121
5
Structures
Analyse
40.
What do you think this bridge is used for? What do
you think is below it? Is it a foot bridge or can vehicles
cross over it?
The bridge crosses an area of wetland in a depression.
Underneath the bridge there would be a stream or small
watercourse. It is for pedestrian use.
41.
Write the names of the numbered elements in the
picture and say what material they are made of.
1 steel arch 2 cable suspenders 3 deck 4 steel column 5 steel
brace 6 concrete footing 7 lower steel beams 8 steel cross-
bracing.
42.
Copy the side elevation of the bridge in your notebook.
Show how it would deform under the effect of the
loads of its own weight and the weight of the people
walking on it.
Students’ own drawings
43.
Explain the types of stress that act on each element of
the bridge under the effect of these loads.
Element
Force
Arch
Compression
Cable suspenders
Traction
Deck panels
Bending
Column
Compression
Brace
Compression
Footing
Compression
Lower beam
Bending
Cross-bracing
Traction or compression
44.
Draw arrows to show the direction of the loads going
to the ground inside each element on the bridge.
45.
Could any other materials be used for the deck and
the arch?
Steel and wood are both capable of resisting traction and
compression. However, steel is better able to resist the stresses
exerted on this bridge, as a wooden bridge would need a
lot of individual parts. Wood is a better choice for a walking
surface. Therefore, the two materials are not interchangeable .
46.
How would you join the beam, the cable suspenders
and the deck? Design a joint for each one.
The cables are joined to the beam
using tension members, as in the
photo. The deck panels are then
screwed on at four points to the
sides of the beam’s cross-section.
47.
Copy and complete the
following table.
Element
Form Material
Function
Force
Arch
Parabola Steel
Hold up the
bridge
Compression
Cable
suspenders
Linear
Steel
Strengthen the
resistance of the
arch
Compression
Deck
panels
Stretched
rectangular
prisms
Wood
Form the
walking
platform
Bending
Column
Linear
Steel
Transfer the
loads from the
upper part to
the foundation
Compression
Brace
Linear
Steel
Reduce the span
of the beam
Compression
Footing
Rectangular
prisms
Reinforced
concrete
Transfer the
loads of to the
ground
Compression
Lower
beam
Linear
Steel
Transfer the
loads from the
panel to the
columns
Bending
Cross-
bracing
Linear
Steel
Prevent
deformation on
the sides of the
arch
Compression
