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Design of long span floor system

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Design of long span floor system

  1. 1. Department of Civil Engineering University of Engineering and Technology Taxila, Pakistan Presented To: Professor Dr. Muhammad Yaqub Presented By: Khadim Hussain 2K17-MS-STR-FT-07 Rana Dilawar khan 2K17-MS-STR-PT-02 M. Farrukh Javaid 2K17-MS-STR-PT-11 STRUCTURAL DESIGN PRACTICE Design of Long Span Floor System
  2. 2. 1. Introduction to Long Span Floor System 2. History and Evolution of Long span Floor System 3. Classification of Long Span System 4. Material for long span structures 5. Common Structural Forms for Long Span 6. Conclusion Contents 3Department of civil Engineering, University of Engineering and Technology, Taxila
  3. 3. Introduction 4Department of civil Engineering, University of Engineering and Technology, Taxila Visibility Flexibility Large Scale Storage Auditoriums Stadiums Exhibition halls Manufacturing facilities Aircraft hangars  Long span structures create unobstructed, column-free spaces greater than 30m (100 feet) for a variety of functions.
  4. 4.  Dated back to the Roman civilization However, most long-span buildings then were single level constructed using vaults and domes.  By the late 20th century, durable upper limits of span were established for these types:  The largest covered stadium had a span of 204 meters (670 feet).  The largest exhibition hall had a span of 216 meters (710 feet).  And the largest commercial fixed-wing aircraft had a 75–80 meter (250–266 foot) span hangar.  In these buildings the structural system needed to achieve these spans is a major concern. History and Evolution 5Department of civil Engineering, University of Engineering and Technology, Taxila
  5. 5. History and Evolution 6Department of civil Engineering, University of Engineering and Technology, Taxila The major evolution in long span section- active structures has occurred in the aspect of shift from in-situ to precast construction Old-to-New long span structures with their height and spans
  6. 6. Classification Department of civil Engineering, University of Engineering and Technology, Taxila 7  One way to classify long-span and complicated structures  Form active systems  Vector active systems  Section active systems  Surface active systems
  7. 7.  Form active structural systems are systems of flexible, non-rigid matter, in which the forces is carried by the form and type of material. Example of structures: 1. Cable structures 2. Tent structures 3. Pneumatic structures 4. Arch structures Form active structural systems 8Department of civil Engineering, University of Engineering and Technology, Taxila
  8. 8. Place/Country: Berlin/Germany; Completion: 2000; Business area: Steel-Glass- Structure; Type: Cable Structures Place/Country: Berlin/Germany; Completion: 2000; Business area: Steel-Glass- Structure; Type: Cable Structures Place/Country: Berlin/Germany; Completion: 2000; Business area: Steel- Glass- Structure; Type: Cable Structures Place/Country: Berlin/Germany; Completion: 2000; Business area: Steel- Glass- Structure; Type: Cable Structures 9Department of civil Engineering, University of Engineering and Technology, Taxila
  9. 9. 10Department of civil Engineering, University of Engineering and Technology, Taxila Pneumatic structures Air-inflated system air pressure 30–700 kN/m2 (common used)
  10. 10. Tent structures Khalifa International Stadium to feature tensile roofing system 11Department of civil Engineering, University of Engineering and Technology, Taxila
  11. 11. 12Department of civil Engineering, University of Engineering and Technology, Taxila Arch structure
  12. 12. Vector active structural systems 13Department of civil Engineering, University of Engineering and Technology, Taxila  Vector active structural systems are systems of solid, straight linear members, in which the redirection of forces is effected by vector partition, i.e. by multidirectional splitting of single force simply to tension or compressive elements Example of structures: 1. Flat trusses 2. Curved trusses
  13. 13. 14Department of civil Engineering, University of Engineering and Technology, Taxila Flat trusses
  14. 14. 15Department of civil Engineering, University of Engineering and Technology, Taxila Curved Truss
  15. 15. 16Department of civil Engineering, University of Engineering and Technology, Taxila Curved Truss
  16. 16.  Section active structural system are systems of rigid, solid, linear elements, in which redirection of forces is done by structural member’s section and their load transferring efficiency.  Example of structures: 1. Frame structures Section active structural systems 17Department of civil Engineering, University of Engineering and Technology, Taxila
  17. 17. Frame structures 18Department of civil Engineering, University of Engineering and Technology, Taxila
  18. 18.  Surface active structural systems are systems of flexible or rigid planes able to resist tension, compression or shear, in which the redirection of forces is done by curved geometry in 3 dimension.  Example of structures: 1. Folded plates structures 2. Shell structures 19Department of civil Engineering, University of Engineering and Technology, Taxila Surface active structural systems
  19. 19. THE LEIPZIG MARKET HALL Leipzig, Germany 1929 Span: 68.5 m Reinforced concrete shells 20Department of civil Engineering, University of Engineering and Technology, Taxila
  20. 20. 21Department of civil Engineering, University of Engineering and Technology, Taxila
  21. 21. 22Department of civil Engineering, University of Engineering and Technology, Taxila Folded plate structures
