Origami - Folded Plate Structures

This research investigates new methods of designing folded plate structures that can be built with cross-laminated timber panels. Folded plate structures are attractive to both architects and engineers for their structural, spatial, and plastic qualities. Thin surfaces can be stiffened by a series of folds, and thus not only cover space, but also act as load bearing elements. The variation of light and shadow along the folded faces emphasizes the plasticity of space and envelope. Folds not only create structural depth, but also perceptual deepness. Folds give rhythm to space, and variations can be used to express a spatial sequence as well as to modify the structural strength. Because of this we are convinced that a design method which rapidly generates and modifies folded plate structures is of great interest, and can form the basis of a productive collaboration between architects and engineers. In the last fifteen years the timber industry has developed new, large size, timber panels. Composition and dimensions of these panels and the possibility of milling them with Computer Numerical Controlled machines shows great potential for folded plate structures. An interdisciplinary team investigates architectural, structural and mathematical aspects of folded plate structures. The main focus of the architectural portion is the form-finding process which is inspired by Origami, the Japanese art of paper folding. Based on a simple technique, Origami gives birth to an astonishing formal richness and variability. Complex geometries are generated in an economic way and this research aims at transferring these principles to construction with timber panels. In an intuitive approach, we investigate different folding patterns with paper folding. The geometry of selected patterns is analyzed with the aim to generate them in 3D modeling software. We develop a method that generates doubly-corrugated surfaces by two polygonal lines: the corrugation profile and the cross section profile. The corrugation profile defines the characteristics of simply-corrugated surfaces, composed of straight main folds. Simply-corrugated surfaces can be bent by reverse folds. A series of investigations outlines the parameters which influence the geometry of reverse folds. The cross section profile introduces a secondary corrugation. It outlines the general shape of the folded plate geometry and defines the bending angles of the reverse folds. The pattern of folded plate geometries is qualified by the configuration of the two profiles. We establish the conditions which allow control of the pattern type and design of folded plate geometries which respect a given corrugation amplitude. This allows rapid representation of complex folded plate structures in space as well as unfolded. A great variety of forms can be generated. This variability is attractive because it allows the engineer as well as the architect to react on project specific conditions by modifying different parameters of the folded plate structure without distorting its expressive character. Further on the possibilities of offseting the generated surface are investigated. The influence of different parameters on the offset geometry is shown. Finally a series of prototypes investigates the feasibility of folded plate structures generated with the proposed design method.

