For knowing the estimation for the cost of the structure, it’s essential to know the quantities of materials including those of the reinforcement. Precise quantities of the concrete and brickwork can be calculated from the layout drawings. If working drawings and schedules for the rebar aren’t available then it’s essential to provide an estimate of the anticipated quantities. The quantities are generally described as per the requirements of the standard method of measurement of building works.
Methods for Estimating the Quantities of Reinforcement
The simplest method is based on the type of structure and the volume of the reinforced concrete elements. Given are some examples with typical values:
However, while this method is a helpful check on the total estimated quantity, it’s least precise, and it needs substantial experience to break the tonnage down to standard method of measurement requirements.
Another method is using the factors that convert the structural areas obtained from the initial design calculations to weights. If the weights are divided into practical bar diameters and shapes, this method give a reasonably precise evaluation. The factors, however, do assume a degree of standardization both of structural form and detailing. This method is likely to be the most flexible and relatively accurate in practice, as it’s based on reinforcement requirements indicated by the initial design calculations.