Research based teaching as a model for developing complex pre-cast concrete structures

Research based teaching as a model for developing complex pre-cast concrete structures

Ole Egh olm Pedersen Aarhus Sch ool of Architecture

Abstract: This paper describes the potentials of utilising research-based teaching as a method for developing advanced concrete structures in an architectural context. A novel technique for casting concrete elements in PETG plastic is described as a body of research that formed the basis of a case in which master students assisted in the development and realisation of an amorphous, catenary grid-shell. Development in many areas simultaneously was essential for the success of the case studies, which made them suitable for a research-based teaching setup, where didactic considerations on a general and specific level were important: On a general level, three didactic tools were used: the first being the presentation of knowledge generation as something that happens between researcher and student. The second involved presenting students with a narrow focus before presenting a wide one, and the third: viewing the teaching studio as an interdisciplinary laboratory. On a specific level, didactic considerations involved a division of responsibility into smaller areas of investigation, allowing the students to conduct relevant experimentation while negotiating other areas of the research. Also, the presentation of the concept of tectonics provided a means for discussion, evaluation, and qualifying of decisions.

1. INTRODUCTION In sch ools of archi tecture th ere is an increasing focus on inv olving in students in research. On e reason is th e possibility of saving resources when students con tri bute to research findings, as opposed to making arbitrary projects, th e findings of which are discarded by the en d of semester. More importan tly, inv olving studen ts in research as collaborators, n ot h elpers, creates a strong in citem ent wi th th e indivi dual stu dent for learning an d refl ecti on within com pl ex an d highly specialised areas of archi tectural inv estigati on . From th e perspectiv e of th e research er, working wi th stu den ts infuses th e research wi th resources and i deas oth erwise ou t of reach within th e research fram ework.

This paper presen t a case study ‘ReVault’, set forth as research based teaching. Based on a th eoreti cal fram ework, di dactic consi derati on, previ ous research, and earli er worksh ops that in spired the setu p, th e aim of th e worksh op was to work with students in devel oping a n ov el con crete constructi on techni qu e. This led to th e realisati on of an am orph ou s con crete gri d sh ell (figure 1), as well as the proposal of three di dacti c tool s rel evan t to thi s m ode of teaching.

Figure 1: The research pavilion ‘ ReVault’ - a result of a research-based teaching setup at the Aarhus School of Architecture in 2011.

2. BACKGROUND 2.1 THEORETI CAL BACKGROUND

Th e theory of Te ctonics is u sed as a conceptual apparatus to qualify deci si ons in dev el oping th e casting m eth od. Tectoni cs can be descri bed as th e relati on between material, techni qu e, an d form (Figure 2 l eft) [Christiansen 2004].

This definiti on is deriv ed from the German architect and th eori st Gottfried Sem per, wh o descri bes tectonics as th e descripti on of a uni ty between i dea, acti on , an d con structi on [Sem per 1851]. Or, gen erally speaking, th e unificati on of m eans an d end [Frampton 1995].

In order to effectively investigate geom etry an d techni qu es related to concrete casting, th e MTF-m odel has been dev el oped to in clude con structi on an d th e m oul d, in a re lations model (Figure 2 righ t). Th e m ould has th e cen tral positi on in th e m odel , because it directly gen erates form. (Pedersen 2011)

Figure 2: Left: Tectonics defined as the evaluation of relationships between material, technique, and form. Right: A proposed relational model that places the mould in the centre of a realisation process addressing complex shaped constructions.

2.2 PREVI OUS CONCRETE WORKSHOPS

Th e worksh op setup builds on a stu dent driv en research -worksh op format devel oped by Archi tect Professor Karl Christian sen an d Architect, Lecturer Anders Gamm elgaard, wh o con ducted two worksh ops, testing aspects of th eir research in to concrete casting in h otwire-cu t polystyren e m olds. In th ese worksh ops, on e in Rom e in 2004 (figure 3) an d on e in Berlin in 2005 (figure 4), studen ts worked on expl oring th e poten tials for creating two ty pol ogi es, th e column, an d a column-beam assembly , respectively .

