901 SPERIMENTAZIONI E RICERCHE STRUTTURALI ATELIER BUGIO ... · atelier bugio, ricardo bak gordon,...

ITALIAN+ENGLISH EDITIONANNO LXXXIII — SETTEMBRE 2019ITALIA €12,00 AUT €22,50. BEL €21,70. CAN $37,00. CHE IT CHF27,00. CHE DE CHF27,50. DEU €28,50. ESP €21,40. FIN €22,00. FRA €20,00. PRT CONT €20,10. USA $31,50.

901 SPERIMENTAZIONI E RICERCHE STRUTTURALIBEAUDOUIN ET LODS,CONZETT BRONZINI,FRANCO ALBINI,ICD/ITKE,LEONARDO MOSSO

SULLA COLLINA DEL CASTELLO DI LISBONAATELIER BUGIO,RICARDO BAK GORDON,JOÃO FAVILA MENEZES

DAL 1928

901 SPERIMENTAZIONI E RICERCHE STRUTTURALIBEAUDOUIN ET LODS,CONZETT BRONZINI,FRANCO ALBINI,ICD/ITKE,LEONARDO MOSSO

SULLA COLLINA DEL CASTELLO DI LISBONAATELIER BUGIO,RICARDO BAK GORDON,JOÃO FAVILA MENEZES

DAL 1928

ITALIAN+ENGLISH+JAPANESE EDITIONCASABELLA-JAPAN.JP

60 61cASAbellA 901

Le conseguenze della formaMarco Biagi

Conosciuto e apprezzato sia in patria che in ambito internazionale, ma finora indagato e valorizzato meno di quanto avrebbe forse meritato, il sodalizio professionale fra Eugène Beaudouin (1898–1983) e Marcel Lods (1891–1978) ha prodotto, negli anni Trenta in Francia, significative innovazioni tecniche nel campo delle costruzioni metalliche e della sperimentazione tipologica sull’architettura, nonché opere autenticamente emblematiche degli ideali di progresso sociale che hanno alimentato la stagione “eroica” del Movimento Moderno. Personalità fra loro antitetiche, ma complementari, separati da sette anni di differenza l’uno dall’altro, i due s’incontrano nel 1922 all’École des beaux-arts, frequentando entrambi l’atelier di Emmanuel Pontremoli. Si ritrovano l’anno successivo, dopo il diploma di Lods, a collaborare nello studio dello zio paterno di Beaudouin, Albert, occupandosi insieme della progettazione di complessi d’abitazione a basso costo nei comuni della banlieue parigina: segnatamente Vitry (1925), Versailles (1926), Gennevilliers (1926) e Romainville (1925–27). Dal 1925 si associano al titolare dell’agenzia, che si ritira tre anni più tardi, lasciando loro in eredità consolidati rapporti con la committenza pubblica degli uffici per le HBM (Habitations à Bon Marché) e la SALEFN (Société anonyme des logements économiques pour familles nombreuses). Per tre lustri, fino al 1940, la coppia lavora congiuntamente, coniugando e mettendo a frutto i diversi talenti e interessi dei due soci: per il disegno urbano e la dimensione contestuale dell’architettura, Beaudouin, che collabora con Forestier al piano per l’Havana (1928) e con Prost a quello per la regione di Parigi (1930–36); per la razionalizzazione tecnologica della costruzione e del cantiere, Lods, che sposa e promuove attivamente la causa della prefabbricazione in acciaio, mista o integrale, quale via maestra alla modernizzazione del settore edile e, soprattutto, strumento chiave per ridurre i costi delle case alla scala dei grandi quartieri per le masse popolari.

1schizzo prospettico parziale

partial perspective sketch

«Enfin, le cercle étant le plus simple des lieux géométriques, doit également fournir des solutions constructives extrêmement élégantes, donc légères, par conséquent économiques (car dans les grandes dimensions ce n’est plus seulement la façon d’utiliser la matière, mais surtout le choix de la forme qui importe)».E. Beaudouin e M. Lods, relazione al progetto di concorso OTUA per un Nouveau Grand Palais des Expositions, Parigi 1934

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62 63cASAbellA 901Robert Maillart: Massa o qualità? Mass or quality? Masse oder Qualität?

Nell’arco di poco più di un decennio, i due giovani professionisti –il compositivo e il costruttore– bruciano le tappe realizzando una serie di esperienze pionieristiche e paradigmatiche che esplorano le molteplici prerogative e virtualità dell’architettura industrializzata in metallo. I progetti sviluppati affrontano le principali funzioni di vita associata della città contemporanea –residenza, infrastrutture di trasporto, servizi per l’istruzione, la cultura, il tempo libero, fino al monumento– e il variare dei programmi e la complessità crescente degli interventi sono ogni volta interpretati come opportunità per affinare la collaborazione con gli ingegneri e le imprese coinvolti e approfondire la ricerca, conseguendo importanti avanzamenti operativi e conoscitivi. A Bagneux (Cité du Champ-des-Oiseaux, 1927–33), prima, e a Drancy (Cité de la Muette, 1931–34), poi, il tema degli alloggi sociali finanziati dalla Legge Locheur (1928) è, per Beaudouin e Lods, una palestra ottimale dove iniziare a cimentarsi con le problematiche e la disciplina della industrialisation ouverte, della costruzione standardizzata, per componenti seriali prodotti in officina, da assemblare a secco, scoperta grazie all’incontro decisivo con l’ingegnere-impresario Eugène Mopin. Drancy, in particolare, con il suo imponente “pettine” di corpi in linea alternati a torri di sedici piani con ossatura d’acciaio e rivestimento in pannelli di calcestruzzo vibrato, costituisce, per l’epoca, un modello inarrivabile di razionalizzazione della costruzione e del cantiere, in notevole anticipo sui grands ensembles del dopoguerra. In seguito, le collaborazioni reiterate con gli Ateliers Jean Prouvé, specializzati nella lavorazione della lamiera piegata, d’acciaio e alluminio, e con l’ingegnere civile e aeronautico Vladimir Bodiansky, inducono i due progettisti non solo a perlustrare il terreno dell’industrialisation fermée, della prefabbricazione chiusa di sofisticati organismi composti da elementi interamente coordinati –per esempio nel piccolo prototipo di casa “smontabile” per il weekend B.L.P.S. (1937–38) presentato all’Exposition de l’Habitation nel

1939– ma, in aggiunta e in special modo, a indagare l’opzione di un’architettura meccanizzata e trasformabile, la cui variabilità d’assetto funga da moltiplicatore d’efficienza e versatilità prestazionale del dispositivo edilizio. Questo, sia attraverso l’articolazione distributiva e l’ideazione di raffinati meccanismi di apertura e movimentazione delle facciate o delle partizioni interne degli edifici, come nel caso dei raffinati serramenti vetrati coulissantes messi a punto per spalancare i volumi delle aule nell’esperimento “igienico-pedagogico” dell’École de plein air di Suresnes (1931–35), sia introducendo soluzioni di parziale automazione del manufatto, come nel futuribile bijou mécanique della Maison du Peuple di Clichy (1935–39): mercato coperto, la mattina, casa del popolo, la sera, inopinatamente portato a termine in concomitanza con lo scoppio della guerra.

