Johnson's Formula:
Definition: Johnson's formula calculates the critical load for intermediate columns that fail by inelastic buckling.
Purpose: It helps engineers determine the safe load capacity of columns that are too long to be treated as short columns but too short to fail by elastic buckling.
The calculator uses Johnson's formula:
Where:
Explanation: The formula calculates the material constant based on stress, load, geometric properties, and slenderness ratio.
Details: This constant helps determine the transition point between short and long column behavior, crucial for structural design.
Tips: Enter all required values (all must be > 0). The ±5% indicates typical tolerance ranges for these parameters.
Q1: What does the ±5% tolerance mean?
A: It indicates the typical uncertainty range for each parameter in practical applications.
Q2: When is Johnson's formula applicable?
A: For intermediate columns where the slenderness ratio is between the limits for Euler and simple compression formulas.
Q3: How do I determine the effective column length?
A: It depends on end conditions - use length factors (K) based on column end constraints.
Q4: What's a typical value for Johnson's constant?
A: It varies by material but often ranges between 1-10 for common structural materials.
Q5: Does this include safety factors?
A: No, the calculated constant should be used with appropriate safety factors in design.