BAR BENDING SCHEDULE OF SLABS

 

Standard reinforcing bars, also known as rebars, typically come in various sizes and weights. The dimensions and weights can vary somewhat depending on the specific standard used (such as ASTM in the United States or BS in the United Kingdom). Here are some common sizes and weights for reinforcing bars:

1. Rebar Sizes: Rebars are usually designated by their nominal diameter in millimeters.

   • Diameter: Common diameters range from 6 mm to 50 mm or more, with typical increments being 6, 8, 10, 12, 16, 20, 25, 32, and 40 mm.

2. Weights: The weight of a rebar can be calculated based on its diameter. The weight is usually specified in kilograms per meter (kg/m).

   • Weight Calculation: The weight $W$ of a rebar of diameter $d$ in millimeters can be calculated using the formula:

     $$W = \frac{\pi \times d^2}{4} \times \text{Unit weight of rebar}$$

     Where:

     • $\pi$ (pi) is approximately 3.14159,
     • $d$ is the diameter of the rebar in millimeters,
     • Unit weight of rebar varies by standard and grade (e.g., ASTM A615/A615M in the US specifies different weights for different grades).

3. Example Weights (Approximate values):

   • For a 12 mm diameter rebar (which is quite common):

     • Weight per meter: Approximately 0.89 kg/m

   • For larger diameters:

     • For a 16 mm diameter rebar:
       • Weight per meter: Approximately 1.58 kg/m

   • For a 20 mm diameter rebar:

     • Weight per meter: Approximately 2.47 kg/m

   • For a 25 mm diameter rebar:

     • Weight per meter: Approximately 3.85 kg/m

These weights are approximate and can vary slightly depending on the specific standard and the exact composition of the rebar. For precise values, consulting the standards like ASTM A615/A615M, BS 4449, or others relevant to your region would be necessary.

Bar bending shedule of slab

• Obtain the structural drawings of the slab, which typically include plan views, sections, and details showing the reinforcement requirements.

2. Identify Slab Details:

• Locate the slab section or details where reinforcement is required. Pay attention to areas such as main slabs, drop panels, openings, and edge beams if applicable.

3. List of Bars:

• Prepare a list of all the different types of reinforcement bars required for the slab. This includes:
  • Main bars (Bottom reinforcement): Bars running in the longer span direction.
  • Distribution bars (Top reinforcement): Bars running perpendicular to the main bars, often placed closer to the top surface of the slab.
  • Stirrups (if applicable): Typically used around columns or at regular intervals along beams.

4. Bar Bending Shapes and Details:

• Based on the structural drawings, determine the bending shapes and details for each type of reinforcement bar. This includes:
  • Bar diameter: Specify the diameter of each bar (e.g., 10 mm, 12 mm, etc.).
  • Bar shape: Specify the shape of bends, hooks, and any other special configurations required.
  • Length: Calculate the total length required for each type of bar in meters or pieces.

5. Quantity Calculation:

• Calculate the quantity of each type of bar required:
  • Main bars: Determine the total length or number of bars required based on the span and spacing specified in the drawings.
  • Distribution bars: Calculate based on the spacing and layout specified.
  • Stirrups: Calculate the number of stirrups required based on beam and column dimensions and specified spacing.

6. Drawing Preparation:

• Prepare a drawing or sketch that shows the layout of reinforcement for clarity. Include dimensions, spacing, and any other relevant information.

7. Additional Details:

• Include any additional details or specifications such as lap lengths, clear cover requirements, bar bending radius, and any special notes as per the design specifications.

Example Format:

• A typical format for presenting the bar bending schedule includes columns for:
  • Bar mark (identification): Unique identifier for each type of bar.
  • Bar diameter: Diameter of the reinforcement bar.
  • Bar shape: Details of bending shapes and hooks.
  • Length/quantity: Total length or quantity of each type of bar required.
  • Remarks: Any additional notes or specifications.

Importance:

• The BBS is crucial for ensuring accurate and efficient placement of reinforcement during construction, which directly affects the structural integrity and performance of the slab.

By following these steps and using the structural drawings as a guide, you can create a comprehensive bar bending schedule for the slab that meets the project's requirements and specifications.