UNIT 2 Truss: Classification and Importance in Engineering
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Questions and Answers

What is the primary function of a truss in civil and structural engineering?

  • To enhance aesthetics
  • To provide insulation
  • To increase flexibility
  • To support loads and resist forces (correct)
  • What distinguishes Space Trusses from Planar Trusses?

  • Space Trusses are one-dimensional while Planar Trusses are two-dimensional
  • Space Trusses lie entirely within a plane while Planar Trusses extend into space
  • Space Trusses are always statically indeterminate unlike Planar Trusses
  • Space Trusses have members and joints in three dimensions, unlike Planar Trusses (correct)
  • Why are Simple Trusses classified as statically determinate?

  • Because equilibrium equations alone can solve for all member forces (correct)
  • Because they contain non-linear elements
  • Because they are more aesthetically pleasing
  • Because they have a complex geometric arrangement
  • How do Compound Trusses differ from Simple Trusses?

    <p>Compound Trusses are made up of simple trusses connected together</p> Signup and view all the answers

    Why are Plane Trusses analyzed using two-dimensional methods?

    <p>To simplify calculations and analysis</p> Signup and view all the answers

    Which type of truss has members and joints lying within a single plane?

    <p>Plane Trusses</p> Signup and view all the answers

    Which type of friction occurs when an object rolls over a surface?

    <p>Rolling friction</p> Signup and view all the answers

    What is the maximum value known as for static friction?

    <p>Limiting static friction</p> Signup and view all the answers

    What does the cone of friction help visualize in soil mechanics?

    <p>Distribution of soil forces around a foundation</p> Signup and view all the answers

    Which type of friction resists the motion of two objects sliding past each other?

    <p>Kinetic friction</p> Signup and view all the answers

    Why is the cone of friction important in engineering design?

    <p>Ensures stability against horizontal forces</p> Signup and view all the answers

    What is another name for fluid friction?

    <p>Viscous friction</p> Signup and view all the answers

    In which field is skin friction particularly relevant?

    <p>Soil mechanics and geotechnical engineering</p> Signup and view all the answers

    What does rolling friction make easier compared to sliding friction?

    <p>Rolling objects on a surface</p> Signup and view all the answers

    Which property of soil is related to the outward slope of the cone of friction?

    <p>Angle of internal friction</p> Signup and view all the answers

    What helps resist the lateral force applied to a foundation or object according to the cone of friction concept?

    <p>Frictional resistance along the surface of the cone</p> Signup and view all the answers

    What is one of the main advantages of the method of sections over the method of joints?

    <p>Focuses on specific sections or portions of a truss</p> Signup and view all the answers

    What assumption is typically made in truss analysis regarding joints?

    <p>Joints are perfectly rigid</p> Signup and view all the answers

    What type of friction opposes the initiation of motion between two surfaces?

    <p>Static friction</p> Signup and view all the answers

    How does the method of sections handle isolated members in truss analysis?

    <p>Allows focusing on specific isolated members or sections</p> Signup and view all the answers

    Which assumption is NOT typically made in truss analysis?

    <p>Deformable joints</p> Signup and view all the answers

    What makes the method of sections more applicable to complex trusses?

    <p>Allows simplification by choosing strategic sections</p> Signup and view all the answers

    When is static friction observed between two surfaces?

    <p>At rest relative to each other</p> Signup and view all the answers

    What characteristic distinguishes static friction from kinetic friction?

    <p>Static friction acts during motion</p> Signup and view all the answers

    Study Notes

    Truss Structure

    • A truss is a structure composed of straight members connected at their ends by joints, typically slender and arranged in a triangular or polygonal pattern.
    • Trusses are widely used in civil and structural engineering to support loads and resist forces.

    Classification of Trusses

    • Planar Trusses: All members and joints lie within a single plane, the most common type of truss.
    • Space Trusses: Members and joints are three-dimensional, extending into space rather than lying entirely within a plane.
    • Simple Trusses: Made up of linear elements, statically determinate, and the equilibrium equations alone are sufficient to solve for all member forces.
    • Compound Trusses: Composed of simple trusses connected to form a more complex structure, statically determinate or indeterminate.
    • Plane Trusses: Members and joints are all in one plane, analyzed using two-dimensional methods.
    • Multi-Storey Trusses: Used in multi-storey buildings, supporting vertical loads over several levels.
    • Howe Truss, Pratt Truss, and Warren Truss: Examples of different geometric configurations, named after their respective designers.

    Assumptions in Truss Analysis

    • Joint Rigidity: Joints are assumed to be perfectly rigid, allowing forces to be transmitted only along the members.
    • Straight Members: Truss members are assumed to be straight, with any deformations neglected.
    • Pin Joints: Joints are considered frictionless and hinged, allowing rotation but no translation.
    • No Thermal Effects: Thermal effects are neglected in truss analysis.

    Method of Sections

    • Advantageous for selective analysis of specific sections or portions of a truss.
    • Simpler and more efficient when dealing with isolated members or sections.
    • Enables elimination of redundant members, focusing on relevant ones.
    • Applicable to complex trusses, simplifying analysis and focusing on critical areas.
    • Convenient for handling external loads applied away from joints.

    Friction

    • A force that opposes the relative motion or tendency of motion between two surfaces in contact.
    • Types of friction:
      • Static Friction: Opposes initiation of motion between two surfaces.
      • Kinetic Friction: Opposes motion of two objects sliding past each other.
      • Rolling Friction: Occurs when an object rolls over a surface, smaller than sliding friction.
      • Fluid Friction (Lubricated Friction): Occurs when an object moves through a fluid, influenced by viscosity.
      • Internal Friction: Resistance to motion within a material, contributes to vibration damping.
      • Skin Friction (Shear or Traction): Resistance to motion at the surface of contact between two materials.

    Cone of Friction

    • A concept in soil mechanics and geotechnical engineering, visualizing the distribution of soil forces around a foundation or object.
    • Key points:
      • Geometry: A three-dimensional shape extending outward and downward from the base of the foundation.
      • Frictional Resistance: Lateral soil resistance is mobilized along the surface of the cone.
      • Angle of Internal Friction: Related to the angle at which the cone slopes outward, a property of the soil that describes its resistance to shearing.
      • Stability: The stability of a foundation or structure subjected to lateral loads depends on the interaction between the applied forces and the cone of friction.
      • Design Considerations: Engineers use the cone of friction concept in designing foundations and retaining structures to ensure stability against horizontal forces.

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    Description

    Explore the concept of trusses as structures composed of interconnected members for supporting loads and resisting forces. Learn about the classification of trusses and their significance in civil and structural engineering projects, such as roofs, bridges, and frameworks.

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