| AISC (American Institute of Steel Construction) is | | | | distribution of forces and moments acting on each |
| the controlling authority for implementing uniform | | | | of these structural beams; the second phase |
| steel fabrication practices in USA. For this, AISC | | | | involves detailing of the load carrying capacity of |
| has provided LRFD Specifications for structural | | | | these beams to withstand these forces and |
| steel buildings to help commercial designers. These | | | | moments acting on them. The more |
| specifications help identify clearly the structural | | | | comprehensive this details, the more exact will be |
| resistance within the elastic and inelastic ranges of | | | | the design and the more reliable will be the |
| behavior and the maximum load limit state. | | | | structure. |
| The objective of structural beam design is to | | | | Since the load carrying capacity of structural |
| create a physical structure that can withstand all | | | | beam is dependent on the type of loads acting on |
| environmental conditions to which it is subjected. | | | | the beam, geometrical irregularities and material |
| Many factors influence the design process, from | | | | properties, load-carrying capacity is determined |
| foundation to loading to dimension lay out to risk | | | | mostly on the basis of full scale tests for axially |
| and cost, but ultimately the final design is a | | | | loaded beams and beam-column interaction |
| reflection of the properties of the construction | | | | curves. These beam strength curves are |
| material and the geometrical imperfection of its | | | | commonly coded as the beam strength curves or |
| structural components, and in particular its | | | | equations for design purpose. |
| mechanical properties. | | | | At present, the structural engineer evaluates |
| Today, in engineering design practice, there exists | | | | design primarily on the simple model of linear |
| a basic two-stage process for structural beam | | | | elasticity of the material. Structural steel beam |
| design: firstly, the forces acting on each structural | | | | design emerges successful only when proper |
| beam in the structure are calculated; secondly, the | | | | analysis is done (many times using CAD 3D |
| load carrying capacity of each of these structural | | | | models) and with right structural analysis |
| beams to those forces acting on it is evaluated. | | | | considering both axial forces and bending |
| The first phase involves an analysis of the | | | | moments. |