Estimating Sheet

# How to arrange the bar bending schedule for floor slabs

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Bar bending schedule is a crucial document for structural engineering that aptly provides the disposition, bending shape, total length, and quantity of all the reinforcements included in a structural drawing.

It is arranged in a separate sheet (generally A4 paper) from the structural drawing. The bar marks from structural detailing drawing are transmitted directly to the bar bending schedule.

Generally, reinforcements are calculated on the basis of their total mass in tonnes or kilograms. For smaller projects, estimation can be done depending on the required length.

Unit mass of rebars: The unit mass of the reinforcements are generated from the density of steel. Here, the density of steel is taken as 7850 kg/m3.

As for instance, select 12mm bar.

The area is provided as (πd2)/4 = (π × 122)/4 = 113.097mm2 = 0.0001131m2

Based on the unit length of the bar, it can be examined that the volume of a metre length of the bar is 0.0001131m3

Density = Mass/Volume = 7850 kg/m3 = Mass/0.0001131
So, the unit mass of 12mm bar = 7850 × 0.0001131 = 0.888 kg/m
So, for any diameter of bar;

Basic weight = 0.00785 kg/mm2 per metre
Weight per metre = 0.006165 ϕ2 kg
Weight per mm2 at distance s(mm) = 6.165ϕ2/s kg

Here; ϕ stands for the diameter of bar in millimeters

Bending Shapes: There exist some elementary standard shapes that contain specific shape codes in the code of practice. But presently, it is recommended to sketch the bending shape on the document to ignore the confusion regarding the selection of the shape code from perfect document. If possible, all these information should be arranged in the document.

To get the length of reinforcement bars, apply the relation given below;

Length of bar = Effective Length + Width of Support – Concrete cover (s) – Tolerances

To get the standard values of tolerances (deductions), go through the following link www.structville.com