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  1. 1. THE STRUCTURES. By: Daniel Fernandez Martinez José Barquero García
  2. 2. What's a structure? A structure is a group of elements somehow united to support a load with stability. Everything has a structure. For example: humans have skeleton, bicycles have a frame, houses have columns, beams and a roof.
  3. 3. TYPES OF STRUCTURES <ul><li>Frame structures. </li></ul><ul><li>Shell structures. </li></ul><ul><li>Arch structures. </li></ul><ul><li>Mass structures. </li></ul><ul><li>Suspension structures. </li></ul>
  4. 4. FRAME STRUCTURES. <ul><li>It' s the most common choice of structures, they are composed of long elements joined to each other at the ends. They' re strong. </li></ul><ul><li>Advantages: easy to build, inexpensive and lightweight. </li></ul><ul><li>Disadvantages: not good for very big loads or strong impacts. </li></ul>
  5. 5. SHELL STRUCTURES <ul><li>They are made of a thin outer layer of material that surrounds a volume. Natural shell structures: eggs, shellfish. Artificial shell structures: cardboards boxes, balloons, etc. </li></ul>
  6. 6. ARCH. <ul><li>The romans invented the arch. There are many types, but the semicircular arch, which was the roman arch, still remains the most used. Its own weight is the main load and the geometry of the arch displaces the forces to the sides. The stone at the very top is called the keystone. </li></ul>
  7. 7. MASS STRUCTURES <ul><li>They' re simply made of clump material, filling the body completly. They' re made of low quality materials, but the structure is normally thick. Examples of natural mass sturctures are mountains and coral reefs. Examples of man made mass structures are sandcastles, dams, load-bearing walls. </li></ul>
  8. 8. SUSPENSION STRUCTURES. <ul><li>A suspension structure holds an elements by cables that are held from the top of a tall column. </li></ul><ul><li>The space between one column and the next is called the span. </li></ul><ul><li>Advantages: Good for covering a very large span. </li></ul><ul><li>Disadvantages: Expensive to build. </li></ul>
  9. 9. STRUCTURAL ELEMENTS. <ul><li>An element can be defined as the simplest part of the whole. </li></ul><ul><li>In a structure, the forces for every element are calculated and the element is designed to withstand them. </li></ul>
  10. 10. TYPES OF UNIONS. <ul><li>The structural elements must be united. </li></ul><ul><li>Permanent unions are meant for structures that will not need to be disassembled. They' re welding, rivets, glue... </li></ul><ul><li>Non-Permanent unions are those designed to assembled and disassembled the elements of the structures as many times as necessary. </li></ul>
  11. 11. FORCES ON STRUCTURAL ELEMENTS <ul><li>A succesful structure must be able to withstand all the forces that it will expensive without toppling over or collapsing. </li></ul><ul><li>Types of forces on structural elements: </li></ul><ul><li>Tensional strain. </li></ul><ul><li>Compression forces. </li></ul><ul><li>Shear strain. </li></ul><ul><li>Torsion forces. </li></ul><ul><li>Bending forces. </li></ul>
  12. 12. TYPES. <ul><li>Tensional forces: </li></ul><ul><li>Is the strain that causes </li></ul><ul><li>an element to stretch. </li></ul><ul><li>It can be due forces </li></ul><ul><li>that pull an element </li></ul><ul><li>from its ends. </li></ul><ul><li>Compression forces: </li></ul><ul><li>They are those forces </li></ul><ul><li>which cause an </li></ul><ul><li>element to get </li></ul><ul><li>squeezed or buckled. </li></ul>
  13. 13. TYPES. <ul><li>Shear strain: </li></ul><ul><li>Shear forces act across </li></ul><ul><li>a material in such a </li></ul><ul><li>way that they can force </li></ul><ul><li>one part of an element </li></ul><ul><li>to slide over another. </li></ul><ul><li>Torsion forces: </li></ul><ul><li>If yoy apply a turning </li></ul><ul><li>force called torque at </li></ul><ul><li>one end of an element </li></ul><ul><li>and, if the element is </li></ul><ul><li>fixed to a support at the </li></ul><ul><li>other end, the element </li></ul><ul><li>twists. </li></ul>
  14. 14. TYPES. <ul><li>Bending forces: </li></ul><ul><li>Bending forces act at </li></ul><ul><li>an angle to a member </li></ul><ul><li>(at 90º from the axis </li></ul><ul><li>line in the drawing), </li></ul><ul><li>making it bend. </li></ul>
  17. 17. <ul><li>THE END </li></ul>