In the design of concrete pad footings, Prokon’s Base module uses two different reinforcement sets during analysis. Understanding the difference between them is essential for achieving accurate and constructible designs.
Required (Theoretical) Reinforcement
This is the reinforcement calculated automatically by the program based on:
- Applied loads
- Material properties
- Footing geometry
- Code-based design requirements
Entered (Provided) Reinforcement
This is the reinforcement manually entered by engineer under the Bending Schedule tab.
It reflects what the actual reinforcement that will be detailed and installed on site.
Difference between required and entered reinforcement typically arise due to:
- Practical bar size rounding
- Minimum spacing limitations
- Minimum cover
- Constructability consideration.
Why These Two Sets Affect Shear Calculations
Shear capacity in pad footing design is influenced by the amount of flexural reinforcement, especially when:
- Depth modification due to tension reinforcement
- Concrete contribution
- Shear resistance enhancements from provided steel
Therefore, shear checks may differ when using:
- Required reinforcement, or
- Entered reinforcement
How to Toggle Between the Two Modes
In the Base Design interface, you will find the option:
“Calculate shear using the entered flexural reinforcement”
This toggle determines which reinforcement set is used during shear checks.
Mode 1: Shear Based on Required Reinforcement
- Uses the theoretical reinforcement calculated by Prokon.
- Ideal for initial design, sizing and quick optimization.
- Helps determine the minimum reinforcement needed.
Mode 2: Shear Based on Entered Reinforcement
- Uses reinforcement manually specified in the bending schedule
- Provides the true design result that reflects actual construction.
- Essential before issuing final drawings or any documentation.
Best Practice Recommendations
To ensure safe, buildable designs:
- Provide reinforcement as close as possible to the required values.
- Before finalising drawings, always run shear checks using the entered reinforcement mode.
- Compare both modes for heavily loaded or critical foundations.
- Ensure any practical adjustments (bar size changes, spacing, or cover constraints) do not reduce shear capacity.
