Concrete estimating procedure

Concrete and Structural Steel quantities can be easily checked with the quick estimating procedures in Chapter 19. 

The unit hours shown in the concrete and insulation estimating procedures are intended for planning and scheduling only, since the unit costs are based on all inclusive subcontract prices. 

The thorough treatment of the experimental data does allow one to obtain reliable values of the reactivity ratios. The results of such a treatment are presented in Table 6.3 for some concrete system let us form a notion about an accuracy of the reactivity ratios estimations. The detailed analysis of such a significant problem in the case of the well-studied copolymerization of styrene with methyl methacrylate is reported in Ref. [227]. Important results on the comparison of the precision of rj, r2 estimates by means of different methods are presented by O Driscoll et al. [228]. Such a comparison of six well-known linear least-squares procedures [215-218,222,223] with the statistically correct non-linear least-squares method leads to the conclusion that some of them [216, 217, 222] can provide rather precise rls r2 estimates when the experiment is properly planned. 

Other workers have published improved procedures for inspecting both reinforced concrete and prestressed concrete structures with regard to determination of the embedded steel components [110]. A prototype ultrasonic procedure was developed to determine the condition of prestressed and pretensioned tendons in concrete. The application of electrochemical surface-mounted systems for estimating the rate of corrosion of reinforcing steel and other embedded steel components in large concrete structures was described using this technique. 

Table 12.5 Initiation time for chloride-induced corrosion estimated for different concrete cover thicknesses, utilising apparent diffusion coefficients of chlorides (D,pp) evaluated on specimens submerged in the North Sea for 16 y (concrete of 420 kg/m of Portland cement, OPC, or blast furnace slag cement with 70% GGBS and identical curing procedures) [18]...

It is normal (in the United Kingdom and Europe) to determine the chloride concentration as a percentage by mass of sample but to quote chloride concentrations in weight percent of cement so the cement content must be known or estimated (usually assumed to be 14%). This is not a very accurate procedure which is why in North America they quote chloride contents in pounds per cubic yard of concrete. The European approach has a better grounding in the mechanism of corrosion, while the North American approach is more accurate in practice, but slightly less informative. 

In the recipe adopted for treatment of the fast-neutron attenuation, it is assumed that all fast neutrons entering the concrete are captured after penetrating the concrete by a distance equal to the "age displacement." IHie secondary y rays so formed are then postulated to all flow outward with the estimated 10 cm relaxation length. The required shielding is calculated on the basis that these y rays and the neutrons are to be attenuated to tolerance. It can be shown that this- is a more conservative- procedure than that of considering an exponentially distributed source of capture y rays from the absorption - of the neutrons in the- shield. ... 

Proposed procedures are applied in the assessment of an existing reinforced concrete road bridge. Partial factors are estimated on the basis of new information about the bridge conditions and requirements for a remaining working life. 

Detailed analytical procedures have been evolved for the estimation of phosphorus in such diverse materials as drinking water, sea water, food products, plants, concrete, ores and rocks, oils, metals, pesticides and fertilizers. Each of these materials has its own special analytical requirements. In the case of fertilizers, for example, it is usual to estimate (a) water-soluble phosphate which relates to available phosphorus and (b) citrate-insoluble phosphate which is a measure of the phosphorus which plants cannot utilise. In the case of seawater, both dissolved P and particulate P content may be estimated. 

Yield drift obtained through Eq. 3 is generally evaluated as the comer for an ideal envelope approximating a bilinear force deformation response of the element and not as the drift corresponding to the first yielding in the reinforcement steel (or equivalently in the concrete) at the first section of the element. Figure 3 shows the procedure by Elwood and Eberhard (2009) for the definition of yielding displacement on the envelope of measured lateral load-displacement relationship corrected for P-delta. Elwood and Eberhard s procedure covers both the cases in which yield force is attained in the envelope (Fig. 3a) and cases in which the calculated yield force is not attained (Fig. 3b) in fact, it provides an estimate of effective stiffness also in the case of columns that do not yield (see Fig. 3b). 

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