Why is steel used to build a bridge?

Answer 1

Putting aside the architectural reasons of competing designs available,

engineering decision is made based on the span length of the bridge

and the economical factors.

Generally speaking, bridges are built in the following materials in the order

of increasing span length;

1.Wood

2.Concrete

3.Steel

4.Post-tensioned Concrete

If, in your area the steel industry is highly developed and it is relatively

cheap and the skilled work force for steel work is easy to come by, the

engineering decision may tend to steel regardless of the span length unless,

it is long enough to make a steel bridge structurally unsound.