Ps,effas J

The above expression, which is valid only for as > asr, is a function of 3 parameters. Therefore some assumption regarding peff must be made in order to obtain table 7.2. The assumption which will be made is that peff =peff,min (i.e. as = asr). This assumption is justified because lower values of as will not produce cracking and because if cracking does occur, then formula (7.14) will give smaller bar diameters if the smallest the value of peff is used. The value of peff can therefore be taken from the following equation:

If the above value of peff is substituted into Eq. (7.12), this equation can be simplified into:

In Table 1 the minimum reinforcement ratio which can to be used in equation (7.14) is given for each stress level. In the same table, the maximum bar diameter obtained using equation (7.14) for wk=0.3 mm and that included in MC-90 Table 7.4.3 are also given.

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