures en béton soumises à de sévères conditions environnementales. La conception des éléments en béton armé de barres en PRF est généralement gouvernée par l'état de service plutôt que l'état ultime. Par conséquent, il est nécessaire d'analyser les performances en flexion et le comportement en service en termes de déflexion et de largeur de fissures des éléments en PRF sous charges de service et de vérifier que ces éléments rencontrent les limites des codes. Aussi, de récents développements dans l'industrie des PRF ont conduit à l'introduction des barres en PRF avec des configurations de surface et des propriétés mécaniques différentes. Ces développements sont susceptibles d'affecter leur performance d'adhérence et, par conséquent, la largeur des fissures dans les éléments en PRF. Cependant, les codes de conception et les guidelines de calcul fournissent une valeur unique pour le coefficient d'adhérence (k[indice inférieur b]) en tenant compte des configurations de surface et en négligeant le type de barre en PRF, le diamètre de la barre, et le type de béton et de sa résistance. En outre, le code canadien S807-10 "Spécifications pour les polymères renforcés de fibres" fournit une étape en classant les barres en PRF par rapport à leur module d'élasticité (E[indices inférieurs frp]). Ces classifications ont été divisées en trois classes : Classe I (E[indices inférieurs frp]<50 GPa), Classe II (50 GPa [plus petit ou égal] E[indices inférieurs frp]< 60 GPa) et Classe III (E[indices inférieurs frp] [plus grand ou égal] 60 GPa). Ce programme de recherche vise à étudier expérimentalement le comportement en flexion des éléments en béton en service armé avec différents paramètres sous charges statiques. Le programme expérimental est basé sous plusieurs paramètres, dont les différents ratios de renforcement, différents types de barres (différentes classes comme classifiées par le CAN/CSA S807-10), le diamètre et la surface de la barre, la configuration ainsi que la résistance du béton. De plus, les recommandations actuelles de design pour les valeurs de k[indice inférieur b] et la vérification de la dépendance des valeurs de k[indice inférieur b] sur le type de barres (verre ou carbone), le diamètre des barres et le type de béton et sa résistance ont été étudiées. Le programme expérimental comprenait la fabrication et les essais sur 33 poutres à grande échelle, simplement appuyées et mesurant 4250 mm de long, 200 mm de large et 400 mm de hauteur. Vingt et sept poutres en béton ont été renforcées avec des barres en PRF à base de verre, quatre poutres en béton ont été renforcées avec des barres de PRF à base de carbone, et deux poutres ont été renforcées avec des barres en acier. Toutes les poutres ont été testées en flexion quatre points sur une portée libre de 3750 mm. Les paramètres d'essai étaient: le type de renforcement, le pourcentage d'armature, le diamètre des barres, configurations de surface et la résistance du béton. Les résultats de ces essais ont été présentés et discutés en termes de résistance du béton, de déflection, de la largeur des fissures, de déformations dans le béton et l'armature, de résistance en flexion et de mode de rupture. Dans les trois articles présentés dans cette thèse, le comportement en flexion et la performance des poutres renforcées de barres en PRFV et fabriquées avec un béton normal et un béton à haute performance ont été investigués, ainsi que les différentes classes de barres en PRFV et leurs configurations de surface. Les conclusions des investigations expérimentales et analytiques contribuent à l'évaluation des équations de prédiction de la déflection et des largeurs de fissures dans les codes de béton armé de PRF, pour prédire l'état de service des éléments en béton renforcés de PRF (déflection et largeur de fissures). En outre, à la lumière des résultats expérimentaux de cette étude, les équations de service (déflection et largeur des fissures) incorporées dans les codes et guidelines de design [ACI 440.1R-06, 2006; ISIS Manual No.3, 2007; CAN/CSA-S6.1S1, 2010; CAN/CSA-S806, 2012] ont été optimisées. En outre, les largeurs de fissures mesurées et les déformations ont été utilisées pour évaluer les valeurs courantes de k[indice inférieur b] fournies par les codes et les guidelines de calcul des PRF. En outre, les conclusions ne prennent pas en charge la valeur unique de k[indice inférieur b] pour les barres en PRF de types différents (carbone et verre) avec des configurations de surface similaires et s'est avéré être dépendant du diamètre de la barre.
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Amleh, Lamya. "Influence of corrosion of reinforcing bars on the bond between steel and concrete." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24050.
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Tension tests have been carried out for a preliminary study of the influence of the steel reinforcement corrosion on bond behaviour. The bond strength was studied through both transverse and longitudinal splitting cracks and a relative bond effectiveness of the corroded bars was determined from the crack spacing. Different stages of the corrosion were established to study their relative bond behaviour, ranging from no corrosion to complete corrosion at the steel-concrete interface. These stages have been achieved by using an accelerated corrosion method. An electrochemical method was used to accelerate corrosion within the specimens. Direct current was applied for increasing periods of time to the reinforcing bar embedded in the tension specimens, immersed in a concentrated sodium chloride solution (5% NaCl). The reinforcing bar served as anode, while a steel bar in water served as the cathode. The chloride content of the concrete plays an important role in the rate of corrosion. Chloride content was obtained for each tension specimen using the Volhard Method. Bond strength decreases rapidly with an increase in the corrosion level, especially in the case of any severe localized corrosion. It has been found that the first level of corrosion, which is 4 percent weight loss due to corrosion, resulted in a 9 percent decrease of nominal bond stress, while the sixth level of corrosion, with a 17.5 percent weight loss, resulted in a 92 percent weight loss of nominal bond stress. Bond behaviour is influenced by deterioration of the reinforcing bar ribs, and by reduced adhesion and cohesion of the reinforcing bar due to widening of the longitudinal splitting crack resulting from corrosion. (Abstract shortened by UMI.)
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Less, Thomas Matthew. "Structural Performance and Corrosion Resistance of Fiber Reinforced Polymer Wrapped Steel Reinforcing Bars." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366222349.
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Shah, Falak Dipak. "Time-dependent behavior of pretensioned stainless steel bars used for structural rehabilitation and retrofitting." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53063.
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The objective of this study is to characterize the long-term behavior of an austenitic-ferritic stainless steel-based pretensioned system for strengthening reinforced concrete bridge pier caps in shear. Stress relaxation experiments were conducted on UNS S32101 stainless steel bars subjected to various initial stresses and temperatures within the low homologous temperature (LHT) regime. Data from these experiments were used to develop a viscoplastic constitutive model to describe the long-term time- and temperature-dependent behavior of the stainless steel bars. This mechanics-based approach is integrated with an analytical method based on strut-and-tie analysis to compute the shear strength of reinforced concrete pier caps strengthened with this external pretensioned system.
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Belghiti, Moulay El Mehdi. "Influence of steel fibres on response of beams." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100222.