È però grazie ad alcuni concorsi indetti, sempre durante gli anni Trenta, dall’OTUA, l’Office Technique pour l’Utilisation de l’Acier, che la riflessione di Beaudouin e Lods sulla costruzione metallica acquisisce un respiro diverso e si sposta concettualmente dal piano dell’uniformazione a quello dell’unicità, dal pragmatismo tecnologico dell’oggetto outil all’eccezionalità dell’invenzione strutturale. Dopo un primo saggio nel 1933, con il progetto di un Hangar per aeroplani di forma circolare, in acciaio e lamiera piegata, sostenuto da un solo appoggio centrale attorno al cui asse una generatrice parabolica descrive per rotazione un’enorme pensilina autoportante a fungo, è con l’impegnativa competizione per un Nouveau Grand Palais des Expositions, bandita dall’OTUA a cavallo fra il 1933 e il 1934, che trova formulazione la visione più eclatante e spettacolare elaborata in carriera dai due architetti parigini. In vista dell’imminente Exposition Internationale des Arts et Techniques dans la Vie Moderne del 1937, infatti, il concorso vaglia l’opportunità di dotare la capitale di un nuovo palazzo delle esposizioni polivalente, capace di accogliere le enormi folle veicolate dalle moderne reti di trasporto di massa e restituire al

5, 6le torri per appartamenti prefabbricate della Cité de La Muette

the prefabricated apartment towers of Cité de La Muette

7, 8pianta, sezioni e fotomontaggio nella natura della Casa “smontabile” per il weekend B.L.P.S. progettata con Jean Prouvé, 1937–38

plan, sections and photomontage in nature of the “demountable” B.L.P.S. weekend house, designed with Jean Prouvé, 1937–38

2Eugène Beaudouin e Marcel Lods all’inizio degli anni Trenta

Eugène Beaudouin and Marcel Lods at the start of the 1930s

3, 4vedute aeree della Cité de La Muette, a Drancy, 1931–34

aerial views of the Cité de La Muette, at Drancy, 1931–34

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Paese il primato di una costruzione simbolo del progresso tecnico come ai tempi della Tour Eiffel.

La richiesta è di una sala colossale di 120.000 mq, a copertura piana e pianta quadrilatera, priva di sostegni interni e con una campata minima di 250 m lineari. Le ipotesi di localizzazione sono demandate ai concorrenti. Alla gara sono ammessi dodici raggruppamenti di progettisti e imprese. Beaudouin e Lods partecipano coadiuvati da Vladimir Bodiansky e Désiré Douniaux, ingegnere dello stabilimento di costruzioni metalliche dei Frères Paindavoine. La proposta che presentano è senza dubbio, fra tutte, la più originale e memorabile, l’unica, forse, come rileva Georges-Henri Pingusson commentando gli esiti della gara sulle pagine di «Chantiers» (supplemento tecnico de «L’Architecture d’Aujourd’hui»), nel giugno 1934, che non si limita a «trasporre forme conosciute, anche moderne, in dimensioni di un altro ordine di grandezza», ma con coraggio e spregiudicatezza individua una risposta nuova e convincente poiché conforme alla scala inedita del problema. Scartate molteplici alternative, la soluzione che permette di “quadrare il cerchio”, conciliando ragioni statiche, funzionali ed espressive, si basa, paradossalmente, sull’adozione di una geometria circolare che contraddice lo schema planimetrico quadrangolare prescritto dal bando e costa agli autori la squalifica del progetto, da parte della giuria, in sede di valutazione. La forma circolare permette di trasformare l’immensa copertura in un leggero velario di vetro, funzionante a trazione anziché a compressione. La struttura, simile a un’enorme ruota di bicicletta coricata in piano, si compone di una corona d’acciaio di 400 m di diametro sollevata a 51 m da terra per mezzo di quattro archi ellittici divergenti al vertice e concorrenti all’imposta. La corona scatolare sostiene una raggiera pressoché orizzontale di cavi d’acciaio in tensione, raccordati al centro da un anello metallico di 15 m di diametro sormontato da una calotta ribassata in mattoni di vetrocemento. Il tetto si comporta come una sorta di cupola rovesciata, sollecitata da forze centripete lungo il perimetro. La configurazione garantisce un perfetto bilanciamento dei carichi e il carattere

indeformabile della cintura, esclusivamente compressa, le permette di sopportare sforzi notevoli, evitando la necessità di contrappesi e riducendo ai minimi termini la freccia d’inflessione delle funi. L’utilizzo di archi al posto di pilastri per reggere la copertura comporta il vantaggio di concentrare gli appoggi a terra in soli quattro punti, liberando da impedimenti il recinto cilindrico che può pertanto essere aperto, mediante pareti scorrevoli a tutt’altezza, per metà del suo sviluppo, sui lati est e ovest, convertendo di fatto l’edificio in una piazza coperta facilmente accessibile e rapidamente evacuabile da moltitudini di persone. Un doppio traliccio di forcelle al di sopra degli archi fornisce sostegni cadenzati alla trave torica di bordo, mettendola in grado di conservare un profilo sufficientemente sottile ed elegante. Esso ospita, inoltre, nel suo spessore, rampe che consentono alle automobili di raggiungere la pista panoramica ricavata al colmo della cornice e, al pubblico, di distribuirsi coreograficamente, come un vero e proprio rivestimento vivente, sugli otto ordini di ballatoi metallici che irrigidiscono i telai dei grandi serramenti mobili.

Tralasciando i dettagli, il disegno del nuovo Grand Palais des Expositions si risolve, in definitiva, in un puro volume di acciaio e vetro, nudo e astratto nell’immagine, diafano nella consistenza a dispetto delle misure, il cui carattere architettonico, come si legge nella relazione tecnica di accompagnamento, risiede anzitutto nella «sincerità dell’espressione costruttiva». Un aspetto interessante a margine della vicenda è tuttavia rappresentato dal fatto che, come si è detto, questo concorso costituisce uno dei rari episodi, nel percorso di ricerca svolto prima della guerra da Beaudouin e Lods intorno alla costruzione metallica, in cui la questione della forma si pone esplicitamente come punto di partenza del processo progettuale. E ciò è inevitabile, secondo i due autori, quando l’opera supera una certa soglia dimensionale: «Poiché, nelle grandi dimensioni –essi scrivono– a contare non è più soltanto il modo di utilizzare il materiale, ma soprattutto la scelta della forma».

13, 14l’esterno e la sala di proiezione al primo piano della Maison du Peuple di Clichy, 1935–39

the exterior and screening room on the first floor of the Maison du Peuple of Clichy, 1935–39

15prospettiva del progetto di concorso OTUA per un Hangar per aeroplani ad appoggio centrale unico, 1933

perspective of the project in the competition held by OTUA for an aircraft hangar with a single central support, 1933

9–12veduta d’insieme e particolari dei percorsi pensili e delle aule apribili dell’École de plein air di Suresnes, 1931–35overall view and details of the roof paths and opening classrooms of the Ecole de plein air of Suresnes, 1931–35

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16tavola di inquadramento urbano del progetto, strategicamente collocato sull’Esplanade de la Défense, tra aeroporti e nuove infrastrutture di trasporto, quale testa di ponte di una futura espansione di Parigi verso ovest, al termine della celebre prospettiva che dal Louvre interseca la Concorde e Place de l’Étoile

urban contextualization of the project, strategically located on the Esplanade de la Défense, between airports and new transport infrastructures, as the bridgehead of the future expansion of Paris to the west, at the end of the famous perspective that from the Louvre intersects La Concorde and Place de l’Etoile

17prospettiva a volo d’uccello

bird’s-eye perspective18vista del modello con gli archi ellittici che sostengono la cintura esterna superiore

view of the model with the elliptical arches supporting the upper external ring

Grand Palais des Expositions, Parigi, Francia, 1933–34

Progetto di concorso per un nuovo Grand Palais des Expositions, Parigi, Francia, 1933–34

scheda del progettoprogetto

Beaudouin et Lods Architectesprogettisti

Eugène Beaudouin, Marcel Lods

strutture e impiantiDésiré Douniaux, Vladimir Bodiansky

impresaÉtablissements Paindavoine Frères

committenteOffice Technique pour l’Utilisation de l’Acier

cronologia1933–34: progetto

dati dimensionali120.000 mq superficie coperta totale

localizzazionePlace de la Défense, Parigi, Francia

fotografieHenri Lacheroy, René Picard

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19facciata sud

southern facade20facciata est

eastern facade21vista della maquette

view of the model22spaccato assonometrico

axonometric cutaway23pianta delle fondazioni a livello -17 m, riportante la proiezione del livello -5 m con il teatro sotterraneo centrale da 6000 posti e le sue due gallerie di accesso

plan of the foundations at level -17 m, showing the projection of level -5 m with the central underground theater for 6000 seats and the two access tunnels

24pianta ai livelli 0 e +4 m

plans at levels 0 and +4 m

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71cASAbellA 90170 Robert Maillart: Massa o qualità? Mass or quality? Masse oder Qualität?

