Fillet welds at the sides of a base: What is the predominant internal action experienced by the weld metal when fillet welds are placed along the sides of a base connection (e.g., base plate to a supporting member)?

Difficulty: Easy

Correct Answer: Shear

Explanation:


Introduction / Context:
Fillet welds are widely used to join base plates, stiffeners, and brackets. Understanding the primary stress in the weld throat helps size the weld and check capacity against code-allowed stresses.


Given Data / Assumptions:

  • Fillet welds along the sides of a base connection (e.g., base plate to supporting steel).
  • Typical axial or shear loads transmitted through the joint.
  • No unusual torsional demand unless explicitly stated.


Concept / Approach:

The design of fillet welds is typically governed by shear stress on the effective throat area of the weld. While local components of tension/compression may exist under eccentric or combined loading, the controlling check for most base side fillet welds is shear on the throat and fusion faces, as per common design provisions.


Step-by-Step Solution:

Identify the load path from base plate to supporting member.Resolve resultant into shear across the weld throat.Select the stress type used for capacity checks: shear.


Verification / Alternative check:

Weld design chapters compute required weld size by V = allowable_shear * throat_area, confirming shear as the governing stress for typical fillet welds at bases and stiffeners unless strong eccentricities cause additional bending distribution around the weld group.


Why Other Options Are Wrong:

  • Tension/compression: normal stresses can appear locally but are not the primary basis for standard fillet throat design.
  • Bending or torsion: may act on the weld group as a whole in eccentric cases but the elemental weld check remains shear on the throat.


Common Pitfalls:

  • Ignoring eccentricities that produce additional weld group moments.
  • Underestimating effective throat (0.707 * leg size) in capacity calculations.


Final Answer:

Shear.

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