The unit weight of steel bars can be calculated using the formula for the weight of a cylindrical object, which takes into account the density of steel and the cross-sectional area of the steel bar. Here’s the formula:

Unit weight of steel bar=Cross-sectional area×Length×Density of steel

The cross-sectional area of the steel bar can be calculated using the formula for the area of a circle:

$Cross-sectional area=π×Diameter $

Where:

- Diameter: Diameter of the steel bar in inches or millimeters.
- Length: Length of the steel bar in inches or feet (for imperial units) or in millimeters or meters (for metric units).
- Density of steel: The density of steel is typically taken as 7850 kilograms per cubic meter (kg/m³) or 490 pounds per cubic foot (lb/ft³), although slight variations may occur depending on the specific grade and composition of the steel.

Here’s a step-by-step example of how to calculate the unit weight of a steel bar:

- Determine the diameter of the steel bar (in inches or millimeters).
- Calculate the cross-sectional area using the formula: $Cross-sectional area=π×Diameter $
- Determine the length of the steel bar (in inches or feet for imperial units, or in millimeters or meters for metric units).
- Multiply the cross-sectional area by the length and the density of steel to obtain the unit weight of the steel bar.

For example, let’s say we have a steel bar with a diameter of 1 inch and a length of 10 feet:

$Cross-sectional area=π×(inch)2/4 ≈0.7854square inches$

Unit weight of steel bar=0.7854 square inches×(10 feet)×(490 lb/ft3)

Unit weight of steel bar≈3846 pounds

So, the unit weight of the steel bar is approximately 3846 pounds.