Investigating Structures and Materials

Structures Activity

Tarr Steps – A Prehistoric Beam Bridge, Devon, UK

Mode of transport – foot; material - stone

1. Take one span of the bridge and use the drawing tools to indicate which part is in tension and which is in compression? Also draw forces on the beam.

2. Is stone good in compression or tension?3. Why do you think this bridge is still standing?

Trestle Bridge – Noojee, Victoria

Rail bridge constructed from wood. About 100 years old

1. On various members, draw where they may be in tension and compression.2. Is this structure good in compression or tension? What is the difference in

strength between wood in tension and compression? How does wood act under load? (Is it brittle or tough?)

Arch bridge – Avenel, Victoria

Originally used by horse and cart – 100+ years old stone structureArch construction a technique perfected by the ancient Romans1. Draw an arch and indicate where the load is distributed on the arch.2. Why is the arch such an effective structure?3. Is the structure designed for tension or compression?

Railway bridge - Malmsbury

• Another example of an arch bridge

• What does the keystone do?

Inverted brick arch – Old Post Office, Bendigo

Located adjacent to foundations1. Draw the forces acting on the structure.2. What effect does inverting the arch have on the load?

Some information on the arch

Arch Bridge – Wycoller, England

1. Draw the forces acting on the right-hand arch. Is it in compression or tension?

2. List some possible reasons for the left-hand arch being on a lean.

Suspension Bridge – Ambyne, Victoria

Originally used by horse and cart, now motor vehicles; constructed from wood and steel1. Draw on the photograph which segments are in tension, which are in compression.2. Why are wood and steel used in their particular locations? What effect would

replacing the wood sections with steel and the steel sections with wood have?3. How could we strengthen this bridge?

Cable staid bridge - Tasmania

Use - Motor vehicles; constructed from steel and concrete1. Identify the main parts of the bridge.2. Identify areas of compression and tension.3. Why are steel and concrete used in a structure such as this?4. Why would a truss be used in this structure?

Truss Bridge – Walhalla, Victoria

Used for motor vehicles; constructed from steel and concrete1. Draw one section of the truss shown above. On this indicate which member

would be in compression and which would be in tension.2. Why is the truss made from steel only? Could parts of it could be constructed

of other materials?3. If the load was decreased significantly, which materials could the bridge be

constructed from?

Railway overpass under construction – Princes Highway between Morwell and Traralgon

Constructed from steel and concreteNote the rail tunnel in the background – this is a reinforced earth structure,

comprising a steel core with compacted earth surrounding it1. Why are the piers made from reinforced concrete?2. How would the load be distributed around the reinforced earth structure?

Swing Bridge - near Sale, Victoria

Steel bridge swings so that two cantilever spans are present1. Draw the areas of tension and compression on the bridge in both the

closed position (as shown) and when allowing river traffic to pass.2. What properties of the bridge prevent it from failing when in use?

North Arm Bridge – Lakes Entrance

Use - motor vehicles; constructed from reinforced and prestressed concrete1. How does prestressing work? Why would you used prestressing?

Cantilever Verandah

• Draw a diagram of each of the two verandahs and show where the forces may be in the structures.

• Why would one have supports holding it up and the other one not have supports?

• If this was constructed from reinforced concrete, where would the reinforcing best be placed?

Foundations

• Why would these foundations be spread?