What are the advantages and disadvantages of steel as a structural material?

Advantages:

Maintains its strength indefinitely- does not deteriorate with age like timber and concrete, provided its surface is protected from rust.

Very strong and flexible - steel framed houses are ideal in cyclone/hurricane prone regions. The best material for bridges and skyscrapers.

Can be recycled

Structures can be prefabricated (welded) in large sections, and lifted into place with cranes and bolted together- buildings can be erected quickly. Many section types are made (square, tube, H-section, etc).

Versatile- Radical architecture is possible using steel.

Disadvanages:

Heavy and thus expensive to transport, susceptible to corrosion- steel bridges must be painted continuously, particularly in a salty environment.

Has a high expansion rate in changing temperatures, and this must be allowed for in the engineering. In conditions of repeated stress and changing temperatures, can suffer fatigue and cracks, and more corrosion.

Energy intensive to produce.