Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Reinforced concrete Plastic properties.
Дисертації з теми "Reinforced concrete Plastic properties"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Reinforced concrete Plastic properties".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Alameddine, Fadel 1964. "FLEXURAL STIFFNESS OF CIRCULAR REINFORCED CONCRETE COLUMNS (SLENDERNESS, ACI CODE, LOAD, DESIGN)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276368.
Повний текст джерела
2
Abdulmajid, Amin Ali Ahmed. "Strengthening of reinforced concrete beams using carbon fibre reinforced plastic." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/1998.
Повний текст джерела
3
Thomas, Jeff Scott. "Plastic fiber rolling for concrete reinforcement." Diss., Rolla, Mo. : University of Missouri-Rolla, 1996. http://scholarsmine.mst.edu/thesis/pdf/Thomas_09007dcc805b0f25.pdf.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Missouri--Rolla, 1996.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 24, 2008) Includes bibliographical references (p. 117-118).
4
Whitehead, Paul Arthur. "Shear strength of concrete containing fibre-reinforced-plastic reinforcement." Thesis, University of Bath, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275880.
Повний текст джерела
5
Malek, Amir Masoud 1959. "Analytical study of reinforced concrete beams strengthened with fiber reinforced plastic plates (fabrics)." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282316.
Повний текст джерелаАнотація:
Epoxy-bonding a composite plate to tension face, is an effective technique for repair and retrofit of reinforced concrete beams. Experiments have indicated local failure of the concrete layer between the plate and longitudinal reinforcement in retrofitted beams. This mode of failure is caused by local stress concentrations at the plate end, as well as at the flexural cracks. A method has been presented for calculating shear and normal stress concentrations at the cut-off point of the plate. Stress concentrations predicted by this method have been compared to both finite element method and experimental results. The analytical models provide closed form solutions for calculating stresses at the plate ends and can easily be incorporated in design equations. The ultimate capacity of the reinforced concrete beams strengthened by composite plates bonded to the tension face, is controlled by either compression crushing of concrete, rupture of the plate, local failure of concrete at the plate end, or debonding of the plate. These failure modes have been considered in developing design guidelines for flexural strengthening of reinforced concrete beams using fiber composite plates. Bonding composite plates (fabrics) to the web of reinforced concrete beams can increase the shear and flexural capacity of the beam. An analytical model has been developed to calculate the stress distribution in the strengthened beam, and the shear force resisted by the composite plate before cracking and also after formation of flexural cracks. Parametric study has been performed to reveal the effect of important parameters such as fiber orientation, and plate thickness. The ultimate shear capacity of reinforced concrete beams is also increased by epoxy-bonding composite plates to the side faces of the beam. Truss analogy and compression field theory have been used to determine the effect of the composite plate on the crack inclination angle and the shear capacity of reinforced concrete beams at ultimate state. The effects of important parameters such as plate thickness and fiber orientation angle on the crack inclination angle and the shear capacity of the strengthened beam have been investigated through a parametric study.
6
Branch, James. "Plastic properties of fresh high strength concrete." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/842953/.
Повний текст джерелаАнотація:
This thesis describes the novel test techniques that were developed to measure the parameters associated with the plastic shrinkage, and subsequent possible plastic shrinkage cracking, of high strength concrete. The parameters measured during the first 24 hours after placing were the stress- strain relationship, negative pore pressure and free shrinkage strain development. The plastic behaviour of eight high strength concrete mixes was quantified and these mixes were then tested to assess their propensity towards plastic shrinkage cracking, using restrained ring tests. A review of the parameters associated with plastic shrinkage cracking was carried out. The general view was that as the particle size in a cement matrix gets smaller, then the negative pore pressures developed are greater and hence shrinkage increases. This meant that the presence of secondary cementing materials, of very small diameter, such as microsilica, in high strength concretes would explain their apparent susceptibility to plastic shrinkage cracking. Eight high strength concrete mixes were tested in exposed and sealed conditions. It was found that when tested in sealed conditions none of the parameters measured presented itself as the sole driving force behind plastic shrinkage or plastic shrinkage cracking. Also, when cured in sealed conditions, none of the mixes tested in the restrained ring test apparatus cracked. When tested in exposed conditions, the presence of wind had little effect on the stress-strain relationship of the mixes tested. However the presence of wind seemed to cause negative pore pressures to develop earlier than in the sealed samples and increased free shrinkage by 3 to 40 times depending on the mix. The samples that exhibited the highest free shrinkage strains, in exposed conditions, were the mixes that cracked when tested in the restrained shrinkage rings. The mixes that cracked all contained microsilica and these mixes did not crack when the same mixes were tested without microsilica. Polypropylene fibres were found to reduce the cracked area of the samples that cracked. The supplementary cementing materials used in this study were ground granulated blast furnace slag, metakaolin, microsilica and pulverised fuel ash.
7
Soong, Wai How. "Bonding between the concrete and Fiber Reinforced Plastic, FRP, rods." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62851.pdf.
Повний текст джерела
8
Tao, Shicheng. "Bond of glass-fiber-reinforced-plastic reinforcing bars to concrete." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186823.
Повний текст джерелаАнотація:
The objective of this research project was to study the bond behavior of Glass-Fiber-Reinforced-Plastic (GFRP) reinforcing bars (rebars) to concrete. A total of 102 specimens were experimentally investigated and theoretically analyzed at The University of Arizona. The static tensile load was applied to the rebars in a gradual increment of load level until splitting of concrete, rebar pull out failure, or rebar fracture occurred. The slip between the rebars and concrete was measured at the loaded and free ends at each load level. Variables included in the specimens were concrete compressive strength, embedment length, clear concrete cover, rebar diameter, concrete cast depth, radius of bend, tail length, and lead embedment length. On the basis of the experimental results, the study showed that concrete compressive strength, embedment length, clear concrete cover, concrete cast depth, and radius of bend had significant effects on bond of GFRP rebars to concrete. New criteria for acceptable bond performance of GFRP rebars to concrete were established. Furthermore, the practical design guidelines for calculating the development lengths of straight and hooked GFRP rebars to concrete were determined. In addition, confinement factors were also derived to reflect the influence of concrete cover and casting position.
9
Ball, Ryan. "Experimental analysis of composite reinforced concrete beams." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1177002341.
Повний текст джерела
10
Lee, Hon. "Fatigue behavior of concrete beams prestressed with glass fiber reinforced plastic (GFRP) tendon /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20LEE.
Повний текст джерела
11
Dimov, Dimitar. "Fundamental physical properties of graphene reinforced concrete." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34648.
Повний текст джерелаАнотація:
The global warming has increased with unprecedented levels during the last couple of decades and the trend is uprising. The construction industry is responsible for nearly 10% of all carbon emissions, mainly due to the increasing global population and the large demand for housing and civil infrastructure. Concrete, which is the most used construction material worldwide, is found in every type of building as it provides long term structural stability, support and its main constituent cement, is very cheap. Consequently, due to the raising concerns of high average temperatures, the research community started investigating new, innovative methods for substituting cement with 'greener' materials whilst at the same time improving the intrinsic properties of concrete. However, the manufacturing complications and logistics of these materials make them unfavourable for industrial applications. A novel and truly revolutionary method of enhancing the performance of concrete, thus allowing for decreased consumption of raw materials, lies in nanoengineering the cement crystals responsible for the development of all mechanical properties of concrete. Graphene, a two-dimensional sheet of carbon atoms arranged in a hexagonal lattice, is the most promising nanomaterial for composites' reinforcement to this date, due to it's exceptional strength, ability to retain original shape after strain, water impermeability properties and non-hazardous large scale manufacturing techniques. I chose to investigate the addition of liquid-phase exfoliated graphene suspensions for concrete reinforcement, aiming to improve the fundamental mechanical properties of the construction material and therefore allowing the industry to design buildings using less volume of base materials. First, the method of liquid exfoliation of graphene was developed and the resulting water suspensions were fully characterised by Raman spectroscopy. Then, concrete samples were prepared according to British standards for construction and tested for various properties such as compressive and flexural strength, cyclic loading, water impermeability and heat transport. A separate, in-depth, study was carried out to understand the formation and propagation of micro-structural cracks between the concrete's internal matrix planes, and graphene's impact on total fracture capacity and resistance of concrete. Lastly, multiple experiments were performed to investigate the microcrystallinity of cement hydration products using X-Ray diffraction. In general, all experimental results show a consistent improvement in concrete's performance when enhanced with graphene on the nanoscale level. The nanomaterial improves the mechanical interlocking of cement crystal, thus strengthening the internal bonds of the composite matrix. This cheap and highly scalable method for producing and mixing graphene with concrete turns it into the first truly applicable method for industrial applications, with a real potential to have positive impact on the global warming by decreasing the production of concrete.
