Curved Folded Plate Timber Structures

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.

Origami - Folded Plate Structures

Hans Ulrich Buri

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.

EPFL2010

Displacement Study of a Large-Scale Freeform Timber Plate Structure Using a Total Station and a Terrestrial Laser Scanner

Anh Chi Nguyen, Yves Weinand

Recent advances in timber construction have led to the realization of complex timber plate structures assembled with wood-wood connections. Although advanced numerical modelling tools have been developed to perform their structural analysis, limited experimental tests have been carried out on large-scale structures. However, experimental investigations remain necessary to better understand their mechanical behaviour and assess the numerical models developed. In this paper, static loading tests performed on timber plate shells of about 25 m span are reported. Displacements were measured at 16 target positions on the structure using a total station and on its entire bottom surface using a terrestrial laser scanner. Both methods were compared to each other and to a finite element model in which the semi-rigidity of the connections was represented by springs. Total station measurements provided more consistent results than point clouds, which nonetheless allowed the visualization of displacement fields. Results predicted by the model were found to be in good agreement with the measurements compared to a rigid model. The semi-rigid behaviour of the connections was therefore proven to be crucial to precisely predict the behaviour of the structure. Furthermore, large variations were observed between as-built and designed geometries due to the accumulation of fabrication and construction tolerances.

2020

Origami - Folded Plate Structures

Hans Ulrich Buri

EPFL2010