Steel is the most commonly used construction material in the world today. Its strength-to-weight ratio, durability, elasticity, pliability, eco-friendliness, and plain aesthetic appeal have, in the 100-plus years since its invention, established steel as the integral structural component of virtually every sizable commercial structure in existence. From skyscrapers to bridges, automobiles to ships, pipelines to rocket gantries, the durability and versatility of steel makes these fixtures of modern civilization possible.
Of course, with the advent of steel came the concept of structural steel design. To be properly erected, the geometric configurations of steel structures, the various factors involved in the building of a steel skyscraper, for instance, must be calculated and refined, often before the steel to be used is even cast. In the progression of a steel structure from idea to erection, a steel structural engineer is among the first experts to be enlisted in the building process.
The essential of structural steel design, as opposed to architectural design, is the assurance of the structural integrity of a steel building, bridge, vehicle, tower, etc. Structural steel design encompasses familiarity with the different types of steel and steel-based alloys, reliance on formulas depicting stress-resistance and load-bearing factors of, among other things, steel beams, columns, braces, connectors, and hangers, as well as a vast command of geometrical forms and the mathematics of construction. Should any of the design or physical components fail, disaster is the inevitable result. Aesthetic considerations are more directly the provenance of an architect, and have no bearing on the proper performance of the steel skeleton of a structure.
Structural steel design has evolved from concentrating solely on the rigidity that steel can and does provide a structure, to the advantages that steel provides in structural flexibility, allowing a structure to better resist the stresses of nature, and man. Interestingly, the major impetus for this evolution in structural steel design was earthquakes. The preliminary design of multi-story steel structures and lengthy steel spans is ordinarily predicated first on how effectively the structure will withstand a major earthquake. Wind resistance is also a major factor in the design and construction of tall steel structures, as is terrorism.
In its infancy, structural steel design was accomplished through hours of painstaking physical calculation, drafting, and, very often, trial and error. As the quality of steel itself has improved, so have the mechanics of structural steel design. Computer assisted design (CAD) is perhaps the most innovative and effective tool in the advancement of structural steel design, relieving the structural engineer of the tedium and error inherent in physical calculation and hand drafting. CAD ensures a much quicker and far more accurate design process at significantly less cost.