Answer:
It can be said that the most crucial milestone attained in construction engineering during the age of enlightenment is the introduction and use of iron and steel in civil engineering.
The use of these materials spurred a new ways and methods of construction. This is because they are far stronger, could be used for taller structures with less expenditure of material than stone, brick, or wood and can produce greater unsupported spans over openings and interior or exterior spaces.
The evolution of steel frame construction in the 20th century entirely changed the concept of the wall and the support
Before 1800, metals played an supplementary role in architecture. They were used for for tension members (chains strengthening domes, bonding masonry (dowels and clamps), tie rods across arches to reinforce the vaults), and for roofing, doors, windows, and decoration.
Cast iron, the first metal that could be substituted for traditional structural materials, was used in bridge building as early as 1779. Its ability to bear loads and to be produced in an endless variety of forms, in addition to its resistance to fire and corrosion, quickly encouraged architectural adaptations, first as columns and arches and afterward in skeletal structures.
In the 19th century, steel took over from cast iron because it was much more suited for columns rather than beams. It had more compressive strength than tensile qualities. Steel is more uniformly strong, elastic, and workable, and its high resistance in all stresses can be closely computed.
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