12
Combrinck, Riaan. "Plastic shrinkage cracking in conventional and low volume fibre reinforced concrete." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6572.
Повний текст джерелаАнотація:
Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2011.ENGLISH ABSTRACT: Plastic shrinkage cracking (PSC) is the cracking caused by the early age shrinkage of concrete within the first few hours after the concrete has been cast. It results in unsightly surface cracks that serve as pathways whereby corroding agents can penetrate the concrete which shortens the expected service life of a structure. PSC is primarily a problem at large exposed concrete surfaces for example bridge decks and slabs placed in environmental conditions with high evaporation rates. Most precautionary measures for PSC are externally applied and aimed to reduce the water loss through evaporation. The addition of a low dosage of polymeric fibres to conventional concrete is an internal preventative measure which has been shown to reduce PSC. The mechanisms involved with PSC in conventional and low volume fibre reinforced concrete (LV-FRC) are however not clearly understood. This lack of knowledge and guidance leads to neglect and ineffective use of preventative measures. The objective of this study is to provide the fundamental understanding of the phenomena of PSC. To achieve the objective, an in depth background study and experiments were conducted on fresh conventional concrete and LV-FRC. The three essential mechanisms required for PSC are: 1→ Capillary pressure build-up between the particles of the concrete is the source of shrinkage. 2→ Air entry into a concrete initiates cracking. 3→ Restraint of the concrete is required for crack forming. The experiments showed the following significant findings for conventional and LV-FRC: PSC is only possible once all the bleeding water at the surface has evaporated and once air entry has occurred. The critical period where the majority of the PSC occurs is between the initial and final set of concrete. Any preventative measure for PSC is most effective during this period. The bleeding characteristics of a mix have a significant influence on PSC. Adding a low volume of polymeric fibres to concrete reduces PSC due to the added resistance that fibres give to crack widening, which increases significantly from the start of the critical period. The fundamental knowledge gained from this study can be utilized to develop a practical model for the design and prevention of PSC in conventional concrete and LV-FRC.
AFRIKAANSE OPSOMMING: Plastiese krimp krake (PSK) is die krake wat gevorm word a.g.v. die vroeë krimping van beton binne die eerste paar ure nadat die beton gegiet is. Dit veroorsaak onooglike oppervlak krake wat dien as kanale waardeur korrosie agente die beton kan binnedring om so die dienstydperk van die struktuur te verkort. Dit is hoofsaaklik ʼn probleem by groot blootgestelde beton oppervlaktes soos brug dekke en blaaie wat gegiet is in klimaat kondisies met hoë verdamping tempo’s. Meeste voorsorgmaatreëls vir PSK word ekstern aangewend en beperk die water verlies as gevolg van verdamping. Die byvoeging van ʼn lae volume polimeriese vesels is ʼn interne voorsorgmaatreël wat bekend is om PSK te verminder. Die meganismes betrokke ten opsigte van PSK in gewone beton en lae volume vesel versterkte beton (LV-VVB) is vaag. Die vaagheid en tekort aan riglyne lei tot nalatigheid en oneffektiewe aanwending van voorsorgmaatreëls. Die doel van die studie is om die fundamentele kennis oor die fenomeen van PSK te gee. Om die doel te bereik is ʼn indiepte agtergrond studie en eksperimente uitgevoer op gewone beton en LV-VVB. Die drie meganismes benodig vir PSK is: 1→ Kapillêre druk tussen die deeltjies van die beton is die hoof bron van krimping. 2→ Lugindringing in die beton wat krake inisieer. 3→ Inklemming van die beton is noodsaaklik vir kraakvorming. Die eksperimente het die volgende noemenswaardige bevindinge opgelewer: PSK is slegs moontlik indien al die bloeiwater van die beton oppervlakte verdamp het en indien lug die beton ingedring het. Die kritiese periode waar die meerderheid van die PSK plaasvind is tussen die aanvanklike en finale set van die beton. Enige voorsorgmaatreël vir PSK is mees effektief gedurende die periode. Die bloei eienskappe van ʼn meng het ʼn noemenswaardige effek op die PSK. Die byvoeging van ʼn lae volume polimeriese vesels tot beton verminder die PSK deur die addisionele weerstand wat die vesels bied teen die toename in kraakwydte. Die weerstand vergroot noemenswaardig vanaf die begin van die kritiese periode. Die fundamentele kennis wat in die studie opgedoen is, kan gebruik word vir die ontwikkeling van ʼn praktiese model vir die ontwerp en verhoed van PSK in gewone beton en LV-VVB.
13
Combrinck, Riaan. "Plastic shrinkage cracking in conventional and low volume fibre reinforced concrete." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71648.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Plastic shrinkage cracking (PSC) is the cracking caused by the early age shrinkage of concrete within the first few hours after the concrete has been cast. It results in unsightly surface cracks that serve as pathways whereby corroding agents can penetrate the concrete which shortens the expected service life of a structure. PSC is primarily a problem at large exposed concrete surfaces for example bridge decks and slabs placed in environmental conditions with high evaporation rates. Most precautionary measures for PSC are externally applied and aimed to reduce the water loss through evaporation. The addition of a low dosage of polymeric fibres to conventional concrete is an internal preventative measure which has been shown to reduce PSC. The mechanisms involved with PSC in conventional and low volume fibre reinforced concrete (LV-FRC) are however not clearly understood. This lack of knowledge and guidance leads to neglect and ineffective use of preventative measures. The objective of this study is to provide the fundamental understanding of the phenomena of PSC. To achieve the objective, an in depth background study and experiments were conducted on fresh conventional concrete and LV-FRC. The three essential mechanisms required for PSC are: 1→ Capillary pressure build-up between the particles of the concrete is the source of shrinkage. 2→ Air entry into a concrete initiates cracking. 3→ Restraint of the concrete is required for crack forming. The experiments showed the following significant findings for conventional and LV-FRC: PSC is only possible once all the bleeding water at the surface has evaporated and once air entry has occurred. The critical period where the majority of the PSC occurs is between the initial and final set of concrete. Any preventative measure for PSC is most effective during this period. The bleeding characteristics of a mix have a significant influence on PSC. Adding a low volume of polymeric fibres to concrete reduces PSC due to the added resistance that fibres give to crack widening, which increases significantly from the start of the critical period. The fundamental knowledge gained from this study can be utilized to develop a practical model for the design and prevention of PSC in conventional concrete and LV-FRC.
