Art and Science of Building in Concrete; The Work of Pier Luigi Nervi by Mario a. Chiorino

7/28/2019 Art and Science of Building in Concrete; The Work of Pier Luigi Nervi by Mario a. Chiorino

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32 march 2012 Concrete international

Art and Science of

Building in Concrete:The Work ofPier Luigi NerviInterntionl exhibition nd acI Spring 2012 convention sessionsre dedited to this grnd mster of onrete strutures

by Mario A. Chiorino

Palazzo del Lavoro in Turin, Italy (photos courtesy of Istituto Sperimentale Modelli e Strutture (ISMES) archives, MAXXI archives, M. Carrieri, and/or D. Chemise)


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Concrete international march 2012 33

Described by Nikolaus Pevsner as the mostbrilliant artist in reinorced concrete o our time,Pier Luigi Nervi (1891-1979) (Fig. 1) was one o

the greatest and most inventive designers and builders othe 20th century. He shared the cultures o architects and

engineers, operating at the very intersection between theart and the science o building. With his masterpiecesscattered the world over, Nervi contributed to the creationo a glorious period or structural architecture.

His personality comprised many acets, includingdesigner, builder, researcher, and creator o new construc-tion techniques. He was also a Proessor and Lecturerat prestigious universities around the world and authoro books debating the conceptual and technologicalundaments o construction, with particular regard toconcrete construction.

He has been described as having an engineers auda-ciousness, an architects imagination, and a business-mans practical realism. His use o the most advancedtechnical solutions always went hand-in-hand not onlywith the pursuit o ormal elegance but also with anequally strong attention to the technical and economicaspects o the building process.

In 2009, on the 30th anniversary o Nervis death, abroad research and educational program was promotedwith the intent o disseminating Nervis cultural legacyand exploring the complexity o his extraordinary statureas a structural artist. The program culminated in theinternational traveling exhibition, Pier Luigi NerviArchitecture as Challenge, highlighting some o his

most celebrated works o genius. This article presents abrie synthesis o this comprehensive exploration o hislies work. It also serves as a preview to presentations atthe International Lunch and two technical sessions atthe ACI Spring 2012 Convention in Dallas, TX.

The International Exhibition: Pier LuigiNerviArchitecture as Challenge

A broad research-educational program on Nervislie and work started in 2009, and it culminated in theinternational traveling exhibition, Pier Luigi Nervi

Architecture as Challenge. The work was promoted bythe Pier Luigi Nervi Project Association (PLN),* theoundation devoted to the dessimination o Nerviscultural legacy. The program has the scientic supporto the Politecnico di Torino, the University o Rome,and La Cambre-Horta School o Architecture o theUniversity o Brussels. The exhibition was organizedby PLN and the Centre International pour la Ville etlArchitecture (CIVA), Brussels, in cooperation with theItalian National Museum o the Arts o the 21st Centuryin Rome (MAXXI) and the Study Center and Commu-nication Archive (CSAC) o the University o Parma,

Italy, under the auspices o the President o the ItalianRepublic and o other prominent institutions, includingthe Vatican City, the European community, and theInternational Olympic Committee. ACI co-sponsoredthe exhibition in recognition o the ACI HonoraryMembership awarded to Nervi in 1969 and in consid-eration o the signicant number o his celebratedworks in North America.

Accompanied by a catalog assembling the resultso the research program, the exhibition started itsextremely successul tour in Brussels, Belgium, in 2010.The subsequent venues in Italy included the Venice

Biennale, the MAXXI, and the Turin Exhibition Hallabuilding designed by Nervi himsel (as shown in Fig. 8).Aer visiting other venues in Denmark, Germany, andSwitzerland, the exhibition is expected to visit venuesin North America in 2013. On this occasion, the reprintby PLN o the Charles Eliot Norton Lectures given byNervi at Harvard in 1961 will be available.

On the eve o the North American tour, it is appropri-ate to dedicate presentations to Pier Luigi Nervi duringsessions on Structural Concrete: An Art Form at theACI Spring 2012 Convention in Dallas, TX, in March,particularly because the general convention theme is Arto Concrete. The author will deliver the keynote lecture,bearing the same title as this article, at the conventionsInternational Lunch. In two technical sessions, addi-tional speakers will review the work o other eminentpioneers and discuss recent trends in the merging oarchitecture and structural engineering.

*www.pierluiginervi.orgPier Luigi Nervi: Architecture as Challenge, C. Olmo and

C. Chiorino, eds., Silvana Editoriale, Cinisello Balsamo, Italy,2010, 240 pp.

Nervi, P.L.,Aesthetics and Technology in Buildings, The CharlesEliot Norton Lectures, Harvard University Press, Cambridge, MA,1965, 210 pp.