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The following thesis presents the results of six full scale beams tests as part of a research program conducted at McGill University on the effect of steel fibres on the shear capacity of a beam with an aid ratio greater than 2.5. The test specimens had the following dimensions: 4400 mm long, 300 mm wide and 500 mm long. The beams had 4-25M bottom reinforcing bars and 2-20M top reinforcing bars. Two series were designed with different reinforcing details: the "BA" series contained transverse reinforcement spaced at 275 mm center to center while the "BB" series had no transverse reinforcement. The specimens were cast in three batches of two specimens from each series, with each batch containing concrete with respectively 0%, 0.5% and 1% fibres content by volume. The beams were simply supported and were tested with two equal point loads located at 500 mm from the centre of the beam.This research project demonstrated a clear improvement of the shear capacity resulting from the use of steel fibres for the beams without transverse reinforcement. For the beams with transverse reinforcement, displacement ductility was highly increased. This suggests that fibres have the potential to reduce the congestion of the reinforcement if fibres are designed to replace partially closely spaced transverse reinforcement. Also, it was noted that a redistribution of stresses occurred resulting in the formation of more well-controlled cracks. Finally, the strength predictions using the method developed by Aoude (Aoude, 2007) agree very well with the experimental results.
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Wassouf, Mohamad. "Bond and ductility of concrete reinforced with various steel bars surface and ductility conditions." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6272/.
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Reinforced concrete is a wide field for researches and studies in civil engineering subject. It is due to the fact that reinforced concrete is the most widely used material for the infrastructure in the world. Reinforced concrete consists of two main materials: reinforcing steel and concrete, each of those two materials has its own effect on the performance of the structure. In this thesis, the change in RC performance due to different steel properties and specifications will be investigated. The study focuses on the bond interaction between steel and concrete and the flexural behaviour of RC beams. Pull-out forces have been exerted on the reinforcing bars in RC blocks to examine the impact of steel properties on the bond strength and failure mode of the blocks. In addition to that, flexural tests have been conducted on simply supported RC beams to investigate how reinforcement properties can affect the ductility of reinforced concrete. Comparison of results of the previous two tests with codes and analytical models have been carried out to verify the outcome of this research.
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Khanna, Om Shervan. "Experimental investigation of transverse confinement in deck slabs by glass fibre reinforced polymer and steel bars." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ42717.pdf.
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Li, Jing, and 李靜. "Effects of diagonal steel bars on performance of interior beam-column joints constructed with high-strength concrete." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244464.
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Weidenmüller, Jens [Verfasser]. "Optimization of Encircling Eddy Current Sensors for Online Monitoring of Hot Rolled Round Steel Bars / Jens Weidenmüller." Aachen : Shaker, 2014. http://d-nb.info/1058316036/34.
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Moallemi, Pour Sadaf. "Investigation of compressive bond behavior of steel and fiber reinforced polymer bars embedded in recycled aggregate concrete." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57927.
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Over the past several years, one of the important issues concerning the construction
industry has been sustainable development. Therefore, usage of sustainable building materials and the reuse and recycling of previously used building materials have been considered in many areas. Recycling of construction and demolition (C&D) wastes could prevent their costly disposal which is hazardous to the environment. Utilization of demolished concrete as a coarse aggregate, often termed as recycled coarse aggregate (RCA) for producing industry quality concrete, could lead to a solution to the environmental conservation and pave the way towards sustainability by reducing the consumption of natural aggregate. During the development of this new generation product, it is essential to investigate the structural properties of reinforced RCA concrete to promote its application, in the construction industry. Besides, fiber reinforced
polymer (FRP) composite rebars have been widely used in construction instead of steel rebars. Their non-corrosive nature and high tensile strength are the main reason of this replacement. Performance of reinforced concrete members at serviceability and ultimate limit states is controlled by the bond between reinforcement and concrete which is a critical design parameter. This research aims to evaluate RCA application in structural concrete and investigate the bond properties between reinforcing steel/FRP bars and RCA concrete. Bond performance of 35 MPa RCA concrete was assessed through an experimental plan. Five RCA replacement percentages and different diameters of reinforcing bars were used. Effects of embedment length and concrete cover to bar diameter ratio on the bond strength were moreover considered. It was observed that under constant mix proportions, an increase in the bar size and the embedment length to bar diameter ratio leads to a reduction in the bond strength due to growth of voids trapped between the bar surface and concrete. Like regular concrete, larger concrete cover helps improving the bond behavior. On average, acceptable bond strengths were observed in RCA samples which were close to control results. In addition, smaller bar diameter and larger concrete cover can improve bond behavior of specimens embedded with FRPs in comparison with steel ones.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
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Abushoglin, Fathi. "Computer-aided nonlinear analysis of simple beams and one way slabs reinforced by FRP and/or steel bars." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ32391.pdf.
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Ding, Yongcong. "Residual stresses in hot-rolled solid round steel bars and their effect on the compressive resistance of members." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0030/MQ62207.pdf.
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Abushoglin, Fathi Carleton University Dissertation Engineering Civil and Environmental. "Computer-aided nonlinear analysis of simple beams and one way slabs reinforced by FRP and/or steel bars." Ottawa, 1997.
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Andreolli, Mauro. "Giunti semirigidi con barre incollate per strutture lignee = Ductile moment-resistant steel-timber connections with glued-in bars." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/368695.
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Il lavoro di tesi riguarda la caratterizzazione meccanica di un giunto, adatto per la realizzazione di differenti configurazioni in strutture intelaiate pesanti di legno, costituito da un elemento metallico flangiato collegato agli elementi strutturali in legno per mezzo di barre incollate. Questo sistema di connessione presenta alcune interessanti proprietà meccaniche in termini di prestazioni meccaniche, versatilità e prefabbricazione.
Un modello analitico in grado di valutare la risposta del giunto in termini dei parametri meccanici chiave (modalità di rottura, resistenza ultima, rigidezza e capacità rotazionale) è stato proposto e validato attraverso un’ampia campagna sperimentale. A tale scopo il metodo per componenti, originariamente proposto per giunti semi-rigidi in acciaio, è stato adattato per modellare i giunti acciaiolegno, consentendo l'applicazione del capacity design e permettendo di progettare connessioni in grado di presentare valori di duttilità necessari ad applicazioni in campo sismico. Le prove effettuate hanno mostrato una soddisfacente rispondenza tra i risultati teorici e quelli sperimentali: in particolare la previsione affidabile delle modalità di rottura del giunto, permette la progettazione di connessioni resistenti a momento in grado di presentare alte deformazioni plastiche senza fenomeni di rotture fragili, con un notevole grado di duttilità strutturale a livello globale e di dissipazione energetica in seguito a sisma.
ENGLISH VERSION
This thesis investigates the mechanical characterisation of a joint, suitable for different configurations within a heavy timber frame, consisting of a wooden element connected to a steel stub by means of an end-plate and glued-in steel rods. This connection system has some interesting properties in terms of mechanical performance, versatility and prefabrication.
An analytical model to predict the joint response in terms of its key parameters (e.g. failure mode, ultimate resistance, stiffness and rotation capacity) is proposed and validated through an extensive experimental programme. The component method, originally proposed for semi-rigid joints in steel frameworks, is adapted in order to set up a feasible general model for steel–timber joints, enabling application of the capacity design approach and offering the required ductility for applications in seismic zones. The tests carried out indicate satisfactory agreement between theoretical and experimental results: the reliable prediction of joint failure modes allows design of moment-resistant connections that can sustain high plastic deformation without brittle rupture, with a remarkable degree of global ductility and energy dissipation under alternate loading.
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Andreolli, Mauro. "Giunti semirigidi con barre incollate per strutture lignee = Ductile moment-resistant steel-timber connections with glued-in bars." Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/509/1/PhD_Thesis_ANDREOLLI.pdf.
