descriptive note on bar bending shedule

Bar bending schedule or BBS is a list of reinforcement bars in tabular form which provides the following important details:

1. Bar mark, which indicates the right position of the bar in a structure.
2. The diameter of the bar.
3. The shape of the bar.
4. The dimension of bending of the bar.
5. The number of same bar types.
6. The length of all bars.
7. Total length.
8. Weight .
9. Total weight.

From BBS we can know the reinforcement of different bar sizes and bars are cut and bent appropriately at the job site. It also ensures proper checking and completion of estimates in a short time. The dimension of bends should be so given in the BBS that minimum calculation is required for the making of bars and further setting the machine and stops.

The shapes and proportions of hooks and bends in the reinforcement bars are shown in Fig. 1– these are standard proportions that are conformed to:

(a) Length of one hook = (4d ) + [(4d+ d )] – where, (4d+ d ) = 9d. (Curved portion)

(b) The additional length (la) that is introduced in the simple, straight end-to-end length of a reinforcement bar due to bending at θ° say 30o to 60o, generally, 45o is considered)

∴ la = l1 – l2

Fig 1: Hooks and bends in Reinforcement

Let θ = 30°, 45°, 60° respectively

The length of hooks and the total length of a given steel reinforcement is achieved by the following method.