Elementary Theory of Statically Determinate Structures

The use of diagrams is a particular instance of that method of symbols which is so powerful an aid in the advancement of science. A diagram differs from a picture in this respect, that in a diagram no attempt is made to represent those features of the actual material system which are not the special objects of our study . . . when studying the equilibrium of a framework . . . in which each piece acts only by tension or pressure between its extremities, it is not necessary to know whether a particular piece is straight or curved or what may be the form of its section. In order, therefore, to exhibit the structure of the frame in the most elementary manner we may draw it as a skeleton in which the different joints are connected by straight lines. — James Clerk Maxwell, “On Bow’s Method of Drawing Diagrams in Graphical Statics” (1876), Scientific Papers, Vol. II, p. 492.

Many of the most important applications of the theory of statics are in the field of structural design. One of the first steps in the design of any structure is the calculation of the forces which act in the various members of the structure. Some of the special applications of statics which are used extensively in this field will be discussed in the following pages.