1. Structures Technology Department IES Amparo Sanz 1º E.S.O. European Section

3. Shell structures

4. Structural member

6. Compression/Pressure

7. Shear

8. Torsion

10. Bridges

11. Cantilevers

12. Columns and pillars

13. Ties

14. Struts

17. Shell structures: Shell structures rely on the shape they have been moulded into for their strength. They are usually lighter than frame structures. These structures may be man-made or may occur naturally . Cover page

18. FRAME AND SHELL STRUCTURES Cover page

19. Structural Members STRUCTURAL MEMBER A structural member is a part of a structure. Tension Compression Redundant REDUNDANT MEMBER A redundant member is a part of a structure that is neither in tension nor compression. Redundant members can be removed from structures without the structure weakening. A good design has not redundant members. Cover page

20. What is a force? A force is a push or a pull . Forces can make things move. Engines and motors make forces that cause machines to move. The force of gravity pulls everything downwards towards the earth. Force is measured in newtons (N), after Sir Isaac Newton. TYPES OF LOADS: Structures are built to support a load. Loads can be static (not moving) or dynamic (moving) Cover page

22. Compression / Pressure

23. Shear

24. Torsion

25. Bending Cover page

27. Example: A coping saw always has its blade in tension. If the blade is cut, it will pull apart. Cover page

28. Compression / Pressure Compression means being pressed into less space or being flattened by pressure. Something under a heavy load is in compression. Certain materials under compression will get smaller. An object is under pressure if there is a compression force acting on it. Pressure = Force / Area This means that the smaller the area the force is applied to, the greater the pressure. This explains why someone leaning on you with their hand is a lot less painful than the same person leaning on you with a compass point. Cover page

30. Torsion Torsion is the act of twisting a structure. A torsion force causes something to twist or turn. The cube is in torsion, as it is being twisted. Cover page

31. Bending Forces can bend a structure. Example: A bar bends due to the weight of a gymnast swinging on it, or a long narrow shelf may bend with books on it. In these situations, the upper surface is in compression and the lower surface is in tension. The beam is being bent with the weight. Cover page

33. Bridges

34. Cantilevers

35. Columns and pillars

36. Ties

37. Struts

38. Triangulation Cover page

39. Beams A beam is a long rigid piece of wood or metal. It is the simplest way of supporting a load across a gap. It is the simplest structure, but it can also be part of a more complex structure. Circular section Square section Triangular section L-section beam I-section beam U-section beam T-section beam Cover page

40. Bridges A bridge is used to “bridge” a gap, usually between the banks of a river. A bridge has supports at two ends. The first bridges were simple wooden beams, but nowadays they are often huge, complicated structures. Golden Gate (St. Francisco) Tower Bridge (London) New River Gorge Bridge Fayetteville (USA) Cover page

41. Cantilevers Cantilevers are beams that are held and supported at one end only. They are brackets for supporting balconies, shelves, tree branches, etc. Cover page

42. Columns and pillars Columns and pillars are vertical beams, normally designed to support loads directly on top. Example: Table legs. Cover page

43. Ties A tie is a part of a structure in tension for keeping two objects from spreading or separating. Ties are usually thin. Example: The cross piece on a swing. Tensor Cover page

44. Struts A strut is a part of a structure in compression for keeping two objects from coming closer together. Struts are usually thick. Example: A pillar supporting a roof. The wires on either side of the flagpole are being stretched, and so, therefore, are the ties. The pole is in compression due to gravity, and so, therefore, is the strut. Cover page

45. Triangulation Triangulation means using triangles arranged together to form a frame or part of a frame, with increased rigidity . Structures made from triangles are strong. Eiffel Tower Pylon Tecnology Project Cover page

47. There is pollution from the lorries and trucks used in the construction of the structure.

48. The iron, stone and other raw materials have to be sourced in quarries and mines, which damage the landscape. There is further environmental damage in converting the raw materials into a form that can be used in the structure.

49. Wildlife is disturbed and may no longer survive. Cover page

50. THE END Cover page