Structural systems 1

natural structures

evolved in nature; efficient and strong

human made structures

engineered to solve needs using materials like steel, concrete, timber

structure

something built to support a load safely

types of structure

frame: network of parts: lightweight and strong
shell: thin outer surface supports load: curved shapes
solid: entirely solid material: relies on weight/mass

simply supported beam

supported at both ends: can flex slightly (basic bridges)

fixed beam

both ends rigid ; resists bending (reinforced concrete)

cantilever beam

supported at one end only (balconies)

continuously supported beam

resting on 3+ supports (large buildings)

columns

vertical element carrying compressive loads to foundation
use: buildings, towers

dead load

permanent weight (walls, floors)

live load

variable weight (people, furniture, vehicles)

environmental load

natural forces (wind, rain, earthquakes)

static forces

constant forces (weight of roof)

dynamic forces

changing/moving forces (wind)

compression

pushing/squashing force (columns)

tension

pulling/stretching force (cables)

torsion

twisting force (screwdriver)

bending

top compressed, bottom stretched (shelf under load)

shear

sliding force in opposite directions (like scissors)

young’s modulus

stiffness of a material

high young’s modulus 

stiff, resists bending (steel, carbon fibre)

low young’s modulus 

flexible, absorbs energy (rubber, foam)

equilibrium

forces and moments balanced = structure stays balanced

failure

unbalanced forces/moments, weak joints, material limits

struts

resist compression; prevent sagging/buckling

shape

triangles/arches distribute load evenly

lamination

layers bonded = stronger, resists bending

composite materials

combine materials = stronger, lighter, durable

safety factor

extra strength for unpredictable loads, wear or misuse