AFRIKAANSE OPSOMMING: Plastiese krimp krake (PSK) is die krake wat gevorm word a.g.v. die vroeë krimping van beton binne die eerste paar ure nadat die beton gegiet is. Dit veroorsaak onooglike oppervlak krake wat dien as kanale waardeur korrosie agente die beton kan binnedring om so die dienstydperk van die struktuur te verkort. Dit is hoofsaaklik ʼn probleem by groot blootgestelde beton oppervlaktes soos brug dekke en blaaie wat gegiet is in klimaat kondisies met hoë verdamping tempo’s. Meeste voorsorgmaatreëls vir PSK word ekstern aangewend en beperk die water verlies as gevolg van verdamping. Die byvoeging van ʼn lae volume polimeriese vesels is ʼn interne voorsorgmaatreël wat bekend is om PSK te verminder. Die meganismes betrokke ten opsigte van PSK in gewone beton en lae volume vesel versterkte beton (LV-VVB) is vaag. Die vaagheid en tekort aan riglyne lei tot nalatigheid en oneffektiewe aanwending van voorsorgmaatreëls. Die doel van die studie is om die fundamentele kennis oor die fenomeen van PSK te gee. Om die doel te bereik is ʼn indiepte agtergrond studie en eksperimente uitgevoer op gewone beton en LV-VVB. Die drie meganismes benodig vir PSK is: 1→ Kapillêre druk tussen die deeltjies van die beton is die hoof bron van krimping. 2→ Lugindringing in die beton wat krake inisieer. 3→ Inklemming van die beton is noodsaaklik vir kraakvorming. Die eksperimente het die volgende noemenswaardige bevindinge opgelewer: PSK is slegs moontlik indien al die bloeiwater van die beton oppervlakte verdamp het en indien lug die beton ingedring het. Die kritiese periode waar die meerderheid van die PSK plaasvind is tussen die aanvanklike en finale set van die beton. Enige voorsorgmaatreël vir PSK is mees effektief gedurende die periode. Die bloei eienskappe van ʼn meng het ʼn noemenswaardige effek op die PSK. Die byvoeging van ʼn lae volume polimeriese vesels tot beton verminder die PSK deur die addisionele weerstand wat die vesels bied teen die toename in kraakwydte. Die weerstand vergroot noemenswaardig vanaf die begin van die kritiese periode. Die fundamentele kennis wat in die studie opgedoen is, kan gebruik word vir die ontwikkeling van ʼn praktiese model vir die ontwerp en verhoed van PSK in gewone beton en LV-VVB.
14
Allen, Peter A. "A study of fiberglass-reinforced plastic for reinforcing concrete bridge decks." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-07112009-040533/.
Повний текст джерела
15
Vichit-Vadakan, Wilasa. "Shear behavior of pre-cracked, reinforced concrete beams retrofitted with glass fibert reinforced plastic sheet." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10737.
Повний текст джерела
16
Peng, Brian Hsuan-Hsien. "Seismic performance assessment of reinforced concrete buildings with precast concrete floor systems." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2009. http://hdl.handle.net/10092/3103.
Повний текст джерелаАнотація:
In the seismic design of reinforced concrete frames, plastic hinges are allocated to beams such that a ductile beam-sway mechanism will form in preference to other less ductile mechanisms in the event of a major earthquake. This is achieved by ensuring that the flexural strength of columns is greater than that corresponding to the maximum likely flexural strength of beam plastic hinges.
Recent experimental studies in New Zealand have shown that elongation of ductile beam plastic hinges, and its interaction with nearby floor slab containing precast-prestressed floor units, increases the strength of beams much more than that specified in New Zealand and American Concrete standards. This level of strength enhancement has raised concern on the adequacy of the current design provisions. To further investigate this problem, a research project was initiated to examine the strength of beam plastic hinges in reinforced concrete frames containing precast-prestressed floor units.
In this research, the strength of beam plastic hinges was assessed through experimental and analytical studies. A three-dimensional, one-storey, two-bay reinforced concrete moment resisting frame with prestressed floor units and cast-in-situ concrete topping was tested under quasi-static displacement-controlled cyclic loading. The experimental results provided insight into the mechanics associated with frame-floor interaction. Subsequently, improved design specifications were proposed based on the observed behaviour.
To analytically predict the beam-floor interaction, a ductile reinforced concrete plastic hinge multi-spring element was developed and validated with experimental results from cantilever beam and frame sub-assembly tests reported in the literature. The comparisons have demonstrated the ability of the proposed plastic hinge element to predict the flexural, shear, axial, and most importantly, elongation response of ductile plastic hinges.
The proposed plastic hinge element was implemented into an analytical model to simulate the behaviour of the frame-floor sub-assembly tested in this research. Specially arranged truss-like elements were used to model the linking slab (the region connecting the main beam to the first prestressed floor unit), where significant inelastic behaviour was expected to occur. The analytical model was found to be capable of predicting the non-linear hysteretic response and the main deformation mechanisms in the frame-floor sub-assembly test.
The analytical frame-floor model developed in this study was used to examine the effect of different structural arrangements on the cyclic behaviour of frames containing prestressed floor units. These analyses indicated that slab reinforcement content, the number of bays in a frame and the position of frame in a building (i.e., perimeter or internal frame) can have a significant influence on the strength and elongation response of plastic hinges.
17
Hall, Joanne Elizabeth. "Combined pultrude fibre reinforced plastic reinforcement and permanent formwork for concrete members." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365306.
Повний текст джерела
18
Manarakis, George S. "Properties and applications of fresh fibre reinforced concrete." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262346.
Повний текст джерелаАнотація:
Concrete is possibly the most widely used man-made construction material in the world. Low cost, versatility and adequate compressive strengths are reasons for the popularity of concrete construction. In the present investigation various properties of polyproplene and steel fibre reinforced cementitious composites in their plastic state, which influence slipforming (Chapter 3), such as early age shrinkage (Chapters 4, 5) and uniaxial tensile strength (Chapter 6) are investigated, while properties of the same mixes in their hardened state such as compressive and tensile splitting strength are also determined (Chapter 9). Three new experimental apparatae were developed during this investigation - one for the determination of the tensile stress-strain curve of fresh concrete (Chapter 6) and two for the investigation of early age shrinkage cracking of fresh concrete (Chapter 7). Theoretical aspects relating to the obtained experimental results were also considered (Chapters 6, 8). The experimental data was analysed by a digital computer with the aid of five FORTAN 77 computer programmes which were written by the author specifically for this purpose (Chapter 10).
19
Yurtseven, Alp Eren. "Determination Of Mechanical Properties Of Hybrid Fiber Reinforced Concrete." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605268/index.pdf.
Повний текст джерелаАнотація:
ABSTRACT
DETERMINATION OF MECHANICAL PROPERTIES OF
HYBRID FIBER REINFORCED CONCRETE
Yurtseven, Alp Eren
M.Sc. Department of Civil Engineering
Supervisor: Prof. Dr. Mustafa Tokyay
Co-Supervisor: Asst. Prof. Dr. . Özgü
r Yaman August 2004, 82 pages Fiber reinforcement is commonly used to provide toughness and ductility to brittle cementitious matrices. Reinforcement of concrete with a single type of fiber may improve the desired properties to a limited level. A composite is termed as hybrid, if two or more types of fibers are rationally combined to produce a composite that derives benefits from each of the individual fibers and exhibits a synergetic response. This study aims to characterize and quantify the mechanical properties of hybrid fiber reinforced concrete. For this purpose nine mixes, one plain control mix and eight fiber reinforced mixes were prepared. Six of the mixes were reinforced in a hybrid form. Four different types of fibers were used in combination, two of which were macro steel fibers, and the other two were micro fibers. Volume percentage of fiber inclusion was kept constant at 1.5%. In hybrid reinforced mixes volume percentage of macro fibers was 1.0% whereas the remaining fiber inclusion was v composed of micro fibers. Slump test was carried out for each mix in the fresh state. 28-day compressive strength, flexural tensile strength, flexural toughness, and impact resistance tests were performed in the hardened state. Various numerical analyses were carried out to quantify the determined mechanical properties and to describe the effects of fiber inclusion on these mechanical properties. Keywords: Fiber Reinforcement, Hybrid Composite, Toughness, Impact Resistance
20
Øfsdahl, Ellen. "Fibre-reinforced Self-compacting Concrete : Prediction of Rheological Properties." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18826.
Повний текст джерелаАнотація:
The purpose of this thesis is to investigate the relationship between measured rheology and proportioning properties with particular attention to maximum packing fraction, thickness of fiber lubricating matrix and fiber rotational overlap.This is done by conducting experiments on fresh concrete where the amount of matrix and fibres are varied, and comparing the rheological results with the proportioning parameters.The importance of an accurate grading curve is also evaluated.The hypothesis is that it is possible to find a correlation between calculated proportioning parameters and resulting rheology that will enable prediction of rheological properties.The results show that the variation in grading curve for the same aggregate is not very relevant to the proportioning parameters.The air content is shown to be of great importance regarding the correlation between matrix volume and packing fraction. Also it is found that it can be possible to predict the air volume based on matrix volume and fiber content.
