1 The Span (L) is the distance between one support and the other support, at each end of the Beam. 2  Once you have all of the above information then you will start the Actual Beam Design. 3  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). 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).