Do I need to install anything?

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

For Students · Wind Load Package

Wind Load Package for a stair stringer

Built for students learning it for a class or exam. See the concept move instead of memorizing formulas — and check your homework intuition. Simulate a stair stringer live below — adjust the inputs and watch it respond, right in your browser.

Airfoil Polar

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Airfoil Lift & DragLive

the wing's polar

Controls

Presets

Angle of attack (°)

Aspect ratio

Lift rises almost linearly with angle of attack — until the airflow separates and the wing stalls, losing lift sharply. Drag has a fixed part plus induced drag that grows with lift squared and shrinks with aspect ratio. The lift-to-drag ratio, peaking at a modest angle, is the single number that governs a wing's efficiency.

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Data Inspector

Lift coeff. CL0.53

Drag coeff. CD0.033

Lift/Drag16.0

Statusattached

Governing equation

C_{D} = C_{D 0} + \frac{C _{L}^{2}}{π A R e} = 0.020 + \frac{0.5 3 ^{2}}{π \cdot 8 \cdot 0.85} = 0.033

Reading this result: Pre-stall: lift rises almost linearly with angle of attack at 6°, well below the ~15° stall angle. Adding camber would lift the entire curve higher.

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

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Base Shear

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Seismic Base ShearLive

equivalent lateral force

Controls

Presets

Number of stories

Weight per floor (kN)

Design accel. SDS (g)

Response factor R

Importance factor I

The equivalent lateral force method estimates the total earthquake base shear as V = Cs·W, where the seismic coefficient Cs scales the design acceleration by the structure's ductility (R) and importance (I). The base shear is distributed up the building, concentrating force at the top. Educational tool, not a code design.

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Data Inspector

Seismic coeff. Cs0.150

Total weight W9,000 kN

Base shear V1350 kN

Roof force386 kN

Governing equation

V = C_{s} W = min (\frac{S _{D S} I}{R}, 0.15) W = 0.150 \times 9, 000 = 1350 kN

Reading this result: Cs would be 0.167 but is capped at 0.15, so base shear is code-floored here — cutting R further will not add demand.

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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Frequently asked questions

Is this good for students?: Yes — this version of "Wind Load Package for a stair stringer" is framed for students learning it for a class or exam. See the concept move instead of memorizing formulas — and check your homework intuition.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.