21
Zanganeh, Mehdi. "Mechanical properties of fiber reinforced concrete with ACM applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0013/MQ52021.pdf.
Повний текст джерела
22
Mohammed, Hafeez. "Mechanical Properties Of Ultra High Strength Fiber Reinforced Concrete." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431021338.
Повний текст джерела
23
Masri, Haji Mohammad Khairul Ja'afar Awang Haji. "Elastic properties and local buckling of pultruded fibre reinforced plastic profiles." Thesis, Cardiff University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548179.
Повний текст джерела
24
SALAMI, MOHAMMAD REZA. "CONSTITUTIVE MODELLING OF CONCRETE AND ROCKS UNDER MULTIAXIAL COMPRESSIVE LOADINGS." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/184202.
Повний текст джерелаАнотація:
Characterization of stress-deformation behavior of concrete and rocks have been a subject of active research for a long time. Linear elastic, nonlinear (piecewise) linear elastic, elastic-plastic and endochronic models have been proposed and used by various investigators and the literature on the subjects is very wide. A review of various models together with their implementation is numerical (finite element) procedures is presented in Ref. (77). The primary objective of the present study is to develop a generalized constitutive model based on the theory of plasticity. Although such a model can be used for a wide range of materials, in this dissertation its applications to plain concrete and rocks are emphasised. One of the main objectives of this dissertation is to study constitutive behavior of concrete and soapstone under multiaxial load histories by using a truly triaxial or multiaxial testing device. The truly triaxial device is capable of applying a general three-dimensional state of stress. Samples can be tested along any three dimensional stress path. Therefore, constitutive behavior of concrete and soapstone can be studied under all possible states of stress. The conventional, octahedral, proportional loading and circular stress test series are conducted using the truly triaxial cubical device. For meaningful results, samples with consistent initial properties are essential. In order to produce samples with uniform initial properties such as density, equipment and procedures are developed to standardize the sample preparation process. The test data is used to determine the material constants associated with the proposed constitutive model. The model is then verified by back-predicting the stress-strain curves obtained from the laboratory.
25
Lim, Ee Yeong. "Bond strength and characteristics of Carbon Fibre Reinforced Plastic, CFRP, bars in concrete beams." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0034/MQ62242.pdf.
Повний текст джерела
26
Kazaz, Ilker. "Dynamic Characteristics And Performance Assessment Of Reinforced Concrete Structural Walls." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611712/index.pdf.
Повний текст джерелаАнотація:
The analytical tools used in displacement based design and assessment procedures require accurate strain limits to define the performance levels. Additionally, recently proposed changes to modeling and acceptance criteria in seismic regulations for both flexure and shear dominated reinforced concrete structural walls proves that a comprehensive study is required for improved limit state definitions and their corresponding values. This is due to limitations in the experimental setups, such that most previous tests used a single actuator at the top of the wall, which does not reflect the actual loading condition, and infeasibility of performing tests of walls of actual size in actual structural configuration. This study utilizes a well calibrated finite element modeling tool to investigate the relationship between the global drift, section rotation and curvature, and local concrete and steel strains at the extreme fiber of rectangular structural walls. Functions defining more exact limits of modeling parameters and acceptance criteria for rectangular reinforced concrete walls were developed. This way a strict evaluation of the requirements embedded in the Turkish Seismic Code and other design guidelines has become possible. Several other aspects of performance evaluation of structural walls were studied also. Accurate finite element modeling strategies and analytical models of wall and frame-wall systems were developed for seismic response calculations. The models are able to calculate both the static and dynamic characteristics of wall type buildings efficiently. Seismic responses of wall type buildings characterized with increasing wall area in the plan were analyzed under design spectrum compatible normal ground motions.
27
Maritz, Jaco-Louis. "An investigation into the use of low volume - fibre reinforced concrete for controlling plastic shrinkage cracking." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19983.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Plastic shrinkage cracking (PSC) in concrete is a well-known problem and usually occurs within the first few hours after the concrete has been cast. It is caused by a rapid loss of water from the concrete, either from the surface through evaporation or through absorption by dry subgrade or formwork in contact with the concrete and results in an overall reduction in concrete volume. If this volume reduction or shrinkage is restrained, plastic shrinkage cracks can occur. Plastic shrinkage cracks create an unsightly appearance on the concrete surface which reduces the quality of the concrete structure. These cracks also develop weak points in the concrete which can be widened and deepened later on by drying shrinkage and thermal movement. As a result harmful substances may enter the cracks causing accelerated concrete deterioration. These cracks may also expose the steel reinforcement causing it to corrode more aggressively. Consequently, the aesthetic value, serviceability, durability and overall performance of the concrete will be reduced. Therefore it is important to consider methods of limiting PSC. One of these methods is the addition of low volumes of polymeric fibres to concrete to reduce PSC. However, the application of this low volume fibre reinforced concrete (LV-FRC) is not clearly understood since there is a lack of knowledge and guidance available for the use of LV-FRC. The objective of this study is to gain a full understanding of PSC behaviour in conventional concrete and LV-FRC by investigating the effects of evaporation and bleeding as well as the effect of various fibre properties on PSC. The following significant findings were attained: A basis for a crack prediction model in conventional concrete was developed using the average differences in cumulative evaporation and cumulative bleeding to create a crack prediction value (CPV). This preliminary model showed that there exists a certain CPV range (-0.2 to 0.4 kg/m2 for this study) where a slight decrease in the CPV results in a significant PSC reduction. It also showed that if the CPV falls outside this range, varying the bleeding or evaporation conditions will have very little effect on the PSC. A study on the fibre properties in LV-FRC showed that there exist certain limits to the fibre volume, length and diameter where a further increase or decrease in value will have no or little effect on reducing PSC. It also showed that the effect of the fibres depend on the level of severity of PSC. The knowledge gained from this investigation can serve as a basis for the design of a model that can predict the risk of PSC in conventional concrete and specify preventative measures needed to reduce this risk. It also provides information that can be used to develop guidelines for the effective use of LV-FRC.
AFRIKAANSE OPSOMMING: Plastiese krimp krake (PKK) in beton is `n bekende probleem en vorm gewoonlik binne die eerste paar uur nadat die beton gegiet is. Dit word veroorsaak deur die vinnige waterverlies vanuit die beton, óf deur verdamping vanaf die beton oppervalk óf deur absorpsie van `n droeë grondlaag of bekisting wat in kontak is met die beton. Dit veroorsaak `n algehele vermindering in beton volume. As hierdie krimping van die beton beperk word, kan plastiese krimp krake ontstaan. PKK skep 'n onooglike voorkoms van die beton oppervlakte en verlaag die kwaliteit van die beton struktuur. Hierdie krake tree ook op as swak plekke in die beton wat later kan verbreed of verdiep deur droogkrimping en termiese beweging. Gevolglik kan skadelike stowwe vanuit die omgewing die krake binnedring wat lei tot versnelde agteruitgang van die beton. Hierdie krake kan ook die staalbewapening ontbloot wat veroorsaak dat dit vinniger roes. Gevolglik verminder die estetiese waarde, diensbaarheid, duursaamheid en algehele prestasie van die beton. Daarom is dit belangrik om metodes te ondersoek vir die beperking van PKK. Een van hierdie metodes is die byvoeging van lae volumes polimeer vesels tot beton om PKK te verminder. Die toepassing van hierdie lae volume - vesel versterkte beton (LV-VVB) word egter nog nie volledig verstaan nie as gevolg van 'n algemene gebrek aan kennis en riglyne vir die gebruik van die LV-VVB. Die doel van hierdie studie is om 'n volledige begrip van PKK gedrag in normale beton asook LV-VVB te kry. Dit word behaal deur die effek van verdamping en bloei op PKK sowel as die effek van verskillende vesel eienskappe op PKK te ondersoek. Die volgende noemenswaardige bevindinge is bekry. • Die basis van 'n kraak voorspellingsmodel vir gewone beton is ontwikkel deur gebruik te maak van die gemiddelde verskil tussen die kumulatiewe verdamping en die kumulatiewe bloei om 'n kraak voorspellingswaarde (KVW) te vorm. Hierdie voorlopige model toon dat daar `n sekere KVW interval ontstaan (-0,2 tot 0,4 kg/m2 vir hierdie studie) waar slegs 'n effense vermindering in die KVW 'n geweldige vermindering in die PKK tot gevolg het. Dit dui ook aan dat, indien die KVW buite hierdie interval val, ʼn verandering in die bloei of verdamping toestande `n baie klein invloed op die PKK het. 'n Studie oor die vesel eienskappe in LV-VVB het gewys dat daar sekere grense is aan die vesel volume, lengte en deursnee waardes, waar 'n verdere toename of afname in waarde min of geen effek het op die vermindering van PKK nie. Dit wys ook dat die effek van die vesels grotendeels afhanklik is van die risiko vlak vir PKK. Die kennis wat uit hierdie ondersoek opgedoen is, kan dien as 'n basis vir die ontwerp van 'n model wat die risiko van PKK in gewone beton kan voorspel en daarvolgens besluit op 'n voorkomingsmaatsreël om hierdie risiko te verminder. Dit bied ook inligting wat gebruik kan word om riglyne te ontwikkel vir die effektiewe gebruik van LV-VVB.