Figure 3: Workshop result, La Sapienza, Rome.

Figure 4: Workshop result, Berlin 2.3. BACKGROUND-RESEARCH

Th e research here presented acted as inpu t for a masters studi o where th e research-based teaching environm ent, and speci fic concrete devel opm ent, described in detail in this paper, took place.

This research is an inv estigati on in to n ew way s of casting uni qu e con crete el emen ts, in which th ere is a cl ose connecti on between th e material, th e techn ol ogy , and the form of th e concrete el em ent. Th e project addresses two problem s in the current producti on of con crete el emen ts: • Th e lack of conn ecti on between th e in tenti on of creating variati on in our buil d environm ent, an d the curren t way s of shaping con crete el emen ts. • Th e environmen tal challenges, which primarily call for a reducti on in waste produ cts gen erated in th e producti on of con crete el em ents.

Th e hypoth esi s is that th ese probl ems can be addressed by taking a starting point in th e term tectonics an d th e m odern techn ol ogical situati on , n ew in dustrialised meth ods of producing indivi dualized con crete pan els, can be devel oped. Meth ods which are capabl e of com peting wi th a traditi onal producti on of standardised el em ents, and at th e sam e time hav e an inherent, added architectural valu e, an d a better environm ental profil e.

This hypoth esi s was presented to th e students, an d served as a fram ework for the stu dy bri ef an d assessm ents. Th e study bri ef presented th e stu den ts wi th th e foll owing qu esti on : How can modern te chnology unfold the formal pote ntials of concre te, cre ating concre te with a high architectural value while maintaining a production line that is e nvironmentally sustainable?

A seri es of theoreti cal and material inv estigati ons were con ducted pri or to initiating th e stu di o in order to generate a foun dati on for th e studi o to build on .

2.4 BACKGROUND – TEACHING

Th e teaching setup in whi ch th e research was utilised focused around a speci fic m eth odol ogi cal approach . Cen tral to this was a responsiv e design process shifting between design techni qu es wi th poten tial digitalizati on ,

material qualiti es an d digi tally based fabri cati on. This approach fram ed th e work an d challenged th e collectiv e as well as th e indivi dual process an d project dev el opm ent in uncov ering potentials for a tectoni c approach to architecture.

This architectural analy sis consi dered parametric terms and th e scri pt language, in order to deal wi th the compl exity of a daptability in architecture.

In oth er words, th e aim of th e teaching was to make stu dents con sider h ow digital techn ol ogy can resi st becoming an objectiv e in i ts own right but rath er a m eans for supporting the human being as th e objective of archi tectural creati on .

Th e semester assignmen t an d in dividual project dev el opmen t were based on 3 elem ents: • Th e tectoni c approach , focusing on th e Material – techni qu e – form relati on. (As descri bed in secti on 2.1) • Th e worksh op, inv estigating a respon siv e design process, also referred to as a digi tal tectonic approach .

• Site & Program narrativ e story - Uncovering th e existing con di ti ons an d fan tasizing of future potentials.

This paper focuses on th e two first focal poin ts.

2.5 MATERI AL BACKGROUND

As a material basi s on which to build th e research -based teaching setu p, a n ov el casting m eth od was dev el oped.

To en sure the feasibili ty for full-scale produ cti on before using the techni qu e as a basi s for research -based teaching, the casting m eth od was con ceived an d devel oped by the auth or in a scul pture enti tled ‘Hell o World’ (figure 5).

Since the m oulds would all be uni qu e, an d th erefore n ot reusabl e, a materially effi cien t and l ow or zero-waste produ cti on m eth od was desired.

This was achiev ed by the u se of PETG plasti c, which is part of th e PET plastic family . It i s easily recycl ed, by m elting, at 260 ºC, evaporating only CO2 an d water, and i ts m ol ecular structure all ows for infinite use an d re-use wi th out degradati on i f it is kept in a cl osed recy cling process. In terms of the design th eory Cradl e to Cradle, th e PETG i s used as Technical Nutrient, in a zerowaste producti on [McDon ough an d Braungart, 2002]. Im portantly i t does thi s while adhering to th e basic requirem ents of being an appropriate m ould material that is easy to laser cut an d easy to fol d. Th e plastic sh eet com es cov ered with a thin protectiv e film , used to protect the material against scratch es during transport. This film was l eft on during casting an d then rem ov ed to l eav e a cl ean sheet ready for recycling.

