Tectonics Tessellation: Ceramic Structural Surfaces Matías IMBERN1, Felix RASPALL2, Qi SU3 1
Master in Design Studies Candidate. Harvard Graduate School of Design.
2
Doctor of Design Student. Harvard Graduate School of Design.
3
Master in Design Studies Candidate. Harvard Graduate School of Design.
Abstract:
Structural surfaces are extremely efficient in the use of materials and have a unique expressive quality. However, complicated manufacturing involving expensive formworks, excessive waste and intensive hand‐labor, turned into major limitation as labor cost augmented, environmental issues became evident and craft skills diminished. Today, digital tools for design and fabrication, allowing fast and precise study of complex‐form structures and automation of construction and assembly, may give new light to structural surfaces. This research proposes a construction process for ceramic shells that reduces the requirements of formworks, on‐site work and waste production. The process involves a two‐step fabrication including off‐site panel manufacturing and on‐site assembly. Construction system consists of two interlocking triangular ceramic pieces that provide compression resistance and a delicate inner surface finish, embedded in a thin reinforced concrete layer. The paper describes background research, the proposed construction process, methodology, results and conclusions. Introduction Structural surfaces have always been admired due to their lightness, finishing quality and material‐ efficiency. When compared to concrete shells, the use of ceramics for structural surfaces proved more suitable for certain scenarios, taking advantage of lower weight and cost of ceramics elements, reduced need for reinforcement, and the unique quality of its finishing (Fig.1). After a period of development with milestones in the work of Guastavino and Dieste[1], ceramic structural surfaces became unaffordable and their use is today almost inexistent [2]. The main reasons for their decay include expensive formworks (Fig.2), intensive hand‐labor, and need for skilled craftsmanship [3]. Today, digital tools for design and fabrication may reduce the impact of these factors and make ceramic structural surfaces a feasible option in architectural design again [4]. Applications of digital tools proved useful in the reintroduction of catalan vaulting by Ochsendorf, as a means to study the form and structural behavior [5], and in fabrication experiments on masonry at ETH. However, these studies merely cover compression only surfaces and in some cases still rely on intensive hand‐labor.
Fig.1. Rafael G Guastavino. Delicate Interior Finishing.
Fig.22. Eladio Diestee. Construction process with complex reusaable formworkks.
Tessellated Structural C Ceramic She ells The researcch proposes a new consttruction proccess for ceraamic shells that reduces the requirements of formworks and on‐site construction n, while presserving the b benefits of liightness and d delicate intterior m previous m methods by d dividing fabriication into ttwo‐steps: m manufacturin ng of finishing. It differs from nels in digitaal fabrication n shop and simplified on n‐site assemb bly. Panelizaation of the sstructure ceramic pan allows fabrication of ceramic panels in a contro olled environ nment using precise CNC C equipmentt, ents of skilled hand labor. On‐site asssembly, theerefore, is siggnificantly siimplified, reducing the requireme nvolved in th he assemblyy –from thou usands of briicks and rebars to lowering the number off elements in olding. The fo ollowing secctions of thiss paper will p present dozens of panels‐, and tthe complexxity of scaffo nce, the reseearch metho odology, prottotypes, results and in more dettail the proposed fabricaation sequen conclusionss. els Manufacturring of pane The main ceeramic comp ponents of the proposed d system aree two interlo ocking trianggular pieces ((fig.3), which were designed to o create a co ontinuous ceeramic surfacce on one side and provvide space fo or steel he two piecees reinforcemeent and conccrete castingg on the other side. The interlockingg detail of th accepts a ro otation of +//‐ 17°, and its grouping aallows for surfaces with different typ pes of curvatture from flat to anticlastic.
Fig.3. Geomettry of main Cerramic Components.
of a complette shell, which are produ uced in a controlled The pieces aare combineed into panels, sections o shop enviro onment usingg a CNC robo otic arm. Fabrication folllows this sequence: 1. Creaation of the ccurved form m where the pieces will sit. Because tthe pieces are already fiinished, the requirementts for this fo ormwork aree less deman nding than fo ormwork forr reinforced mworks weree studied an nd tested: Co ompressed sand conccrete. Two alternative reeusable form milling (fig.5a) aand pin‐systeem (fig.5b) m over the fo orm. 2. Placement of the ceramic pieces using aa robotic arm he ceramic p pieces. 3. Lyingg of reinforccement bars and castingg of concretee between th
Fig.4. Typical aarrangement o of ceramic elem ments and detaailed section.
Fig.5a. Comprressed Sand Miilling Test
Fig.5b. Pin System Test.
