Thames & Kosmos Architectural Engineering - SQUARE; Stability of a Square; BRACED SQUARE; Reinforced Structures

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EXPERIMENT
HERE’S HOW
With the square flat
on a table, hold one
corner of the square
in one hand and try to
deform it by moving
the opposite corner. Does
the square deform? Also try bending one
corner of the square upward from the table
while holding the other corner. Does it bend?
Stability of a square
Done!
WHAT’S HAPPENING
When you are pushing or pulling on the corner of the square, you are
applying a force, or load, to the structure. A goal of architectural
engineering is to achieve the stability of a structure under different
loads. All structures will change shape to some degree when loads
act on them. In a stable structure, the changes in shape, or
deformations, are small, and forces within the structure return the
structure to its original shape after the load is removed.
In an unstable structure, the changes in shape are large and usually
increase as long as the forces are applied. An unstable structure
does not have the internal forces required to restore the structure to
its original shape. Is the square a stable or unstable structure?
Not only is the structural shape unstable, but the flexibility of the
plastic material itself makes it easy to bend.
SQUARE
BRACED SQUARE
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EXPERIMENT
HERE’S HOW
Repeat Experiment 1 with
the braced square. How
does the braced square
react to the load?
Reinforced structures
Done!
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WHAT’S HAPPENING
By adding the two cross pieces and connecting the two corners,
you made the square model into a much more stable structure.
The cross pieces lock the angle of the other rods. When you
push on the corner of the square, you can feel the model
move a lile bit. As you stop pushing on it, you can feel it
return to its original shape. It’s also significantly more
resistant to bending. However, you used more material to
achieve this. That is called a trade-off in engineering.
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Architects need their buildings to be
structurally stable and to remain
standing despite the all the loads that
act on them. Let’s build some simple
models and conduct simple experiments
with them to show how connecting
structural elements together in different
ways can affect the strength and
stability of a structure.