Determining the Correct Structural I-Beam Dimensions
The I-beam's profile resembles the capital letter "I", consisting of two horizontal flanges connected by a vertical web. Large-scale building endeavors, including high-rises and structures designed to bear heavy loads like multi-level parking facilities, frequently rely on steel I-beams. Selecting the right beam size for a given construction job requires knowing the load that will be imposed on the beam.
By Charlie Davis6 steps
I-beam construction makes the construction of high rise buildings possible.
A steel I-beam takes its name from its cross-sectional shape, which mirrors the letter "I" — a vertical section with a horizontal piece at both the top and bottom. Such beams are frequently employed in major construction work, for instance skyscrapers, as well as in structures that must bear heavy loads, such as parking garages. Determining which I-beam size suits a particular building project calls for knowing the load that the beam will be required to carry.
Step 1
Establish what load you intend to put on the beam. This figure ought to account for both the weight of whatever will occupy the building space and the structural weight of the remaining building components that the beam must hold up.
Step 2
Using a standard I-beam table, find a preliminary I-beam size that roughly matches the anticipated load, expressed as inches times pounds per foot.
Step 3
From the "Area" column of the I-beam table, determine the moment of inertia for that preliminary beam size. In I-beam calculations, the moment of inertia is represented by the letter "I".
Step 4
Find the beam's depth — also referred to as its cross-section height — in the "Depth" column of the I-beam table. The letter "D" stands for depth in I-beam calculations.
Step 5
Consult a shear force diagram to establish the bending moment for the chosen I-beam size. The bending moment corresponds to the point on the diagram where shear force equals zero, determined by where the I-beam is supported within the structure. In I-beam calculations, the bending moment is denoted by the letter "M".
Step 6
To arrive at the proper beam size, work out the following equation for the variable "F": F/(D/2)=M/I
