Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For K-12 Students · Steel Connection Designer

Steel Connection Designer for a truss bridge

Built for k-12 students learning it in middle or high school. Watch the idea come alive with plain-language steps and everyday examples — perfect for projects and homework. Simulate a truss bridge live below — adjust the inputs and watch it respond, right in your browser.

Shear Moment

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Shear & Moment DiagramsLive

simply-supported beam

Controls

Presets

Span L (m)

Point load P (kN)

Load position a (m)

Uniform load w (kN/m)

Shear and bending-moment diagrams show the internal forces along a beam. Shear jumps at each point load; the moment is the running integral of shear and peaks where shear crosses zero. Engineers size beams for this maximum moment. Educational tool, not a substitute for structural design.

▶ Run in Python

Data Inspector

Reaction A28.3 kN

Reaction B21.7 kN

Max moment46.6 kN·m

at x2.01 m

Governing equation

\frac{d V}{d x} = - w = - 5, \frac{d M}{d x} = V, M_{m a x} = 46.6 kN\cdotm

Reading this result: Combined loading: reactions RA=28.3 and RB=21.7 kN, and the maximum moment 46.6 kN·m lands at x=2.0 m where shear crosses zero.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

↓

Mohrs Circle

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Mohr's CircleLive

2D stress transformation

Controls

Presets

σx (MPa)

σy (MPa)

τxy (MPa)

Mohr's circle is a graphical way to transform a 2D stress state to any rotated axis. The circle's center is the average normal stress and its radius is the maximum shear. Where it crosses the horizontal axis gives the principal stresses — the orientation with zero shear. Educational tool.

▶ Run in Python

Data Inspector

σ₁ (max principal)92.4 MPa

σ₂ (min principal)7.6 MPa

τmax42.4 MPa

Principal angle22.5°

Governing equation

σ_{1, 2} = \frac{80 + 20}{2} \pm (\frac{80 - 20}{2})^{2} + 3 0^{2} = 92.4, 7.6 MPa

Reading this result: The circle radius sets τmax = 42.4 MPa on planes 45° from the principals; rotate the element by 22.5° to reach the shear-free principal orientation.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

↓

Fatigue

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Fatigue (S-N Curve)Live

failure under cyclic load

Controls

Presets

Ultimate strength (MPa)

Stress amplitude (MPa)

Ferrous (has endurance limit)

Repeated loading well below the ultimate strength can still break a part — metal fatigue. The S-N curve plots stress amplitude against cycles to failure. Steels have an endurance limit: below it they last essentially forever, but aluminum has none and eventually fails at any stress. Cause of many catastrophic aircraft and bridge failures.

▶ Run in Python

Data Inspector

Endurance limit250 MPa

Cycles to failure1.17e+5

Verdictfinite life

Governing equation

N = (\frac{σ _{a}}{σ _{f}^{'}})^{1/ b}, σ_{a} = 300 MPa \Rightarrow N = 1.17 e + 5 cycles

Reading this result: At 300 MPa the part fails after about 1.2e+5 cycles. Drop below the 250 MPa endurance limit to reach infinite life.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

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Frequently asked questions

Is this good for k-12 students?: Yes — this version of "Steel Connection Designer for a truss bridge" is framed for k-12 students learning it in middle or high school. Watch the idea come alive with plain-language steps and everyday examples — perfect for projects and homework.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.