28
Walker, Adam Francis. "Assessment of material Strain Limits for Defining Different Forms of Plastic Hinge region in Concrete Structures." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2007. http://hdl.handle.net/10092/1231.
Повний текст джерелаАнотація:
The New Zealand Structural Loading Standard, until its latest revision, was using the structural displacement ductility factor as a measure of the deformation demand of all potential plastic hinges in a structure. In the revised version of New Zealand Structural Loading Standard for Earthquake Actions (NZS 1170.5:2004) the detailing of potential plastic regions is determined according to the local inelastic deformation demand in these regions. The change has been prompted by evidence that the structural ductility factor gives a poor indication of the demand on individual plastic regions. This is a major paradigm shift in international design codes. This new approach has been adopted by the New Zealand Concrete Structures Standard (NZS 3101:2006) which classifies potential plastic regions into three categories (namely ductile, limited ductile and nominally ductile) based upon their inelastic deformation demand which has been specified in terms of material strain limits in the form of curvatures or shear deformations. The values of material strain limits currently used in New Zealand Concrete Standard (NZS 3101:2006) to categorise the plastic regions are based on limited evidence and need a closer revision. This research attempts to obtain more justifiable values of material strain limits through experimental data existing in literature. Moreover, experimental testing is also conducted to compensate for a lack of data in the nominally ductile range of detailing. The experimental work explores the effects of transverse reinforcement arrangement, reinforcing steel grade and plastic hinge type. Together the literature review and experimental work provide a sound basis for re-defining the material strain limits for different plastic regions.
29
Kluyts, Grant. "Investigation of the effect of selected polypropylene fibres and ultra-fine aggregate on plastic shrinkage cracks on South African roads." Thesis, Nelson Mandela Metropolitan University, 2005. http://hdl.handle.net/10948/174.
Повний текст джерелаАнотація:
Plastic shrinkage cracks, although not inherently structurally debilitating, expose the reinforcement in low-volume reinforced concrete roads to deleterious substances, which may reduce its effectiveness leading ultimately to structural failure. In un-reinforced low-volume concrete road these cracks appear unsightly and cause the road user an unpleasant riding experience. Many researchers believe that plastic shrinkage crack development remains a concern to the concrete industry, occurring in particularly large–area pours such as low-volume concrete roads, and therefore requires further research to understand their formation and minimization. This study reports findings on the effectiveness of oxyfluorinated polypropylene fibres to control plastic shrinkage cracks, and the effect the addition of ultra-fine material has on the formation and/or propagation of these cracks. Findings indicate that low volume dosages (2 kg/m³), of oxyfluorinated polypropylene fibre significantly reduced the formation of plastic shrinkage cracks under test conditions. Furthermore, that the addition of ultra-fine material in excess of 63 kg/m³ increased the formation and/or development of plastic shrinkage cracks.
30
Ulas, Esref M. "The comparative performance and behaviour of concrete elements containing glass-fibre reinforced plastic reinforcing bars." Thesis, Sheffield Hallam University, 2001. http://shura.shu.ac.uk/20467/.
Повний текст джерелаАнотація:
Corrosion of steel reinforcement is a major concern in concrete construction, particularly in aggressive environments. Therefore corrosion resistant materials such as fibre composites are becoming increasingly feasible as an alternative concrete reinforcement. There are relatively few reported design guidelines for fibre composites in concrete. Hence, there is an urgent need for research and development to extend existing guidelines and standards such as those produced by the UK Institution of Structural Engineers and the ACI Committee (US), to encourage the wider use and acceptance of fibre composites as an alternative to steel in reinforced concrete elements. This investigation compares the behaviour and properties of a range of reinforced concrete beams under two point loading comprising different concrete grades and types using both steel and Glass Fibre Reinforced Plastic (GFRP) as primary and secondary reinforcement. A variety of conventional and 'novel' rebar configurations were used to assess their effect upon material efficiency and load capacity. Compressive and tensile strength and elastic moduli of all component properties were measured together with load, deflection, rebar and concrete strains on the reinforced concrete beams. Health and safety concepts through a risk assessment process were introduced for the testing at an early stage of the investigation. Principal measures of beam performance include the ultimate load capacity, stiffness and failure modes together with a 'performance quotient'; a mathematical expression derived as an efficiency comparator for beams of different types and composition. Photographic and video records were also used to monitor behaviour throughout. Experimental measurements generally showed good agreement with the corresponding theoretical, quasi-theoretical and design based values although the latter tended to overestimate the structural performance of the beams. In general, load capacity increased with increase in main rebar area but was affected to a lesser extent by concrete strength. The beams reinforced with steel had a greater load capacity than those reinforced with GFRP. However, GFRP reinforced beams generally displayed a greater capacity to absorb energy than steel but exhibited reduced stiffness at any given load although this was enhanced by the inclusion of glass fibres in the mix. Cracks in the GFRP reinforced beams were usually larger and deeper compared with those in the equivalent steel reinforced beams. Failure of the more lightly reinforced steel beams, including one GFRP beam, were predominantly in 'flexure'. The more heavily reinforced steel and the remainder of the GFRP reinforced beams exhibited mostly 'shear-bond' type failure. The 'novel' rebar geometry proved to be a simple, efficient and viable alternative to conventional rebar configurations in terms of load capacity and preferred mode of failure. It is suggested that further developments and applications could focus on small reinforced concrete elements such as lintels in aggressive environments and further refinement of the 'performance quotient' concept.
31
Lai, Tin Ka. "Effects of fiber addition on various properties of shotcrete and concrete /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202002%20LAIT.
Повний текст джерелаАнотація:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 162-163). Also available in electronic version. Access restricted to campus users.
32
Adwan, Osama K. "Engineering properties and structural behaviour of high strength reinforced concrete beams." Thesis, University of Abertay Dundee, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360744.
Повний текст джерела
33
Bajaj, Srikanth. "Effect of Corrosion on Physical and Mechanical Properties of Reinforced Concrete." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353961865.
Повний текст джерела
34
Acun, Bora. "Energy Based Seismic Performance Assessment Of Reinforced Concrete Columns." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611728/index.pdf.
Повний текст джерелаАнотація:
Severe seismic events in urban regions during the last two decades revealed that the structures constructed before the development of modern seismic codes are the most vulnerable to earthquakes. Sub-standard reinforced concrete buildings constitute an important part of this highly vulnerable urban building stock. There is urgent need for the development and improvement of methods for seismic performance assessment of existing reinforced concrete structures.
As an alternative to current conventional force-based assessment methods, a performance evaluation procedure for structural members, mainly reinforced concrete columns is proposed in this study, by using an energy-based approach combined with the low cycle fatigue concept. An energy-based hysteresis model is further introduced for representing the inelastic response of column members under severe seismic excitations. The shape of the hysteresis loops are controlled by the dissipated cumulative energy whereas the ultimate strength is governed by the low cycle fatigue behavior. These two basic characteristics are obtained experimentally from full scale specimens tested under constant and variable amplitude
displacement cycles.
