Below you will be shown how all of this works and How to Design and Select a Beam (wood or steel). We will also touch on the selection of a Concrete Beam. 1  Decide what material you want to use (Wood or Steel). 2  We are not designing Concrete Beams in the Section of the Web Site. Once you have all of the above information then you will start the Actual Beam Design. 2  The equation Total Load = W x L is to determine the Total Load on a Simply Supported Beam for a Length (L) with a Uniform Load (W).