When exposed to fluid con crete material , 1 mm PETG sh eets hav e a high degree of deformati on . It was practical to perform stress and deformati on simulati on s as part of the dev el opm ent of componen ts, in order to ch eck that th e PETG coul d withstand th e weight an d hy drostati c pressure from li qui d concrete. (Figures 6) [Pedersen 2011].

Figure 5: Material research background: A series of parametrically defined, reinforced concrete beams and columns, cast in PETG plastic.

2.6 DI DACTI C BACKGROUND

In order to point towards possibl e way s of m erging research through design in with research -based teaching on a masters l ev el, it i s rel evant to present some basi c consi derati on regarding th eory of learning. This i s parti cularly importan t to preven t what is referred to as misalignmen t [Kei ding et.al 2007] – a situati on wh ere a discrepancy occur – often inadv erten tlybetween the presen ted l earning goals an d the actual learning. In this case a misalignm ent may arise between the narrow focus of research as opposed to an archi tecture stu dy programme that is required to provide a much broader perspective on architecture. (Stu di eordning for kandi datuddannel sen på Arki tektskol en Aarhus, 2012) Th e l earning theory constructivism offers a vi ew of th e in dividual as a constantly activ e part in th e gen erati on of kn owl edge, as opposed to an activ e reci pi ent of instructi ons. As such, l earning i s form ed by the in dividual an d in dividual ´s capabiliti es to build u p kn owledge, n ot a direct translati on of kn owl edge from teacher to in dividual . (Dewey , 1938) It foll ows that the teach er must ackn owledge that the student is a partici pant in forming realisati ons abou t architecture.

This is in con trast to the tightly con troll ed worksh op, wh ere th e worksh op l eader / researcher has a clear idea about what th e ou tpu t of the worksh op sh oul d be. This approach draws on behavi ouristi c l earning theory, in which th e master dictate soluti on s, whi ch the students acquire by m eans of copying th e master.

When th e teaching is taking place on a masters l ev el, a chall enge occurs, because th e l ev el of specialisati on is high, while th e area of inv estigati on is compl ex an d abstract, requi ring a great deal of self stu dy an d refl ecti on from th e stu dents.

Th e stu di o setup descri bed in the foll owing i s an a ttem pt to achiev e both a high degree of specialisati on , whil e insisting on stu dents taking initiativ es to take decisiv e steps, som ething that is essential in a worksh op with a high l evel of compl exity .

3. CASE: THE WORKSHOP A case stu dy was built on th e backgroun d research an d di dactic consi derati on , and was carri ed out as a focu sed investigati on, wh ere stu den ts an d research ers collaborativ ely dev el oped an d realised an am orph ous, catenary gri d-sh ell.

Specifically , th e worksh op investigated the applicati on of small -scal e compon ents with triangulated surfaces an d a small casting h eight, in order to eliminate deformati on s du e to the hydrostati c pressure of concrete. Th e case study was carri ed out at Aarhus Sch ool of Architecture in th e fall of 2011 (Figure 7). Ov er the course of three weeks the auth ors, with th e ai d of Civil En gineers Jacob Christen sen, an d Ronni Madsen an d 12 Master of Archi tecture stu dents, design ed an d built a 16 square m etre by 2 m etre tall pavili on consi sting of 110 di screte concrete el em ents, cast in PETG (figure 6).

Figure 6: The ReVault case study: A concrete grid shell pavilion made up of 110 discrete elements.

