Shear Tensile Compression Stresses Slip

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Shear - Tensile -Compression StressesSlip

• Ted 126
• Spring 2007

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Shear

• Shear strength in mechanical engineering and
  structural engineering is a term used to describe
  the strength against the type of structural
  failure where a component fails by shearing when
  it splits into two parts that slide past each
  other.
• The shear strength of a component is most
  important for beams but also relevant for e.g.
  plates.
• In a reinforced concrete beam, the main purpose
  of stirrups is to increase the shear strength.

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Shear

• Riveted and bolted joints may also be mainly
  subjected to shear stress.
• Cantilevers, beams, consoles and column heads are
  subject to composite loading, consisting of
  shear, tensile and compressive stress.

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Tensile stress

• Tensile stress (or tension) is the stress state
  leading to expansion that is, the length of a
  material or compression member tends to increase
  in the tensile direction.
• Tensile stress is the opposite of compressive
  stress.
• Structural members in direct tension are ropes,
  soil anchors and nails, bolts, etc.
• Beams subjected to bending moments may include
  tensile stress as well as compressive stress
  and/or shear stress.

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Tensile Strength

• The tensile strength of a material is the maximum
  amount of tensile stress that it can be subjected
  to before failure.
• The definition of failure can vary according to
  material type and design methodology.

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Compressive stress

• applies to materials resulting in their
  compaction (decrease of volume).
• When a material is subjected to compressive
  stress then this material is under compression.
• Usually compressive stress applied to bars,
  columns, etc. leads to shortening.

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Slip

• A slip joint is a mechanical construction
  allowing extension and compression in a linear
  structure.
• A slip-critical joint, from structural
  engineering, is a joint which relies on friction
  (rather than shear or tensile strength) to hold
  two things in place.

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Slip

• The most common slip-critical joint is where a
  girder meets a larger beam.
• Typically an angle plate joins the two.
• One beam is welded to the angle plate, the other
  has holes which are generally oversized or
  slotted.
• The bolt through this plate doesn't actually take
  the load as a shear joint or a bearing joint,
• it simply creates normal force and therefore
  friction between the two steel faces.