Fundamentals of Structural Analysis

STRUCTURE

  • A structure is an assembly of members designed to resist loads and transfer them safely to the foundation

    • buildings, birdges, water tanks, towers, industrial sheds

TYPES OF LOAD

  • Dead load due to self-weight of all components

  • Live load due to temporary or movable loads

  • Wind load due to horizontal force caused by wind

  • Seismic Load are forces generated during earthquakes

  • Special loads such as temperature, snow, impact, and water pressure

FORCE

  • A force is an action that tends to change the state of rest or motion of the a component/body

    • Units: kN

  • Tension, Compression, Shear, Bending Torsion

EQUILIBRIUM

  • Drawing a force diagram all of the forces on the x,y,z plane need to have a sum of 0 (static equilibrium) in order for a structure to remain stable

SUPPORT CONDITIONS

  • Fixed support restrains horizontal, vertical, rotation loads

  • Hinged (pinned) support restrains horizontal, vertical and allows rotation

  • Roller support restrains vertcial, allows horizontal and rotation

STRUCTURAL MEMBERS

  • Beams resists bending loads

  • Columns resist compression loads

  • Slabs transfer load to beams

  • Footing transfer load to soil

  • Truss members carry axial tension or compression only

INTERNAL FORCES

  • When external loads act on a member, internal forces develop

    • Axial force acts along the members axis

    • Shear force acts perpendicular to the member axis

    • Bending moment causes bending

    • Torsional moment causes twisting

DETERMINATE & INTDETERMINATE STRUCTURES

  • statically determinate structure means all reactions and internal forces can be calculated using equilibrium equations

  • statically indeterminate structure means unkowns exceed eqilibrium equations.

STRESS & STRAIN

  • Stress is internal resistant per unit area

  • Strain is deformation per unit length

HOOKE’S LAW

  • relationship between stress and strain within elastic limit

STRUCTURAL STABILITY

  • A structure must have strength, stability, serviceability, durability.

  • Failure may occur due to overloading, buckling, excessive deflection, foundation settlement.