Full textAbstract:
Il lavoro di tesi riguarda la caratterizzazione meccanica di un giunto, adatto per la realizzazione di differenti configurazioni in strutture intelaiate pesanti di legno, costituito da un elemento metallico flangiato collegato agli elementi strutturali in legno per mezzo di barre incollate. Questo sistema di connessione presenta alcune interessanti proprietà meccaniche in termini di prestazioni meccaniche, versatilità e prefabbricazione.
Un modello analitico in grado di valutare la risposta del giunto in termini dei parametri meccanici chiave (modalità di rottura, resistenza ultima, rigidezza e capacità rotazionale) è stato proposto e validato attraverso un’ampia campagna sperimentale. A tale scopo il metodo per componenti, originariamente proposto per giunti semi-rigidi in acciaio, è stato adattato per modellare i giunti acciaiolegno, consentendo l'applicazione del capacity design e permettendo di progettare connessioni in grado di presentare valori di duttilità necessari ad applicazioni in campo sismico. Le prove effettuate hanno mostrato una soddisfacente rispondenza tra i risultati teorici e quelli sperimentali: in particolare la previsione affidabile delle modalità di rottura del giunto, permette la progettazione di connessioni resistenti a momento in grado di presentare alte deformazioni plastiche senza fenomeni di rotture fragili, con un notevole grado di duttilità strutturale a livello globale e di dissipazione energetica in seguito a sisma.
ENGLISH VERSION
This thesis investigates the mechanical characterisation of a joint, suitable for different configurations within a heavy timber frame, consisting of a wooden element connected to a steel stub by means of an end-plate and glued-in steel rods. This connection system has some interesting properties in terms of mechanical performance, versatility and prefabrication.
An analytical model to predict the joint response in terms of its key parameters (e.g. failure mode, ultimate resistance, stiffness and rotation capacity) is proposed and validated through an extensive experimental programme. The component method, originally proposed for semi-rigid joints in steel frameworks, is adapted in order to set up a feasible general model for steel–timber joints, enabling application of the capacity design approach and offering the required ductility for applications in seismic zones. The tests carried out indicate satisfactory agreement between theoretical and experimental results: the reliable prediction of joint failure modes allows design of moment-resistant connections that can sustain high plastic deformation without brittle rupture, with a remarkable degree of global ductility and energy dissipation under alternate loading.
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Habeeb, M. N. "Flexural behaviour of continuously supported FRP reinforced concrete beams." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5727.
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This thesis has investigated the application of CFRP and GFRP bars as longitudinal reinforcement for continuously supported concrete beams. Two series of simply and continuously supported CFRP and GFRP reinforced concrete beams were tested in flexure. In addition, a continuously supported steel reinforced concrete beam was tested for comparison purposes. The FRP reinforced concrete continuous beams were reinforced in a way to accomplish three possible reinforcement combinations at the top and bottom layers of such continuous beams. The experimental results revealed that over-reinforcing the bottom layer of either the simply or continuously supported FRP beams is a key factor in controlling the width and propagation of cracks, enhancing the load capacity, and reducing the deflection of such beams. However, continuous concrete beams reinforced with CFRP bars exhibited a remarkable wide crack over the middle support that significantly influenced their behaviour. The ACI 440.1R-06 equations have been validated against experimental results of beams tested. Comparisons between experimental results and those obtained from simplified methods proposed by the ACI 440 Committee show that ACI 440.1R-06 equations can reasonably predict the load capacity and deflection of the simply and continuously supported GFRP reinforced concrete beams tested. However, The potential capabilities of these equations for predicting the load capacity and deflection of continuous CFRP reinforced concrete beams have, however, been adversely affected by the de-bonding of top CFRP bars from concrete. An analytical technique, which presents an iterative procedure based on satisfying force equilibrium and deformation compatibility conditions, has been introduced in this research. This technique developed a computer program to investigate flexural behaviour in particular the flexural strength and deflection of simple and continuously supported FRP reinforced concrete beams. The analytical modelling program has been compared against different prediction methods, namely ACI 440, the bilinear method, mean moment inertia method and Benmokrane's method. This comparison revealed the reliability of this programme in producing more enhanced results in predicting the behaviour of the FRP reinforced beams more than the above stated methods.
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OLIVEIRA, WALTER EDGLEY DE. "EXPERIMENTAL STUDY ON THE INFLUENCE OF CONCRETE COVER ON THE INTERACTION BETWEEN STEEL BARS AND CONCRETE IN ELEMENTS SUBJECTED TO COMPRESSION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=13067@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O presente trabalho trata da influência do cobrimento da armadura longitudinal sobre a resistência de aderência em regiões de emenda por traspasse de elementos de concreto armado comprimidos. Neste estudo foram ensaiados dezoito pilares de concreto armado com seção transversal de 200 mm x 150 mm e comprimento de 1100 mm, com armadura longitudinal composta de barras de aço CA-50 com diâmetro nominal de 12,5 mm e estribos de 5 mm. O arranjo da armadura longitudinal definiu três séries de pilares, sendo a Série 1 composta por seis pilares com a armadura longitudinal contÃnua, e as Séries 2 e 3 cada uma composta por seis pilares com a armadura longitudinal, tendo uma emenda por traspasse localizada na região da metade da altura do pilar de 470 cm e 235 mm de comprimento, respectivamente. Os ensaios consistiram na aplicação de uma força de compressão com uma excentricidade de 20 mm, sendo tal excentricidade aplicada apenas na direção da menor dimensão da seção transversal. Para os seis pilares de cada série o cobrimento da armadura longitudinal variou de 25 mm até que a metade do diâmetro da barra longitudinal ficasse exposta. Os resultados obtidos indicam que a influência do cobrimento sobre a capacidade do pilar resistir à s solicitações torna-se visÃvel quando a relação c/ à da espessura do cobrimento c e do diâmetro da barra à é inferior a 0,4. Para pilares com barras emendadas por traspasse e com armadura exposta até a metade de seu diâmetro, a aderência na zona da emenda foi substancialmente afetada, provocando a ruptura do pilar sob forças inferiores à s alcançadas em pilares com cobrimento adequado.
The present work describes the influence of the concrete cover of the longitudinal reinforcement on the bond strength along the overlapping splice zones of compressed elements. Tests have been carried out on eighteen reinforced concrete columns, with cross section of 200 mm x 150 mm and 1100 mm of length. The longitudinal reinforcement consisted of CA-50 steel bars with nominal diameter of 12,5 mm and stirrups of 5 mm. Three series of columns (Serie 1, Serie 2 and Serie 3) were defined according to the arrangements of the longitudinal reinforcement: Series 1 composed by six columns with continuous longitudinal reinforcement; Series 2 and 3 composed by six columns each, presenting an overlapping splice of 470 mm and 235 mm of lenght, respectively. The columns were submited to a load apllied with an eccentricity of 20 mm in the direction of the smallest dimension of the cross section. In each series, the concrete cover varied from 25 mm to a value corresponding to the situation in which half of the diameter of the longitudinal bar was exposed. The results showed that the influence of the concrete cover on the column strength becomes relevant when the ratio c/ à of the cover thickness c to the bar diameter à is less than 0,4. For columns with overlapping splice and reinforcement exposed up to the half of diameter, the bond along the overlapping zone has been substancially affected, resulting in the column failure at lower loads when compared to columns with proper value of concrete cover.