The first phase of the experimental program presented in the study constitutes of testing sub-standard non-conforming column specimens. The second phase of testing was conducted on standard, code compliant reinforced concrete columns. A
total number of 13 specimens were tested. The behavior of these specimens was observed individually and comparatively according to the performance based objectives. The results obtained from the experiments were employed for developing relations between the energy dissipation capacity of specimens, the specimen properties as well as the imposed displacement history. Moreover, the measured rotation capacities at the plastic regions are evaluated comparatively with the limits proposed by modern displacement-based seismic design and assessment provisions.
35
Shirmohammadi, Fatemeh. "Effect of load pattern and history on performance of reinforced concrete columns." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20448.
Повний текст джерелаАнотація:
Doctor of PhilosophyCivil Engineering
Asadollah Esmaeily
Accurate and realistic assessment of the performance of columns in general, and those in critical locations that may cause progressive failure of the entire structure, in particular, is significantly important. This performance is affected by the load history, pattern, and intensity. Current design code does not consider the effect of load pattern on the load and displacement capacity of columns. A primary research sponsored by Kansas Department of Transportation (KDOT) was conducted as the initial step of the present study (No. K-TRAN: KSU-11-5). The main goals of the KDOT project were: (1) investigation of new KDOT requirements in terms of the column design procedure and detailing and their consistency with AASHTO provisions; (2) verification of the KDOT assumptions for the plastic hinge regions for columns and bridge piers, (3) provide assessment of the load capacity of the existing columns and bridge piers in the light of the new specifications and using the new load demand as in the new provisions; and finally recommendations for columns and bridge piers that do not meet the new requirements. A conclusion was drawn that there is a need for conducting more studies on the realistic performance of Reinforced Concrete (RC) sections and columns. The studies should have included performance of RC members under various loading scenarios, assessment of columns capacity considering confinement effect provided by lateral reinforcement, and investigation on performance of various monotonic and cyclic material models applied to simulate the realistic performance. In the study reported here, monotonic material models, cyclic rules, and plastic hinge models have been utilized in a fiber-based analytical procedure, and validated against experimental data to simulate behavior of RC section under various loading scenarios. Comparison of the analytical predictions and experimental data, through moment–curvature and force–deflection analyses, confirmed the accuracy and validity of the analytical algorithm and models. The performance of RC columns under various axial and lateral loading patterns was assessed in terms of flexural strength and energy dissipation. FRP application to enhance ductility, flexural strength, and shear capacity of existing deficient concrete structures has increased during the last two decades. Therefore, various aspects of FRP-confined concrete members, specifically monotonic and cyclic behavior of concrete members confined and reinforced by FRP, have been studied in many research programs, suggesting various monotonic models for concrete confined by only FRP. Exploration of existing model performances for predicting the behavior of several tested specimens shows a need for improvement of existing algorithms. The model proposed in the current study is a step in this direction. FRP wrapping is typically used to confine existing concrete members containing conventional lateral steel reinforcement (tie/spiral). The confining effect of lateral steel reinforcement in analytical studies has been uniquely considered in various models. Most models consider confinement due to FRP and ignore the effect of conventional lateral steel reinforcement. Exploration of existing model performances for predicting the behavior of several tested specimens confined by both FRP and lateral steel shows a need for improvement of existing algorithms. A model was proposed in this study which is a step in this direction. Performance of the proposed model and four other representative models from literature was compared to experimental data from four independent databases. In order to fulfill the need for a simple, yet accurate analytical tool for performance assessment of RC columns, a computer program was developed that uses relatively simple analytical methods and material models to accurately predict the performance of RC structures under various loading conditions, including cyclic lateral displacement under a non-proportionally variable axial load (Esmaeily and Xiao 2005, Esmaeily and Peterman 2007). However, it was limited to circular, rectangular, and hollow circular/rectangular sections and uniaxial lateral curvature or displacement. In this regards, a computer program was developed which is the next generation of the aforesaid program with additional functionality and options. Triangulation of the section allows opportunity for cross-sectional geometry. Biaxial lateral curvature/displacement/force combined with any sequence of axial load provides opportunity to analyze the performance of a reinforced concrete column under any load and displacement path. Use of unconventional reinforcement, such as FRP, in lateral as well as longitudinal direction is another feature of this application.
36
Knox, Joanne Jennefer. "Aspects of modelling plain and reinforced concrete at elevated temperatures." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7713.
Повний текст джерелаАнотація:
Extreme events such as the Mont Blanc Tunnel fire in 1999 (Bettelini et al. 2001) or the Windsor Tower fire in 2005 (Calavera et al. 2005) have shown how concrete failure at elevated temperatures can be hazardous to the safety of members of the public. Generally, there is an absence of understanding of the mechanical behaviour of both plain and reinforced concrete at elevated temperatures, which is essential for computational modelling. Since fire is an extreme event, a certain amount of damage within the structure would be seen to be permissible within its performance objectives. This necessitates analysis in the post-peak regime. As a material, concrete has a very low value of thermal conductivity. This means that large thermal gradients often occur within concrete, causing differential expansion of the material. This, coupled with the change in mechanical properties at elevated temperatures, further complicates analytical analysis procedures. This study investigates issues associated with computational modelling of plain and reinforced concrete at elevated temperatures and its residual behaviour (behaviour when tested after the material has been heated, for example in a fire, and then cooled). In order to achieve this, first the constitutive material properties of both plain and reinforced concrete at ambient and elevated temperatures were investigated. The study showed that mesh sensitivity and localisation of strain softening occurs in plain concrete under both tensile and compressive loading. Path dependency of the stress-strain behaviour of plain concrete was also demonstrated, when it was subjected to loading and heating. Tension stiffening was included in the reinforced concrete material model, to represent the interaction between concrete and reinforcing steel. Complex behaviours were seen for simple reinforced concrete benchmark tests, due to changing material properties at elevated temperatures and differential thermal expansion of steel and concrete. Non-linear load-displacement relationships were seen as a result of complex load-sharing between concrete and reinforcement. A hypothesis was proposed – that variation of temperatures during heating and cooling of a specimen will cause damage, and hence material degradation, in plain and reinforced concrete. On investigation, it was seen that damage due to differential thermal expansion plays a small part in the reduction of elastic load-displacement slope and peak strength seen in experimental data on residual tests, indicating that other factors identified in previous research also affect the residual behaviour of plain and reinforced concrete. Indeed, in reinforced concrete, when tension stiffening was included, it was found that damage due to differential thermal expansion and contraction had a negligible effect on the residual response in the pre-peak regime. The study also found that for a simply supported beam pure thermal expansion caused a localised response, while pure thermal gradient gave distributed yield. When both were present, in this study, distributed yield with no mesh sensitivity was seen. Realistic heating of a restrained reinforced concrete plane strain model caused compressive stresses accompanied by tensile longitudinal total strains and tensile longitudinal plastic strains throughout the depth of the slab, with the largest values occurring near to the model supports. Damage and recovery variables were found to have no effect on the response of the model. When a portal frame was exposed to heating, plastic strains were distributed throughout the beam, with column rotation limiting downward thermal bowing due to a uniformly distributed load or thermal gradient present. Application of displacement loading causing plastic damage changed the behaviour of the structure under heating – instead of symmetrical compressive plastic strains being induced, areas of varying tensile and compressive strain were caused within the beam. Throughout, simple, easily reproducible simulations were used so that single parameters could be altered and considered. This was important, so that the important parameters to computational modelling could be identified. These can be used to guide experimental series to ensure that they are investigated, in order to improve computational material models. Not all variations of parameters were investigated in this study, but it is clear where further repetition would be beneficial (e.g. in varying thermal expansion and thermal gradient ratios in heating regimes). This study looks to address experimentalists and people working in structural analysis, who would be interested in the parameters investigated, as well as practitioners who may want to use these results.
