Why iron base alloys are preferred over aluminum alloys in structural members of bridges and buildings?

Question

Why iron base alloys are preferred over aluminum alloys in structural members of bridges and buildings?

Answer 1

well, Aluminum is light ok, but it's less a factor to consider in making bridges, it's best for aircrafts, and aluminum is weak compared to Iron.

Iron is stronger and has more strength than aluminum which should really be considered in building a safe, strong and durable bridge.

Answer 2

Aluminium is a very reactive metal, which when it has an oxide layer behaves as if it is inert. Concrete is alkaline and dissolves this oxide layer, exposing the very reactive metal beneath which would corrode very rapidly. Iron on the other hand is not oxidised in alkaline environments and so lasts far longer. The cost is also very important.

Answer 3

iron is more malible than aluminium so it bends better when inder stress , dosent bend a lot becouse althought it is heavier it will be stronger , it will also not suffer stress fracturess as much

where as aluminium will suffer cracks

Answer 4

Primarily, cost. Also, aluminium alloys do not have an infinite cycle load life (for moderately low level cyclical loads) like iron alloys have, and since bridges are expected to last over a century, this capability has an influence. Bridges do not have to be light, making them light is only the result of wanting to make them cheaper, using less material.