Internal reinforcement

The ultrasonic tomograph A1230 was developed to visualize in case of one side access the internal reinforced concrete structure at the depth of 1 m. This device uses 36-elements matrix array. 

Internal At one time open-weave hessian cloth was very largely used as an internal reinforcement material, but experience showed that this is subject to rotting in the soil. Even when the material appears to be covered with enamel, some of the fibres must protrude, and thus moisture is absorbed so that after a period of years the hessian is generally found to be in a waterlogged condition and forming food for bacteria. 

The lattice-type shelf is functionally as good as the others, but it may not look appropriate for a book shelf in the context of a library. A second consideration is a combination of physical requirements and appearance. A simple plastic beam that will function adequately in terms of strength and stiffness may be rather thin. A shelf of this type can look flimsy even if it is functional. This impression is useful to the designer since the solid plate is probably an uneconomical use of material. A requirement was added that the design should look like a wood shelf since this is the context in which it is to be used. To produce the desired thickness appearance either a lipped pan with internal reinforcement can be used or, alternatively, a sandwich-type structure with two skins and a separator core. In either case the displacement of the material from the plane of bending will improve the stiffness efficiency of the product. The appropriate procedure is to... 

Use of coupling agents for internally reinforced rayon fibers... 

Coupling agents can enhance the adhesion in internally reinforced rayon fibers. This improvement over fibers coated without a coupling agent is dependent on... 

Internal reinforcement A study by Sen et al. (1998) conducted over a 45-month period indicated that bond degradation adversely affected the ultimate capacity of AFRP-reinforced pretensioned piles driven in tidal waters, whereas the CFRP-reinforced piles were largely unaffected. 

Internal reinforcement Odagiri et al. (1997) investigated relaxation characteristics of 6 and 7.4 mm (0.24 and 0.29 in) diameter AFRP tendons with anchorages. Overall, the relaxation rates for AFRP rods were found to be approximately 11% at 1000 hours, and 15% at 17,700 hours (two years). Creep rupture, the tensile rupture of a material subjected to sustained high stress levels over a period of time, is another important concern for FRP reinforcing bars. 

Internal reinforcement In the case of internal reinforcement, fatigue loading is more likely to affect the concrete and the bond between the concrete and the FRP reinforcement than the FRP itselt It should, however, be noted that cracking in concrete could cause abrasion-related damage to the FRP surface, which could result in higher environmental exposure to moisture and solutions. 

Internal reinforcement UV radiation is not a concern for internal radiation. 

For the cross-section analysis, different bond properties must be considered by using the bond coefficients k = 0.7 and Kt = 0.9 for the internal reinforcement steel bars and the externally bonded strips, respectively. For compatibility relationships in the cross-section analysis, the mean values of the strains, s, in the internal steel reinforcement and ft in the EBFR can be used however, for the equilibrium relationships, the maximum values of the strains for the internal reinforcement steel bars and the externally bonded strips. 

The fundamental idea behind the SLS verification is to limit the strain in the EBFR to ensure that the internal steel reinforcement does not yield at serviceability. The strains in the internal reinforcement, and in the EBFR, Ei, can be calculated using cross-section analysis identical to that used for the ultimate hmit state and should be limited to... 

To ensure enough ductility of the strengthened structure at failure, fib-bulletin-14 (2001) gives limitations for the minimum strain in the internal reinforcement ... 

Fibre reinforced polymer (FRP) composite materials for internal reinforcement... 

Howe, R.J. and Owen, M.J., Cumulative damage in CSM/polyester resin laminates, BPF 8th International Reinforced Plastics Conference, Brighton, 1972. 

Fig. 2. a The organisation of the corneocytes, mutually fixed by desmosomes, provides a scaffold for (b) stacked bilayers of lipids in the intercellular space between corneocytes. c, d The dispersion of keratin fibrils in the plane of the skin surface results in an internal reinforcement that stabilises the cell form in this plane, e This intracellular reinforcement allows expansion of the cell only in the direction perpendicular to the skin surface... 

Energy Content of Reinforced Plastics Materials, International Reinforced Plastics Industry (IRPI), London, Nov. 1981. 

In the particular case of the apphcation of glass-fibre reinforced vinylester composites as internal reinforcement for concrete bridge deck slabs, the results showed their superior fatigue performance and longer fatigue life when compared with the steel-reinforced ones (El-Ragaby et al., 2007). 

Internal reinforcement of concrete structures using FRP bars in replacement of steel gratings... 

Passive FRP bars are increasingly being used as internal reinforcement for concrete structures (beams, slabs, columns, decks), especially in Canada and in the United States where the weather conditions can be very harsh. 

To account for the material evolutions, guidelines dedicated to the external or internal reinforcements of concrete structures using FRP composites usually introduce substantial durability parameters (reduction factors on FRP tensile properties and on shear characteristics of FRP/concrete bonded interfaces, creep stress levels and fatigue limits) see, for instance, ACI 440.2R-08 (2008) and ACI 440.1R-06 (2006). However, further research is still needed to refine the design codes and better calibrate the durability reduction factors taking into account synergistic effects between various environmental factors. 

During the last decade, there have been continuous improvements in the selection of constitutive materials, in the manufacturing processes and the field implementation of polymer composites for civil engineering applications. The use of FRP materials as externally bonded reinforcement is now an attractive solution to increase the lifespan of existing concrete infrastructures, while their use as internal reinforcing bars or as structural members is intended to prevent corrosion problems and increase the overall durability of new constructions exposed to severe environments. Nevertheless, key issues regarding the long-term durability of FRPs for infrastructure applications have been only partially addressed, and there remain considerable needs for research and development in this field ... 

Hybrid FRP/concrete stmetural columns filled with concrete with or without internal reinforcement have been investigated by many researchers including Fam and Rizkalla (2001a) Mirmiran (2003) and Xiao (2004). This work was extended to two concentric FRP tubes where the annulus was filled with... 

European Polymer Journal Dental materials NDT International Reinforced Plastics... 

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