Le alternative strutturaliMarco Biagi

25, 26viste del modello dall’alto, sul particolare del velario plissettato di vetro, sospeso tra cavi d’acciaio ad alta resistenza di 74.400 mmq di sezione, disposti a raggiera lungo l’anello perimetrale a intervalli di 18 m l’uno dall’altro

view of the model from above, showing the pleated glass curtain suspended between high-strength steel cables with a section of 74,400 mm2, arranged like spokes along the perimeter ring at intervals of 18 m

Schematizzate nei disegni riprodotti in questa pagina –già pubblicati su «La construction moderne», n. 3, del 1934– la soluzione strutturale prescelta e quelle invece studiate e infine scartate da Beaudouin, Lods e Bodiansky per il progetto del nuovo Grand Palais des Expositions presentato al concorso bandito dall’OTUA nel 1933. Le linee continue rappresentano le travi maestre, quelle tratteggiate le travi secondarie. 1 Travatura rettilinea su pianta rettangolare. Grande incidenza del peso proprio rispetto al sovraccarico. La portata delle travi determinata dalle prescrizioni del programma è vicina al limite di utilizzo; l’equilibrio è difficilmente raggiungibile. Aumentando il numero delle travi maestre si ottengono elementi lunghi, di piccola sezione, soggetti a flessione, che comportano perciò una cattiva utilizzazione del metallo. Il peso cresce rapidamente, gli sforzi tendono a convergere al centro della trave.2 Gli stessi svantaggi del primo caso. Gli sforzi convergono ancora al centro della trave. Il movimento è però meno rapido rispetto al primo caso, con una certa riduzione dei pesi.3 Griglia nervata. Possibile riduzione dei sistemi parassiti; campionatura più piccola delle travi maestre. Apparizione di elementi sottili soggetti a flessione. L’aumento dell’interasse fra le travi comporta un incremento del sistema parassita. Circolo vizioso. Il volume complessivo degli sforzi tende sempre a dirigersi verso il centro.4 Stesse caratteristiche del caso 2; in aggiunta occorre osservare la spinta degli archi. L’importanza del sistema parassita non può essere contrastata se non attraverso la moltiplicazione degli archi, il che riporta al caso 2. La distribuzione degli sforzi è stabile, il peso proprio può essere ripartito uniformemente sulla

lunghezza dell’arco. 5 Stessi svantaggi dei sistemi parassiti. Riduzione del peso del sistema principale e migliore utilizzo del metallo. Gli sforzi si dirigono verso gli appoggi, con conseguente riduzione dei pesi e possibilità di luci maggiori. Aumento del volume dei supporti e tensione dei cavi da assorbire attraverso contrappesi esterni.6 Schema poligonale. Le travi maestre si appoggiano l’una sull’altra. Riduzione significativa del peso proprio, le travi sono più leggere verso il centro del poligono e la luce libera dei sistemi parassiti decresce parallelamente anch’essa. Il peso proprio della costruzione è ripartito sugli appoggi come nel caso 5.7 Variante sullo schema poligonale. Le travi sono sostituite da archi sollecitati a compressione. Le estremità degli archi sono raccordate da una cintura perimetrale che lavora a trazione. Il peso proprio della costruzione è scaricato sugli appoggi più che nel sesto caso. Vi è l’inconveniente del sistema parassita secondario; l’instabilità a flessione degli elementi non permette di moltiplicare gli archi.8 Cupola rovescia, velario a pianta circolare su cavi in tensione. La distribuzione degli sforzi è stabile. Gli altri pesi sono scaricati sul piano di appoggio. Una corona esterna bilancia per compressione la somma delle sollecitazioni di trazione trasmesse dai cavi e consente la rimozione dei contrappesi di ancoraggio esterni. La portata del sistema parassita è ridotta al minimo (semplice vetratura). La moltiplicazione dei cavi assicura una ripartizione uniforme degli sforzi di compressione lungo l’anello esterno. La compressione è assorbita dall’ampia sezione dell’anello esterno, poco soggetto a flessione.

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27, 28viste del modello con il sistema delle rampe perimetrali che permettono alle automobili di raggiungere la pista circolare predisposta in copertura

views of the model with the system of perimeter ramps permitting automobiles to reach the circular track on the roof

29, 30, 31pianta, facciata e prospettiva del progetto di Paul Tournon e Marcel Chappey, vincitore del primo premio al concorso

plan, facade and perspective of the project by Paul Tournon and Marcel Chappey, winner of first prize in the competition

32il modello nello studio degli architetti

the model in the architects’ studio

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page 20Veliero: Franco Albini’s celibate

machine Roberto Dulio

The Veliero by Franco Albini came down with a crash, not driven onto the cliffs of a rocky shoreline, but in the architect’s home in Milan. The collapse was caused by the weight of books on the glass shelves sustained by ties, which formed the slender, daring structure of the futuristic bookcase.

The works of Franco Albini in the 1930s and 1940s –installations and furnishings, more than works of architecture, or namely what we would call “design” today, though at the time it was part of a more substantial field of action of architects– are frequently cited as examples of a rigorous functionalism or a strict observance of rationalism. These are vague definitions, never fully clear and thus interchangeable. These works by Albini, to a superficial glance, would seem to jibe perfectly with the rhetorical definition of those dubious critical categories. But their nature, and their very origin, beyond the useful purpose, are extraneous to mere functionality and to any act of rationalist faith, since they find their inspiration in an imaginary oriented by other perspectives.

Albini’s apprenticeship in the studio of Gio Ponti is often reduced to a Novecento interval that comes prior to the birth of the unbendingly avant-garde architect. But instead of seeking formal –and undoubtedly unripe– echoes of that initial phase, it seems worthwhile to reflect on the conception of design Ponti developed in his Milanese workshop, based on an incessant and renewed dialogue of architecture with the other arts, and of the architect with artists.

Also Edoardo Persico, beyond the mythopoeia that clings to his relation-ship with Albini, was substantially poised between art and architecture, those with a background that was utterly heterodox with respect to those spheres themselves. Much has been written about the figure of the Neapolitan critic: whatever the true depth of his personality, his ability to stimulate the imagination of artists and architects remains unchallenged. And, like Ponti, he urged them to heed the suggestions of the artists.

It is not too farfetched to think that Albini fed on the artistic research of his time, also in less conventional expressions and in directions abso-lutely independent with respect to those of his mentors. Given his verbal reticence, we do not know what his references were, but in some of his more experimental works we can clearly see the surfacing of a underly-ing Surrealist temptation. After all, the magazine Minotaure (1933–39), which was to represent an incisive channel of the spread of that move-ment, did circulate in Italy. Well known to Ponti himself, as well as to Carlo Mollino, it spread in the context of an essentially French-speaking cosmopolitanism. An indisputable go-between for Albini with French literary and artistic culture was his sister Maria, who moved to Paris in

1936. And it seems significant that Carla, the other sister, was involved in the world of the arts, being an illustrator herself.

Therefore certain choices of installation and furnishing presented at the Milan Triennales can be traced back to this subtle influence. Among them, we find the bed suspended at a dizzying height, and the shower in a glass cylinder of the “Room for a Man” at the 6th Triennale (1936); the glass radio (1938); the Mitragliera lamp (1938–40); the meadow of daisies under a glass floor, the paraboloid aviary and the cableway seats sus-pended in the “Living Room in a Villa” at the 7th Triennale (1940).

In particular, the use of glass, the leaning towards a technical imaginary and at the same time the decontextu-alization of common objects, screened or suspended through transparent crystals, seem to establish a surpris-ing parallel with a famous work by Marcel Duchamp: La mariée mise à nu par ses célibataires, même (1915–23), better known as Le Grand Verre. A celibate machine to the extent that the two parts that sublimated the male and female universes through complex symbolism could not come into contact, separated by the two different panels of the same work.

