360R-06 Design of Slabs-on-Ground
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| 10.3.2.8 Durability in corrosive environments—Plain
carbon steel fibers are protected from corrosion by the alkaline environment of the cementitious matrix and their electrical discontinuity. Laboratory and field testing of intact steel FRC shows that in the long term, steel fiber corrosion is limited to a depth of 0.1 in. (2.5 mm). Laboratory and field testing of cracked steel FRC in an environment containing chlorides indicates that fibers passing across the crack can corrode similar to conventional reinforcement but without causing spalling (Hoff 1987). Previous studies showed that crack widths of less than 0.004 in. (0.1 mm) do not allow corrosion of steel fibers passing the crack (Morse and Williamson 1977); however, more recent studies show that crack widths up to 0.02 in. (0.5 mm) have no adverse effect on corrosion of steel fibers. If cracks wider than 0.02 in (0.5 mm) are limited in depth, the consequences of this localized corrosion may not be structurally significant. 10.3.3 Thickness design methods—Three methods available for selecting the thickness of steel FRC slabs-on-ground are described in this section: • PCA, WRI, and COE thickness design methods; • Elastic method; • Yield line method; • Nonlinear finite modeling; • Combined steel FRC and bar reinforcement. These design methods are dependent on steel FRC attaining a minimum level of ductility. In addition, suggested performance levels are provided in Table 10.1 for various floor loading conditions. These values represent a compila- tion of performance values obtained from trade literature. 10.3.3.1 PCA/WRI/COE method—The PCA/WRI/COE methods described in Chapter 6 may all be applied to the design of steel FRC slabs-on-ground. Using this approach, steel fiber reinforcement will be used for serviceability design issues such as temperature and shrinkage crack control, enhanced joint stability, and impact and fatigue resistance. For specific designs or steel fiber quantities, fiber manufacturers should be consulted. tải về 2.35 Mb. Chia sẻ với bạn bè của bạn:
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