Design of CASTonCAST shell structures based on Load Path Network Method
L. Enrique
2011 - 2017

Figure 1: Cantilevering stadium roof modelled using Load Path Network Method.

Figure 2: Analysis of two load paths in a freeform shell structure using Load Path Network Method.

Nowadays a building project is often the result of a sequence of separate phases: architecture, structure and realisation. For most projects, the separation between these phases has important economic consequences. Furthermore, this situation often weakens the architectural concept since it does not allow designing an appropriate structural solution for it. For these reasons, it is important to investigate in ways to bridge between these different disciplines. This thesis studies the integration of structural concerns at an early phase of the design process of the building project. This helps smoothening the transition between the design and realization phases. In this process, two main problems are detected: first, the general problem of designing structures and, second, the more specific problem of integrating structural concerns in an existing project with its own set of special constraints.

Regarding the first general problem, a new method called Load Path Network Method was developed (Enrique and Schwartz, SEI, 2016) (Enrique and Schwartz, IASS, 2016) (fig. 1 and 2). LPNM is an equilibrium‐based method for the design and analysis of three-dimensional structures based on the lower bound theorem of the theory of plasticity (Muttoni et al. 1997). The goal of this method is to stimulate the exploration of possible three‐dimensional flows of internal forces in equilibrium in a statically indeterminate structure, represented as Strut-and-Tie models, in order to help the integration of structural concerns during the design process of a building project. The method allows modelling intuitively structural sketches for spatial structures (fig. 1) or visualizing feasible and optimal paths of internal forces in a given structure (fig. 2).

Regarding the second specific problem, a method for the integration of structural concerns in the CASTonCAST system was developed for the design of shell structures from precast stackable components (Enrique and Schwartz, AAG16, 2016) (fig. 3). This method, which is similar to a form-finding method, searches for those shapes which fulfill both the manufacturing constraints characteristic of the CASTonCAST system and also structural requirements. The method uses LPNM in order to use the different flows of the internal forces as a leading parameter during the design process. Since the method must fulfill two different goals, the design process is similar to a negation process in which the designer has to decide among a range of different convenient solutions.

This research project is supported by “La Caixa” Foundation.

Figure 3: 1:10 prototype of a prestressed shell structure built from stackable components.

last modified 9.11.2016