BOLT FORCE DISTRIBUTION _ CIRCULAR PATTERN

Bolt force distribution in circular pattern by elastic analysis.

When analyzing a circular pattern of bolts for a connection carrying bending moments in two planes and an axial force, the bolt forces can be determined using an elastic analysis approach. Here's a general outline of the process:

1. Identify the applied loads: Determine the bending moments in two planes (e.g., X and Y directions) and the axial force acting on the connection. Ensure you have accurate values for these loads.

2. Determine the bolt pattern: Determine the circular pattern of bolts and the spacing between them. Specify the diameter and number of bolts in the pattern.

3. Analyze the connection elasticity: Consider the elastic behavior of the connection and assume that it behaves linearly. This assumption allows for the distribution of the applied loads among the bolts based on their stiffness.

4. Determine the stiffness of individual bolts: Calculate the stiffness of each bolt based on its size, material properties, and the connection geometry. The stiffness is typically determined based on the bolt's cross-sectional area and Young's modulus.

5. Calculate the bolt forces: Set up a system of equations based on the equilibrium conditions and compatibility of deformations. The equations should consider the forces in each bolt, the applied loads, and the stiffness of the bolts. By solving these equations, you can determine the bolt forces.

6. Check bolt capacity: Compare the calculated bolt forces to the bolt's capacity. Ensure that the bolt's strength properties, such as tensile strength, shear strength, and fatigue strength, are sufficient to withstand the calculated forces.

It's important to note that the elastic analysis approach provides an approximation of the bolt forces and assumes linear elastic behavior. Depending on the specific design requirements, connection geometry, and load conditions, additional considerations or refinements may be necessary, such as considering the effects of gaskets, flange rotation, or non-linear behavior.