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Walker, Jason Matthew. "Evaluation of elliptical, glass fiber reinforced polymer, and stainless steel dowel bars in concrete pavements with consideration to subgrade resilient modulus." [Ames, Iowa : Iowa State University], 2008.
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Imohamed, Imohamed Ali Omar <1981>. "Experimental Study of the Bond Behaviour of Steel FRP-Concrete Joints and Shear Behavior of Concrete Beams Reinforced with GFRB Bars." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7857/1/Imohamed_ImohamedAliOmar_tesi.pdf.
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The current research is mainly focused on the use of glass fiber reinforced polymer (GFRP) bars as internal reinforcement for simply supported concrete beams and the use of steel reinforced polymer (SRP) system externally for debonding and confinement investigation. Since GFRP and SRP are newly developed strengthening materials, a better understanding of the mechanical behaviour of these composite systems is needed. The objective of this research program is to investigate a number of issues related to GFRP bars, and SRP composite strips: 1) To investigate the shear strength of concrete beams reinforced with GFRP bars. 2) To investigate the debonding mechanism between SRP composites strips and the concrete surface, using two different set-up; concrete specimens were tested using the single-lap shear test set-up and specimens were tested using a three-point bending set-up, and compare the results obtained based on two different test set-ups. 3) To investigate the behavior of short concrete prisms with a square cross-section confined by SRP composite strips. A total of 96 concrete (beams, prisms) were tested in the course of this research; 14 as part of a shear strength of concrete beam reinforced with GFRP bar study, 7 as part of the debonding phenomenon study, 19 as part of the bond study, 31 as part of the fracture mechanics study and 25 as part of the confinement study.
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Yosefani, Anas. "Flexural Strength, Ductility, and Serviceability of Beams that Contain High-Strength Steel Reinforcement and High-Grade Concrete." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4402.
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Utilizing the higher capacity steel in design can provide additional advantages to the concrete construction industry including a reduction of congestion, improved concrete placement, reduction in the required reinforcement and cross sections which would lead to savings in materials, shipping, and placement costs. Using high-strength reinforcement is expected to impact the design provisions of ACI 318 code and other related codes.
The Applied Technology Council (ATC-115) report "Roadmap for the Use of High-Strength Reinforcement in Reinforced Concrete Design" has identified key design issues that are affected by the use of high-strength reinforcement. Also, ACI ITG-6, "Design Guide for the Use of ASTM A1035 Grade 100 Steel Bars for Structural Concrete" and NCHRP Report 679, "Design of Concrete Structures Using High-Strength Steel Reinforcement" have made progress towards identifying how code provisions in ACI 318 and AASHTO could be changed to incorporate high-strength reinforcement.
The current research aims to provide a closer investigation of the behavior of beams reinforced with high-strength steel bars (including ASTM A615 Grade 100 and ASTM A1035 Grades 100 and 120) and high-strength concrete up to 12000 psi. Focus of the research is on key design issues including: ductility, stiffness, deflection, and cracking.
The research includes an extensive review of current literature, an analytical study and conforming experimental tests, and is directed to provide a number of recommendations and design guidelines for design of beams reinforced with high-strength concrete and high-strength steel. Topics investigated include: strain limits (tension-controlled and compression-controlled, and minimum strain in steel); possible change for strength reduction factor equation for transition zone (Φ); evaluation of the minimum reinforcement ratio (þmin); recommendations regarding limiting the maximum stress for the high-strength reinforcement; and prediction of deflection and crack width at service load levels. Moreover, this research includes long-term deflection test of a beam made with high grade concrete and high-strength steel under sustained load for twelve months to evaluate the creep deflection and to insure the appropriateness of the current ACI 318 time-dependent factor, λ, which does not consider the yield strength of reinforcement and the concrete grade.
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Gravina, Rebecca Jane. "Non-linear overload behaviour and ductility of reinforced concrete flexural members containing 500MPa grade steel reinforcement." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phg777.pdf.
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Includes corrigenda (inserted at front) and list of publications published as a result of this research. Includes bibliographical references (leaves 192-199) Investigates the overload behaviour and modes of collapse of reinforced concrete flexural members containing 500MPa grade reinforcing steel and evaluates the adequacy of current ductility requirements for design according to AS 3600 to ensure strength and safety.
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Heathcote, Lydia. "An Inductive Scanning System for Detection of Corrosion in Reinforcing Steel Bars at Distances of up to 90mm and a Procedure to Extract Bar Dimensional Information." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525292.
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Rivera-Corral, Jesus Octavio. "Contribution à l'évaluation de l'état de dégradation de divers types de barres d'acier utilisées comme armatures dans des bétons carbonatés ou pollués par des chlorures." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30210/document.
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Le béton armé est sans conteste le matériau le plus utilisé dans la construction, et permet de réaliser la plupart des infrastructures dans tous les pays du monde. Cependant, sa durabilité peut être compromise de façon prématurée par la corrosion des aciers, qui est la pathologie considérée comme la plus dangereuse vis-à-vis du maintien de l'intégrité des ouvrages de Génie Civil. Afin d'obtenir une meilleure résistance face au risque de corrosion, l'acier conventionnel (AC) peut être soumis à divers traitements, dont les plus connus sont le recouvrement superficiel par d'autres matériaux métalliques à base de zinc (AG), ou par des revêtements doubles métal-polymères (AD). Cependant, il existe aussi des barres d'acier thermiquement traitées (ATT) qui ne sont actuellement quasiment pas utilisées en tant qu'armatures. De ce fait, leur comportement face aux mécanismes de détérioration comme la corrosion en milieu cimentaire causée par les chlorures ou la carbonatation est encore très peu connu. Dans ce travail, le comportement des différentes barres d'acier mentionnées ci-dessus a été étudié. Des éprouvettes prismatiques de béton, incluant ces types d'armatures, ont été fabriquées avec deux rapports E/C : 0,45 et 0,65. Avant leur utilisation, les barres ont été caractérisées mécaniquement et métallographiquement. Ensuite, les éprouvettes ont été placées dans différentes conditions d'exposition : un environnement urbain/industriel ou côtier, et un environnement contrôlé en laboratoire. Des mesures du potentiel de corrosion, de résistance de polarisation linéaire, et de spectroscopie d'impédance électrochimique ont été mises en œuvre durant la période d'exposition. Pour chaque série, la teneur critique en chlorures a été déterminée, et la progression de la profondeur de carbonatation a été suivie. En outre, en induisant un couple galvanique par effet de la carbonatation, des mesures originales du comportement électrochimique de ces barres ont été effectuées puis une analyse, en s'appuyant sur une modélisation en éléments finis, en a été faite. Dans l'environnement contrôlé en laboratoire, l'ordre de dépassivation des différentes barres exposées a été observé de façon similaire pour les deux rapports E/C, à savoir : ATT, AC, AG et enfin AD. Une teneur critique en chlorures plus élevée a été obtenue pour les barres AG et AD. Cependant, lors de l'inspection visuelle, les dommages causés sur les armatures AG étaient plus élevés que sur les autres types de barres. Enfin, durant l'étape de propagation, la densité de courant de corrosion des barres ATT et des barres AG s'est révélée inférieureCorrosion of reinforcing bars in concrete is considered as the most important problem that affects the integrity of the civil structures. In order to obtain a better resistance to corrosion, various superficial processes as coatings with zinc (AG) or such as the dual covering metallic-polymeric (AD) are applicate to ordinary steel bars (AC). On the other hand, steel bars with thermal treatments (ATT), principally developed as an alternative to improve the mechanical properties without the use of ferroalloys, are not used in concrete. The behavior of these kinds of bars in front of mechanisms of deterioration as the corrosion induced by chlorides or carbonation has not yet been studied. In this work, all these various steel bars (AG, AD, AC and ATT) were embedded in prismatic specimens of concrete made with two ratio water/cement: 0.45 and 0.65. Previously, steels bars were characterized by mechanical tests and metallographic identifications. Then, specimens were placed in several sites of exposition: urban/industrial environment, or coastal environment, or controlled atmosphere in laboratory. During these expositions, measurements of corrosion potential, linear polarization resistance, and electrochemical impedance spectroscopy were regularly carried out. For each type of steel bar, chloride threshold level and progress of the carbonation depth were determined. Furthermore, by means of the induction of a galvanic couple during design of new samples, the electrochemical behavior of the steels bars AC, ATT and AG was followed up experimentally and then analyzed with finite element model. It was founded that the different steels bars exposed in controlled atmosphere of laboratory followed a same sequence in depassivation for both ratios water/cement: ATT, AC, AG and AD. The chloride thresholds were higher for steels bars AG and AD. However, visual inspection showed that the morphology of damages caused on AG bars was most important compared with the other steel bars. In the propagation phase, the corrosion current density of the ATT bars was lower, even to that obtained by the AG bars
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Pappas, Adlreburg Nickolas. "To Make Iron of Iron : A Comprehensive Analytical Study of Spade Shaped Iron Bars." Thesis, Stockholms universitet, Arkeologiska forskningslaboratoriet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-145694.