Le Grand Verre was shown at the Brooklyn Museum in New York in 1926 and 1927, and published in issue 6 of Minotaure (1935) to illustrate an article by André Breton on Duchamp, after which the Museum of Modern Art of New York presented the exhibition Fantastic Art, Dada, Surrealism (1937–38). It is probable that Albini saw the article by Breton in Minotaure –the magazine was easily available in Ponti’s library, and perhaps in that of «Casabella» or of the sisters Maria and Carla– and that unusual use of glass might have attracted his prehensile eye. The fact remains that the definition of a celibate machine perfectly fits his Veliero bookcase (1938), so disastrous-ly unsuitable for the storage of books.

Impressed by the ribs, longerons, struts and tie-rods of airplanes – a knowledge and interest borne out by the photographs conserved by the architect himself, probably for the installation of the Hall of Aerodynam-ics in the Mostra dell’Aeronautica italiana at the Palazzo dell’Arte in Milan (1934), while the immediately prior years were those of a relation-ship of clientele (1931–33) with the famous pilot Arturo Ferrarin – Albini configured a daring device, a sort of hymn in praise of “suspension” through chains and stays, which probably also reflects the images of the utopias of Soviet Constructivism, especially that of Ivan Leonidov. It was Franca Helg, after World War II, who gave the bookcase the Veliero name (meaning “sailboat”), making the nautical aspect prevail – that of shrouds and masts, which were also part of Albini’s imaginary.

Two reticular struts in ash wood with brass tips, splayed and hinged to a base, also in ash, are held taut by four metal tie-rods –the shrouds– on each side, arranged in pairs and anchored to the base by tensioning mechanisms. The two struts are

joined together in the upper part by two cables, also pulled by tensioners: the upper one functions as a catenary, while the lower one is attached to the central framework of the metal tie-rods, arranged at a distance that would become variable, determined by the reticular holes in the two wooden struts. Small wooden shelves are attached to the tie-rods, and extend crosswise on the width of the base. On these shelves, stabilized by pairs of ulterior inclined tie-rods, made of brass, the shelving is placed in “fervetro,” i.e. tempered glass, which leaves the central part in which the vertical ties pass unencumbered. A complex, unstable system, not so much due to the slimness of the structure –in any case reinforced with respect to the initial, smaller version (13 days earlier!), with just four shrouds and the base reduced to two crossed parts– as to the precarious character of the static behavior and vertical balancing. When the book-case is empty, in fact, the upper cables are put under tension determined mainly by the lateral shrouds. But when the books are inserted, their weight on the shelves pulls on the lowered upper cable, and tends to bring the posts closer together, without encountering resistance to the compression. The increasing proximity of the two struts can only be countered by the lateral shrouds, which however wind up forcefully stressing the base, on the four corners where they are attached. Another point of great stress on the base –com-pression, in this case– is located in the central point of attachment of the hinge of the two struts. These different and opposing stresses tend to make the base flex markedly. To counter this, the base itself was thickened in the section at the center, like a very flattened pyramid. Clearly these measures did not suffice to prevent the collapse of the bookcase, which in the photographs of the time, in any case, is always shown with only moderate loads on the shelves.

In Duchamp’s celibate machine the female part could not join with the male part; in Albini’s Veliero the static model of the bookcase without books could not coincide with that of the bookcase loaded with books. Precisely this factor –far more plausible than the legendary high-pitched sound said to have broken the glass and caused the collapse– can be evoked to justify the spectacular débâcle of the striking aerial structure deployed as a book-case.

The Veliero appears in issue 163 of Domus in July 1941, also on its cover. In the Milanese living room of the apartment of Albini, on Via De Togni, the bookcase displayed its enigmatic and unstable balance. In a photo-graph probably taken between 1927 and 1933, almost definitely unknown to Albini, we see Le Grand Verre in the apartment of the American collectors Louise and Walter Arensberg, with the glass broken after shipping following the closing of the exhibition at the Brooklyn Museum. Set in a domestic space, with books in the background seen through the transparency of the work, a resemblance surfaces between the celibate machine of Duchamp and

that of Albini. The parallels between the two works are striking: even if Albini was not aware of Le Grand Verre by Duchamp, the conceptual conver-gence of the two lines of research would be surprising to say the least. Two immaterial prisms in which the glass, in different ways, supports the suspension of elements –enigmatic objects for Duchamp, books for Albini– that are artificially suspended in the space of an almost traditional bourgeois parlor. The collapse caused by the breaking of the glass also suggests the kinship between the two experimental works.

An initial reworking of the Veliero –we don’t know if it was prior to or after the spectacular shipwreck– must have taken place before 1948. This is the date of the famous photographic portrait of the architect made by Irving Penn, which would be pub-lished the following year, together with those of other Italian designers, in the American edition of «Vogue», accompanied by a text by Ernesto Nathan Rogers. Next to the portrait of Albini there is also a photograph of the Veliero, defined in the caption as “his experiment in suspension – a crystal and wire bookcase, handsome as a great bridge.” In the image, with respect to the photographs published in Domus in 1941, we can see that the wooden base of the bookcase seems to be raised off the ground to permit the insertion of a sturdy structure, probably in metal, that would stiffen the base against the stress generated by the hinge for the attachment of the struts and the tensioners of the shrouds. In the same photograph we can also observe that the vertical tie rods of the shelves are simultaneously attached, in a clearly inconsistent manner, both to the upper catenary and to the lower cable. This second detail can also be seen in another portrait of Albini, shortly thereafter, this time made by Mario De Biasi, who photographed the architect across the shelves of the Veliero.

Only later did Franco Albini hand over the parts of the bookcase to the most expert producer of his furniture, Roberto Poggi, hypothesizing a revision of the project, perhaps in order to put it into production, as had already happened for other “unstable” pieces by Albini, including the rocking chair that appeared in the 1930s among the architect’s experimental furnishings, and was produced by the workshop in Pavia starting in 1959. In Poggi’s workshop, where the Veliero was stored until 2010, two struts have recently been rediscovered. One of them has the same length as the originals (about 270 centimeters), and was probably made by Poggi himself to test the possible workmanship of the piece. The other is shorter, with a length that corresponds exactly to the upper distance between the two struts of the bookcase (about 200 centime-ters), and was plausibly made in the 1950s by the same craftsmen –un-known thus far– who made the Veliero. The hinge attachments at the extremi-ties of the bronze tips of this third strut also perfectly accommodate the blade visibly added to the two upper tips of the splayed struts. The third strut, replacing the cables, would have

formed a rigid structure, together with the other two: a strong triangle that would stand up to the stresses of the bookcase. But it was probably Albini himself who discarded this solution, which would have weighed down and disfigured “his experiment in suspension,” already before he called on Poggi.

At the time, the idea of putting the Veliero into production remained a mere hypothesis, blocked by the difficulty of making such a precarious construction system stable. It was only after Albini’s death, at the time of the exhibition in Milan at Rotonda della Besana Franco Albini. Architettu-ra e design 1930-1970 (1979), and then in the exhibition at the Castello Visconteo of Pavia Poggi. Design per un’industria (1986), that Roberto Poggi, with the help of his son Carlo, a structural engineer, was able to reconstruct the Veliero, leaving it without books and stiffening the base with iron beams placed below it. This latter device has also been used for the recent reissue of the bookcase (2011), which remains stable only under a modest load (150 kg).

Today the Veliero, after the latest shipwreck, proudly displays its broken tie-rods. In any case, this object draws on an imaginary universe, indicated starting with the name with which it became famous, that brings together the most refined technical aspects of airplanes and ships; the desire for a lightness that defies the laws of gravity and any functional or techni-cal logic; the adventure of sailing on the sea; the reversal between symbolic form and legitimized meaning of the Surrealist aesthetic. A dream that had to remain suspended on the air and on the waves, without being useful, except as a way of feeding the imagi-nation.

page 46Experimentation and research

on light structures: two possible interpretationsMassimo Curzi

Architecture has always spoken of the historical period in which it was made, condensing its thought, the ability to obtain and work with materials, to calculate structures and to take a position on themes being debated in the society in that mo-ment.

