In this paper, possibilities and challenges of novel robotic manufacturing processes for segmented timber shells are presented and evaluated. This is achieved by comparing two newly developed construction systems for segmented plate structures: one system consisting of cross-laminated timber elements that are connected with crossing screws, and one system consisting of light-weight, hollow components with finger joints as well as bolted connections. Segmented timber shells are introduced as an emerging structural typology transitioning from applied research to the building industry, enabled by new developments in computational design and digital fabrication methods. Although the two construction systems share their underlying segmentation strategy, they differ in their joint design approach and ensuing fabrication complexity. While the first construction system can be produced with conventional machining technology in the timber industry, the second system was developed in conjunction with innovative robotic manufacturing methods. In order to evaluate the relationships and trade-offs of fabrication complexity and performance, the two systems are compared on a range of metrics, including material use, environmental impact and costs.
This paper presents an integrated design tool for structures composed of engineered timber panels that are connected by traditional wood joints. Recent advances in computational architecture have permitted to automate the fabrication and assembly of such structures using Computer Numerical Control (CNC) machines and industrial robotic arms. While several large-scale demonstrators have been realized, most developed algorithms are closed-source or project-oriented. The lack of a general framework makes it difficult for architects, engineers and designers to effectively manipulate this innovative construction system. Therefore, this research aims at developing a holistic design tool targeting a wide range of architectural applications. Main achievements include: (1) a new data structure to deal with modular assemblies, (2) an analytical parametrization of the geometry of five timber joints, (3) a method to generate CNC toolpath while integrating fabrication constraints, and (4) a method to automatically compute robot trajectories for a given stack of timber plates.
Project contact is André Potvin at Université Laval
The biomimetic approach in architecture explores the genius of organic natural forms resulting from a long process of environmental adaptation. These forms often have a high compactness and an optimal material / volume ratio in line with the importance of reducing the material in the building to limit its environmental impact in terms of energy and resources. What are the natural forms and processes of growth of the form most appropriate to the physical properties of wood? What design process promotes the integration of a biomimetic approach from the earliest stages of design? Based on a review of the main achievements claiming this approach, this project will develop a taxonomy of the different biomimetic typologies and identify the most promising in the context of a wood realization. A digital manufacturing process will be developed to reflect the complexity of natural shapes and flows in an organic architecture that optimizes environmental performance and aesthetics.
The high performance in-plane of cross laminated timber (CLT) panels has created a potential for the use of CLT members act as diaphragms in steel structures. The behaviour of this diaphragm system depends strongly on the connections involved in linking the panels together and to the steel members. A study of the connections at both locations was made using experimental testing of two connection designs for the panel-to-panel case, and the development of a staggered lag screw connection for the panel-to-steel beam case. The results showed good performance for the double spline and fully-threaded inclined screws panel-to-panel connections. The lag screw connection showed high strength, stiffness, and ductility. The CSA Standard O86-09 was found to best predict the strength of both types of connections. Characteristic design stiffness values were presented for the stiffness at low levels of displacement and the initial, elastic stiffness.
This research is about the design process, development and fabrication of a free-form structure in crosslaminated timber (CLT) panels. Since sustainability, ecology and structural design are now relevant in any building project, the purpose of this research is to demonstrate that CLT panels can be used as an ecoresponsive strategy based on a building form. This paper presents the use of a tessellation construction system for designing and producing a freeform surface in CLT for a specific regional and industrial context. The research/creation process and the retroactive simulation generated by the parametric modelling software enabled the development of a singular architectural project where the structural aspect and the manufacturing are the inherent part of the integrated design process. Finally, the cutting files can be generated automatically for an easy transfer to CNC machine tools.
Traditional wood-wood connections, widely used in the past, have been progressively replaced by steel fasteners and bonding processes in modern timber constructions. However, the emergence of digital fabrication and innovative engineered timber products have offered new design possibilities for wood-wood connections. The design-to-production workflow has evolved considerably over the last few decades, such that a large number of connections with various geometries can now be easily produced. These connections have become a cost-competitive alternative for the edgewise connection of thin timber panels. Several challenges remain in order to broaden the use of this specific joining technique into common timber construction practice: (1) prove the applicability at the building scale, (2) propose a standardized construction system, (3) develop a convenient calculation model for practice, and (4) investigate the mechanical behavior of wood-wood connections. The first building implementation of digitally produced through-tenon connections for a folded-plate structure is presented in this work. Specific computational tools for the design and manufacture of more than 300 different plates were efficiently applied in a multi-stakeholder project environment. Cross-laminated timber panels were investigated for the first time, and the potential of such connections was demonstrated for different engineered timber products. Moreover, this work demonstrated the feasibility of this construction system at the building scale. For a more resilient and locally distributed construction process, a standardized system using through-tenon connections and commonly available small panels was developed to reconstitute basic housing components. Based on a case-study with industry partners, the fabrication and assembly processes were validated with prototypes made of oriented strand board. Their structural performance was investigated by means of a numerical model and a comparison with glued and nailed assemblies. The results showed that through-tenon connections are a viable alternative to commonly used mechanical fasteners. So far, the structural analysis of such construction systems has been mainly achieved with complex finite element models, not in line with the simplicity of basic housing elements. A convenient calculation model for practice, which can capture the semi-rigid behavior of the connections and predict the effective bending stiffness, was thus introduced and subjected to large-scale bending tests. The proposed model was in good agreement with the experimental results, highlighting the importance of the connection behavior. The in-plane behavior of through-tenon connections for several timber panel materials was characterized through an experimental campaign to determine the load-carrying capacity and slip modulus required for calculation models. Based on the test results, existing guidelines were evaluated to safely apply these connections in structural elements while a finite element model was developed to approximate their performance. This work constitutes a firm basis for the optimization of design guidelines and the creation of an extensive database on digitally produced wood-wood connections. Finally, this thesis provides a convenient design framework for the newly developed standardized timber construction system and a solid foundation for research into digitally produced wood-wood connections.