3.1 DI VISI ON OF RESPONSI BI LITY

To all ow students to con duct focused inv estigati ons an d dev el opmen t, Th e stu den ts were organised in fou r grou ps: • Ov erall geometry / form finding • Com ponen t design • Falsework • Con necti ons OV ERALL GEOMETRY / FORM FIN DIN G Th e overall geom etry grou p used a meth od for form finding using dynamic relaxati on of a n etwork of flat curv es. This created a three-dim ensi onal wireframe m esh , from whi ch th e task was to gen erate v olum etri c con crete compon ents (Figure 7). This mean t that the grou p ha d to work cl osely with th e com pon ent design grou p, as well as wi th engineers, wh o con ducted Finite El emen t analysi s to calculate th e shear forces an d bending m omen ts in the joints.

Figure 7: investigation of different geometries by the overall geometry group.

COMPON EN T DESIGN Th e m ol ds had to be manufactured from 900 x 1600 millimetre sh eets of PETG. The com pon ent design grou p determined th e si ze an d shape of th e in dividual com pon ents, so th ey were abl e to m eet th e pavili on shape suggested by th e overall geom etry grou p, while respecting material an d producti on restraints (figure 8).

Figure 8 right: the final component design. Left: The component design group learned a scripting language to parametrically generate templates for lasercutting.

On e importan t dev el opm ent in this area was th e triangulati on of each compon ent arm, which added stiffness to th e m old whil e all owing th e compon ent to meet the many di fferent angles that occur wh en an am orph ous ov erall form is panelised. Dev el opm ent al so addressed the need to stay wi thin tol eran ces. Th e PETG m oulds were fixed to a blueprint, gen erated from the digital m odel, which enabl ed positi oning of the en ds of the three compon ent arms with a tol eran ce of l ess than one millimetre. Flaps added to th e en ds di ctated th e angl e of th e com pon ent arms (Figure 9).

Figure 9: The mold for one of the base components

FA LSEWORK

A prototy pe test (figure 11) discl osed that precise falsework would be importan t to positi on th e componen ts correctly in th e com pressiv e arc. This l ed to the task of designing an d drawing a viabl e, param etri cally defined falsework, gen erated di rectly from the spatial com pon ents m odel using Grasshopper, a gen erative m odelling plugin for Rhinoce ros. Fabri cati on was don e by m eans of laser cutting recy clabl e cardboard (Figure 10) [Pigram et al . 2012].

Figure 10: The structure being assembled against the parametrically generated falsework.

CONN ECTION S Prin cipally there woul d be n o sh ear forces in th e join ts, the structure being in pu re com pressi on. To test this, a worst-case prototy pe, with n o conn ecti ons, was constructed. Also, Finite El emen ts analysi s was used to cal culate th e sh ear forces in the joints. Failure of the prototy pe an d th e appearance of sh ear forces in th e FE analysi s provided th e students with eviden ce that a conn ecti on pulling elem ents togeth er woul d be importan t.

Figure 11: The ‘worst-case’ prototype after structural failure.

Sh ear happen ed du e to th e large passage openings in the m esh, and du e to lack of preci si on , both in th e produ cti on of th e componen ts, and in th e process of assembling the stru cture. Th e dev el opm ent of sev eral conn ecti on details began , an d resulted in th e im plem entati on of zi p-ti e conn ecti ons.

Figure 12: Component connections

4 IMPACT ON TEACHING Th e sem ester projects that foll owed th e ReVault worksh op were qualifi ed by both th e meth od an d th e findings, regarding material observati ons as well as param etri c and algorithmic workfl ows. A s an exampl e, on e stu dent devel oped a fabric casting system using gravity simulati on software to gen erate tem plates for casting con crete in catenari es arches using fabric m ol ds (figure 13).

Figure 13: Concrete casting by master student Jon Andersen.

5. FINDINGS 5.1 DIDACTI C TOOLS ON A GENERAL LEVEL

On the basis of th e case study three didacti c tools hav e been i dentifi ed. Th ey serv e to qualify both teaching and research output, wh en th e m ode of in quiry is research by design, inv olving stu dents. In oth er words, th ey are proposed as tool s that may hel p bri dge th e gap between research an d teaching,

between th e specific problem an d the gen eralist nature of studying architecture.

