Why does this exist?
Because engineering is easier to understand when you can push on it. Structional started as a YouTube channel about how structures work. This site is the next step: one place where you can move a load, watch a beam bend, and then prove you get it.
What do we believe?
Picture first
You see the thing move before you see a formula. Then the formula explains what you just watched.
Every number checked
Numbers in lessons come from a small calculation engine, tested against hand calculations, not from typing.
Free for learners
Lessons, Spans and tools stay free. Companies pay for tests and team trainings.
Gentle, not addictive
Points for solving things. No streaks to lose, no popups, no nagging notifications.
How do we keep the numbers right?
The lessons, the Sandbox and the tests all use the same engine: beams, frames, trusses, buckling and concrete. The engine is tested against hand calculations, and every lesson number has its own test. Here is one check, worked out when this page was built:
A 8 m beam, 10 kN at 3 m from the left
- Engine
- R_A = 6.25 kN, R_B = 3.75 kN
- By hand
- R_A = 10 × 5 / 8 = 6.25 kN
They match.
A 24 ft beam, 2 kip at 9 ft from the left
- Engine
- R_A = 1.25 kip, R_B = 0.75 kip
- By hand
- R_A = 2 × 15 / 24 = 1.25 kip
They match.
How is it paid for?
Learning is free and stays free. Companies pay for qualification tests and team trainings, which is the part that costs us real work. Later there may be an optional paid plan with extras, but nothing that's free today will be locked away. There are no ads, and we don't sell data.
Found a mistake? Have an idea?
Tell us. Every report is read, and fixed lessons say so in the change log.