Structures unit 5

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Forces are anything that can deform a body

(static effect) or change its movement

(dynamic effect).

Examples are gravity (weight), forces that move

mechanisms or machines, pressures of fluids,

(gases, steam, water, wind).

3Static Dynamic

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Load is a force that acts on a structure.

There are two types:

Permanent load.

Variable load.

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Loads that cause internal tensions

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Image Structure Effort

A Cable Traction

B Shock absorber Compression

C Rope guide Traction

AB

C

1

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D

E

Image Structure Effort

D Column Compression

E Bridge Flexion/Bending

2

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Image Structure Effort

F Nut Torsion

G Rivet Shear

FG

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Image Effort

1 Traction

2 Flexion/Bending

3 Compression

4 Flexion/Bending

5 Compression

6 Traction

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A structure is the set of elements in an object that

support the effects of the forces that act on it and

transmit them to the ground. The structure

prevents an object from breaking or becoming too

deformed.

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Natural

Artificial

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The first structures were made of wood,

then man also used stone. Nowadays, we

use concrete and steel aluminum

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When structures remain upright (steady) and not

tip over or fall down.

The centre of gravity (mass centre) should be

centered on the base and close to the ground; in

that case the structure is stable. (cardboard cdg

experiment)

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Ways to increase stability: (modeling experiment

at the same time)

Adding mass to its base and/or making the base bigger.

Burying its base underground.

Bracing it. Placing some cables (tie rods).

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Back

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Back

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When structures resist stresses (forces) without

breaking. (experiment with sticks or sheets of

paper)

The type of material and the shape are very

important to determine its resistance.

Which situation is

more stable?

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Structures are rigid when they aren’t or are slightly

deformed when a force is applied.

The rigidity of a structure is based on triangulation.

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Great amount ofmaterial: rocks, stones,concrete, mortar.Support compression’sefforts & has very fewspaces.

Examples:Walls: Great China Wall

Pyramids

Ancient “Old” temples

Dams

Sea ports

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Massive structure

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Massive structure

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Massive structure

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Great amount ofmaterial: rocks, stones,concrete, mortar.Support compression’sefforts & has very fewspaces.

Examples:Ancient “Old” temples:

Greek & Roman

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Lintel structure

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Built with the arch.The repetition ofarcs are called vaults(Bóveda).Domes CúpulaExamples: cathedrals,Mosques, aqueducts,bridges.

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sVaulted structure

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Vaulted structure

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Vaulted structure

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Vaulted structure

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Vaulted structure(Dome)

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Vaulted structure(Dome)

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Made from curved or bent sheets of

metal, plastic or composite materials.

They are used as shells for all types

of objects.

Shell structure or casing structures

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Rolled and plate structures

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Rolled and plate structures

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Rolled and plate structures

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Rolled and plate structures

Carton of juice, milk, etc

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Divided into:

Lattice

Triangulated

Suspended

Made fromprofiles tobuiltframework

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They are used for

constructing majority of

buildings today.

Scaffolding.

Rigid elements made of wood, steel or

other metals, using cement, concrete or

reinforced concrete, forming a rigid grid.

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Lattice structure

Lattice structure

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Lattice structure

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Lattice structure

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These structures

use metal bars forming

triangles (triangular

shapes).

Oil rig

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Triangulated

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sTriangulatedCrane

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TriangulatedPylon

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Based on the use of

cables, braces or tie

rods.

They are used in

bridges and to cover

stadiums and sports

facilities.

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Suspended

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sSuspended

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Suspended

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sSuspended

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It contains compressed air inside.

It's light and can be dismantled.

Bouncing House

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Contains three-dimensional triangulated bars and combines

the properties of vaults and bar structures.