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STRUCTURES

Structures are groups of elements somehow joined together to support a load with stability.

There are five different types of structures:

Frame structuresShell structuresArchsMass structuresSuspension structures

Frame structures

These are the most common structures.

They are composed of long elements which are joined to each other at the ends.

Elements are built with strong materials and the space between them is empty space.

They are easy to desing and build, inexpensive, lightweight and they don't require much materials.

However they are not goodfor very big loads or strong impacts.

Shell structures

These are made of a thin material that surrounds a volume.

That volume can be empty or filled with something that has not structural relevance.

It mantains the shape and it's strong.

The cut layer can be thin because the forces are spread throughout the whole structure.

Archs

Archs were invented by Romans.

Althought there are many types the semicircular arch is the most used.

They are made of stone and the stone at the very top is called the “key stone”.

They are used like bridges, the key is that the geometry of the arch spreads the forces to the sides leaving a space under the arch.

Mass structures

They are made of clump materials filling the body completly.

Mass structures can be made by piling up materials into a shape or desing.

They have some advantages its held by its own weight and losing small parts has little effect on the overall strength of the structure.

However they also have disadvantages, they are heavy, need much material and occupy large areas.

Suspension structures

A suspension structure holds an element by cables that are held from the top of a tall column.

The space between one column and the next is called span.

They are the best for bridges.

They are good for covering a very large span.

However they are very expensive to build.

Local structures

International sructures

Structural elements

An element can be defined as “the simplest part of the whole”

In a structure the forces for every elements are calculated and the element is desingned to whithstand the force

Types of unions

The structural elements must be united

The whole structure is often united to the floor

The union are classified as permanent and non-permanent

Permanent unions.

They are meant for structures that will not need to be disassembled. Ex. Weldings, rivets, glue...

Non-permanent

Those desinged to assemble and disassemble the elements of the structure as many times as necessary.

Forces on structural elements

Each of the elements in the structure will whithstand a particular force which is a result of the load that the structure is supporting.

There are five tipes of forces:

Tensional straing: Is the strain that causes an element to strech. It can be due to forces that pull an element from its ends.

Compression forces: They are those forces which causes an element to get squeezed.

Shear strain: Shear forces act across a material in such way that they can force one part of an element to slide over another.

Torsion forces: If you apply turning force at one end of an element and, if the element is fixed to a support at the other end, the element twist.

Bending forces: Bending forces act at an angle to a member making it bend

BY: Paola Caro Domínguez & Maria Alejo Hernández