Eduardo Torroja: Resistance

“Clay masonry, like concrete, is a "plastic" material that permits the pouring in situ of large monoliths of any shape or form, with certain limitations and by using special methods. Its economical possibilities when used in walls of popular housing, its excellent heat and sound insulation, as well as its aesthetic possibilities, should not be underestimated. Its resistance and durability can be substantially improved by using modern techniques and methods, for example, admixture of small amounts of Portland cement in accordance with granulometric investigation, petrographic composition, and rheological behaviour of all constituents.”

“[E]very structure has a resistant function to fulfill… to ensure …the static equilibrium of the structure for a long period of time.”

“Stone can effectively resist compression but is relatively weak in tension. Because of its mass and weight it may be used advantageously in structural types that can be made stable by the proper weight (dead load, gravity) and are but slightly exposed to lateral forces.”

“The material in all elementary parts of a structure must have the properties of resistence to all internal forces produced by general loading conditions and by the action of any exterior force.”

“Even children know that drafting rule is easier to bend flat than across the edges; and… they will not be much surprised if told that for the same width of the rule its resistance is proportional to the square of the thickness and the deflection is inversely proportional to the cube of the thickness. Nevertheless some modern designers seem to be unaware… since they require… beams of such slenderness that they resemble springboards…”

“[M]aterials should resist mechanical forces and other effects… starting with all types of loading and external forces… and with the mechanical properties of the materials… constitutes the part given most emphasis in technical books and schools.”

“Long before… our techniques of today, men could conceive and build structures adapted to the requirements of resistance… because he had observed… the branches of a tree bending under the weight of fruits and the tensioned cords of strings in which children have rocked from time immemorial…”

“[T]here are three different but interconnected conceptions to be considered in every structure, and in every structural element involved: equilibrium, resistance, and stability.”

“Lightweight concrete obtained with special admixtures producing bubbles throughout the mass shows lower resistance, which makes it less suitable for structural purposes; its practical application is limited to smaller structural elements adequately reinforced in which thermal insulation is required.”

“One should become so familiar with the structure as to have the feeling of being, in full vitality and sentiment, part of it and of all its elements. …it is necessary to achieve a sincere Einfühlung [empathy] of the process of resistence… through the deformation that is always essentially united with the process of stressing. …[T]he comprehension of a structure requires intuitive knowledge of the ethology of its resistance and of its constituent materials.”