| 1. |
- Claeson-Jonsson, Christina, 1967, et al.
(författare)
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Slender concrete columns subjected to sustained and short-term eccentric loading
- 2000
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Ingår i: ACI Structural Journal. - 0889-3241. ; 97:1, s. 45-52
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Tidskriftsartikel (refereegranskat)abstract
- A test series examining the structural behavior of six slender reinforced concrete columns subjected to short-term and sustained loading is presented. The columns had cross sections 200 x 200 mm and were 4 m long. Concrete strengths used were 35 and 92 MPa with a load eccentricity of 20 mm. Key parameters such as concrete strength, concrete and steel strains, cracking, midheight deflection, and loading rate were studied. The high-strength (HSC) columns subjected to short-term loading displayed less ductility and more sudden failures than the normal strength concrete (NSC) columns. Furthermore, the tests conducted indicated that the structural behaviour of the HSC is favorable under sustained loading, i.e., the HSC column exhibited less tendency to creep and could sustain the axial load without much increase in deformation for a longer period of time. An analysis based on a simplified stability analysis, using a stress-strain relation for concrete that includes creep, aging, and the confining effect of the stirrups was carried out. The model was shown to simulate the load-deflection curves satisfactorily for all of the concrete columns.
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| 2. |
- Fall, David, 1983, et al.
(författare)
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Non-linear Finite Element Analysis of Steel Fibre Reinforced Beams with Conventional Reinforcement
- 2012
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Ingår i: 8th RILEM International Symposium on Fiber Reinforced Concrete: challenges and opportunities (BEFIB 2012). - 9782351581322 ; , s. 1033-1045
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study has been to investigate the behavior of elements reinforced with both conventional steel reinforcement and steel fibres in order to support future applications of such composites. Three beams of varying fibre content were tested in four-point bending. The results were then compared with results from nonlinear FE-analyses and the calculation method suggested in fib Model Code 2010. The beams were a part of a larger experimental programme where relevant properties were investigated in uniaxial tension tests and pull-out tests. The FE-modeling was performed using a two dimensional plane stress model. General agreement between experiments and the FE-analyses was obtained with regard to load-displacement behavior. The crack patterns from the FE-analysis and experiments agreed in general, although the crack patterns in the analysis were more distributed close to the reinforcement. Crack localization was enhanced by modifying the bond-slip behavior to include the bond loss at yielding. Calculations in accordance with fib Model Code 2010 yield conservative results in comparison with both experiments and FE-analysis.
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| 3. |
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| 4. |
- Fall, David, 1983, et al.
(författare)
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Reinforcing tailor-made concrete structures: Alternatives and challenges
- 2012
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Ingår i: Engineering Structures. - : Elsevier BV. - 1873-7323 .- 0141-0296. ; 44, s. 372-378
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in automated concrete production make it possible to produce geometrically complex concrete structures. The purpose of this paper is to review reinforcement alternatives suitable for such structures and to analyse the problems associated with the geometrical complexity, not only in the reinforcement itself, but also in design. A review of the literature on reinforcement alternatives and governing standards shows that conventional steel reinforcement load bearing structures cannot easily be set aside. Any deviation from the standard structural elements, e.g. beams, walls and slabs, introduces design problems for most structural engineers. Approaches to problems of this complex nature are discussed here. Further developments needed are indicated: being able to choose the reinforcement direction, and optimisation with regard to parameters other than the reinforcement amount, e.g. feasibility of production. Furthermore, the need for a rational design process is discussed and some key issues, such as software incompatibilities are raised.
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| 5. |
- Fall, David, 1983, et al.
(författare)
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Skräddarsydda betongkonstruktioner
- 2010
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Ingår i: Bygg & Teknik. - 0281-658X. ; 2010:7:2010:7 Oktober, s. 20-22
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Att kunna skräddarsy betongkonstruktioner, så att man på ett rationellt sätt kan ta tillvara betongens formbarhet i olika konstruktioner är målet med EU-projektet TailorCrete. Med moderna hjälpmedel är det är idag fullt möjligt att, med hjälp av en industrirobot, direkt från en tredimensionell modell fräsa ut betongformer i formsand eller cellplast. Detta har i forskningssyfte utförts i forskningsprojektet Unikabeton (www.unikabeton.dk) av bland annat. Teknologisk Institut och Mærsk Mc-Kinney Møller Instituttet på Syddansk Universitet. Genom att tillämpa sådan modern teknik undviks avancerade handgjorda formverk, vilka idag är tidsödande, dyra och stället höga krav på hantverksskicklighet.
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| 6. |
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| 7. |
- Fang, Congqi, 1963, et al.
(författare)
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Bond behaviour of corroded reinforcing steel bars in concrete
- 2006
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 36:10, s. 1931-1938
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Tidskriftsartikel (refereegranskat)abstract
- The effect of steel corrosion on bond between steel bars and the surrounding concrete was investigated for different corrosion levels. Both pullout tests and finite element analysis were used and the results from the two were compared. An electrolyte corrosion technique was used to accelerate steel corrosion. For confined deformed bars, a medium level (around 4%) of corrosion had no substantial influence on the bond strength, but substantial reduction in bond took place when corrosion increased thereafter to a higher level of around 6%. It is demonstrated that the confinement supplied an effective way to counteract bond loss for corroded steel bars of a medium (around 4% to 6%) corrosion level. The results of finite element analyses, where it was assumed that rust behaved like a granular material, showed a reasonably good agreement with the experiments regarding bond strength and bond stiffness.
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| 8. |
- Fang, Congqi, 1963, et al.
(författare)
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Effect of corrosion on bond in reinforced concrete under cyclic loading
- 2006
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 36:3, s. 548-555
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Tidskriftsartikel (refereegranskat)abstract
- Cyclic loading can result in severe deterioration in the bond between reinforcing steel bar and the surrounding concrete, especially when the reinforcement is corroded. In this study, tests were carried out for bond stress-slip response of corroded reinforcement with concrete under cyclic loading. Parameters investigated include: corrosion level, confinement, bar type, and loading history. The results revealed that bond behaviour was significantly reduced under cyclic loading. Degradation in bond was significantly less for deformed bars than for smooth bars at the initial loading cycle, but the difference was diminished with loading. The bond reduction was more substantial for unconfined steel bars than for confined bars. The relatively high level of corrosion caused degradation primarily in the initial five cycles, the effect of corrosion being decreased with loading. It was also demonstrated that the cyclic bond stress-slip curves depended on loading history.
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| 9. |
- Fang, Congqi, 1963, et al.
(författare)
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The effect of corrosion on concrete bridges
- 2004
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Ingår i: Bridge Maintenance, Safety, Management and Cost / edited by Eiichi Watanabe, Dan M. Frangopol, Tomoaki Utsunomiya. - 9058096807
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Konferensbidrag (refereegranskat)
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| 10. |
- Grassl, Peter, 1974, et al.
(författare)
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A damage-plasticity model for the dynamic failure of concrete
- 2011
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Ingår i: 8th International Conference on Structural Dynamics, Leuven, Belgium.
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Konferensbidrag (refereegranskat)abstract
- A constitutive model based on the combination of damage mechanics and plasticity is developed to analyse concretestructures subjected to dynamic loading. The aim is to obtain a model, which requires input parameters with clear physicalmeanings. The model should describe the important characteristics of concrete subjected to multiaxial and rate-depending loading.This is achieved by combining an effective stress based plasticity model with an isotropic damage model based on plastic andelastic strain measures. The model response in tension, uni-, bi- and tri-axial compression is compared to experimental results inthe literature.
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