1.0 Introduction To Structure


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1.0 Introduction To Structure

  2. 2. Objectives:At the end of the lesson, students will be able to:1.Name types of forces.2.Name types of loads.3.Distinguish characteristics of primary materials in main structural construction.
  3. 3. What is forces? Definiton:Any influence that causes an objectto undergo a certain change, either concerning its movement, direction, or geometrical construction.
  4. 4. Do youknow the types of forces?
  5. 5. Types Of Forces: TENSION FORCE (daya regangan) 1 Tension refers to when a force is applied that pulls outward against the face of a structural element and stretches it (e.g., stretching a rubber band).
  6. 6. Types Of Forces: COMPRESSION FORCE (daya mampatan) 2 Compression represents when a force is applied inward against the face of a structural element, thereby shortening it.
  7. 7. Types Of Forces: SHEAR FORCE (daya ricihan) 3 Shear is when a force is applied in parallel to the face of a structural element at an angle that is perpendicular to either compression or tension forces.
  8. 8. 1. 2. Dead load Live load LOADS 4. 3.Seismic load Wind load
  9. 9. Dead load What it means: Forces incurred due to the weight of all the materials used in the construction of a home. E.g: Roof, ceiling, floor, wall & partition. What it affects: • A constant over the life of the structure. • Big impact on the long- term deflection/ creep of framing members.
  10. 10. Live load What it means: Produced by the users of a home. E.g: People, furniture, storage items. What it affects: • Exert force on almost all of a house’s framing components. • Goal: To design floor systems that limit deflection & vibration.
  11. 11. Wind load What it means: +ve @ -ve pressures exerted on a house when it obstructs the flow of moving air. Act perpendicular to the surfaces of a house What it affects: • Depends on: location, height, roof pitch. • Most sig. impact: roof framing, overhangs, large openings.
  12. 12. Seismic load What it means: The inertial forces acting on a house due to earthquake- induced ground motions. Act horizontally on each element of the structure & are proportional to their mass. What it affects: • All components of a frame. • Shear-resisting elements are most affected
  13. 13. Do you know thecharacteristics of primary materials inmain structuralconstruction?
  14. 14. 1 1. TIMBER • The oldest of structural materials. • The properties of timber are non-linear and very variable, depending on the quality, treatment of wood, and type of wood supplied. • Wood is strong in tension and compression, but can be weak in bending due to its fibrous structure. • Reasonable cost, ease of working, attractive appearance and adequate life if protected from moisture and insects. • Wood is relatively good in fire as it chars, which provides the wood in the centre of the element with some protection and allows the structure to retain some strength for a reasonable length of time.
  15. 15. 2. BRICKS2 • A brick is a block, or a single unit of a ceramic material used in masonry construction, usually stacked together, or laid using various kinds of mortar to hold the bricks together and make a permanent structure. • Made from: Various kiln-baked clay and shale mixtures. • Typically produced in common or standard sizes in bulk quantities. • Burnt-clay bricks have good resistance to moisture, insects and erosion, and create a good room environment. • They are moderate in cost and have medium to high compressive strength. • Long lasting
  16. 16. 3 3. CONCRETE • Made by: Mixing cement paste (portland cement & water) with aggregate (sand & stone). • Concrete is used extremely widely in building and civil engineering structures, due to its:  Low cost, flexibility, durability, high strength, high resistance to fire, strong in compression, hardness, imperviousness and mouldability. • Flaws: Very weak in tension.
  17. 17. 1.Reinforced concreteReinforced concrete is concrete in which steelreinforcement bars ("rebars"), plates or fibershave been incorporated to strengthen a materialthat would otherwise be brittle. In industrialisedcountries, nearly all concrete used in constructionis reinforced concrete. Due to its weakness intension capacity, concrete will fail suddenly and inbrittle manner under flexural (bending) or tensileforce unless adequately reinforced with steel.2. Prestressed concretePrestressed concrete is a method for overcomingthe concretes natural weakness in tension. It canbe used to produce beams, floors or bridgeswith a longer span than is practical with ordinaryreinforced concrete. Prestressing tendons(generally of high tensile steel cable or rods) areused to provide a clamping load which produces acompressive stress that offsets the tensile stressthat the concrete compression member wouldotherwise experience due to a bending load.
  18. 18. 4 4. STEEL • Iron alloy with between 0.2 and 1.7% carbon. • Steel is used extremely widely in all types of structures, due to its:  Low cost, high strength to weight ratio, speed of construction, strong in tension and compression.  Flaws: Weak in fires, very prone to corrosion (rust). • Steel is a ductile material, which will behave elastically until it reaches yield (point 2 on the stress-strain curve), when it becomes plastic and will fail in a ductile manner (large strains, or extensions, before fracture at point 3 on the curve).
  19. 19. Stainless steel• An iron-carbon alloy with a minimum of 10.5% chromium content.• There are different types of stainless steel, containing different proportions of iron, carbon, molybdenum, nickel. It has similar structural properties to steel, although its strength varies significantly.• It is rarely used for primary structure, and more for architectural finishes and building cladding.• It is highly resistant to corrosion and staining.