Compressive Stress Calculator Formula
Understand the math behind the compressive stress calculator. Each variable explained with a worked example.
Formulas Used
Compressive Stress
comp_stress = f_n / areaVariables
| Variable | Description | Default |
|---|---|---|
force | Compressive Force (F)(kN) | 200 |
area | Cross-Sectional Area (A)(mm^2) | 2500 |
f_n | Derived value= force * 1000 | calculated |
How It Works
Direct Compressive Stress
Compressive stress develops when a member is pushed axially.
Formula
sigma_c = F / A
The formula is identical to tensile stress, but the member may also need a buckling check if it is slender. Short, stocky members fail by crushing; long, slender members fail by buckling at a load lower than the crushing capacity.
Worked Example
A concrete column with 2500 mm^2 effective area under 200 kN axial load.
- 01Convert force: 200 kN = 200,000 N
- 02sigma_c = 200,000 / 2,500 = 80 MPa
- 03For 30 MPa concrete, this exceeds capacity. A larger section or higher-strength concrete is needed.
Frequently Asked Questions
How does compressive strength differ from tensile strength?
Many materials have different capacities in tension versus compression. Concrete is strong in compression (20-50 MPa) but weak in tension (about 10% of compressive strength). Steel has roughly equal tensile and compressive yield strengths.
When do I need to check for buckling?
When the slenderness ratio (effective length divided by radius of gyration) exceeds about 20-30, buckling becomes a concern and the Euler or inelastic buckling formula should be checked.
What is bearing stress?
Bearing stress is a localized compressive stress where one member presses against another, such as a beam sitting on a support plate. It equals force divided by the contact area.
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Open Compressive Stress Calculator