Interior partition walls for non-residential and high-rise residential construction are an US$8 billion market opportunity in Canada and the United States (Crespell and Poon, 2014). They represent 1.6 billion ft² (150 million m²) of wall area where wood currently has less than 10% market share. To approach this market a new system would be needed to compete against the incumbent system (wood/steel stud plus gypsum). The system would need to have an installed cost before finishing of approximately US$5 per ft² or lower. The system would also need to meet several code requirements for strength, sound transmission and fire resistance (flame spread and burn through). Crespell and Poon further concluded that to be truly transformative, the system would also need to address major trends impacting the building industry including reducing labor, reducing skilled labor, reducing onsite waste, reducing call-backs, and easily recyclable with low environmental impact. A likely market entry point for wood-based interior partition systems may be in taller and larger wood buildings.
Work described in this report investigated the fabrication, installation, acoustic and combustion properties of prototype interior partition wall designs.
Two types of non-structural prototype interior wall panels designated Type A and Type C were installed between two offices in the FPInnovations Vancouver laboratory. Wood sill plates for mounting the prototype panels were fastened to the concrete floor, sides and top of the opening between the two offices to produce a frame for mounting the test panels. Panels were fastened to the frame using dry wall screws. This same method of installation is envisioned in practice. The installation method makes it easy and fast to both install and remove the wall panels.
Acoustic tests showed the difference in ASTC rating measured between a double wall composed of Type A and Type C prototype panels compared with a double wood stud wall with gypsum board faces was approximately 6 ASTC points. A 6 point difference would be clearly noticeable. Although the results of this study are largely qualitative, they suggest that the prototype interior partition panels would have an acoustic advantage compared to stud wall designs.
In a related study summarized in this report, the combustion properties of three prototype interior panel constructions, including Types A and C evaluated in this report, indicated that any of the three types of partition constructions could be used in combustible construction in accordance with Division B of the National Building Code of Canada.
A second related study, also summarized in this report, estimated an installed cost of US$4.07 per ft² including overhead and profit for unfinished panel partitions comparable to panel construction Type C (gypsum/OSB/wood fibre insulation) as evaluated in this study. Thus, there would appear to be potential installed and finished cost advantages for the wood-based panel partitions compared to steel or wood stud walls with gypsum faces.
Other potential advantages of the prototype interior partition panels compared with the most common, currently-used systems (wood/steel stud plus gypsum) include ease and speed of installation, ease and speed of removal, design flexibility, prefabrication including pre-finishing, and easy installation of services.
Based on the positive results of these exploratory studies, further development of wood-based interior partition systems including design, fabrication, installation and in-service performance would appear justified. Knowledge of the products and testing methods developed in these studies would be expected to speed further development.
A. Fire Test Results Summary
B. Test 1a (Test 1): Beam-Exterior Column Connection Report
C. Test 1a (Test 2): Beam-Exterior Column Connection Report
D. Test 1a (Test 3): Beam-Exterior Column Connection Report
E. Test 1a (Test 4): Beam-Exterior Column Connection Report
F. Test 1b (Test 1): CLT Deck to Beam Report
G. Test 1b (Test 2): CLT Deck to Beam Report
H. Test 1b (Test 3): CLT Deck to Beam Report
I. Test 1c: Penetrations Fire Resistance Rating Report (TBD)
J. Test 1d: Wall Fire Resistance Rating Report
This paper presents a new approach to robotic fabrication in the building industry through the conceptualization, development and evaluation of a largescale, transportable and flexible robotic timber construction platform – named TIM. Novel solutions are necessary to make robotic fabrication technologies more accessible for timber construction companies. The developed robotic system is location independent and reconfigurable. It can be rapidly integrated into existing fabrication environments of typical carpentries on a per-project basis. This allows the exploitation of emerging synergies between conventional craft and specialized automation technologies and benefits both quality and productivity of the trade. We portrait how the platform enabled the effective robotic prefabrication of a complex segmented wood shell structure and discuss the fabrication system based on critical performance parameters. Further research is needed to disentangle the mutual dependencies of building-systems and respective automation technologies.
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.