Page 1 - Mechanics of Structures – Chapter 1

Mechanics of Civil Engineering Structures – Chapter 5

SHEAR STRESS

This topic covers the basic knowledge of relationship between shear stress, shear strain
and modulus of rigidity. It also covers the calculation of shear stress in plate, bolt or rivet
and shear stress distribution in beams.

7.1 Introduction

When beam is loaded , shear force and bending moment is produced. To resist
shear force, internal stresses in beam section are induced. These internal stresses in beam
section are shear stresses.

If the applied load consists of two equal and opposite parallel forces which do not share the same
line of action, then there will be a tendency for one part of the body to slide over, or shear from
the other part. A shear stress occurs as a result of a shear force. Shear forces therefore act
perpendicular to the axis of the member.
As with direct stresses, shear forces must be opposed by equal forces in the opposite direction
– for example, you wouldn’t be able to slice a piece of bread without holding the loaf in place
with your other hand (which provides the opposing force) at the same time.

Shear stress (τ) = Shear force (V)
Area (A)

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