Daniel Sonntag

Abstract

The presented research describes the holistic development of a modular lightweight timber shell. So-called segmented timber shells approximate curved geometries with the use of planar plates, thus combining the excellent structural performance of double curved shells with the resource-efficient prefabrication of timber modules using only planar elements. Segmented timber shells constitute a novel building system that demands for innovative approaches on structural design and construction technologies. The geometric complexity of plate shells in conjunction with the particularities of the building material wood pose great challenges to the computational design and planning processes as structural requirements and fabrication constraints determine the shell design at early design phases. This paper discusses the design development and construction of the BUGA Wood Pavilion: A segmented timber shell structure made of hollow cassette components. Particular emphasis lies on the technical challenges of the employed building system, notably structural design and analysis, detailing solutions and the construction process. The authors further describe the integrative structural design and optimization methods developed for the timber shell in question. The BUGA Wood Pavilion demonstrates the possibilities of lightweight and sustainable wood architecture merging the merits of integrative design, structural engineering and high-tech robotic fabrication methods.

Abstract

In architectural research, pavilions play a special role because, as temporary structures, they present an opportunity to investigate specific issues without having to fulfill all requirements for permanent buildings. The findings resulting from this investigation can then be utilized in the design and implementation of permanent buildings. In this contribution we describe the context in which the Rosenstein Timber Pavilion was created, and the special issues that were investigated in the project, as well as the knowledge gained from it. In addition, we provide an outlook on other current research topics in the field of segmented timber shells and their application in architecture.

Abstract

In the research field of segmented timber shells, two construction systems have lately received much attention, which both expose interesting structural and constructional characteristics: planar plate structures made of thin plywood and actively bent plywood structures. The research presented in this article combines elements of both approaches, resulting in a construction system for segmented shell structures with elastically bent elements. The increasing complexity of this approach requires a sophisticated design process, which integrates fabrication constraints as well as structural feedback. As a consequence, form-finding strategies of bending-active timber shells are discussed, with a special focus on the programming of the stiffness distribution in order to fulfil geometrical requirements. The authors also reflect on the specific structural challenges of joining thin sheets of plywood by transferring traditional textile connection methods to timber construction. Investigations of biological role models such as the sand dollar led to transfers of constructional principles on different levels. The resulting construction system was validated through the design and construction of a full-scale architectural prototype

Abstract

Concrete double-curved shell constructions have been used in architectural design and building constructions since the beginning of the twentieth century. Although monolithic shells show a high stiffness as their geometry transfers loads through membrane forces, they have been mostly replaced by the more cost-efficient lattice systems. As lattice systems are covered by planar glass or metal panes, they neither reach the structural efficiency of monolithic shells, nor is their architectural elegance reflected in a continuous curvature. The shells of sand dollars’ – highly adapted sea urchins – combine a modular and multi-plated shell with a flexible, curved as well as smooth design of a monolithic construction. The single elements of the sand dollars’ skeleton are connected by calcite protrusions and can be additionally supported by organic fibres. The structural efficiency of the sea urchin’s skeleton and the principles behind them can be used for innovations in engineering sciences and architectural design while, at the same time, they can be used to illustrate the biological adaptations of these ecologically important animals within their environments. The structure of the sand dollar’s shell is investigated using modern as well as established imaging techniques such as x-ray micro-computed tomography (μCT), scanning electron microscopy and various optical imaging techniques. 3D models generated by μCT scans are the basis for Finite Element Analysis of the sand dollar’s shell to identify possible structural principles and to analyse their structural behaviour. The gained insights of the sand dollar’s mechanical properties can then be used for improving the state-of-the-art techniques of engineering sciences and architectural design.

Abstract

Recent developments in the field of segmented timber shells have shown promising structural and constructional characteristics. Advancements in computational design and digital fabrication enable architects and engineers to handle the increased geometric complexity necessary for this new construction type, integrating fabrication constraints and structural feedback in one design model. The research presented in this paper builds on new findings from biological role models for the constructional morphology, connection type, and material distribution of segmented shells. Based on the transfer of these principles, a robotic fabrication technique was developed that enables the production of elastically bent, double-layered segments made from custom-laminated beech plywood, by transferring traditional textile connection methods to timber construction. The construction system was evaluated through the design, production, and assembly of a large demonstrator.