POS
 K1a recognize and classify
structural forms and materials
used in construction (identify
examples of frame structures,
such as goal posts and girder
bridges, examples of shell
structures, such as canoes and
car roofs, and examples of
frame-and-shells structures,
such as houses and apartment
buildings.
Unit D: Structures
and Forces
Topic 1 Types of Structures
Topic 2 Describing
Structures
Careers Associated with this Unit
 Engineer
 Materials/civil/mechanical
 Architect
 Construction/carpenter
 Project Manager
 Welder
 Inventor/Designer
 Marketing
 (Lawyers)
Classification of Structures
 Two Major types
 Natural: not made by humans
 Manufactured: made by
humans
 Three sub-types
 Mass
 Frame
 Shell
 Can be made by forming
similar materials into a
particular shape or design
 Mass structures are held
firmly in place by their own
weight
 If small parts break off, it
makes little difference
 The pieces that make up mass
structures are often carefully arranged
 Example: The patterns of bricks in a
wall
 Mass Structures are not always solid
 Ex: Power damns may contain rooms
that hold generators
 Mass structures must be
carefully designed, due their
weight and size
Think of a wall of sandbags that
is holding back a flooding river
How do you think that the wall
structure could fail?
Sandbag Walls Can Fail
Because….
 The wall may not be heavy
enough to stay in place
 The wall may be so heavy that
the earth below it is pressed
down unevenly
 The wall may not be thick
enough or tight enough, so part
of it are pushed out
 The structure may not be
anchored firmly to the ground
 Are a skeleton of very
strong materials that
support the weight of the
roof and covering materials
 Most of the inside of the
building is empty space
 The walls are loading
bearing and support the
structure
Some objects consist only of a frame
More complex objects have other parts added
to the frame
 Frames may be hidden under covering
material
Frames can be left exposed
• Frame structures are easy to design
and build
• One of the least expensive
construction choices
• Lightweight frames need to be
anchored to the ground
• Very tall frames can become
unstable if they are not properly
braced
• Large, complicated projects have
many parts that all have to fit
together perfectly
• Objects that use a thin, carefully
shaped outer layer of material to
provide strength & rigidity
• Strong & hollow
• Keep their shape & support loads
• Completely empty – make good
containers
• Use very little building material
• Forces are spread through the whole
structure and each part only
supports a small part of a load
 Tiny weaknesses can cause
the whole structure to fail
 Flat materials are not easily
turned into a rounded shell
shape
 Assembling flexible pieces
into a shell can be difficult
Examples
(copy this chart, we are going to classify the following structures)
Natural
Manufactured
Mass
-beaver dam
-sand castle
Frame
-human skeleton
-stool
Shell
-turtle shell
-cardboard box
Combined
type
Sod House
(Sod is grass, roots and dirt cut out of the ground in strips)
Epcot Center
(Disney World)
Ant Hill
(Primarily Sand, some tunnels)
Bird Cage
Snail Shell
House “skeleton”
Describing a Structure
 Function:
 What does it do?
 What is it for?
 Aesthetics
 Attractiveness of design
 Safety
 Margin of safety- “extra safe”
range
 Cost (balance with safety)
Materials
 Composite materials
 Layered Materials
 Laminations
 Woven and Knit Materials
Choosing Materials
 Cost
 Appearance
 Environmental Impact
 Energy Efficiency
Joints
 Mobile
 Allow movement
 Ex. Chains, elbows, door hinges
 Rigid
 Fasteners: nails, staples, bolts,
screws
 Ties: string, rope, thread
 Interlocking shapes
 Adhesives
 Melted joints (welding, soldering)
Adhesives &
Melting
Adhesives
Adhesive (Glue):
Sticky substance that holds
stuff together
 Glue may soften in water or
when its very hot
Melting
 Welding: Melts pieces
together
 Soldering: Surrounds pieces
with melted material that
locks them together
Assignments
 Read Topic 2 pgs 282-292, add
to your notes
 Activity pg 293 “Design
Detective”
 Traditional Structures Poster pg
293
 Marshmallow Bridge
 Review Q’s T1-2 pg 296#1,2, pg
297#1,2,3,5,8