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This thesis aims to provide adequate analytical information on the spade shaped iron bars of Norrland and central Sweden. While their significance has been thoroughly debated for decades, analytical research on them has been confined to cases of single artefacts or theoretical interpretations of their value, meaning and origin. In this study a comprehensive approach is taken into consideration. Based on X-Ray fluorescence (XRF), scanning electron microscopy (SEM) and metallographical analysis this thesis seeks to facilitate new interpretations on quality, production centres and usage based on analytical results. Aiming to settle some of the long lasting questions regarding the artefacts while producing results which can further the discussion by raising new questions, previously unasked.
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Gudelis, Andrius. "Klijuotųjų medienių sijų jungties su įklijuotaisiai plieniniais strypais tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090702_141646-55416.
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Baigiamajame magistro darbe aptarti klijuotosios medienos su įklijuotaisiais plieniniais strypais privalumai bei trūkumai, jų panaudojimas ir taikymas statybos pramonėje. Atlikta plieno strypų, įklijuotų medienoje išilgai, skersai ir kampu į medienos pluoštus, teorinių skaičiavimų pagal Europos ir Rusijos normas metodikų analizė. Atlikti teoriniai standžios sijos jungties su įklijuotaisiais plieniniais strypais skaičiavimai. Išanalizuota bandymų metodika. Tiriamojoje dalyje atlikti šie eksperimentiniai bandymai: armatūros strypų takumo įtempių nustatymas; medienos tankio ir drėgnio nustatymas; strypų, įklijuotų medienoje išilgai, skersai ir 45o kampu į medienos pluoštus gniuždymo bandymai; sijos standžios jungties su įklijuotaisiais plieniniais strypais bandymas. Nustatyti esminiai rodikliai, veikiantys bandymų rezultatus, irimo pobūdžiai bei elgsena bandymų metu. Skaičiavimų rezultatai palyginti su eksperimentinių bandymų metu išbandytais natūralaus dydžio bandinių rezultatais. Darbe pateikti, įvertinti ir išanalizuoti teoriniai ir eksperimentiniai rezultatai, jų skirtumai. Pateiktos rekomendacijos ir pasiūlymai skaičiavimų metodikų tobulinimui ir praktiniam įklijuotųjų plieno strypų medienoje panaudojimui.In this master degree paper are discussed advantages and imperfections, practice and use in construction industry of glulam with glued-in steel rods. Theoretical calculations analysis according to Eurocode and Russian standards of glued-in steel rods parallel, perpendicular and at an angle to the grain were made. Theoretical calculations of rigid joint glulam beam with glued-in steel bars were made. Tests methods were analyzed. In the part of the researches these tests were made: yield stress evaluation test of steel rods; moisture and density evaluation tests of wood; parallel, perpendicular ant at an 45 o angle to the grain compression tests of the glued-in steel rods; rigid joint of the glulam beam with glued-in steel rods test. Fundamental factors, which have influence to the results of the tests, character of the disruptions and the behavior of elements during the experiments were defined. The results of the calculations were compared with the results of tests in which natural size specimens were tried. In this work the results of theoretical calculations and experimental tests are proposed, evaluated and analyzed. The reasons of divergence in results are indicated. Recommendations and suggestions how to improve the methods of calculations and for better use the glued-in steel rods in the practice were offered.
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Popovič, Tomáš. "Návrh konstrukce pro fotbalové hřiště." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240365.
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This diploma thesis deals with the static review of structure for a football pitch. It is crosswise prestressed reinforced sliding plate with variable cross section. Assessment of the elements was done according to limit states. Internal forces from the load effects were calculated using the SW SciaEngineer 2015.1. The elements were assessed by SW Idea StatiCa 6. The main outputs of this static calculation are drawings of the shape and drawings of the reinforcement.
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SILVA, Juliano Rodrigues da. "Estudo Experimental de Pavimentos de Concreto: Influência da Posição da Barra de Transferência e do Tipo de Concreto." Universidade Federal de Goiás, 2009. http://repositorio.bc.ufg.br/tede/handle/tde/681.