One of the biggest problems of our planet today is the recycling of materials, granting them a new life that makes it possible to reduce the quantities of energy used and to postpone the moment of their final elimination. The ability to give every material as many “life cycles” as possible becomes a priority. While for many materials like aluminium, paper and glass recycling seems feasible with a minimum expenditure of energy and minimum environmen-tal impact, for many other materials the energy required becomes more of an issue. Furthermore, if some materials at the end of their life can be burned, polluting the environment but providing us with useful energy, for others this passage becomes impossible, because since they cannot

be burned they force is to bury them as a final solution: this is the case of composite materials. This is why composites –carbon, Kevlar and other fibers– are now among the worst pollutants of our planet. As a result, many university research centers and private think tanks are conducting experimentation to invent ways of treating and transforming these materials at the end of their life cycle. Many of these projects call for the structure that transforms composite materials to be easy to transport, permitting further reduction of energy expenditure in the environ-ment. The transformation of compos-ite materials is addressed in two projects developed by two university departments in Stuttgart that have been working on the theme of light structures for years: the Institute for Computational Design and Construc-tion (ICD) and the lnstitute of Build-ing Structures e Structural Design (ITKE).

Both pavilions are located in the undulated landscape of the park of the Bundesgartenschau in Heilbronn, in the Baden-Württemberg region.

If it is true, as Sigfried Giedion* states, that architecture “is the construction of interior space through structure,” in these two cases precise-ly the structural aspect is the protago-nist with two very different materials that share in the will to reduce the structural component to the essential.

The research conducted by the two institutes moves in two different directions of investigation: the use of a natural and traditional material like wood, and the use of glass and carbon fibers. It is therefore interesting to observe the two projects side by side, precisely to understand their differ-ences, in terms of design and imple-mentation of the structures, but also atmospheric and spatial construction. It is clear that in both cases the use of the computer becomes central: its capacity to calculate and to extend that potential in the numerical control of machinery becomes the most important factor, exploiting the speed of calculation and the precision in controlling details that would otherwise be impossible to produce.

In this pursuit of efficiency of form, the computer can optimize the use of materials, combining the calculation of stresses and deforma-tions with the densification of the material. While in the wooden pavilion this solution gives rise to a change of geometries and dimension-ing of the parts, in the fiber pavilion, as in an ulterior shift of scale, there is the addition of the control of the position of the filaments to the millimeter, optimizing the form even further to its structural efficiency. The fascination with light structures has a deeply rooted tradition in Germany, and in Stuttgart in particular, where the presence of Frei Otto triggered a radical change in the architectural approach from the postwar period on. For this type of architecture, where the method of assembly of the parts becomes the most characterizing detail of the spatial continuum, the points of greatest impact and concen-tration of architectural details are the ground seam, the shape of the borders

of the structure and the roofing technique. The ground seam usually solves a problem of geometry and transmission of weights and tensions in relation to the ground. The shape of the borders reveals their role as load-bearing beams, generally display-ing arched forms and illustrating the structural stress, in a sort of visualiza-tion of the moment diagram. The lightness of the structure and the thinness of the roof surface reduce the distance between interior and exterior, natural and artificial to a minimum, directing the architectural research towards something more sustainable for the environment, in a greater proximity between man and nature.

* Sigfried Giedion, The Eternal Present: The Beginnings of Architecture (1957).

page 49BUGA Wood Pavilion

from the project description

Its segmented wood shell is based on biological principles found in the plate skeleton of sea urchins, which have been studied by the Institute for Computational Design and Construc-tion (ICD) and the Institute for Building Structures and Structural Design (ITKE) at the University of Stuttgart for almost a decade.

As part of the project, a robotic manufacturing platform was devel-oped for the automated assembly and milling of the pavilion’s 376 bespoke hollow wood segments. This fabrica-tion process ensures that all segments fit together with sub-millimeter precision like a big, three-dimension-al puzzle. The stunning wooden roof spans 30 meters over one of BUGA’s main event and concert venues, using a minimum amount of material while also generating a unique architectural space. To achieve this goal, the pavilion builds on the biomimetic principle of using “less material” by having “more form”, both on the level of the overall shell and its individual segments. In order to minimize material consump-tion and weight, each wood segment is built up from two thin plates that plank a ring of edge-beams on top and bottom, forming large-scale hollow wooden cases with polygonal forms. The bottom plate includes a large opening, which constitutes a distinc-tive architectural feature and provides access to the hidden connections during assembly. The lightweight building elements are connected by finger joints, which follow the morphological principles of anatomic features found on the edge of sea urchins’ plates. In the assembled state, the shell works as a form-active structure through its expressive doubly curved geometry.

The composition becomes statically stable only when it has been completely assembled. The void inside each element can be exploited, in the lower part, to position a refined LED lighting system, while at the same time the upper part of each element is closed and sealed thanks to a plywood panel glued directly to the framework

on which three other small pieces are placed to permit the deviation, in an organized way, of the outflow of rainwater on the upper surface of the pavilion, towards the three ground supports.

The highly integrative process enables the design and engineering of 376 unique plate segments with 17 000 different finger joints in response to multi- faceted design criteria, from the scale of the overall structure down to sub-millimeter details. Without any loss of precision, this multi-scale approach allows addressing architec-tural and structural considerations concurrently. Despite the pioneering character of the project, and despite an incredible short development time of only 13 months from commission to the opening, the integrative computational process allows for the careful design of each building element in minute detail. For this, a novel, transportable, 14-axes robotic timber-manufacturing platform was developed by ICD University of Stuttgart and BEC GmbH, and located at the industrial partner Mueller Blaustein Holzbauwerke GmbH for production. The platform includes two high-payload industrial robots mounted on a 20-foot standard container base. The flexibility of industrial robots allows the integra-tion of all pre-fabrication steps of the pavilion’s segments within one compact manufacturing unit. During production, each bespoke shell segment is robotically assem-bled. This entails the placement of preformatted timber plates and beams, their temporary fixation with beech nails, and the controlled application for the structural glue joint between plate and beam. In a second step, the intricate finger-joints and openings are machined into the segments with 300 μm accuracy. From the assembly of beams and plates, to multi-tool machining and sensorial process- and image based quality control – everything happens in a fully automated workflow, controlled by 2 million custom lines of robotic code that were directly exported from the computational design framework. On average, the assembly time per segment is 8 minutes, with the high precision milling taking another 20-40 minutes.

page 55BUGA Fiber Pavilion

from the project description

The pavilion demonstrates how combining cutting-edge computation-al technologies with constructional principles found in nature enables the development of truly novel and genuinely digital building system. The pavilion’s load-bearing structure is robotically produced from advanced fiber composites only. This globally unique structure is not only highly effective and exceptionally light-weight, but it also provides a distinc-tive yet authentic architectural expression and an extraordinary spatial experience.

In biology most load-bearing structures are fiber composites. They are made from fibers, as for example

cellulose, chitin or collagen, and a matrix material that supports them and maintains their relative position. The astounding performance and unrivalled resource efficiency of biological structures stems from these fibrous systems. Their organization, directionality and density is finely tuned and locally varied in order to ensure that material is only placed where it is needed.

The pavilion covers a floor area of around 400 square meters and achieves a free span of more than 23 meters. It is enclosed by fully trans-parent, mechanically pre-stressed ETFE membrane. The primary load bearing structure is made from 60 bespoke fiber composite components only. With 7.6 kilograms per square meter it is exceptionally lightweight, approximately five times lighter than a more conventional steel structure. Elaborate testing procedures required for full approval showed that a single fibrous component can take up to 250 kilo newton of compression force, which equals around 25 tons or the weight of more than 15 cars.

The pavilion is made from more than 150.000 meters of spatially arranged glass and carbon fibers. They all need to be individually designed and placed, which is very hard to achieve with a typical linear workflow and established production technologies. Thus, it requires a novel co-design approach, where architec-tural design, structural engineering and robotic fabrication are developed in continuous computational feed-back. In this way, the fiber arrange-ment, density and orientation of each building component can be individu-ally calibrated, structurally tuned and architecturally articulated, while remaining directly producible.

