1. What Happens When a Beam Bends?
When a load pushes down on a beam, it causes bending. This creates powerful internal forces.
- The top gets squeezed together (Compression Stress).
- The bottom gets stretched apart (Tension Stress).
- An imaginary line in the middle, the Neutral Axis, feels no stress at all.
Bending Moment (torque)
Mf = 1/4 x P x L
Compression Stress
No Stress
(Neutral Axis)
Tension Stress
2. Why Use an I-Beam? It's All About Efficiency.
For the same amount of material, an I-beam is much stronger against bending forces than a solid rectangular beam. This chart shows the massive difference in "Bending Resistance" (a simplified term for Moment of Inertia).
I-Beam
Material is concentrated at the top and bottom, where stress is highest.
Rectangular Beam
Same amount of material, but less efficient shape.
3. A Beam's Strength is Directional
An I-beam isn't equally strong in all directions. It must be oriented correctly to do its job.
Major Axis (Super Strong)
When standing up, it can resist massive loads.
Minor Axis (Much Weaker)
When lying on its side, it bends very easily.
4. Connection is Key
A structure is only as strong as its weakest link. Proper connection design is critical. Click each card to learn more.
Twisting Forces
Connections must be centered. If they're off to one side, they can create a twisting force that the beam isn't designed to handle.
Web Crushing
The thin middle "web" can buckle or crush under a concentrated force. Good design spreads the load out evenly to prevent this.
Bolt Placement
Bolts placed too close to an edge can cause the steel to tear, much like punching a hole too close to the edge of paper.