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Previous issue date: 2009-03-12This work presents an experimental study of the behavior of transverse joints in unreinforced concrete slabs under elastic support. Due to the tensions caused by loads and volumetric variations in the slab, transverse joints when badly executed can cause a efficiency reduction in the shear transfer, thus reducing the useful life of the concrete pavement. To have a better efficiency in the shear transfer in joints of concrete pavements, 500 mm transfer bars are used with bar diameters varying from 10 mm to 32 mm. These bars are positioned at midheight of the sawed joints spaced at every 300 mm. This research seeks to verify the influence of the positioning of the transfer bars and the influence of different types of concrete on sawed joints of concrete pavements. Three different types of unreinforced concrete were used: conventional concrete, steel fiber concrete and self-compacting concrete. The experimental program consisted of the application of static monotonic loading in nine concrete plates, simulating concrete pavements, with dimensions 2200 mm x 600 mm, with a sawed joint at midlength supported by an elastic rubber layer. The experimental results showed that joints with transfer bars performed much better than those joints without transfer bars and that bars located at midheight perform better than those bars positioned at 45 mm from the base. The concrete types were quite different, however the steel fiber concrete was shown to be more efficient than the other two concrete types, and the conventional concrete was more efficient than self-compacting concrete, probably because aggregate interlock is better in conventional concrete
Este trabalho apresenta um estudo experimental do comportamento de juntas transversais em placas de concreto simples, apoiadas sobre uma fundação elástica. Devido às tensões provocadas pelo carregamento e por variações volumétricas das placas, as juntas transversais quando mal executadas podem ocasionar uma redução da eficiência da transferência de esforços, reduzindo assim, a vida útil do pavimento de concreto. Para que ocorra uma melhor eficiência da transferência dos esforços nas juntas transversais são utilizadas barras de transferência com diâmetro comercial variando de 10 mm a 32 mm e comprimento de 500 mm. Essas barras são posicionadas sob as juntas serradas na altura de ½ da espessura da placa de concreto e posicionadas a cada 300 mm uma da outra. Esta pesquisa visa verificar a influência das juntas serradas em função do posicionamento das barras de transferência e a influência do uso de concreto simples autoadensável, concreto simples convencional e concreto convencional simples com fibras de aço. O programa experimental constou de ensaios com aplicação de carregamento estático monotônico em nove placas, simulando pavimentos de concreto, com dimensões 2200 mm x 600 mm, dotadas de junta transversal serrada e apoiadas sobre uma camada de borracha. Os ensaios experimentais mostraram que a junta serrada em placas com a presença de barras de transferência tem um desempenho muito melhor do que as placas sem barra de transferência, e que quanto à altura das barras em relação à base, tiveram um melhor desempenho nas barras posicionadas a ½ altura que a 45 mm da base. Os tipos de concreto foram bastante distintos, porém o concreto convencional com fibras se mostrou mais eficiente que os outros dois tipos de concreto, e o concreto convencional se mostrou mais eficiente que o concreto autoadensável, provavelmente em função do intertravamento dos agregados do concreto convencional que são mais solicitados do que os agregados do concreto autoadensável
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Beyer, André. "Résistance des barres en acier à section ouverte soumises à une combinaison d’effort normal, de flexion et de torsion." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0204/document.
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Des barres en acier à section ouverte sont, dans la majorité des cas, soumises à une combinaison d’effort normal et de flexion bi-axiale. Cependant, en raison de leur utilisation elles peuvent également être soumises à un moment de torsion. Même si les barres à section ouverte peuvent être soumises à des charges de torsion en pratique, l’Eurocode 3, ne définit pas comment la résistance de la barre peut être déterminée dans ces conditions. Ce pourquoi, l’objectif principal de cette thèse est de remplir cette lacune. Pour atteindre cet objectif, le comportement des barres métalliques soumises à une combinaison complexe de charges est étudié par voie théorique, expérimentale et numérique. Tout d’abord, la résistance plastique des barres est étudiée. En cas de torsion, il a été montré que les barres à section ouverte possèdent une réserve plastique importante qui ne peut pas être mise en évidence à l’aide d’une simple analyse élastique. Afin de tenir compte de l’effet bénéfique de la réserve plastique en torsion, une méthode d’analyse simplifiée est développée et validée par des analyses numériques. Ensuite, l’interaction plastique entre les efforts internes est étudiée. Des essais en laboratoire ont été réalisés afin de caractériser l’interaction entre l’effort tranchant et le moment de flexion. L’étude est ensuite étendue à l’aide de simulations numériques sur des cas d’interaction plus complexes incluant notamment des moments de torsion. Les essais accompagnés par l’étude numérique ont permis de mettre au point un modèle de résistance basé sur la méthode « Partial Internal Force Method » développée dans le passé. La dernière partie de la thèse concerne la résistance des barres à l’instabilité. Un modèle de résistance incluant l’effet de l’instabilité élasto-plastique est développé pour les barres métalliques en présence de torsion. Cette méthode est basée sur une extension des formules d’interaction proposées dans l’Eurocode. Afin de franchir certaines limitations liées à cette méthode, un deuxième modèle de résistance est développé pour les barres en I dans le format du « Overall Interaction Concept »Structural steel members with open cross-section are, in the majority of cases, subject to a combination of axial forces and mono- or bi-axial bending. Nonetheless, owing to specific use they may be subject to torsion as well. Even if torsional loads are of practical interest for steel members of open section, the European standard for the design of steel structures, Eurocode 3, does not contain a generally accepted design method addressing the resistance of these members. Consequently, the main objective of this thesis is to close the lack in the current standard. So as to attain this objective the behaviour of members of open section subject to a complex load combination has been studied theoretically, experimentally and numerically. First, the plastic resistance of steel members has been analysed. It has been shown that members subject to torsion may possess a high plastic system reserve that cannot be predicted by simple elastic analysis. So as to account for the beneficial effect of the plastic reserve, a simplified analysis method has been developed and validated with numerical simulations. After this, the plastic interaction between all internal forces and moments has been studied. Several laboratory tests have been performed to characterise the interaction between bending moments and the shear force. The study is then extended to more complex interaction cases including torsion by means of numerical simulations. The laboratory test and the numerical simulations allowed the development of a precise resistance model based on the “Partial Internal Force Method” developed in the past. The last part of this thesis was dedicated to the member resistance including instability. A resistance model has been developed based on the Eurocode 3 interaction equations. So as to overcome some of the limitations linked to this method, a second design approach is developed based on the “Overall Interaction Concept”
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Petrík, Tomáš. "Pavilon šelem v zoologické zahradě Lešná." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226062.
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The subject of the diploma thesis is a processed design of a steel construction of a pavilion shaped by spherical segments. The pavilion has exhibition purpose as a part of the zoological garden Lešná, and is intended for African beasts. The design meets architectonical requests - roundness and luminosity. A shape of the pavilion consists of three intersecting cupolas with a frontal curved cut out for glass facade. Construction of the pavilion consists of the radial arranged arched ribs with transversal bars, which are supplemented by horizontal purlins. Forehead of the pavilion is formed by columns and girts. Cladding is designed in combination: aluminum profile and insulated glass. Comparison of alternative steel structure solutions is also a part of the diploma thesis.
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COSTA, ISOLDA. "Effect of minor addition elements on the corrosion behaviour of bare and coated steels." reponame:Repositório Institucional do IPEN, 1991. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10281.
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Tese (Doutoramento)
IPEN/T
University of Manchester, England
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Miàs, Oller Cristina. "Analysis of time-dependent flexural behaviour of concrete members reinforced with fibre reinforced polymer bar." Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/96914.
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In this work, long-term behaviour of FRP RC beams has been investigated both analytically and experimentally to further extend the knowledge in this particular research domain. In this respect, a new methodology to determine the long-term deflections due to creep and shrinkage is presented. Based on multiplicative coefficients, the methodology is straightforward and simple, and therefore suitable to be used in design. In addition, an experimental campaign on two series of GFRP RC beams subject to long-term loading has been performed. Different reinforcement ratios, concrete strengths and sustained load levels have been considered. For comparison purposes steel reinforcement has also been used. The experimental long-term results have been reported and discussed. Furthermore they have been compared to predictions using the most representative procedures, as well as, the proposed methodology presented in this work.En aquest treball, es presenta una nova metodologia per a la determinació de fletxes diferides degudes als efectes de la fluència i la retracció del formigó. La metodologia presentada es basa en coeficients multiplicadors, essent així un mètode directe i simple, apte per ser utilitzar en el disseny. Addicionalment, l’estudi presenta els resultats d’una campanya experimental realitzada en dues etapes, on bigues armades amb barres de material compost han estat sotmeses a càrregues a llarg termini. S’han considerat diferents quanties de reforç, resistències de formigó i nivells de càrrega. Per tal de comparar-ne els resultats, també s’han assajat bigues armades amb barres d’acer. Els resultats experimentals han estat analitzats i comparats amb els models de predicció més significatius, així com amb la metodologia desenvolupada i presentada en aquest estudi.
