FRAME STRUCTURES The frame structure is the most common choice of structure. These structures are composed of long elements (tubes, bars...) joined to each other at the ends. They are easy to design and build, lightweight and do not requiere much material; but it do not resist big loads or strong impacts.
SHELL STRUCTURES They are made of a thin outer layer of material that surrounds a volume. That volume can be empty space or can be filled with something that has no structural relevance. The forces are spread throughout the whole structure.
ARCH The Romans invented the arch. There are many types, but the semicircular arch is the most common. Its own weight is the main load, but it displaces the forces to the sides, so that a large space is left under the arch.
MIX AND MATCH Very often, different types of structures are combined and the combination is a more complex structure. For example, houses have brick walls which are part of mass structures and there are also colums and beams that are part of frame structures.
MASS STRUCTURES They are simply made of clump material, filling the body completely. They are made of low-quality materials. They are heavy, need much material and occupy large amounts of space. They are held in place by its own weight.
SUSPENSION STRUCTURES A suspension structure holds an element by cables that are held from the top of a tal column. The span is the space between one column and the next.
An element can be defined as “the simplest part of the whole”. In a structure, the forces for every element are calculated and the element (beam or column) is designed to withstand them.
TYPES OF UNIONS
All structural elements must be somehow united to the other elements and the whole structure is often united to the floor as well. The unions are classified as permanent or non-permanent.
THE TWO DIFERENT UNIONS :
Permanent They are meant for structures that will not need to be disassembled.
Non-Permanent Non-permanent unions are those designed to assemble and disassemble the elements of the structures as many times as necessary.
FORCES ON STRUCTURAL ELEMENTS
A successful structure must be able to withstand all th forces that it will experience without toppling over or collapsing. They are many types.
TENSION STRAIN Is the strain that causes an element to stretch.It can be due to forces that pull an elements from its ends.
COMPRESSION FORCES They are those forces which cause an elements to get squeezed.
Shear forces act across a material in such a way that they can force one part of an element to slide over.
TORSION FORCES If you apply a turning force at one end of an element and, if the element is fixed to a suport at the other end, the element twists.
Bending forces act at angle to a member (at 90º from the axis line in the drawing), making it bend.