37
永正, 邵., and Yongzheng Shao. "Study on the effects of matrix properties on the mechanical properties of carbon fiber reinforced plastic composites." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12902982/?lang=0, 2015. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12902982/?lang=0.
Повний текст джерелаАнотація:
It was found that a significant improvement of mechanical properties of CFRPs can be achieved by the adjustment of the matrix properties such as toughness and CF/matrix adhesion via the chemical modification, as well as the physical modification by a small amount of cheap and environment-friendly nano fibers. Based on investigation of fracture mechanisms at macro/micro scale, the effects of matrix properties and nano fiber on the mechanical properties of CFRP have been discussed. Subsequently, the relationship has been characterized by a numerical model to show how to modulate the parameters of the matrix properties to achieve excellent fatigue properties of CFRP.博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
38
Mutlu, Mehmet Basar. "Numerical Simulations Of Reinforced Concrete Frames Tested Using Pseudo-dynamic Method." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614460/index.pdf.
Повний текст джерелаАнотація:
Considering the deficiencies frequently observed in the existing reinforced concrete buildings, detailed assessment and rehabilitation must be conducted to avoid significant life and value loss in seismic zones. In this sense, performance based evaluation methods suggested in the regulations and codes must be examined and revised through experimental and analytical research to provide safe and economical rehabilitation solutions.
In this study, seismic behavior of three reinforced concrete frames built and tested in Middle East Technical University Structural Mechanics Laboratory is examined. The specimens are extracted from a typical interior frame of 3-story 3-bay reinforced concrete structure. One of the specimens has compliant design according to Turkish Earthquake Code (2007) and each of the other two specimens represents different types of deficiencies in terms of material strength and detailing. The test specimens were modeled using different modeling approaches and nonlinear dynamic analyses were conducted on the numerical models. Results of continuous pseudo-dynamic testing of three ground motions are presented and compared with the numerical simulations on models. Calibrated finite element models were used for evaluation of performance assessment procedure of Turkish Earthquake Code (2007) and further investigation on local deformation components in light of experimental findings and observations. Deformation sources of columns and joints were studied in terms of their interaction and contributions to the total drift. Estimated plastic hinge lengths of columns were compared with the experimental observations and the proposed expressions in the literature.
39
Chang, Lei. "Experimental Data on Fire-Resistance Behavior of Reinforced Concrete Structures with Example Calculations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3003/.
Повний текст джерелаАнотація:
This thesis selects concrete, steel and their relation as research subjects, mainly commentary and discusses the property changes of steel and concrete materials under and after high temperature.The differences and comparisons of reasearch methods and ways between different researchers and different papers,particularly for chinese researches and chinese papers,and partly for comparison between chinese papers methods and Euro-Amercian papers methods about Fire Resistance Behavior of Reinforced Concrete will be summarized and analyzed.The researches on fire-resistance behavior of reinforced concrete become more and more important all over the world. And I would find differences between Chinese researches results, between Chinese researches results and other countries researches results.
40
Bakhshandeh, Mohammad. "Macro Synthetic Fiber Reinforced Concrete: Effect Of Fiber Embedded Length On Interface Properties." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Знайти повний текст джерелаАнотація:
Summary of the Thesis
This thesis concerns the study of the Macro-Synthetic Fiber, with the main objective of analyzing the effect of fiber embedded length on interface bond properties regard to different concrete mix design parameters. In particular the effect of different fiber embedded length, Water-Cement ratio (W/C), Cement-Sand ratio (C/S) and Cement strength on interfacial bond properties will be studied.
The research is carried on by means of experimental direct pull-out tests on crimped macro-synthetic fibers embedded for two different lengths in a cementitious matrix characterized by different mix design. The experimental program employed is a part of a bigger experimental campaign on macro fiber reinforced concrete behavior which is under investigation at the University of Bologna.
This experimental campaign was done to contribute the overall understanding of the fiber reinforced concrete, with the main goal of the calibration of a constitutive debonding law through numerical model and codification of fiber reinforced concrete in future, which is discussed in details in 5 Chapters in this study.
41
Duraman, Pg Saiful Baharin Pg. "Microstructure and Properties of Steel-Reinforced Concrete Systems Hydrated at 20C and 38C." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485783.
Повний текст джерелаАнотація:
The microstructure and engineering properties of steel-reinforced ordinary Portland cement (OPC) concrete hydrated at standard 20°C and elevat~d 38°C temperatures were investigated. Conduction calorimetry and microanalysis supported the main tests. Neat OPC, and blended OPC with 50% and 70% ground granulated blastfumace slag (GGBS) were' used for all tests. The principal microstructural investigation was quantification of hydration products from both rebar-concrete and aggregate-hcp interfaces using- Image Analysis of Backscattered Electron (BSE) Images. Engineering tests showed that elevated temperature mixes had lower workability and late age strength, and higher early strength and heat evolution compared to standard temperature mixes. Blended OPC mixes had higher workability and lower heat evolution but generally did not exceed their neat OPC mix counterparts In compressive strengths. Quantitative microstructural results showed that OPC mixes had higher calcium hydroxide (CH) and porosity, and lower anhydrous at the interfaces compared to the bulk. The GGBS mixes showed higher porosity, and lower anhydrous and GGBS at - - the. interfaces compared to the bulk, whilst CH levels were low throughout. The interface slope trends of.GGBS showed better packing and hence a narrower interfacial transition zone (ITZ) for the GGBS mixes compared to the OPC mixes. Elevated temperature GGBS mixes showed poorer quality rebar-concrete interfaces suggesting the importance of curing. Microanalytical results showed statistically different Inner Product (IP) C-S-H ratios between the. OPC and GGBS mixes, and generally between the mixes at different temperatures. Predominantly non-statistically significant differences were observed between the different distances from the rebar-concrete interface for the same mixes. The study suggested benefits of GGBS at elevated temperatures, provided sufficient curing is applied. Microstructural tests showed that it was pos~ible to analyse sectioned polished real reinforced concrete specimens. Image Analysis showed that it was possible although difficult to analyse elevated temperature and GGBS mixes.
42
Brockmann, Tanja. "Mechanical and fracture mechanical properties of fine grained concrete for textile reinforced composites." Aachen : Mainz, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=97972127X.
Повний текст джерела
43
Annam, Ramyasree. "Study of Mechanical Properties of PVA Fiber-Reinforced Concrete With Raman Spectroscopic Analysis." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1460.
Повний текст джерелаАнотація:
The brittleness of concrete has always been a safety and economic issue of great concern. The low tensile strength of concrete is the cause of its intrinsic brittle nature. This is critical considering the amount of concrete used for the construction of highways, buildings, and other facilities. The mechanical properties of concrete must be improved to provide upgraded construction. Crack resistant and durable concrete has always been a major goal for engineers. Many approaches have been tried to make concrete a better construction material. Fiber reinforcement is an approach which has been shown to improve the quality and durability of concrete. The focus of this research is to develop a mix design of fiber reinforced concrete and then test these materials for both compressive and tensile strength after casting into cubes. The effect of polyvinyl alcohol fibers on the mechanical properties of concrete was also studied. The impacts of moisture and the stress applied on the fibers were determined using Raman spectroscopy.
44
Roth, Michael Jason 1975. "Flexural and tensile properties of thin, very high-strength, fiber-reinforced concrete panels." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11062007-215816.
Повний текст джерела
45
Stander, Heinrich. "Interfacial bond properties for ECC overlay systems." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/405.
Повний текст джерела
46
Zhang, Yi. "The effect of inkjet printed polymer on the mechanical properties of carbon fibre reinforced plastic." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11184/.
