Funicularity and equilibrium for high-performance conceptual structural design

Abstract

Curved structures are characterized by the critical relationship between their geometry and structural behaviour, and selecting an appropriate shape in the conceptual design of such structures is important for achieving materialefficiency. However, the set of bending-free geometries are limited and, often, non-structural design criteria (e.g., usability, architectural needs, aesthetics) prohibit the selection of purely funicular or antifunicular shapes.In response to this issue, this thesis studies the possibility of achieving an axial-only behaviour even if the geometry departs from the ideally bending-free shape.This dissertation presents a new design approach, based on graphic statics that shows how bending moments in a two-dimensional geometry can be eliminated by adding forces through an external post-tensioning system. This results in bending-free structures that provide innovative answers to combined demands on versatility and material optimization.The graphical procedure has been implemented in a free-downloadable design-driven software (EXOEQUILIBRIUM) where structural performance evaluations and geometric variation are embedded within an interactive and parametric working environment. This provides greater versatility in finding new efficient structural configurations during the first design stages, bridging the gap between architectural shaping and structural analysis.The thesis includes the application of the developed graphical procedure to shapes with random curvature and distribution of loads. Furthermore, the effect of different design criteria on the internal force distribution has been analyzed.iii Finally, the construction of reduced-and large-scale models provides further physical validation of the method and insights about the structural behaviour of these structures.In summary, this work strongly expands the range of possible forms that exhibit a bending-free behaviour and, de facto, opens up new possibilities for designs that combine high-performing solutions with architectural freedom. iv ResumenLas estructuras que trabajan por forma se caracterizan por la íntima e indisociable relación entre geometría y comportamiento estructural. Por consiguiente, la elección de una apropiada geometría es el paso previo indispensable en el diseño conceptual de dichas estructuras.En esa tarea, la selección de las posibles geometrías antifuniculares para las distribuciones de cargas permanentes más habituales son más bien limitadas y, muchas veces, son criterios no estructurales (adaptabilidad funcional, estética, proceso constructivo, etc.) los que no permiten la utilización de dichas geometrías que garantizarían el máximo aprovechamiento del material.En este contexto, esta tesis estudia la posibilidad de obtener una estructura sin momentos flectores incluso si la geometría no es antifunicular para sus cargas permanentes.En efecto, esta tesis presenta un procedimiento, basado en la estática gráfica, que demuestra cómo un conjunto de cargas adicionales, introducidas a través de un sistema de prete...

Conceptual design of externally posttensioned curved structures for live loads

“…The procedure developed by authors to define the layout of a posttensioning system to convert any two‐dimensional curve into an axial‐only solution under permanent loads is based on graphic statics, 7,8 and for reader's convenience can be found in other recent works 9–12 . It is out of the scope of this paper to describe the graphical construction and only the main concepts are explained here.…”

“…The material‐efficiency of these bending‐free structures under permanent loads has been studied in other works, 9,11,12 but their behavior for other load distributions has not been analyzed yet.…”

Fundamentos para la gestión del envejecimiento y conservación sostenible de las estructuras del patrimonio arquitectónico

“… Descripción de las acciones implicadas, del comportamiento estructural y los tipos de materiales [107], [108], [110], [172]- [174], [171].…”