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(Design & Technology: Structures (PYLONS (Triangulation (additional…
Design & Technology: Structures
FORCES
interaction ceases = no longer force
pushing or pulling on component
Compression force
COMPRESSING a material
Shear force
PULLING a material
Torsion force
TWISTING a material
Tension force
STRETCHING a material
PYLONS
Triangulation
additional struts (increases stiffness)
uses internal cross-bracing
designers use to keep stable
triangular shapes = rigid/stiff
Internal cross-bracing
increases load ability
x-shape
two supporting beams cross eachother
huge structure, supports heavy objects
eg. Electrical pylons
withstands force
electricity passes through cables/wires -
transmission lines
function determines design
SPANS
vast distances
USES:
develop technologic knowledge
solve needs
finding solutions
existing problems
creative & innovative
temporary/short term
social & environmental factors
learning to do tech
knowledge, skills, values, resources
makes & designs a product
ARCHES
Bridges
various types
support heavier loads
Dam walls
most suitable for gorges/canyons
forces of water pushes against wall = strengthens wall
arch curves upstream
Buildings
push stones 'lock' into arch tightly
compression forces
curved structures
SPANS
distances
support horizontal structure
STRUCTURAL FAILURES
if stable, does not collapse with force
Toppling Over
base is too narrow
topple if too heavy
not stable
Bending
absorbs some force
= buckling (inward bending)
= flexing (outward bending)
column resists fracture
Fracture
BREAKS into pieces
object lacks strength to resist force
CANTILEVERS
Cable-Stayed Cantilever
eg. bridge - Nelson Mandela Bridge
held by cables connected to bridges
span larger distances
SPANS
only one FIXED end
Simple Cantilever
eg. cantilever (floating) stairs
load is applied = bends
span gap
support beam
FRAME STRUCTURES
Roof Trusses
Queen Post
longer distance
two supporting BEAM on TIE BEAM
Tie beam
rest on 2 opposite column
horizontal beam
Rafter
shape roof
one beam in a series, parallel beam
Ties
stretched in 2 directions
tension force
Struts
compression force
holds frame by
pushing against it
King Post
center TIE BEAM
supporting BEAM
form a strong
triangular shape
supporting base
support weight roof timbers/covering
different bars in FRAMEWORK (makes stronger)
hold objects or keep safe
SPAN - most common span is a bridge
natural/man-made
span distance
support a load + own weight
ALTERNATIVE BRIDGE SUPPORTS
SPANS
long distances
Cable-stayed
cables connected to give supprt
each cable connected to next tower
Suspension
eg. Golden Gate Bridge (San Fran.)
cables suspended between towers
tower raised either side of river
held by cables
BEAM
horizontal -
SPAN
distances
Beam & column bridges
columns = vertical, support load
concrete columns support beams
horizontal beams = concrete
Concrete lintels
holds weight above gap to sides
above window/door
Girder
supports structure + smaller beams
horizontal beam
strong & reliable
steel/aluminium
eg. Steel I-beams (girder), concrete lintels,
beam & column sets
reinforces structures
Design technology - Materials
Woods
Pine
Acasia
Spruce
Oak
Birch
Dark Oak
Beech
MDF
Textiles
Fabric
Cotton
Silk
Wool
Nylon
Waterproof fabric
Plastic
Coloured
PDA
PVC
Metals
Cobalt
Nickel
Aluminium
Steel
