The design and structure of the I beam makes it uniquelycapable of handling a variety of loads. Engineers use I beams widely in construction, forming columnsand beams of many different lengths, sizes, and specifications. Understandingthe I beam is a basic necessity for the modern civil engineer or constructionworker.

I beams come in a variety of weights, section depths, flangewidths, web thicknesses, and other specifications for different purposes. Whenordering I beams, buyers classify them by their material and dimensions. Forexample, an 11x20 I beam would have an 11-inch depth and a weight of 20 poundsper foot. Builders choose specific sizes of I beams according to the needs ofthe particular building. A builder has to take many factors into account, suchas:

·Deflection. The builder will choose a thicknessto minimize deformation of the beam.

·Vibration. A certain mass and stiffness areselected to prevent vibrations in the building.

·Bend. The strength of the I beam’scross-section should accommodate yield stress.

·Buckling. The flanges are chosen to preventbuckling locally, sideways, or torsionally.

·Tension. The builder chooses an I beam with aweb thickness that won’t fail, buckle, or ripple under tension.

The design of the I beam makes it capable of bending under high stress instead of buckling. To achieve this, most of the material in the I beam is located in the regions along the axial fibers – the location that experiences the most stress. Ideal beams have minimal cross-section area, requiring the least amount of material possible while still achieving the desired shape.