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- Gylltoft, Kent, 1945, et al.
(författare)
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Tests to determine the modulus of elasticity for CFRP confined concrete columns in stage above the bearing capacity of unconfined concrete
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This study covered investigations into the compressive behaviors of concretes strengthened by CFRP of various qualities. Concrete of three strengths were used - 20, 40 and 60MPa in cubic strength. The confined specimens had the size of diameter: 150, 250, 350mm keeping the shape ratio of height to diameter = 3 unchanged. The wrapping was 3, 5 and 7 layers for small size specimens (150mm x 450mm) and 5 layers for medium size (250mm x 750mm). The results were that no scale effect was observed between two dimension ratios of concrete samples. It was shown that the loading paths in the normalized stress space merge to the single master curve determined by the line of the concrete strength as function of the lateral pressure. From this observation follows, that in the nonlinear region the tangent modulus of the confined concrete E2 and differential Poisson ratio a can be expressed a simple formulae. The non-dimensional parameter is a function of only non-dimensional parameter , where the lateral modulus El = Ej h/R ( - radius of specimen, - thickness of carbon confinement, - modulus of confinement). The confined column breaks when the stress in the composite jacket reaches its critical level.
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| 2. |
- Rempling, Rasmus, 1976, et al.
(författare)
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Utmattningsbelastad betong
- 2009
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Ingår i: Bygg och Tenkik.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Tepfers, Ralejs, 1933
(författare)
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A theory of bond applied to overlapped tensile reinforcement splices for deformed bars
- 1973
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A bond theory for deformed reinforcing bars in concrete is elaborated taking into account different stages in development of final rupture occurring as splitting or pull-out. The concrete cover splitting resistance is modelled for a thick-walled concrete ring in elastic and plastic stages. Different final possible failure modes are analysed. Stress distributions along the spliced bars and in surrounding concrete are investigated. The theory is applied on overlapped tensile reinforcement splices. Tests have been performed on more than 300 spliced beams and results show plausible agreement with theory. The influence of different types of confinement on splice strength as stirrups and spirals has been investigated. Fatigue of overlapped splices is discussed and investigated.
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| 5. |
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| 6. |
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| 7. |
- Tepfers, Ralejs, 1933
(författare)
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Betona impregnesana ar silaniem
- 2009
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Ingår i: Latvijas buvnieciba. Celvedis Buvniecibas nozares vrzitajiem. - 1691-4058. ; :4, s. 44-46
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
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| 9. |
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| 10. |
- Tepfers, Ralejs, 1933
(författare)
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Bond clause proposal for FRP-bars/rods in concrete based on CEB/FIP Model Code 90 with discussion of needed tests
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- ABSTRACTThe bond clauses in the CEB/FIP Model Code 1990, (MC90), were written for steel reinforcement in concrete. After finalization of the MC90 the further work within CEB and after the merger with FIP in the new organization fib should be directed towards covering up lacunae and also adapting the Model Code to new materials. The basic MC90 concepts should be kept when applied to new materials. Models should be used to justify the clauses. However, the bond clauses in MC90 were not fully based on models, because there are very many options for bond failures and it is difficult to cover up these with few models. Reinforcing steel is more or less just one material. FRPs, on the other hand, are made of a lot of different materials with manifold shapes and all these FRPs perform differently in many contexts. Especially in severe environments, where steel is not durable, FRPs may perform well. To make use of the fiber composites, it is necessary to bring these materials to codes of practice and the closest is to try to adapt the code for steel reinforced concrete to FRP reinforced. The clauses should be given with boxed values open for individual coefficients for different FRPs. The necessary coefficients should be determined for the code models using systems of appropriate and coupled test methods.
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