The building components are produced by robotic, coreless filament winding, a novel additive manufactur-ing approach pioneered and devel-oped at the University of Stuttgart. Fibrous filaments are freely placed between two rotating winding scaffolds by a robot. During this process, the predefined shape of the building component emerges only from the interaction of the filaments, eliminating the need for any mold or core. This allows for bespoke form and individual fiber layup for each component without any economic disadvantage. In addition, there is no production waste or material off-cuts. During manufacturing, a lattice of translucent glass fibers is generated, onto which the black carbon fibers are placed where they are structural needed.

Each component takes between four to six hours to make from around 1000 meters of glass fiber and 1600 meters of carbon fiber on average.

page 60The consequences of form

Marco Biagi

«Enfin, le cercle étant le plus simple des lieux géométriques, doit égale-ment fournir des solutions construc-tives extrêmement élégantes, donc légères, par conséquent économiques (car dans les grandes dimensions ce

cASAbellA 901enGlISh teXtS 105104

n’est plus seulement la façon d’utiliser la matière, mais surtout le choix de la forme qui importe).»(E. Beaudouin and M. Lods, descrip-tion of project for the OTUA competi-tion for a Nouveau Grand Palais des Expositions, Paris 1934)

Known and admired both in France and on an international level, but still seldom studied and appreciated, the professional partnership of Eugène Beaudouin (1898–1983) and Marcel Lods (1891–1978) produced significant technical innovations in the 1930s in France in the field of metal construc-tions and typological experimentation on architecture, as well as works that were authentic emblems of the ideals of social progress that fed the “heroic” period of the Modern Movement. Antithetical but complementary personalities, seven years apart in age, the two met in 1922 at the École des beaux-arts, in the atelier of Emmanuel Pontremoli. They met up again one year later, after Lods had graduated, to work in the studio of the paternal uncle of Beaudouin, Albert, focusing on the design of low-cost housing complexes in the suburbs of Paris: in particular, in Vitry (1925), Versailles (1926), Gennevilliers (1926) and Romainville (1925–27). Starting in 1925 they became partners of the head of the studio, who retired three years later, leaving behind consolidated relations with public agencies such as the HBM (Habitations à Bon Marché) and the SALEFN (Société anonyme des logements économiques pour familles nombreuses). For 15 years, until 1940, the duo worked together, combining and exploiting their different talents and interests: urban design and the contextual dimension of architecture, for Beaudouin, who collaborate with Forestier on the plan for Havana (1928) and with Prost on that of the Paris region (1930–36); technological rationalization of construction and the worksite, for Lods, who actively promoted mixed or complete prefabri-cation in steel as the path to moderni-zation of the construction sector, and above all a key means of reducing the costs of housing on the scale of the large developments for the working class masses. Across a span of little more than one decade, the two young professionals –composer and builder– raced through a series of pioneering and paradigmatic experiences that explored the multiple prerogatives and potentialities of industrialized metal architecture. The projects they developed addressed the main functions of life in the contemporary city –housing, transport infrastruc-ture, education, culture, leisure time, all the way to monuments– and the variations of the programs and growing complexity of the projects were interpreted each time as oppor-tunities to refine their collaboration with the engineers and contractors involved, and to move forward with the research, making important operative and cognitive advances. At Bagneux (Cité du Champ-des-Oi-seaux, 1927–33), first, and at Drancy (Cité de la Muette, 1931–34), later, the theme of social housing financed under the Locheur Act (1928) was an

excellent proving ground for Beau-douin and Lods, in which to begin to tackle the issues and the discipline of industrialisation ouverte, of standard-ized construction for serial compo-nents produced in a factory and then assembled, discovered thanks to a decisive encounter with the engineer-developer Eugène Mopin. Drancy, in particular, with its impressive array of parallel linear volumes alternating with 16-story towers with a steel skeleton clad in vibrated concrete pan-els, was an unrivaled model, at the time, of rationalization of construc-tion and the worksite, a remarkable example and forerunner of the grands ensembles of the postwar era. Later, the repeated collaborations with Ateliers Jean Prouvé, specialized in working with shaped sheet metal, in steel and aluminium, and with the civil and aeronautical engineer Vladimir Bodiansky, prompted the two designers not only to explore the area of industrialisation fermée, the closed prefabrication of sophisticated organisms composed of entirely coordinated parts –for example, in the small prototype of the “demountable” weekend house B.L.P.S. (1937–38) presented at the Exposition de l’Habitation in 1939– but also and especially to investigate the option of mechanized and transformable architecture, whose variable arrange-ment functioned as a multiplier of efficiency and versatile performance of the constructed device. This happened through the layout, and the invention of refined mechanisms of opening and movement of the facades or the internal partitions of buildings, as in the case of the elegant coulis-santes glazed frames developed to open the volumes of the classrooms in the “hygienic-pedagogical” experi-ment of the Ecole de plein air of Suresnes (1931–35), or by introducing solutions of partial automation of the artifact, as in the futuristic bijou mécanique of the Maison du Peuple in Clichy (1935–39): an indoor market in the morning, a community center in the evening, inadvisably completed at the moment of the outbreak of war.

However, it was thanks to several competitions, also in the 1930s, organized by OTUA, Office Technique pour l’Utilisation de l’Acier, that the reflections of Beaudouin and Lods on metal construction took on a different breadth and a conceptual shift from the plane of uniformity to that of uniqueness, from technological pragmatism of the outil object to the exceptional quality of structural invention. After an initial trial in 1933, in the project for an aircraft hangar with a circular form in steel and shaped sheet metal, and a single central support around whose axis a parabolic generator inscribed, by rotation, an enormous self-supporting mushroom-like canopy, it was in the demanding competition for a Nouveau Grand Palais des Expositions, organized by OTUA in late 1933 and early 1934, that the most remarkable and spectacular vision developed in the career of the two Parisian archi-tects was formulated. With an eye on the upcoming Exposition Internation-ale de Arts et Techniques dans la Vie Moderne of 1937, in fact, the competi-

tion assessed the possibility of giving the capital a new multifunctional convention center capable of welcom-ing the enormous crowds conveyed by the modern mass transport network, and of putting the country back at the forefront with a construction that would be a symbol of technical progress, as in the days of the Tour Eiffel.

The request was for a colossal hall of 120,000 m2, with a flat roof and a quadrilateral plan, free of internal supports and with a minimum span of 250 linear meters. The hypotheses of location were left up to the competi-tors. Twelve groups of designers and contractors were allowed to partici-pate. Beaudouin and Lods were joined by Vladimir Bodiansky and Désiré Douniaux, an engineer of the metal construction plant of the Brothers Paindavoine. Their proposal is undoubtedly the most original and memorable of all, and the only one, perhaps, as Georges-Henri Pingusson points out in his commentary on the results of the competition in Chantiers (the technical supplement of L’Architecture d’Aujourd’hui) in June 1934, that is not limited to “transpos-ing familiar, also modern forms into dimensions of another order of magnitude,” but instead courageously and open-mindedly identifies a new and convincing response, suited to the unusual scale of the problem. After the discarding of multiple alternatives, the solution that makes it possible to “square the circle,” reconciling static, functional and expressive factors, is paradoxically based on the use of a circular geome-try that contradicts the quadrangular layout scheme stipulated by the guidelines. This caused the disqualifi-cation of the project on the part of the jury. The circular form, however, made it possible to transform the immense roof into a light curtain of glass, functioning by tension instead of compression. The structure, like an enormous bicycle wheel placed flat, is composed of a steel crown with a diameter of 400 meters, raised 51 meters off the ground by means of four elliptical arches diverging at the top and meeting at the impost. The hollow crown supports a practically horizontal array of spokes in ten-sioned steel cables, connected at the center by a metal ring 15 meters in diameter topped by a low cap of glass blocks and concrete. The roof acts as a sort of overturned dome, subject to centripetal forces along the perimeter. The configuration guarantees perfect balancing of the loads and the undeformable character of the belt, exclusively compressed, permits resistance to remarkable stresses, avoiding the need for counterweights and reducing deflection of the cables to a minimum. The use of arches instead of pillars to support the room has the advantage of concentrating the ground imposts at just four points, freeing the cylindrical enclosure of impediments and thus al-lowing it to be fully open, by means of full-height sliding walls for half the surface, on the east and west sides, thus converting the building into a covered plaza easily accessed and ready for fast evacuation of multitudes

