How to Calculate Beam Failure

Find the beam design table for the type of material you will be using. If home construction is your goal, you will likely be choosing a beam made of wood. A design table will exist for the type of wood you are using, such as fir or oak.

Beams are subject to different types of loads, and determining the type of load distributed over a beam will affect the distribution of the load. For example, a point load indicates a load that is concentrated in one part of a beam. Point load is at its greatest at the middle of a span, where deflection is also greatest. A uniform load means that the load will be evenly distributed over the entire length of the beam. Design tables are typically computed for different types of load.

Design tables are organized along two axes. The columns may have values that correspond to beam depth, and the rows may have values based on span length. The table output value corresponding to a given span length and beam depth will represent the load per inch of beam width possible for that material.

Multiply the output value from the design table by the width of the beam in question. This value represents the toal load in pounds of force that may be safely resisted by a given beam of a given size.