Do I need to install anything?

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

For Engineers · Prestressed Girder

Prestressed Girder for a footbridge

Built for engineers using it for real design work. Go from concept to a running model in the browser, then scale to the cloud when needed. Simulate a footbridge live below — adjust the inputs and watch it respond, right in your browser.

Concrete Beam

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Reinforced Concrete BeamLive

flexural capacity (ACI)

Controls

Presets

Width b (mm)

Effective depth d (mm)

Steel area As (mm²)

Concrete f'c (MPa)

Steel fy (MPa)

A reinforced concrete beam resists bending through a compression block in the concrete and tension in the steel. Setting these forces equal gives the stress-block depth a, and the moment capacity Mn = As·fy·(d − a/2). A tension-controlled section (steel yields first) fails gradually — the ductile behavior codes require. Educational tool, not a design.

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Data Inspector

Stress block a82 mm

Nominal Mn289 kN·m

Design φMn260 kN·m

Behaviortension-controlled

Governing equation

a = \frac{A _{s} f _{y}}{0.85 f _{c}^{'} b} = 82 mm, M_{n} = A_{s} f_{y} (d - \frac{a}{2}) = 1500 \cdot 420 (500 - \frac{82}{2}) = 289 kN\cdotm

Reading this result: Tension-controlled: with ρ ≈ 0.0100 well under 0.75·ρ_bal the steel yields first and the beam warns before it fails, while Mn = As·fy·(d − a/2) rises almost linearly with steel here.

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

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Beam Deflection

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Beam Deflection & BendingLive

Euler-Bernoulli beam theory

Controls

Presets

Span L (m)

Load P (kN)

Flexural rigidity EI (kN·m²)

Euler-Bernoulli theory relates a beam's deflection and internal moment to its load, span, and flexural rigidity EI. Deflection grows with the cube or fourth power of span, which is why doubling a span is far worse than doubling the load. Educational tool — not a substitute for a stamped structural design.

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Data Inspector

Max deflection1.30 mm

Max moment12.5 kN·m

Span/deflectionL/3840

Governing equation

δ = \frac{P L ^{3}}{48 E I} = \frac{10 \cdot 5 ^{3}}{48 \cdot 20000} = 1.30 mm

Reading this result: At L/3840 this beam clears the usual L/360 serviceability limit, so strength (not deflection) is likely to govern the design.

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

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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.

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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 engineers?: Yes — this version of "Prestressed Girder for a footbridge" is framed for engineers using it for real design work. Go from concept to a running model in the browser, then scale to the cloud when needed.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.