of visitors. A double set of forks above the arches provides cadenced support for the circular border beam, enabling it to conserve a sufficiently slim and elegant profile. The beam also contains the ramps that allow automobiles to reach the panoramic track created at the top of the cornice, permitting the public to be choreo-graphically arranged like a true living cladding on the eight orders of metal balconies that stiffen the frames of the large mobile casements. Overlook-ing the details, the design of the new Grand Palais des Expositions, in definitive terms, is a pure volume in steel and glass, bare and abstract in its image, diaphanous in its consisten-cy in spite of its size, whose architec-tural character –as we can read in the accompanying technical report– lies above all in the “honesty of the constructive expression.” An interest-ing aspect on the sidelines of the story, however, is the fact that (as we have seen) the composition represent-ed one of the rare episodes in the path of research conducted prior to the war by Beaudouin and Lods on metal construction in which the question of the form becomes the explicit starting point of the design process. And this is inevitable, according to the two authors, when the work goes beyond a certain dimensional threshold: “because, in large dimensions –they write– what counts is no longer simply the way the material is utilized, but above all the choice of the form.”

page 70The structural alternative

Marco Biagi

Schematically formulated in the drawings shown here –previously published in La construction moderne, no. 3, 21 October 1934– we see the selected structural solution and those studied and discarded by Beaudouin, Lods and Bodiansky for the design of the new Grand Palais des Expositions submitted to the competition organ-ized by OTUA in 1933.

Rectilinear beams on a rectangu-lar plan. Large impact of own weight with respect to overload. The reach of the beams determined by the specifi-cations of the program is close to the limit of use; equilibrium is hard to achieve. Increasing the number of main beams, we obtain long members with a small section subject to flex, leading therefore to poor use of the metal.

The weight grows rapidly, the main beam is heavier at the center (the stresses tend to converge at the center of the beam).

The same disadvantages as the first case. The stresses still converge at the center of the beam. The move-ment, however, is less rapid than in the first case, with a certain reduction of the weights.

Ribbed grille. Possible reduction of parasitic systems; smaller number of main beams. Appearance of slender elements subject to flex. Increase of the interval between the beams leads to increase of the parasitic system. Vicious circle. The overall volume of the stresses still tends to shift towards the center.

Same characteristics as case 2; furthermore, we have to observe the thrust of the arches. The importance of the parasitic system cannot be countered except by multiplication of the arches, which brings us back to case 2. The distribution of the stresses is stable; the weight can be uniformly spread along the length of the arch.

Same disadvantages as the parasitic systems. Reduction of weight of the main system and better use of the metal. The stresses are directed towards the imposts, with subsequent reduction of weights and the possibili-ty of larger spans. Increase in the volume of the supports and tension of cables to be absorbed through external counter-weights.

Polygonal scheme. The main beams rest one on the next. Signifi-cant reduction of specific weight; the beams are lighter towards the center of the polygon and the open span of the parasitic systems decreases parallel to it. The weight of the construction is spread on the sup-ports as in case 5.

Variation of the polygonal scheme. The beams are replaced by arches under compressive stress. The extremities of the arches are connect-ed by a perimeter belt that works under tension. The weight of the construction is discharged on the supports more than in case 6. There is the problem of the secondary parasitic system; the flexion instability of the members does not permit multiplica-tion of the arches.

Reverse dome, circular-plan curtain on tensioned cables. The distribution of stresses is stable. The other weights are discharged on the impost area. An external ring balanc-es through compression the sum of the tensile stresses transmitted by the cables and permits removal of the external anchoring counter-weights. The reach of the parasitic system is reduced to a minimum (simple glazing). The multiplication of the cables ensures uniform sharing of the compressive stress along the outer ring. The compression is absorbed by the large section of the outer ring, with very limited flex.

page 76In Lisbon, on the castle hill

Federico Tranfa

«Drop me off in the Baixa, please, I’ll catch a tram from there, Whatever next, I’m taking you home, it isn’t any trouble, But you’re going out of your way, The car is, not me, It’s quite a climb up to the district where I live, At the foot of the castle, So you know where I live, In the Rua do Milagre de Santo António…»José Saramago, The History of the Siege of Lisbon, 1989.

«The tourist who has time to spare should not miss going up to this castle which is built on an eminence which commands a view of the Tagus and of a great part of the city. The castle has three chief doors, known as Trason, Martim Moniz, and São Jorge doors. The three are very ancient. The castle itself is remarkable enough. It was built by the Moors and formed, so it

seems, part of the defences of Lisbon, with its thick walls, its battlements and its towers. There did kings dwell; and it was the scene of many a remarkable event in the political history of Portugal. Nowadays, though surrounded and choked by a great number of houses, full of barracks, modified, spoilt and mutilated by earthquakes and misuse, it is still worth seeing for what it once was. The view from the castle is marvellous.»Fernando Pessoa, Lisbon: What the Tourist Should See

The hill of the castle of São Jorge does not represent only the geographical center of the Portuguese capital, but also the historical center, since its neighborhoods –Alfama, Castelo and Mouraria– are among those that best survived the catastrophic earthquake of 1755. At the foot to the hill, a short distance from the riverbank, stands the Sé Patriarcal; halfway up there is the Roman Theater, and the castle is at the top. These quick hints will suffice to convey a sense of the importance of the place, but it is above all through the view that we can appreciate its landscape value, even prior to that of its architecture. While the present appearance of the castle of São Jorge is the result of restoration done in the modern era (in 1938, during the regime of António de Oliveira Salazar, otherwise known as Estado Novo), with the intent of returning it to its completeness and monumental dignity, the three neighborhoods that wind across the slopes still conserve their original morphology and street layout. The defense system of historic Lisbon pivoted on the fortified circle of the castle from which the late Roman (later Moorish) walls extended in the direction of the river. Only two centuries after the Reconquest (1147) a second ring of walls (1373–75), known as Fernandina from the patronymic of the ruler Dom Fernando I, enclosed a much larger area, extending all the way to the hill opposite and including the valley in which the so-called Baixa Pombalina was built after the earth-quake. Remains of the Fernandina wall and some of its towers still stand in the urban fabric of contemporary Lisbon, as along the crest to the east of Rua do Alecrim (against which Álvaro Siza Vieira designed one of the most dense and detailed residential projects of his remarkable career). The urban growth of the 18th and 19th centuries assigned the hillside neighborhoods an almost exclusive working-class role, making them the custodians of the tradition, including that of Fado, that spread precisely from the taverns of Alfama and Mouraria. The twisted layout and minute scale of the urban hillside fabric did not lend themselves to new lifestyles, and even less to the modernization of the city, which demanded large spaces and, if possible, straight streets. In recent times, thanks to resources from the European Union, the historical center of Lisbon has been subjected to many projects of regeneration and restora-tion. They also had the objective of preventing population shrinkage, encouraging private investment and

