In the example of the simply supported beam in § 3.4.1 the beam is 4.00 m long and therefore, the total length may vary between 3.96 m and 4.04 m. The constructional deviation does not affect the support rebars (1) and (2), which will be formed with a total length equal to 1.50 m instead of 1.39 (where the last length will become 1.27 rather than 1.16).
The lower and upper rebars of the beam are affected by the constructional deviation. This is the reason why the bars length must be shortened by 40 mm, however, the hooks may become larger so as to achieve the required final length (hooks must not extend outside the concrete’s mass and must abide by the necessary beam’s cover thickness).
The rebars (3) will have a total length of 4.50 m instead of 4.37, with a span length equal to 3.87 rather than 3.91 and their hooks will be 0.38 long instead of 0.30.
Consequently the reinforcement bars (4) will have a total length equal to 3.50 m rather than 3.48, with span length 3.09 instead of 3.13 and their hooks will be 0.23 long rather than 0.20.
The rebars (5) will have a total length of 4.50 m instead of 4.33, with span length equal to 3.82 rather than 3.86 and their hooks will be 0.40 long instead of 0.30.
For further details into the quantity take-off matter but also for all the various matters discussed, it is advisable to study the corresponding printed book.