Which method is NOT used for fireproofing structural steel?

Structural reinforcement is correctly identified as not being a method specifically used for fireproofing structural steel. Fireproofing aims to protect steel from fire damage, ensuring that it retains its structural integrity during a fire event.

The sprayed material method involves applying a fire-resistant substance directly onto the steel surface, providing an insulating layer against heat. Membrane fireproofing involves encasing structural steel in fire-rated materials that create a barrier, which also contributes to maintaining structural integrity. Cementitious methods utilize a mixture that includes cement to provide a protective coating to the steel, further enhancing its fire resistance.

In contrast, structural reinforcement is more about increasing the strength and load-bearing capacity of steel components, rather than providing fire resistance. While reinforcements may indirectly contribute to the overall fire performance of a structure by ensuring it can withstand additional loads, they do not specifically act as fireproofing measures. Therefore, it is clear that this method does not belong within the category of fireproofing techniques for structural steel.