Assembly Sequence ome self‐sup pporting com mponents. Th hey are delivvered and placed on Once panelss are finished, they beco their finals p position on‐site (fig.6a to 6c). Threee strategies ffor interlocking of the paanels provide structural and visual continuity to the whole sh hell. First, thee lips on adjacent panels follow the same nterlocking, leaving no ggap and creaating the spaace for concrete casting.. Second, logic as piecce to piece in rebars on eaach panel exxtend and th hey fit on thee adjacent p panel, as con ncrete layer o on the panel does not reach th he edges (figg.7). Finally, a second layyer of reinfo orced concreete is casted on site, allowing for continuous reinforcemeent ‐and pottentially post tensioningg‐, adding cohesiveness aand resistance to the of the pieces,, including the second laayer of reinforced structure. Fig. 4 shows aa typical arraangement o concrete that is casted on‐site.
Fig 6a. Simple scaffolding on n site to
Fig 6b. Light eq quipment neceessary to
Fig.6c. Comple ete cohesive sh hell, with
panels. receive the seelf‐supporting p
place the paneels (weight < 200kg).
s second layer o of reinforced caasted on‐ s site.
Fig.7. Interlocking o of first reinforcement layer,, showing the aareas of panelss without concrrete that allow ws overlapping o of rebars.
on and digitaal fabricatio on Computatio Design, evaluation and fabrication u using this co onstruction ssystem required the usee and custom mization hinoceros an nd Grasshopper for form m finding, surrface subdivision and of several digital tools, including Rh ode generatio on. machine‐co Prototypes d panel conn nections servved as a Several prottotypes of ceeramic piecees, formworrks, concretee casting and proof of con ncept. A finaal full‐scale p prototype teested the com mplete construction seq quence descrribed by this paper. FFig 8. showss the assemb bly sequencee including the milled formwork, rob botic placem ment, laying of reb bars, castingg of first layeer of concrette, panel inteerlocking an nd second layyer of reinfo orced concrete. Fiig.9a and 9b b reveal the d delicate finisshing achieved in the fin nal prototypee, as well as the self‐ supporting capacity. Figg 9a also inclludes other experimentss realized throughout th he developm ment of uction system m. this constru
Fig.8. Final Pro ototype Assem mbly Sequence..
Fig.9a. Exhibittion on Final Prresentation.
Fig.9 9b. Detail of th he final prototyype
Conclusionss and limitattions This study sshows an inittial feasibilitty of the pan nelization an nd CNC fabriccation as an alternative for reinforced cceramic structural shellss. It confirmss that the prroposed consstruction sysstem can red duce the need for skiilled hand labor, on site workload an nd proposess two alternaatives to con nventional fo ormwork. The final pro ototype also o proves that a unique fiinishing usin ng ceramics, which seem ms to be lost in the past, can bee achieved to oday (fig.2). There is sign nificant deveelopment to o be done to this constru uction system m in order to o become fu ully operational. First, a rigo orous structu ural analysiss of both thee panels and the complete structuree is on method. Second, sevveral fabricattion issues that arouse tthrough essential to support this constructio
prototyping needs to be adjusted: geometry of the ceramic pieces and the procedure for bending and lying of rebars and pouring of concrete. Finally, the on‐site assembly sequence, which includes transportation, placement, scaffolding and second layer of reinforced concrete, requires in‐depth development. Acknowledgements This paper presents the results of a project for the course 9429 Material Processes and Systems: Ceramic LAB, taught by Martin Bechthold and Jonathan King at the Graduate School of Design at Harvard University. Their input and guidance were essential for the development of this project. All ceramic components were developed and fabricated at the Ceramic Program at Harvard, with valuable and generous assistance of Shawn Panepinto and Cathy Moynihan. For programming in all areas including form‐finding, surface discretization, machine code, contribution and support by Panagiotis Michalatos were of crucial importance. References [1] Collins, G.R. 1968, “The Transfer of Thin Masonry Vaulting from Spain to America”, Journal of the Society of Architectural [2] Ochsendorf, J.A. & Freeman, M., 1945 ‐ 2010, Guastavino vaulting: the art of structural tile, 1st edn, Princeton Architectural Press, New York. [3] Anderson, S. & Dieste, E., 1917‐2000. 2004, Eladio Dieste: innovation in structural art, Princeton Architectural Press, New York. [4] Bechthold, M. 2008, Innovative surface structures: technologies and applications, Taylor & Francis, Abingdon, Oxon; New York. [5] Ramage, M., J. Ochsendorf, P. Rich, J. Bellamy, and P. Block. "Design and Construction of the Mapungubwe National Park Interpretive Centre, South Africa." ATDF JOURNAL 7, no. 1/2 (2010).