Повний текст джерелаАнотація:
A new toughening method is presented in this thesis that uses inkjet printing to deposit toughening materials between carbon fibre reinforced plastic (CFRP) laminate plies prior to the curing cycle. Inkjet printing has the ability of precisely depositing material onto targeted positions, thus a controlled amount of toughening materials can be used to print dimension controllable patterns. Poly(methyl methacrylate) (PMMA) and polyethylene glycol (PEG) were dissolved in suitable solvents respectively to form printable solutions for inkjet printing. Different patterns and substrates were employed to investigate the repeatability of using inkjet printing to deposit polymer solutions. Microscopy showed that the designed patterns can be repeatedly printed onto substrates with controllable dimensions. A range of 0.025 – 0.2 vol.% of toughening material was used to prepare CFRP laminates for mechanical tests. Mechanical properties of the inkjet printed CFRP laminates were tested by means of double cantilever beam and short beam shear tests to determine mode I interlaminar facture toughness (GIc) and apparent interlaminar shear strength (ILSS) respectively. The GIc of polymer printed laminates increased as the overall amount of polymer deposits increased before reaching to an optimum. A maximum 40% increase in GIc was observed in a system with printed 10 wt.% PMMA deposits that were hexagonally patterned. Different patterns and pattern densities were investigated, among which the hexagon with a higher pattern density performed the best in terms of material usage efficiency. Although laminates with a printed PMMA film possessed the highest GIc compared to the other printed groups that used discrete dots, the crack propagation was unstable. Additionally, the improvement in GIc did not result in a reduction of the ILSS for the polymer printed laminates, except for the film printed group. The damage tolerance of PMMA printed laminates was also enhanced based on the images obtained from X-ray tomography and scanning electron microscopy (SEM). The proposed toughening mechanism is as follows: the polymer deposits remain strategically dispersed along predicted crack pathways with controllable size. Once microcracks occur between composite plies, the arrayed toughening materials can address crack propagation by plastic deformation and/or deflection of crack pathways due to debonding between toughening material and surrounded epoxy resin. The plasticization of localised epoxy region is also believed to be a contribution to the observed mechanical improvement.
47
Ameli, Mehran. "Investigating the behaviour of FRP strengthened reinforced concrete beams under torsion /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18734.pdf.
Повний текст джерела
48
Ryno, Barnard. "Mechanical properties of fly ash/slag based geopolymer concrete with the addition of macro fibres." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95866.
Повний текст джерелаАнотація:
Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: Geopolymer concrete is an alternative construction material that has comparable mechanical properties to that of ordinary Portland cement concrete, consisting of an aluminosilicate and an alkali solution. Fly ash based geopolymer concrete hardens through a process called geopolymerisation. This hardening process requires heat activation of temperatures above ambient. Thus, fly ash based geopolymer concrete will be an inadequate construction material for in-situ casting, as heat curing will be uneconomical. The study investigated fly ash/slag based geopolymer concrete. When slag is added to the matrix, curing at ambient temperatures is possible due to calcium silicate hydrates that form in conjunction with the geopolymeric gel. The main goal of the study is to obtain a better understanding of the mechanical properties of geopolymer concrete, cured at ambient temperatures. A significant number of mix variations were carried out to investigate the influence that the various parameters, present in the matrix, have on the compressive strength of fly ash/slag based geopolymer concrete. Promising results were found, as strengths as high as 72 MPa were obtained. The sodium hydroxide solution, the slag content and the amount of additional water in the matrix had the biggest influence on the compressive strength of the fly ash/slag based geopolymer concrete. The modulus of the elasticity of fly ash/slag based geopolymer concrete did not yield promising results as the majority of the specimens, regardless of the compressive strength, yielded a stiffness of less than 20 GPa. This is problematic from a structural point of view as this will result in large deflections of elements. The sodium hydroxide solution had the most significant influence on the elastic modulus of the geopolymer concrete. Steel and polypropylene fibres were added to a high- and low strength geopolymer concrete matrix to investigate the ductility improvement. The limit of proportionality mainly depended on the compressive strength of the geopolymer concrete, while the amount of fibres increased the energy absorption of the concrete. A similar strength OPC concrete mix was compared to the low strength geopolymer concrete and it was found that the OPC concrete specimen yielded slightly better flexural behaviour. Fibre pull-out tests were also conducted to investigate the fibre-matrix interface. From the knowledge gained during this study, it can be concluded that the use of fly ash/slag based geopolymer concrete, as an alternative binder material, is still some time away as there are many complications that need to be dealt with, especially the low modulus of elasticity. However, fly ash/slag based geopolymer concrete does have potential if these complications can be addressed.
AFRIKAANSE OPSOMMING: Geopolimeerbeton is ‘n alternatiewe konstruksiemateriaal wat vergelykbare meganiese eienskappe met beton waar OPC die binder is, en wat bestaan uit ‘n aluminosilikaat en ‘n alkaliese oplossing. Vliegas-gebaseerde geopolimeerbeton verhard tydens ‘n proses wat geopolimerisasie genoem word. Hierdie verhardingsproses benodig hitte-aktivering van temperature hoër as dié van die onmiddellike omgewing. Gevolglik sal vliegas-gebaseerde geopolimeerbeton ‘n ontoereikende konstruksiemateriaal vir in situ gietvorming wees, aangesien hitte-nabehandeling onekonomies sal wees. Die studie het vliegas/slagmentgebaseerde geopolimeerbeton ondersoek. Wanneer slagment by die bindmiddel gevoeg word, is nabehandeling by omliggende temperature moontlik as gevolg van kalsiumsilikaathidroksiede wat in verbinding met die geopolimeriese jel vorm. Die hoofdoel van die studie was om ‘n beter begrip te kry van die meganiese eienskappe van geopolimeerbeton, wat nabehandeling by omliggende temperature ontvang het. ‘n Aansienlike aantal meng variasies is uitgevoer om die invloed te ondersoek wat die verskeie parameters, aanwesig in die bindmiddel, op die druksterkte van die vliegas/slagmentgebaseerde geopolimeerbeton het. Belowende resultate is verkry en sterktes van tot so hoog as 72 MPa is opgelewer. Daar is gevind dat die sodiumhidroksiedoplossing, die slagmentinhoud en die hoeveelheid water in die bindmiddel die grootste invloed op die druksterkte van die vliegas/slagmentgebaseerde geopolimeerbeton gehad het. Die styfheid van die vliegas/slagmentgebaseerde geopolimeerbeton het nie belowende resultate opgelewer nie. Die meeste van die monsters, ongeag die druksterkte, het ‘n styfheid van minder as 20 GPa opgelewer. Vanuit ‘n strukturele oogpunt is dit problematies, omdat groot defleksies in elemente sal voorkom. Die sodiumhidroksiedoplossing het die grootste invloed op die styfheid van die vliegas/slagmentgebaseerde geopolimeerbeton gehad. Staal en polipropileenvesels is by ‘n hoë en lae sterke geopolimeer beton gevoeg om die buigbaarheid te ondersoek. Die die maksimum buigbaarheid het hoofsaaklik afgehang van die beton se druksterkte terwyl die hoeveelheid vesels die beton se energie-opname verhoog het. ‘n OPC beton mengsel van soortgelyke sterkte is vergelyk met die lae sterkte geopolimeerbeton en daar is gevind dat die OPC beton ietwat beter buigbaarheid opgelewer het. Veseluittrektoetse is uitgevoer om die veselbindmiddel se skeidingsvlak te ondersoek. Daar kan tot die gevolgtrekking gekom word dat, alhoewel belowende resultate verkry is, daar steeds sommige aspekte is wat ondersoek en verbeter moet word, in besonder die styfheid, voordat geopolimeerbeton as ‘n alternatiewe bindmiddel kan optree. Volgens die kennis opgedoen tydens hierdie studie, kan dit afgelei word dat die gebruik van vliegas/slagmentgebaseerde geopolimeerbeton, as 'n alternatiewe bindmiddel, nog 'n geruime tyd weg is, as gevolg van baie komplikasies wat gehandel moet word, veral die lae elastisiteitsmodulus. Tog het vliegas/slagmentgebaseerde geopolimeerbeton potensiaal as hierdie komplikasies verbeter kan word.
49
Al-Bastaki, Nader Mohamed Saleh. "The effects of strain rate on the mechanical properties of filament wound-fibre reinforced plastic tubes." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364039.
Повний текст джерела
50
Shi, Jiawanjun. "Properties of alkaline-resistant calcium-iron-phosphate glasses." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/Shi_09007dcc8043f8f6.pdf.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 25, 2008) Includes bibliographical references (p. 52-54).