Types of Failures in Steel Structures

Type of Failures:

1. Shearing Failure of Bolts.
2. Bearing Failure of plate.
3. Tearing failure at edge of plate.

Shearing Failure of Bolt:

Bearing Failure of Plate:

Shear & Bearing Area

Tearing Failure at edge of Plate

Eccentricity of Applied Force:

Plates of lap joint tends to bend.

Bending produces non uniform bearing of the fastener on the plates

Tearing failure

Tests showed, failure by tearing through free edge of material will not occur if Le measured parallel to line of applied force is not less dia of bolt multiply ratio of bearing stress to tensile strength of connected part.

Force transmitted by the bolt
P = fp D t ------------------------(A)
Force to cause failure along two shear planes
P = 2(Le - D / 2 ) t u
u = 0.7 Fu
P = 1.4Dt Fu (Le / D -1/2) -----(B)
Equating (A) & (B)

Equation ( C ) can be approximated as

So Equation becomes;