Lesson 1 of 6
Read the reinforcement detail before you calculate
Identify clear cover, stirrup diameter, hook angle and spacing before using them in a steel calculation.
- 1Clear cover
- 2Stirrup diameter
- 3Hook angle
- 4Read spacing along the beam
- 5Your turn
Learn · Part 1
Clear cover
Start at the concrete face and find where the stirrup begins.
Clear cover
25 mm
Cover runs from the concrete face to the outside face of the stirrup. It protects the steel and sets the working rectangle inside the concrete.
Learn · Part 2
Stirrup diameter
Now identify the thickness of the bar that forms the closed link.
Stirrup diameter
8 mm
Diameter describes the steel bar itself. Do not subtract it again after applying the outside-to-outside cover convention.
Learn · Part 3
Hook angle
Look at the two ends where the stirrup closes.
Hook angle
135 °
Both ends use 135° hooks. Their tails add length, and the hook bends also contribute bend deductions.
Learn · Part 4
Read spacing along the beam
Move from the cross-section to the side view to see how often the link repeats.
Stirrup spacing
150 mm centres
Spacing is measured centre to centre along the 4,000mm clear span. Under this lesson’s stated start-at-face convention, that gives 27 stirrups.
Apply what you learned
Your turn.
Which drawing value is measured to the outside face of the stirrup? Enter its value in mm.
See the worked solution
Clear cover = 25mm. Diameter describes the bar itself.
Answer: 25 mm.
Lesson notes & reference
Worked exampleRead 25mm cover, 8mm stirrups, 135° hooks and 150mm spacing before calculating.
Read the complete lesson
1. Clear cover
Start at the concrete face and find where the stirrup begins.
Clear cover · 25 mm
Cover runs from the concrete face to the outside face of the stirrup. It protects the steel and sets the working rectangle inside the concrete.
2. Stirrup diameter
Now identify the thickness of the bar that forms the closed link.
Stirrup diameter · 8 mm
Diameter describes the steel bar itself. Do not subtract it again after applying the outside-to-outside cover convention.
3. Hook angle
Look at the two ends where the stirrup closes.
Hook angle · 135 °
Both ends use 135° hooks. Their tails add length, and the hook bends also contribute bend deductions.
4. Read spacing along the beam
Move from the cross-section to the side view to see how often the link repeats.
Stirrup spacing · 150 mm centres
Spacing is measured centre to centre along the 4,000mm clear span. Under this lesson’s stated start-at-face convention, that gives 27 stirrups.
The schedule you’re building toward
The same worked example throughout the course: three identical beams, with three bottom and three top main bars in each.
| Bar | Shape | Dia | Cutting length | Bars per member | Total bars | Total length | Weight | Notes |
|---|---|---|---|---|---|---|---|---|
| S1 | Stirrup · rectangular, 135° hooks | 8mm | 1220mm | 27 | 81 | 98.82m | 39.04kg | Uniform centres; no zones |
| B1 | Bottom main · straight | 16mm | 5500mm | 3 | 9 | 49.50m | 78.22kg | Straight anchorage at both ends |
| T1 | Top main · straight | 16mm | 5500mm | 3 | 9 | 49.50m | 78.22kg | Straight anchorage at both ends |
Total steel: 195.48kg. Worked quantities exclude wastage. Main bars assume straight anchorage fits each support; use the actual structural detail for a project.
You know what every input means. How do those inputs become one correct stirrup cutting length?
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