• • •

Kn owledge gen erati on between research er and stu dent Th e advanced inv estigati on as a booster Interdisciplinary collaborati on

TOOL #1 : KN OW LEDGE GEN ERA TION BETW EEN RESEARCHER AND STU DENT

Ty pically students produ ce a sem ester project, whi ch is con ducted as project work. This tool in cludes a wi dening of th e term “project work” to include th e research into this project work. Thi s is don e by inclu ding th e worksh ops int th e curri culum, an d m ost im portantly , by creating an environm ent wh ere th e goals for the studi o and research are achi ev ed with th e stu dents, as opposed to being an assi gnment posed by th e teach er / research er for th e stu dents to carry out. Im portantly th e establishm ent of a comm on groun d also inv olved th e alignm ent of a th eoretical an d meth odol ogical fram ework, in this case tectonics and research by design.

This happened by initiating th e sem ester with h e ReVault worksh op, in whi ch th e stu den ts took responsibili ty for th e differen t experimen ts n eeded to dev el op a com pl ex case stu dy . Importantly , th e stu dy sh ould be on e in whi ch th e teach er has an in centiv e to partici pate in , because of i ts rel evance to his or h er research . Th e rel evance to stu den ts sh ould be secured by inscribing th e l earning outcom e in th e study bri ef in such a way that th e students can use th e fin dings in th e foll owing semester project.

TOOL #2: THE A DVAN CED W ORKSHOP A S BOOSTER

This l eads to th e secon d tool, which is m ore of a strategy : To start with a narrow an d framed exercise, that enable th e stu den ts to produce an output wi th a very high quali ty, while introdu cing an d en couraging a research-like approach to the foll owing sem ester project. In other words, to rai se th e bar.

Th e ReVault worksh op serv es as an exampl e of this strategy . An im portant part of the strategy is to formulate an open probl em for th e reminder of th e sem ester, all owing th e stu dents to dem onstrate indepeden ce an d to establish a l earning environmen t in foll owing a constructivist approach .

TOOL #3: INTERDISCIPLINA RY COLLA BORATION

It is im portant to prev ent the research from becoming too specific an d periph eral to the stu dents. Equally im portan t is that th e output from teaching has relevan ce to th e research er. This may be prev ented by establishing a cross-disci plinary collaborati on between multi pl e research ers, in whi ch th e research ers defin e a them e that has rel evance to teaching as well as their respectiv e fi elds of research. Thi s broadens the fiel d, increasing th e relevan ce for stu dents thus minimising th e risk of mis-alignm ent. Also, it creates an opportunity for research ers to hav e th eir fi eld of research m eet an other, which pu ts the research into perspectiv e and open the possi bility for fin dings that woul d n ot be oth erwi se possi bl e. In the case described h ere, research into th e tectonic potential s of con crete by th e au th or, was in fused wi th research into param etri c and algori thmic design by Architect, A djun ct

Niel s Martin Larsen and Architect, Associate Professor Dav e Pigram , whi ch, al ong with th e in clusi on of Engineers, made th e case stu dy possibl e.

On a m ore specifi c l ev el, didacti c con siderati ons inv olv ed a divi si on of respon sibility in to small er areas of investigati on , as described in secti on 3.1, all owing th e stu dents to con duct rel evant experimen tati on while n egotiating other areas of the research . Also, th e presen tati on of the concept of tectonics, as presented in secti on 2.1, provi ded a mean s for discussi on , evaluati on , an d qualifying of decisi on s.

6. CONCLUSION A research based teaching setup is descri bed, in whi ch studen ts an d researchers work collaborativ ely on th e sam e project, prov ed to hav e sev eral advantages. Th e quality of l earning ou tcome and research output was maintain ed by th e establi shment of a setup inclu ding research ers from multi ple fiel ds within material and com putati onal research. Thi s broadened th e fi el d, prev enting a too specifi c learning environm ent. Utilisati on an d devel opm ent of algori thmic, param etri c an d material techni qu es n ecessary to create a compl ex pre-cast concrete constructi on techni qu e was possibl e only because students and research ers worked si de-by-side. Th e worksh op serv ed as a booster for th e foll owing sem ester project, in which stu den ts utilised the worksh op findings in thei r own projects.

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