This category covers special trade contractors primarily engaged in the erection of structural steel and of similar products of prestressed or precast concrete.
Structural Steel Erection Contractors
According to the latest figures available from the U.S. Census Bureau, more than 4,238 establishments are engaged in structural steel erection, generating an estimated $8 billion worth of business. Major uses of structural steel include office and industrial buildings; commercial buildings, including retail stores, restaurants, and service stations; apartment buildings, hotels, and motels; warehouses; and highways, bridges, tunnels, and other transportation facilities. Single-family homes accounted for a very small percentage of the structural steel used in the United States.
The structural steel erection industry felt the effects of the U.S. economic downturn more than other construction related industries because it relied so heavily on commercial and industrial construction, both which saw growth slow dramatically in the early 2000s. Spending on commercial construction declined 1.6 percent in 2001, while spending on industrial construction declined 3.2 percent. The lone bright spot in the U.S. economy@mdash;residential construction@mdash;had little impact on the structural steel sector. Transportation spending had also been trimmed in various rounds of budget cutting during the early 2000s, although increased funding was expected to gain governmental approval in 2004.
French architects began using iron to form the framework of their roofs about 1780. By the 1830s they also were using a form of masonry reinforced with imbedded iron bars that is regarded as the precursor of reinforced concrete. English builders began relying on iron in the construction of factories about 1850, primarily in an effort to make the buildings fireproof. Columns, beams, and window frames were made of cast iron, while exterior walls were made of brick or stone. Many commercial buildings also used iron, with elaborate facades often constructed entirely of cast iron and glass.
Builders in the mid-1800s also used wrought iron, which could be hammered into a sheet and laid between wooden beams, or vice versa, for added strength. Iron...