To ensure accurate cost assessment in construction, it is imperative to estimate the quantity of steel reinforcement for various elements such as slabs, columns, and footings. The process begins with obtaining dimensions and reinforcement details from design drawings, as illustrated in Fig.1.
Refer to design drawings for slab dimensions and reinforcement details. For the main steel bars, use the formula:
No. of bars=Slab length (L)Spacing+1(Equation 1)
Similarly, for shrinkage and temperature steel bars:
No. of bars=Slab length (S)Spacing+1(Equation 2)
Refer to Fig. 1 for a visual representation of types and arrangement of steel bars in a one-way slab.
Determine cutting length for main steel bars using:
Cutting length=Clear span (S)+Ld+Inclined length+2×45∘ bend(Equation 3)
For shrinkage and temperature steel bars:
Cutting length=Clear span (S)+Ld+Inclined length+2×45∘ bend(Equation 4)
Convert cutting length into kilograms or tons using:
Main steel bars=No. of bars×Cutting length×Weight of the bar162(Equation 7)
Note: Weight of a steel bar is derived from its volume times density (7850 kg/m³).
Understanding the size and reinforcement details of the footing is crucial. Follow these steps:
No. of bars=(Length or width (L or W) – Concrete cover for both sidesSpacing)+1(Equation 8)
Length of bar=L or W – Concrete cover for both sides+2×Bend length(Equation 9)
Compute the total length of bars, and convert this length into kilograms or tons by multiplying the cross-sectional area of steel by its total length and the density of steel (7850 kg/m³).
Repeat the calculation procedure for footings with a double reinforcing net.
Acquire column size and reinforcement details from design drawings and proceed with the following steps:
Compute the total length of longitudinal bars, which is the column height plus laps for footing multiplied by the number of longitudinal bars.
Convert this length into kilograms or tons by multiplying the cross-sectional area of steel by its total length and the density of steel (7850 kg/m³).
By following these detailed steps, one can accurately determine the required steel quantity for slabs, footings, and columns in construction projects.