Reuse in Architecture & Structural Design

Jan Friedrich Georg Brütting

Introduction The construction industry has an extensive impact on the global environment and will be facing three big challenges in the next decades: reducing its resource consumption, decreasing its energy use, and limiting its waste production. This is even more crucial, considering global population growth and increasing urbanization. Consequently, a shift of paradigm from a linear economy of make-use-dispose, towards a circular economy that advocates closed loops within the service life of materials and components is required. Recycling currently is the common strategy to make use of obsolete materials; however, it involves energy for reprocessing (e.g. melting steel scrap). Instead, direct reuse of components close to their original form has the potential to reduce environmental impacts further because sourcing additional raw material is avoided and only few energy is spent for transformation [1]. In the case of buildings and infrastructures, load-bearing systems contribute the most to the embodied environmental impacts. This is because of their big mass and energy intensive construction process. These observations suggest that reusing structural elements has large potential to reduce the environmental footprint of building structures. Reused components may consequently have a longer service life than the systems to which they initially belonged and disassembled buildings become a mine for new constructions. This idea is of course not a today’s invention, but has found application already far in the past as well as in recent building projects. Before industrialization, most building materials were sourced locally and reuse of building materials and components was the rule because it was more cost and time efficient than new production [1]. The scarcity of building materials had to be considered in design and construction. A classic example is the reuse of bricks throughout the Roman and Greek eras or in post-war times. Remarkable are also the stone columns of the Great Mosque of Cordoba, Spain, which were reused from nearby Roman and Visigoth ruins to support Moorish double arches (Fig. 1a). More recently, the steel structure of the BedZED project in London (Fig. 1b) was constructed from 90 % locally reclaimed elements [2]. Many other contemporary case studies in which bricks, timber, or steel elements have been reused are reported in [1] and [2]. An outstanding structure is the London Olympic Stadium (Fig. 1c), whose roof truss incorporates 2000 tons of steel pipeline tubes reused from a nearby development project [3]. At smaller scale, a strained grid-shell pavilion made of reclaimed skis has been built by the researchers at EPFL’s Structural Xploration Lab (Fig 1d). Recently this environmental-aware architectural and structural design is evolving. In addition, governments have understood the potential of circular economy and circular design. For instance, the European Commission has issued an EU action plan for the circular economy in order to reduce waste and landfill. Research While historic and contemporary projects, especially in Europe, highlight the environmental, time or cost benefits of building with reclaimed (structural) elements, many technological challenges remain. Buildings have to be carefully disassembled, which is often only possible for steel or wooden structures that are joined with reversible connections, or when elements can be cut and member ends are reshaped to fit new settings. Further, the quality and structural capacity of reclaimed elements has to be ensured. Under these assumptions, this research focuses on the standpoint of composing building structures from a stock of reclaimed elements. This entails reversing the conventional design process. The constrained availability of elements dictates the layout (topology and geometry) of the designed structure due to the a-priori set geometric and mechanical properties. The design shifts towards a “form follows availability” paradigm [1]. Structural optimization methods, which traditionally seek best performing structural systems under given boundary conditions, can be extended to integrate and facilitate element reuse in structural design. This research uses the combination of combinatorial optimization and form-finding methods to design reticulated structures from a given stock of reclaimed elements [4], where: 1) available elements are grouped by material, structural capacity and dimensions, 2) an optimal assignment of a subset of stock elements into a structural system is performed, and 3) the structure geometry is optimized. Generally, the assignment step 2) minimizes the structural weight to optimally utilize the available element capacities, whereas the geometry optimization step 3) is carried out to match truss geometry and available element lengths. This method is applied to optimize truss systems subject to differently composed stocks. In each case, varying cross section sizes or element lengths result in a different outcome of the designs. Figure 2 (a) shows a typical roof truss design, which is loaded at the top chord and is used as the initial topology for the introduced optimization method. The obtained layout for the case of using Stock A is reported in Fig. 1b. This stock consist of elements with 3.00m length which are n = 4 times available for each of the six cross-section groups. The use of the stock is indicated by the superimposed magenta colored bars on top of the grey ones. Due to limitations of the stock to 3.00 m elements only, the truss layout contains two arrays of three almost equilateral triangles. For the truss made from Stock B, which is composed of equivalent cross section groups but with variable element lengths, the found geometry is shallower and vaulted. In both cases, the geometry optimization allows to use most of the stock members with their full length. The exploration of these case studies concludes that the availability of elements has a significant influence on the final structural design as well as its structural performance. For example, if an insufficient amount of elements with small cross-sections is available, the structure will be oversized (i.e. the capacity of available members is not utilized) and environmental savings are diminished. Conclusion The proposed optimization and form finding method renders a first step towards facilitating the design with reused elements where the outcome is not as predictable as in the well-established conventional structural design process. Future research will extend this method towards different structural typologies such as bending and frame systems. Further, the question of customized connection details enabling the joining of stock elements has to be addressed.

2018

Curved Folded Plate Timber Structures

Hans Ulrich Buri, Ivo Stotz, Yves Weinand

This work investigates the development of a Curved Origami Prototype made with timber panels. In the last fifteen years the timber industry has developed new, large size, timber panels. Composition and dimensions of these panels and the possibility of milling them with Computer Numerical Controlled machines shows great potential for folded plate structures. To generate the form of these structures we were inspired by Origami, the Japanese art of paper folding. Common paper tessellations are composed of straight creases. First curved paper models were studied by Joseph Albers and his students in the preliminary course of the Bauhaus. Later, David Huffman explored the form finding possibilities offered by curved creased origami. To form curved creases, we use a model developed to create doubly corrugated surfaces with straight creases and planar faces. This model has been developed to build folded plate structures by assembly of planar timber panels. Doubly corrugated surfaces are defined by the corrugation profile and the cross section profile, where the corrugation profile defines the geometry of a simply corrugated surface and the cross section profile it’s bending in space. However, using undulating corrugation profiles, curved creased origami structures can be generated. Within the scope of this work, curved origami figures are used to develop a structural and load bearing timber component. The proposed element is composed of multiple layers, in order to bend the timber panels and to procure the necessary structural stiffness of the element. Our investigations examine the joint geometry of the bent multi-layer surface and its. Experimental investigations are conducted on a simple geometry (see fig.1), which is composed of three simply curved timber panels. A series of prototypes analyse the feasibility of curved folded plate structures with timber panels in terms of design, manufacturing and montage. Further investigations have to show the structural behaviour of such elements and how multiple elements can be used for roof structures.

IABSE-IASS2011

Reuse in Architecture & Structural Design

Jan Friedrich Georg Brütting

2018

Curved Folded Plate Timber Structures

Hans Ulrich Buri, Ivo Stotz, Yves Weinand

IABSE-IASS2011