Structural steel is a material having very wide capabilities and is compatible with and can be joined to most other materials, including plain concrete, reinforced or prestressed concrete, brickwork, timber, plastics and earthenware. Its co-efficient of thermal expansion is virtually identical with that of concrete so that differential movements from changes in temperature are not a serious consideration when these materials are combined. Steel is often in competition with other materials, particularly structural concrete. For some projects different contractors
often compete to build the structural frame in steel or concrete to maximise use of their own particular skills and resources. This is healthy as a means of maintaining reasonable construction costs. Steel though is able to contribute effectively in almost any structural project  to a significant extent.Steel for structural use is normally hot rolled from billets in the form of flat plate or section at a rolling mill by the steel producer, and then delivered to a steel fabricator’s workshop, where components are manufactured to precise form with connections for joining them together at site.
Frequently used sizes and grades are also supplied by the mills to steel stockholders from whom fabricators may conveniently purchase material at short notice, but often at higher cost. Fabrication involves operations of sawing, shearing, punching, grinding, bending, drilling and
welding to the steel so that it must be suitable for undergoing these processes without detriment to its required properties.