Prestressing 6, 253 cables

Already a brief view on the "translation table , table 1, shows, that the pure analogy-reasoning can neither describe completely nor solve the problem to analyse the elastomechanics of prestressed cable-nets and all their derivatives. Let us look at the example below, table 2 ... 

When additional structural material such as steel reinforcing bars or rebars are added, the concrete is defined as steel reinforced concrete, while when prestressed cables are inserted, concrete is defined as prestressed concrete. As a general rule Portland cement should always... 

Traditional reinforcement of concrete elements in the form of steel bars and prestressing cables or tendons is not studied here as it is mentioned in Section 2.3.1 and only dispersed fibre reinforcement is considered. Macrofibres are usually of 10-60 mm in length and 0.1-1.0 mm in the least dimension. Micro-fibres are of 10-30 pm in diameter and below 10 mm in length. There are several kinds of microfibres non-metallic, including asbestos, polypropylene, mica, wollastonite and xonotlite, and steel fibres. In the following chapter both these gronps of fibres are considered made with different materials (cf. ACT 544.1R-96). 

Fig. 8.1. Sectional view of Wylfa magnox reactor (courtesy of U.K. Central Electricity Generating Board). 1, Reactor pressure vessel 2, fuel elements 3, graphite moderator 4, charge standpipes 5, guide tube assemblies 6, safety relief valve penetration 7, pile cap 8, charge machine on transporter 9, neutron shield 10, boiler 11, radial grid 12, gas circulator 13, gas circulation moter drives 14, pressure vessel prestressing cables 15, core gas inlet plenum 16, vessel man access 17, CO2 penetration 18, structural support columns 19, boiler steam and feed pipework.

The roof steel structure (Fig. 14) consists of six parallel main arches having a span of 60 m and spaced at a distance of 10.5 m that are interconnected by means of purlins and horizontal bracings. Each main arch is pinned on the ground on one edge, while the other edge is supported by a V-shaped column. The arches are suspended by prestressed cables from a 25 m tall pylon, which has a slight inclination with respect to the vertical plane. The stability in and out of plane of the pylons is ensured by two back-stayed prestressed cables. 

Steel wire and strand formed into cables is commonly used in the prestressing of concrete and in suspended or cable stayed structures such as bridges. In both cases it is sometimes necessary to splay the constituent wires or strands at the end anchorages in order to spread the load being transferred to the support material. 

Realkalization has been carried out on prestressed structures, but only on the reinforcing steel. The structure has post-tensioned cables in ducts. These were protected from the current by the ducts and by the fact that they were buried deep in the concrete, well below the reinforcing steel (Miller, 1994). It should be noted that carbonation is a rare problem on prestressed concrete structure.s as they usually use high strength, high cement content, low water/cement ratio concrete mixes that are highly resistant to carbonation. 

Medium and ultra-high strength bar, rod, and cable in prestressed and post-tensioned concrete components. 

Klymov (State Research Institute of Building Construction, Kiev). Monitoring of stressed-strained state and forces in cables of prestressed containment shells of NPPs. Joint Wano/OECD-NEA. Workshop, Civaux, Poitiers, France, 1997. 

Both the Frankline Institute [2] and the Oak Ridge Laboratory [2] in the USA made a start on the research and development required for the Fort St. Vram high-temperature gas-cooled reactor. The choice was made of a cylinder with flat top and bottom caps. Both in the wall and in the cap the prestressing was by means of cables of variable curvature. 

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