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Shi, Feifei. "Comportement des tôles métalliques à gradient de propriété sous chargement dynamique." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0035/document.
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Cette étude vise à bien comprendre puis à modéliser le comportement mécanique dans une large plage de vitesse de déformation des tôles d’acier austénitique AISI304 ayant subis un traitement d'attrition mécanique de la surface (SMAT). Ces tôles ainsi traités sont des matériaux multicouches avec un gradient de propriétés. Les principaux résultats obtenus sont résumés comme suit：(1) La sensibilité globale à la vitesse déformation des tôles d’acier austénitique AISI304 traités avec SMAT est caractérisée par des essais de double cisaillement sous chargements quasi-statiques et dynamiques, qui permet d’atteindre une grande déformation sans instabilité géométrique. Des essais de double cisaillement sous impact sont réalisés à l’aide des barres de Hopkinson de grande diamètre et un système d’attache qui a une même impédance acoustique que la barre. Une sensibilité significative a été révélée et on observe ce renforcement n’a pas induit une réduction importante de la ductilité.(2) Dans le but d’un meilleur dépouillement de ces essais de double cisaillement, leur conditions d’essai est analysé dans le détaillé. Le modèle numérique avec le système d’attache a été construit pour étudier l’influence du système d’attache au début de chargement. On trouve un effet limité pour les diverses conditions imparfaites des essais comme la souplesse de système d’attache, des champs mécaniques non-homogènes, l’état de non-équilibre, etc. Par contre, les études numérique et analytique ont démontré que l’hypothèse simple de petites perturbations habituellement utilisé pour le dépouillement de ces essais n’est pas suffisamment précise. La déformation Eulérien cumulée doit être utilisée pour obtenir un résultat numérique correct. A partir de ce résultat, la sensibilité à la vitesse déformation des tôles d’acier austénitique AISI304 traités avec SMAT obtenue expérimentalement a été retouchée.(3) Un modèle multicouche elasto-plastique en dommageable a été proposé pour décrire le comportement des tôles d’acier austénitique AISI304 traités avec SMAT. Les paramètres sont identifiées à partir des essai de traction. La partie elasto-plastique est calée par une loi d’écrouissage de type Ludwig. Par contre, les paramètres d’endommagement sont obtenus avec une méthode d’identification inverse sur la base de simulation numérique de ces essais de traction. Pour valider ce modèle multi-couche elasto-plastique dommageable, un essai d’indentation/perforation est réalisé sur des tôles d’acier austénitique AISI304 traités avec SMAT. Des simulations numériques correspondantes montres que ce modèle multi-couche elasto-plastique en dommageable une prédiction plutôt précise de ces essais de d’indentation/perforation.(4) Pour évaluer la performance anti-perforation des tôles d’acier austénitique AISI304 traités avec SMAT, des essais de perforation sous impact a été réalisés avec des barres de Hopkinson. Des simulations numériques de ces essais de perforation sous impact sont réalisées avec un modèle numérique comparable avec le cas quasi-statique. ́tant donne que la sensibilité globale à la vitesse déformation des tôles d’acier austénitique AISI304 traités avec SMAT est caractérisée par des essais de double cisaillement, la sensibilité à la vitesse a été introduite dans le modèle multi-couche elasto-plastique en dommageable. Le résultat numérique correspond bien à la mesure expérimentale, ce qui indique non seulement l’efficacité du modèle numérique mais aussi celle du modèle multicouche elasto-plastique en dommageableThis Ph.D dissertation aimed at the comprehensive understanding and the constitutive modeling of the mechanical behaviours of the surface mechanical attrition treatment (SMAT) treated AISI304 stainless steel sheet under a large range of loading rates. SMAT treated AISI304 stainless steel sheets are multi-layered functionally graded materials (FGM). The main research results and conclusions are summarized as followed:(1) The overall rate sensitivity SMAT treated AISI304 stainless steel sheet is characterized by the double shearing test under quasi-static and dynamic loading where a large strain can be achieved without geometry instability. Impact double shear test are performed with a large diameter Hopkinson bar system and an adapted equal-impedance clamping device. Significant rate sensitivity is found. It is also observed that such a rate enhancement does not induce an important reduction of the ductility.(2) In order to extract accurate material information from the double shear tests, their testing conditions are thoroughly analyzed using numerical simulation. Numerical models including clamping devices have been built to investigate the influence of this clamping device at the early stage of loading. A limited effect was found for various imperfect testing conditions such as the clamping device stiffness, non-homogeneous stress and strain fields, non-equilibrium state, etc. On the contrary, numerical and analytical study shows that the simple small strain assumption usually used in double shear tests are not accurate enough. Eulerian cumulated strain definition should be used to get consistent numerical results. From this finding, the experimental rate sensitivity obtained for the SMAT treated AISI304 stainless steel sheet are recalculated.(3) A multi-layers elastic plastic damageable constitutive model is proposed to model SMAT treated AISI304 stainless steel sheet. The parameters are identified using tensile testing results. The elastic plastic behavior is curve fitted with a simple Ludwig hardening model. However, the damage parameters should be identified using an inverse method on the basis of numerical simulation of these tensile tests. In order to validate this multi-layer elastic plastic damageable constitutive model, indentation/piercing tests on SMAT treated AISI304 stainless steel sheet are performed. Numerical simulation of this indentation/piercing tests is also realized. It is found that the identified multi-layer elastic plastic damageable constitutive model allows for a quite accurate prediction of the experimental piercing tests.(4) In order to evaluate the impact anti-piercing capacity of the SMAT treated AISI304 stainless steel sheet, the impact perforation tests using Hopkinson bar are carried out. Numerical simulation of these impact perforation tests are realized with a similar FEM model as the quasi-static case. As the rate sensitivity of SMAT treated AISI304 stainless steel sheet is experimentally characterized with double shear test, a rate sensitive multi-layer elastic plastic damageable constitutive model is introduced. The numerical results agree well with the experimental ones, which indicates the effectiveness of the numerical model as well as the rate sensitive multi-layer elastic plastic damageable constitutive model
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Baxant, Radek. "Řešení stability prutových konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227507.
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This diploma thesis deals with the subject of slenderness bars’ stability assessment, especially in the steel structures. Before the assessment of bars in the frame constructions, we search for the influence of the computational model’s settings on the final result. The initial geometrical imperfections are examined on the model of Euler’s bar. The influence of the rigidity of girders on the poles’ buckling length is examined on the basic frame construction. The buckling lengths are assessed in the comparison with the figures we got from the statistical tables and the computational software. The influence of construction’s initial tilt and its replacement by the system of outer forces is examined on the frame structure. Three-hinged frame structure with variable cross-section member is designed then and the influence of non-linear calculations on the inner forces is studied. In the complex frame assessment, the influence of the number of parts of variable cross-section member on the bars’ buckling length is examined.