  22. 22. 23Department of civil Engineering, University of Engineering and Technology, Taxila Kamalapur Rail Station Bangladesh
  23. 23. Materials suitable for various forms of long span 1.All reinforced concrete including precast 2. All metal (e.g. mild-steel stainless steel or alloyed aluminum 3. Timber 4. Metal/RC combined 5. Plastic-coated Textile material 6. Fiber reinforced plastic Department of civil Engineering, University of Engineering and Technology, Taxila 24 24
  24. 24. 25Department of civil Engineering, University of Engineering and Technology, Taxila Common Structural Forms for Long Span Building Structures Common Structural Forms for long span structures are 1. Insitu RC 2. Precast concrete 3. Structural steel – erected on spot 4. Structural steel – prefabricated and installed on spot
  25. 25. 26Department of civil Engineering, University of Engineering and Technology, Taxila Common Structural Forms for Long Span Building Structures 5. Cable suspended structures 6. Inflated structures 7. Shell structures 8. Folded plate structures 9. Dome structures
  26. 26. 27 LIMITATIONS Arch: H/S ratio Truss: Heavy Material Shell: Surface Geometry Cables: Wind,Vibration,Moving Loads Pneumatic: Mechanical Failure
  27. 27. Shell Structures Department of civil Engineering, University of Engineering and Technology, Taxila 28 28
  28. 28. Shell Structures 29Department of civil Engineering, University of Engineering and Technology, Taxila  Shell is a type of building enclosures.  Shells belong to the family of arches .  They can be defined as curved or angled structures capable of transmitting loads in more than two directions to supports.  A shell with one curved surface is known as a vault (single curvature).  A shell with doubly curved surface is known as a dome (double curvature).
  29. 29. Classification of shells 30Department of civil Engineering, University of Engineering and Technology, Taxila  There are many different ways to classify shell structuresbut two waysare common: 1. Based on the material which the shell is made of like reinforced concrete, plywood or steel, because each one has different properties that can determine the shape of the building and therefore, these characteristics haveto be considered in the design. 2. Basedon thickness: shells canbe thick or thin.
  30. 30. Thin Concrete Shells 31Department of civil Engineering, University of Engineering and Technology, Taxila There are two important factors inthedevelopment of thethin concrete shellstructures:  The first factor is the shape which was developed along the history of these constructions. Some shapes were resistant and can be erected easily. However, the designer’s incessant desire for more ambitious structures did not stop and new shapes were designed.  The second factor to be considered in the thin concrete shell structures is the thickness, which is usually lessthan 10 centimeters. For example, the thickness of the Haydenplanetarium was7.6centimeters.
  31. 31. 32Department of civil Engineering, University of Engineering and Technology, Taxila Thin Concrete Shells Barrels shells  The cylindrical thin shells, also called barrels, should not be confused with the vaults even with the huge similarity in the shape of both structures, because each of these structures has a different structural behavior as well as different requirements in the minimum thickness and the shape.
  32. 32. Thin Concrete Shells 33Department of civil Engineering, University of Engineering and Technology, Taxila  On one hand, the structural behavior of the vault is based on connected parallel arches, which transmit the same effort to the supports .  Therefore, the materials used in these structures have to be able to resists compressions (e.g. stone) and the thickness is usually higher. Furthermore, the shape of the vaults must be as similar as possible to the arch in order to achieve the optimum structural behavior.
  33. 33. Thin Concrete Shells 34Department of civil Engineering, University of Engineering and Technology, Taxila  On the other hand, the structural behavior of the barrels shell is that it carries load longitudinally as a beam and transversally as an arch. and therefore, the materials have to resist both compression andtension stresses.  This factor takes advantage of the bars of the reinforced concrete, because these elements can be placed where tension forces are needed and therefore, the span to thickness Ratios can be increased. Furthermore, the shapehasfewer requirements than the vaults and therefore, new curves like the ellipse or the parabola can be used improving the aesthetic quality of the structure
  34. 34. 35
  35. 35. 36
  36. 36. Advantages and Disadvantages of Shells  ADVANTAGES  Verylight form of construction.  To span 30.0 m shellthicknessrequired is60mm  Dead load can be reduced economizing foundation and supporting system  They further take advantage of the fact that arch shapes can span longer  Flat shapes by choosing certain arched shapes  Esthetically it looks goodoverother forms of construction 37
  37. 37. Advantages and Disadvantages of Shells  DIS-ADVANTAGES:  Shuttering problem  Greateraccuracy in formwork isrequired  Good/Skilled Labour and supervisionnecessary  Rise of roof may be a disadvantage 38
  38. 38. Folded Plates 39Department of civil Engineering, University of Engineering and Technology, Taxila  Athin-walled building structure of the shell type.  Folded plates are assemblies of flat plates rigidly connected together along their edges in such a way that the structural system capable of carrying loads without the need for additional supporting beams along mutual edges. Engineer Eudene Freyssinet performed the first roof with thefolded structure in 1923 asan aircraft hangar at Orly Airport inParis.
