Iron has been used as construction material in human society for long time. The first iron-chain suspended bridge, 106 m span Jihong Bridge, was built in Southwest China in 1400s. In Europe, the first cast iron bridge appeared in 1700s in Telford, England. Cast iron was later replaced by more reliable wrought iron for construction of most railway bridges in early 1800s. It was not until late 1800s / early 1900s that steel structural systems appeared and took over iron in modern construction industry. Based on the manufacturing procedure, steel structures can be separated into two main categories: hot-rolled steel and cold-formed steel. Accordingly, there are two independent design and constructional systems.