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T1-L16: Bridge Types & Engineering Forces

Year 7 Technology Mandatory — Engineering Technologies & Systems — Bridge It
Supplementary worksheet
Outcomes: TE4-MSC-01 TE4-SDP-01 TE4-PDP-01 Folio Supplementary worksheet
Learning Intention
We are learning about different types of bridges and the forces that act on them.
Success Criteria
  • I can name and describe at least 4 types of bridges
  • I can explain compression, tension and shear
  • I can identify forces in a bridge structure
  • I can explain why triangulation makes structures stronger
Do Now
Name any bridge you know. What type do you think it is?
#QuestionYour answer
1Name a bridge you know
2What type do you think it is?
3Where is this bridge?
4What is its shape? (arch, cables, flat, triangles?)
📚
Key Vocabulary

Standard: Fill in the definition.  |  Support: Definitions shown in grey — read and copy into your folio.  |  Extension: Use each term in a sentence.

TermDefinitionUse in a sentence (Extension)
Beam Simplest bridge — horizontal deck on supports
Arch Curved structure that transfers load through compression
Truss Framework of triangles that distributes load efficiently
Suspension Deck hangs from cables draped over towers
Cable-stayed Cables run directly from towers to deck
Cantilever Extends horizontally, supported/anchored at one end
Compression Squeezing force that pushes inward
Tension Stretching force that pulls outward
Shear Sliding/cutting force — two forces in opposite directions
Dead load Permanent weight of the structure itself
Live load Temporary/changing loads — traffic, wind, people
Span Distance between the supports of a bridge
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Bridge Types Reference

Complete the reference table for 6 major bridge types.

Bridge typeKey featureMaximum spanDominant forcesFamous exampleDraw a simple sketch
BeamDraw in folio
ArchDraw in folio
TrussDraw in folio
SuspensionDraw in folio
Cable-stayedDraw in folio
CantileverDraw in folio
🔎
Bridge Type Identification

Identify the type of each bridge and explain what clue helped you decide.

#BridgeTypeClue that helped you identify it
1Sydney Harbour Bridge
2Golden Gate Bridge
3ANZAC Bridge
4Log across a creek
5Railway truss bridge
6Forth Bridge (Scotland)
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Where Are the Forces?

For each bridge type, identify where compression and tension occur.

Bridge typeCompression at…Tension at…
Beam
Arch
Truss
Suspension
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Why Triangles?

Triangles are the strongest shape in engineering. Answer these questions to understand why.

#QuestionYour answer
1Why can’t a triangle deform (change shape) without breaking a side?
2What is triangulation?
3Push the corners of a square frame. What happens? Now push a triangle frame. What happens?
4Draw a Warren truss pattern in your folio (alternating triangles). How many triangles are in your truss?
🌎
Aboriginal Engineering: Brewarrina Fish Traps

The Brewarrina Fish Traps (Baiame’s Ngunnhu) are over 40,000 years old — among the oldest human-made structures on Earth.

#QuestionYour answer
1What forces did the builders need to understand?
2How is this similar to bridge design?
3Why is sustainability built into the design?
🔵 Support — Bridge & Forces Help

Use these simplified definitions:

  1. Compression = PUSH (squeezing force)
  2. Tension = PULL (stretching force)
  3. Bridge type flashcards with diagrams are available
  4. Printed vocabulary reference card is available
  5. Pre-drawn bridge outlines are available for labelling

Sentence starters:

  1. “This bridge is a _______ bridge because it has…”
  2. “Compression occurs at… because the force pushes…”
  3. “Tension occurs at… because the force pulls…”
Word Bank
beamarchtrusssuspension cable-stayedcantilevercompressiontension sheardead loadlive loadtriangle
🟠 Extension — Advanced Bridge Engineering

Local bridges: Research 3 Sydney/NSW bridges and classify them by type.

Bridge name & locationTypeKey engineering feature

Tacoma Narrows: Research the Tacoma Narrows Bridge collapse (1940). What force caused it to fail?

Hybrid bridge: Design a bridge that combines 2 different types. Explain why this combination would work.

Compare: How do the Brewarrina Fish Traps compare to a modern dam? What engineering principles do they share?

🎫
Exit Ticket — Reflection
1. Why are TRIANGLES used in bridge design? Explain in 1–2 sentences.
2. Name the 4 engineering forces we learned today.
3. Choose ONE bridge type and explain where compression and tension occur.
Self-Assessment
Success Criteria Got it 🟢 Nearly there 🟠 Need help 🔴
I can name and describe at least 4 types of bridges
I can explain compression, tension and shear
I can identify forces in a bridge structure
I can explain why triangulation makes structures stronger