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Your First Calculation

Let's walk through a real engineering example: calculating the bending stress in a simply-supported steel beam. You'll see how EngCanvas handles units, variables, and formulas.

Step 1: Open a spreadsheet tab​

When you launch EngCanvas, you start with a blank spreadsheet grid. Each cell can hold a number with units, a formula, or a variable assignment.

Step 2: Define your inputs​

Click cell A1 and type each formula in successive rows. Press Enter after each to move down:

L = 20 ft           // span length
w = 1.5 kip/ft      // uniform distributed load

EngCanvas evaluates each formula immediately, showing the result with its unit and a LaTeX-rendered display.

Continue with the section properties:

b = 8 in             // flange width
d = 18 in            // beam depth
tf = 0.75 in         // flange thickness
tw = 0.45 in         // web thickness
Units on every input

Every physical input should have a unit. 20 is ambiguous, but 20 ft is unambiguous and enables dimensional checking downstream.

Step 3: Calculate section properties​

Compute the moment of inertia using the variables you just defined:

Ix = (b * d^3) / 12 - ((b - tw) * (d - 2 * tf)^3) / 12

EngCanvas evaluates this and returns a result in in⁴ — the correct dimension for second moment of area (L⁴).

Step 4: Calculate maximum moment​

For a simply-supported beam with uniform load, the maximum bending moment is:

Mmax = w * L^2 / 8

The result is in kip·ft — force × length, the correct dimension for bending moment.

Step 5: Calculate bending stress​

The flexure formula is M·c / I:

c = d / 2
fb = Mmax * c / Ix

EngCanvas automatically converts all values through SI and returns the stress in ksi (kip per square inch).

Dimensional analysis at work

The formula Mmax * c / Ix has dimensions:

  • Mmax → F·L (force × length)
  • c → L (length)
  • Ix → L⁴ (length to the fourth)

Result: F·L·L / L⁴ = F/L² = stress ✓

Step 6: Check against allowable stress​

Fy = 50 ksi              // yield strength (A992 steel)
Fb = 0.66 * Fy           // allowable bending stress (ASD)
ratio = fb / Fb           // demand/capacity ratio (dimensionless)

The ratio result has no units — stress ÷ stress cancels out — confirming dimensional consistency.

Step 7: Add a pass/fail check​

Use the IF function:

check = IF(ratio < 1, "OK", "NG")

What you've learned​

ConceptExample
Variable assignmentL = 20 ft
Formulas with variablesMmax = w * L^2 / 8
Unit propagationkip/ft * ft^2 = kip·ft
Dimensional checkingCan't add ft + kip
FunctionsIF(ratio < 1, "OK", "NG")

Next steps​