Simply supported beam—dummy unit load method

[Equations in this post may not look right (or appear at all) in your RSS reader. Go to the original article to see them rendered properly.] We’re in the home stretch of this series, so ANIAT will soon go back to complaining about Apple’s UI choices.1 Next week’s WWDC keynote should provide some inspiration. But today’s post covers our eleventh method for deriving the center deflection of a uniformly loaded simply supported beam: the dummy unit load method. When I was an undergraduate, this was the method we used to determine the deflections of truss structures, but it’s more general than that. My favorite explanation of why it works is in Nicholas J. Hoff’s The Analysis of Structures. I have the original Wiley hardcover of this book, but you can apparently get both paperback and hardcover reprints. Hoff uses the principle of virtual work in his explanation, and I’d like to quote him here, but unfortunately his explanation is split between one section on the analysis of trusses and…