modernization of services, which the difficult topography and lack of resources had made obsolete. Anyone who has at least once roamed the countless flights of steps and ramps that wind along the slopes of the castle hill will still remember the level shifts of the urbanized strips, and the effort it takes to reach the top of the buildings that are often without elevators. These interventions as a whole, done over the span of 15 years, have objectively improved the life of the residents, although in tune with the attenuation of the economic crisis they have also favored a massive conversion of residences into tempo-rary lodgings and second homes. Already during the first “rediscovery” of the Baixa Pombalina, whose rebirth began with the reconstruction that be-came indispensable after the great fire of Chiado on 25 August 1988, the focus of developers, and the most sensitive designers, concentrated on the environmental potential of the hill, especially in its southwestern portion with its fine view of the city and the river below. Starting from these conditions, the meaning of our survey is double: to assess the state of advance of an important public project of vertical access towards the top of the hill, and to present two original residential projects, one created from scratch in an urban void, and another based on restoration and transformation of a historical building. The makers of the projects are two architects born in Lisbon, with deep ties to the history and culture of the city: Ricardo Bak Gordon (b. 1967) and João Favila Menezes (b. 1966). Favila, since 2009, is in charge of three projects emerging from the plan for the vertical access systems of the castle hill, with a preliminary study co-authored by him with João Simões, Pedro Domingos and Rui Mendes. The first route, already partially in use, is the “Percur-so da Mouraria,” a system of steps and escalators that will lead in two segments from Praça Martim Moniz to the level of Rua Costa do Castelo, continuing upward through the recovery of an existing walkway near the walls. The second, known as “Percurso da Graça,” will connect the Mouraria district with Miradouro da Graça, situated at a level slightly below that of the castle of São Jorge. The third, called “Percurso da Sé,” is now under construction, and is based on the installation of a new elevator that will transport pedestrians from Rua Afonso de Albuquerque to Rua Cruzes da Sé, along the southern side of the cathedral. All the projects, with the aim of simplifying implementation procedures, have been designed on public land or make use of buildings that are municipal properties to contain the necessary infrastructures connecting the various levels. This extremely effective strategy links back to the one implemented in 2009-2013 by João Pedro Falcão de Campos (b. 1961), hired by the municipal govern-ment to identify a path of crossing of the Baixa and of ascent to the castle starting from the new Chiado station of the Metro line. Falcão de Campos, on that occasion, made use of a municipal building to insert public

elevators spanning the level shift between Rua dos Fanqueiros and Rua da Madalena, from which the ascent continues using the elevator of the former Mercado do Chão do Loureiro (José de Lima Franco, 1951), which reaches the intersection of Rua Costa do Castelo and Calçada do Marquês de Tancos. Treating the castle hill as an independent subject, but also as a hinge capable of connecting different urban zones, has improved ease of use, demonstrating that the residen-tial zone could be drawn out of the marginal status of its traditional occupancy. In any case, it is clear that the transformation of Lisbon into a popular tourist attraction, and not just a destination for the educated traveler, raises new issues regarding the preservation of its historical center, which looks more cared-for but also quite lacking in authentic life. This is a dilemma that is impacting many big cities in southern Europe (in Italy we could cite Naples and Paler-mo, but also Genoa, Bari or Catania), and in this sense the policies imple-mented in Lisbon can be of help to cope with an unavoidable and complex phenomenon using the tools of planning and design.

Learning from the section. A single-family house on Rua Costa do Castelo

As can be seen in the longitudinal sections, the building at the edge of Rua Costa do Castelo and aligned with its frontage has a dual function: it is a private home and a vertical access system from street level to the level of the castle walls. An extreme synthesis of what has been implemented on an urban scale by the plans for recovery and enhancement of the paths along the slopes of the hill. Resulting from a long program of research and selection of a suitable lot, involving necessary reinforcements and the construction of proper foundations, the house designed by Ricardo Bak Gordon is comparable to a site-specif-ic installation whose aim is to shed light on the rules through which to design a new type of inhabited space, exploiting the limitations implied by the topography of the site. Without a basement, the four above-ground levels of the building form a vertical sequence of spaces, the first of which is the portico with parking places, separated from the street by means of a metal gate, but having a pavement that is basically continuous with the street. The first level contains the studio, the second the children’s bedrooms, and the third is for the master bedroom, introduced by a vestibule-closet. The rooms are connected by a fair-face concrete staircase and an elevator. In this portion of the house there are windows on the street that establish a relationship of proximity with the surroundings. Large windows, though not so large as to compromise privacy in the rooms, positioned so as not to correspond to those of the building in front, only a few meters away. What is striking about the openings is their position with respect to the floor level, because the designer has placed them at variable heights, depending on the function of the rooms. They are high

(with opaque glass) in the studio, low in the bedrooms to widen the view and to provide an unexpected perspective of the street. Reaching the fifth level, the space suddenly and surprisingly expands, reaching the level of the surrounding rooftops, to look towards a dual horizon: that of the city and that of the hill. Observing the longitudinal sections we can see that the house, whose summit is detached from the streetfront, attempts to establish a relationship with the landscape, but also offers reserved, perfectly domestic outdoor spaces. The living room necessarily faces in the direction of the Baixa and the river, while the kitchen faces a patio from which a flight of steep steps crosses a terraced garden. Climbing up, one shortly arrives at the foot of the castle walls, as the gaze extends from the Mar da Palha to Ponte 25 Abril and beyond. The material quality of the building is of the sort used increasingly often by Bak Gordon: floors in polished concrete, ceilings in fair-face concrete, semi-built-in lighting (simple lamp sockets positions so that only a portion of the bulb remains visible). The spaces are completed by fixed furnishings and casements in wood, made to measure, as are the handrails and parapets in coated steel tubing. A terse vocabulary that has the aim of focusing all the attention on the space and the light, avoiding useless affectations.

Time as palimpsest. A residential building on Largo Santa Cruz do

Castelo

Behind a simple 19th-century facade, the construction renovated by João Favila Menezes conceals a typological complexity that is the result of overlapping interventions, from the medieval period to the present. In this sense, the presence of a large under-ground cistern is emblematic, a vast yet invisible spaces that makes the history of the building and its countless transformations even more enigmatic. The request of the clients, who live in one portion, was to separate the construction on the street from the more internal volume located at the boundary with the walls of the castle of São Jorge. This would make it possible to rent the perimeter housing units, while making perma-nent use of the spaces spanning the two courtyards (Pátio da Cerqueira and Pátio da Cisterna), though this would alter the original use made of the spaces, since the rooms inhabited by the previous owners were those facing Largo Santa Cruz do Castello. In the implementation phase the already complex program had to come to terms with the constructed substance of the building, so old as to require constant consideration of the need to intervene in an invasive, non-reversible way. Through slow, patient unraveling, the constructive and typological tangle of the building gradually reveals a possible key of interpretation that led to the design of a commercial space and three independent apartments as well as the home of the clients, accessed across the internal courtyard. The Pombali-na standard of post-earthquake

reconstruction called for extensive use of wood in the structures and floors, with the aim of making them more flexible. Following this criterion, Favila Menezes has reconstituted the internal spaces and concealed a new stairway offering access to the three levels. Stone was used traditionally to equip kitchens with worktops and sinks, or to make custom articles for the bathrooms. An external staircase leads to the level of the patio at the entrance door of the house of the clients, whose service spaces are below, at the level of the garden. The recovery of the wooden carpentry of the roofs was long and meticulous, like the preparation of the stucco used for the outer facades and the rooms of the four apartments. It is clear that the timing and the criteria of interven-tion applied by the owners and the designers have nothing in common with the familiar approach to real estate transformations also taken in Lisbon, whose objective is the “stage” the typical architecture generated the (often haphazard) conservation of the enclosure, with a complete replace-ment of the internal structures using conventional, stereotyped construc-tion techniques. In this case, instead, we can see how the enhancement of a place, an artifact and an asset cannot be separated from knowledge of its culture of origin. A material culture that is indispensable to guide design-ers through an aware process of selection and synthesis. These two meaningful architectural episodes, inserted in a delicate context, repre-sent a concrete response to a recur-ring problem, demonstrating that with sensitivity it is possible for themes of regeneration and reuse –if authentically rooted– to offer archi-tects opportunities for expression and experimentation. For all too long, the spheres of conservation and composi-tion have been kept artificially separate, while instead it is time to encourage and intensify the occasions of dialogue and collaboration, in an idea of continuity of history.

«Casabella» è disponibile anche in edizione giapponese, attraverso:Architects Studio Japan Inc.8-1 24F Kakuda-cho, Kita-ku, Osaka530-0017 Japantel +81.06.63635701www.asj-net.com

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numero 901/issue 901n. 09/2019anno/year LXXXIIIsettembre/September 2019

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