Page 2 - Mechanics of Structures – Chapter 1

Mechanics of Civil Engineering Structures – Chapter 5

7.1.1 Shear Strain

We can define shear strain exactly the way we do longitudinal strain: the ratio of deformation to
original dimensions. In the case of shear strain, though, it's the amount of deformation
perpendicular to a given line rather than parallel to it. The ratio turns out to be tan A, where A is
the angle the sheared line makes with its original orientation. Note that if A equals 90 degrees,
the shear strain is infinite.

7.1.2 Modulus Of Rigidity

Modulus of Rigidity (or Shear Modulus) is the coefficient of elasticity for a shearing force. It is
defined as "the ratio of shear stress to the displacement per unit sample length (shear strain).

Modulus of Rigidity can be experimentally determined from the slope of a stress-strain curve
created during tensile tests conducted on a sample of the material.

7.2 Types of Shear

DOUBLE
SHEAR

SINGLE
SHEAR

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