A FIRST STEP INTO NONLINEAR STATICS

In the introductory courses in Statics and Structural Mechanics, the role played by nonlinearities is often left out, to make more room to details in linear problems, which can be faced with relatively simple mathematical tools. Behavior of structures is appropriately modeled as linear in many circumstances, although we have to take nonlinearities into account whenever stresses or strains become large enough, or members have very small thickness or even very large slenderness, and so on. Hence, we could say that behavior of structures is inherently nonlinear, and linear approximation is valid provided specific requirements on the order of magnitude of given ingredients of the problem under consideration are fulfilled. The scope of this brief contribution is reveal, through a paradigmatic example, how nonlinearity naturally emerges.