Resumen
What a structural milestone is? From a thermodynamical point of view, the efficiency is the measure
that allows to compare solutions for a problem. Galileo was the first to introduce a rule for its measurement,
as the ratio of useful weight to the whole supported weight. He foresaw that insurmountable
sizes have to exist, those that bound the solution size for each problem and for which the efficiency
of optimum solution is zero. A design theory aims to determine the shape for the insurmountable
size of each problem and the maximum efficiency for lesser sizes or alternative forms. Only then it
is possible to measure the relative merit of any solution and to determine if it is an actual milestone,
that is to say, a move toward the maximum efficiency.
Later researches by Maxwell, Michell and others enlightened how the optimum shapes could
be determined in the case of a unity efficiency (the null self-weight case), but ignoring the general
approach of Galileo. Near 1970 Aroca clearly saw the connection between both approaches, defining
the properties of the structural form (size, scheme, proportion and thickness) and formulating a new
synthesis of the structural design theory.
Some examples about how the theory makes the difference between very actual milestones and
mere linguistic vanities will be presented. Furthermore, the current shortcomings of the theory will be
examined and future research lines will be proposed to address them.
