**Understanding Bolt Preload: Calculations and Formulas**

Bolts are integral components in various engineering and construction applications. Ensuring their proper functionality and safety is paramount. One crucial aspect is calculating the Bolt Preload Force, which is essential for both permanent and re-use connections. In this article, we will delve into the formulas and provide you with an HTML code for a Bolt Preload Calculator with a clickable button for easy calculations.

**Bolt Preload Calculation Formulas**

To calculate the Bolt Preload Force, you’ll need two key parameters:

**Tensile Shear Area (A):**This represents the area of the bolt subjected to tension or shear. You can calculate it using the following formula:`A = π * (d^2) / 4`

Where:

- A is the Tensile Shear Area in square inches (in^2).
- d is the diameter of the bolt in inches.

**Proof Load of Bolt (85% yield strength) (P_proof):**The Proof Load is the maximum load a bolt can handle without permanent deformation. It is typically calculated as 85% of the bolt’s yield strength. The formula is as follows:`P_proof = 0.85 * Sy * A`

Where:

- P_proof is the Proof Load in pounds per square inch (psi).
- Sy is the yield strength of the bolt material in psi.
- A is the Tensile Shear Area in square inches (in^2).

**Bolt Preload Force Calculation**

Now that you have the Tensile Shear Area (A) and Proof Load of the Bolt (P_proof), you can calculate the Bolt Preload Force for both permanent and re-use connections using the following formulas:

**Bolt Preload Force (Permanent Connection) (F_permanent):**`F_permanent = P_proof`

The Bolt Preload Force for a permanent connection is simply equal to the Proof Load of the bolt.

**Bolt Preload Force (Re-use Connection) (F_reuse):**`F_reuse = 0.75 * P_proof`

For re-use connections, the Bolt Preload Force is typically set to 75% of the Proof Load to account for potential degradation over time.