Question

Which of the following statements is/are correct in the context of steel construction?

• A. Weathered steel forms a rust-like layer when exposed to weathering.
• B. Intumescent paints on steel sections improve passive fire protection.
• C. For the same weight, steel I-beam has more flexure-bearing capacity in comparison to Castellated steel beam.
• D. Outrigger systems provide additional torsional rigidity against lateral loads in tall structures.

Hint:

Check each claim: weathering steel's patina and intumescent coatings are both real, but a castellated beam, not a plain I-beam, has the greater flexural capacity for the same weight.

Answer 1

The Correct Option is A, B, D

This question tests four separate facts about steel members used in construction, so each option needs to be checked on its own rather than solved with one formula.

1. Weathered steel forms a rust-like layer when exposed to weathering: true. Weathering steel is designed to build up a tight, stable oxide skin on its surface within the first few years of exposure, and this skin looks like rust but actually protects the metal below it from further loss.
2. Intumescent paints on steel sections improve passive fire protection: true. These coatings sit dormant at room temperature and expand into an insulating char only once fire heat hits them, slowing the rate at which the steel loses its load-bearing strength, so they count as passive, not active, fire protection.
3. For the same weight, steel I-beam has more flexure-bearing capacity than a Castellated steel beam: false. A castellated beam is cut and re-welded from an ordinary I-beam to gain extra depth without much extra weight, and moment capacity rises sharply with depth, so the castellated beam actually carries more bending moment for the same steel weight, not less.
4. Outrigger systems provide additional torsional rigidity against lateral loads in tall structures: true. An outrigger ties the building's core to its perimeter columns, so under wind or seismic load the perimeter columns are pulled into the picture and resist rotation and overturning together with the core, adding stiffness against lateral and torsional effects.

Three of the four statements hold up, and only the I-beam versus castellated beam claim is backwards.

Let's summarize:

• Correct: the weathering steel patina, intumescent fire coatings, and outrigger stiffening
• Incorrect: the I-beam versus castellated beam comparison is reversed

So the correct statements are (A), (B) and (D).