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Bettanin, Viviane. "Tanino da ac?cia negra como inibidor da corros?o de a?o API5L X65 em meio ?cido." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8353.
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
In order to reduce the environmental impacts caused by chemical harmful to the environmental and to human health, the development of natural substances that are able to substitute these dangerous components have been increased. Tannins are a group of natural poliphenolic components extracted from plants that could be used as corrosion inhibitors. This study investigates the utilization of two bark of black wattles (Acacia mearnsii) as corrosion inhibitors, Weibull and Macrospec, in acidic medium and in atmospheric environment and in aqueous CO2 rich medium under high pressure. API 5L X65 steel samples were exposed to a corrosive medium (0.1 M HCl) with different tannin concentrations. The best results were duplicate to an environmental with CO2 saturated water at 15 MPa and 50?C. In order to characterize the specimens scanning electron microscopy by gun field emission, energy dispersive spectroscopy, X ray diffraction, mass loss tests and potenciodynamic polarization tests were used. The results indicated that both tannins, at atmospheric pressure and 0.1 M HCl corrosive environment have similar performance as corrosion inhibitors, and the higher dosage tested (12 g/L) exhibited the best efficiency. However, when the tannins were tested in environment with presence of CO2 under high pressure (15 MPa) and 50?C the results were different, and only Macrospec tannin had an inhibitory action under the conditions tested.
Visando diminuir os impactos ambientais causados por subst?ncias qu?micas nocivas ao meio ambiente e ? sa?de humana, a procura por substitutos naturais destes compostos em diversas aplica??es vem sendo intensificada. Taninos compreendem uma classe de compostos polifen?licos naturais extra?dos de plantas, podendo ser usados como inibidores de corros?o em meio aquoso. Neste estudo avaliou-se a utiliza??o de dois taninos vegetais da ac?cia negra (Acacia mearnsii), Weibull (em p?) e Macrospec (l?quido), como inibidores de corros?o em meios ?cidos em ambiente atmosf?rico e em ambiente com a presen?a de CO2 a alta press?o. Corpos de prova de a?o API5L X65 foram expostos a meio acidificado com HCl 0,1 M com diferentes concentra??es de taninos e o melhor resultado no que se refere ? concentra??o do tanino para a inibi??o de corros?o foi replicado para um meio com ?gua saturada com CO2 a 15 MPa e 50?C. Para caracteriza??o foram realizadas as an?lises de microscopia eletr?nica de varredura, difra??o de raios X, medidas eletroqu?micas de polariza??o potenciodin?mica, e testes de perda de massa. Os resultados indicaram que ambos os taninos, em meio de HCl 0,1 M e press?o atmosf?rica, apresentaram desempenho similar no que diz respeito aos efeitos de inibi??o da corros?o e a maior dosagem utilizada (12 g/L) foi a que apresentou melhor efici?ncia de inibi??o. Por?m, quando testados em meio de ?gua saturada com CO2 a 50?C e 15 MPa o comportamento dos taninos foi distinto, sendo que apenas o tanino Macrospec teve a??o inibit?ria nas condi??es testadas.
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Tunková, Martina. "Městské lázně." Master's thesis, Vysoké učení technické v Brně. Fakulta architektury, 2010. http://www.nusl.cz/ntk/nusl-215713.
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Hsieh, Man-yun, and 謝嫚紜. "Compression behavior of corroded steel deformed bars." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/52342192450196648678.
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碩士國立臺灣科技大學
營建工程系
102
This research uses the steel tension and compression test to investigate the effects of corrosion bars. Through use the electrochemical method to achieve the bars corrosion behavior. There are 6 groups of RC specimens. It contain three different weight loss rete are 10%, 20% and 30% respectively. Remove corrosion bars from RC specimens and do the bars tension and compression test. Then directly test none corrosion bars. Currently, there is only one group of RC specimens (10% of the corrosion ratio) take into test, containing 8 bars for each longitudinal and transverse bar. Randomly select the bar from none corrosion and 10% of the corrosion ratio of longitudinal bar to test. As the result, the ultimate stress and yield stress of the corrosion bars is slightly less than none corrosion bar in tensile test. But the strain difference between it is approximately 10%. And the stress of none corrosion bar is generally greater than the corrosion bar in compression test. Compare the terms of the deformation curve, the deformation of longer length of the unsupported steel are also larger.
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Yang, Li Tai, and 楊禮黛. "Bond Behavior Between Steel bars and Steel Fiber Reinforced High Performance Concrete." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/17011357398822957935.
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碩士國立臺灣科技大學
營建工程系
87
In this research, macro mechanics behavior and micro interface of steels and local concrete TAICON with the addition of steel fiber is investigated. The aim is to understand the change of bonding behavior after different amount of steel fiber is added in TAICON and conventional concrete. Besides, through micro observation, the mechanism of bonding behavior is analyzed and discussed. The results indicate for both TAICON mixed by Densified Mixture Design Algorithm (DMDA) and conventional concrete that has followed the ACI specification, slump and slump flow loss occur after steel fiber is added. However, for TAICON, after 1.5% steel fiber is added, the workability can be maintained, but for conventional concrete, after mixing and compacting process, honey comb, cave and bleeding appear, and tensile resistance, toughness and crack resistance of fiber concrete can not be improved, consequently influencing the quality and durability of concrete. The interfacial bonding of steel and concrete is an important factor that will influence the bonding failure; therefore, the mechanical test results and the micro structure of interface are studied to analyze the quality of interface. The compressive strength of TAICON grows slower than that of conventional concrete in the early age, and then it performs better after long-term test. Further, from the splitting test and ultrasonic pulse velocity, it is found that the more the steel fiber of TAICON is, the better the quality of concrete will be. In other words, the interfacial texture between steel fiber and TAICON concrete can be dense enough to ensure the constraining and bonding ability. The results can be observed from the micro structure before and after interface failure, and the bonding strength of TAICON can be improved.
50
王家儀. "Evaluating Corrosion Conditions of Steel Bars in Concrete." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91045757456191305903.
Full textAbstract:
碩士建國科技大學
土木與防災研究所
100
The main purpose of this research is to evaluate corrosion conditions of steel bars in concrete by non-destructive testing, using an electrochemical method able to detect the corrosion potential of steel bars in concrete and concrete current impedance. According to ASTM C876 description, when the corrosion potential measurement values of the steel bar below -350 mV, corrosion may be more than a 90 percent chance. If the concrete current impedance below 10 kΩ-cm, the Steel bar there is the possibility of corrosion. In accordance with the different corrosion factors, the factors of the test planning changes are as follows: concrete containing different concentration of chloride ions, and the steel bar to connect the current to accelerate the corrosion reaction. In addition, plan the use of spraying the solution of chloride ions, the simulation of reinforced concrete structures by sea tidal erosion, the observation of reinforced concrete corrosion process, as the future use of electrochemical detection reference. According to the experimental observations, the concrete containing chloride ions is very easy to cause internal corrosion of the steel bar. In addition, the specimens were placed in a large area of water vapor, water will penetrate through the pores will lead to concrete impedance and corrosion potential decreased, resulting in early damage to reinforced concrete. Current impedance of the concrete can be used as the basis for assessment of concrete internal humidity and moisture content, with the increase in curing time of concrete resistance was correspondingly increased.