  39. 39. Folded Plates FOLDING SYSTEMSIN NATURE The principle of folding as a tool to develop a general structural shape has been known for a long time. Folded structure systems which are analogous to several biological systems such as found at broad leaf-tree leaves, petals and foldable insect wings, are adopted to be employed in anew, technical way 40 Leafof PalmTree Beetle InsectWith FoldableWings Seashell
  40. 40. Folded Plates The structural characteristics of folding structures depend on:  Thepattern of thefolding.  Their geometrical basicshape.  Its material.  Theconnection of the differentfolding planes  Thedesign of the bearings.  Movable form work canbeemployed.  Form work required is relatively simpler.  Design involves simpler calculations. 41
  41. 41. Folded Plates Structuralbehavioroffolding 42  Load Distribution process:  At first, the external forces are transferredto the shorter edgeofone folding element.  There, the reaction asan axial force is divided between the adjacent elements.  Thenthe forces transferred to thebearings. StructuralConditionOf Foldingstructures
  42. 42. Folded Plates Classificationof folded structuresbasedonthe material they are made of:  Folded structures made of reinforced concrete  Metal folded structures  Folded structures of wood  Folded structures of glass  Folded structures of plastic materials  Folded constructions made in combination of different materials 43
  43. 43. Folded Plates Types TYPESOFFOLDEDSTRUCTURE Basedon geometric shapefolded structures canbe divided into:  Folded plate surfaces structures : 1. Prismatic: Rectangular plates. 2. Pyramidal: Non-rectangular plates. 3. Prismoidal: Triangular or trapezoidal plates  Folded plate frames structures  Spatial folded plate structures 44
  44. 44. Folded Plates Types 45Department of civil Engineering, University of Engineering and Technology, Taxila
  45. 45. Folded Plates Types 46Department of civil Engineering, University of Engineering and Technology, Taxila GEODESICDOME FOLDEDPLATERIGIDFRAME TAPERED FOLDED PLATES
  46. 46. Folded Plates Types THEAPPLICATIONOFFOLDEDSTRUCTURES 47 AsRoofStructure Miami Marine Stadium,Florida AsWallStructure Church of Notre DamedeRoyan, France
  47. 47. Folded Plates Types FOLDED PLATE HUT-JAPAN 48
  48. 48. Advantages and Disadvantages of Folded Plates 49 Advantages  Dead load can be reduced economizing foundation and supporting system  Theyfurthertakeadvantageofthe fact that archshapes can span longer  Flat shapesby choosingcertain archedshapes
  49. 49. Advantages and Disadvantages of Folded Plates Disadvantages: Shuttering is difficult. Greater accuracy in formwork is required. Good labor and supervision necessary. Rise of roof may be a disadvantage. 50
  50. 50. 51 Domes
  51. 51. Domes 52 Thedome is essentially an arch rotated around acenter point 180 degrees, "...a group of archesconjoinedradially around avertical axis"
  52. 52. Domes 53 Materials usedto construct Bricks,mud, stone, glass,wood, metal, plastic and concrete
  53. 53. Domes 54 MUD STONE METAL CONCRETE
  54. 54. Domes 55 Domes WOOD GLASS
  55. 55. Domes 56 Forces in Domes
  56. 56. Domes  Some of the terminology that isoften associated with domes include  Apex: the uppermost point of a dome (also known as the ‘crown’).  Cupola: a small dome located on a roof or turret.  Extrados: the outer curve of a dome.  Haunch: part of an arch that that lies roughly halfway between the base and the top.  Intrados: the inner curve of a dome.  Springing: the point from which the dome rises 57
  57. 57. Examples of Domes 58 Epcot Center, Orlando, 1982
  58. 58. 59 Taj Mahal (1647, Quing Dynasty), Agra, India, 125 ft (38 m) span corbelled dome
  59. 59. Advantages of Domes  Reduces slab curling and shrinkage cracks, providing a higher quality surface.  Provides an under-slab void for running cables and pipes, simplifying post-construction installation of new wiring and utilities.  Allows forming of complete structural suspended slabs on beam pile foundations.  Can be designed to create under-slab water reservoirs for storm water management and fire suppression water storage. 60
  60. 60. Disadvantages of Domes The major and simplest disadvantage one can think of is that domed roof doesn't allow to go beyond ground floor  A non accessible roof is very less preferred Maintenance of domed roof is difficult Difficult to carry out roof top installations , for eg. setting of water storage tanks at top or maintenance room for lifts 61
  61. 61. Conclusion These structures are preferred as having following features These structural systems reduce the loads on buildings. Light weight. Conventional system. Economy. Geometry. 62
  62. 62. 63
  63. 63. 64 Thank you

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