Structural steel – Typical application of bulb angles In steel construction practice, bulb angles are most commonly used in which type of construction because of their excellent flange stiffness and compact geometry?

Introduction / Context:
Bulb angles are a special rolled steel section where an unequal angle has a thickened, rounded “bulb” along one leg. This shape offers high stiffness-to-weight ratio and better resistance to local buckling in thin plating applications. Understanding where such sections are predominantly used helps students connect section properties with practical design contexts.

Given Data / Assumptions:

• The question asks for the most common application domain of bulb angles.
• We compare typical structural sectors: buildings, bridges, ships, and water tanks.
• No numerical calculations are required; the concept is application-based.

Concept / Approach:
Bulb angles are particularly well-suited to stiffen thin plates, as found in hulls and decks. Their geometry allows efficient welding and riveting to plating, reducing stress concentrations and providing torsional and out-of-plane stiffness. This is why naval architecture standards and shipyards specify bulb flats/angles extensively for longitudinal and transverse stiffeners.

Step-by-Step Solution:

Verification / Alternative check:
Look at classification society details (general knowledge): scantling rules and shipyard catalogues list extensive bulb flat/angle sizes for hull stiffening, confirming the typical application.

Why Other Options Are Wrong:
Column building and water tank building rarely need plate stiffeners of this type. Bridge building uses standard I/H sections, channels, and plates; bulb angles are uncommon. Industrial shed purlins are typically cold-formed Z/C or channels, not bulb angles.

Common Pitfalls:
Confusing bulb angles with normal equal/unequal angles; assuming any “angle” is interchangeable across sectors without considering plating needs.

Final Answer:
Ship building