Fig. 1: ACI Honorary Member Pier Luigi Nervi, 1891-1979


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Early InfuencesPier Luigi Nervi graduated with a degree in civil engi-

neering at the University o Bologna, Italy, in 1913, duringa ertile period or scientic, technical, and architectural

ideas. Thanks to the contribution o a ew pioneers, builders,and designers such as Wayss, Hennebique, and Maillart, thenew technology o reinorced concrete was ast developingin the early years o the 20th century. From the very begin-ning, the new eld was associated with a conscious searchor artistic results.1

It is against this background that Pier Luigi Nervisproessional career began. Aer an initial period o trainingin the technical oce o a construction company, Nervi setup his own design and construction business in 1920. Nerviwas to maintain this dual role o designer and builderthroughout his lie.

Early WorksThe stadium in Florence (1930, Fig. 2) was Nervis rst

great work that attracted the attention o critics and thepublicboth in Italy and abroad. Besides the intrinsic

beauty o the project, characterized by the elegance andstrong visual impact o the curved tapered corbels o thecantilevered roo and the spatial sculptural orms o thehelicoidally warped stairs, Nervis design was chosen

because o the low construction cost.From 1935 through 1940, a series o great hangars wasbuilt or the Italian air orce at Orvieto (Fig. 3) and Orbetello.Probably inspired by hangars and temporary exhibitionhalls constructed in steel and laminated wood (primarily inGermany), Nervi designed a daring, yet dramatically simplein structure, geodetic roo with intersecting arched ribs.The rst group o hangars was built using traditionalscaolding and wooden orms or the concrete structure.Those that ollowed were built using ribs consisting oprecast elements that were connected on-site. From thattime on, the use o precast components would becomea constant in Nervis work, as he sought to exploit andmaximize the outstanding compositional and structuralreedoms oered by this technology.

The hangars were also the rst structures or which,in addition to static calculations, Nervi relied on tests o

Fig. 4: Celluloid model of hangar at Orbetello tested at the Model

and Construction Testing Laboratory, Politecnico di Milano, Italy

Fig. 2 (left and right): Nervis first great work: the stadium in Florence, 1930

Fig. 3: Hangar at Orvieto, 1935


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reduced-scale models. The tests were perormed byACI Honorary Member Guido Oberti (1907-2004) at thePolitecnico di Milano, Italy, in the Model and ConstructionTesting Laboratory created by Arturo Danusso (1880-1968),using celluloid elastic models on a 1:30 scale (Fig. 4). Nerviwould maintain this procedure or most o his later works.2

Ferrocement ReinventedIn his rst important post-war workthe astonishing

central hall o the Turin Exhibition Complex built in 1948(Fig. 5)Nervi used errocement to make the precastelements or the halls magnicent, transparent, 94 m

(308 ) span barrel vault. This technology had been orig-inally adopted by Jean Louis Lambot in 1846, at the verydawn o reinorced concrete, to produce a erciment boathull. The hull comprised a thin layer o concrete reinorcedwith a thick mesh o small-diameter wires, and it exhibitedremarkable ductility and resistance to cracking.3

Aer using it or an experimental warehouse at thesite o his construction company at La Magliana, near

Rome, Italy, and also or the hulls o small ships (Fig. 6),Nervi made extensive and innovative use o errocementin the majority o his most daring and ascinating projects.He is thus credited as the reinventor o this technique.

Fig. 6: Nervi reintroduced the use of ferrocement: (left) experimental warehouse in ferrocement, La Magliana, Rome, Italy, 1945;

and (right) Pier Luigi Nervi in front of one of his ferrocement boats

Fig. 5 (left and right): Central hall (Hall B) of Turin Exhibition Complex, Turin, Italy, 1948


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Ferrocement can be used to mold elements o anygeometric shape. The shapes can then be connected bycast-in-place concrete. The geometric shapes can beundulatingas in the case o the vault o the TurinExhibition Complex and in the great ribbed spherical capdome, with a diameter o almost 100 m (328 ), o thelarge Sports Palace in Rome (1960, Fig. 7)or they can

be simple tile shapes.For the 55 x 157 m (180 x 515 ) dome o Hall C o the

Turin Exhibition Complex, designed and built by Nervi in1950, the precast errocement elements are in the orm o20 mm (0.8 in.) thick, diamond-shaped tiles that wereassembled and then served as ormwork or cast-in-placeconcrete on their upper suraces and within the contactchannels ormed at the tile edges. The result is a particularlyelegant mesh o reinorced intersecting ribs (Fig. 8). Thesame pattern characterizes the structural abric o the vaultsand domes o some o Nervis most amous later works: theKursaal at Ostia (1950); the Ballroom at the Chianciano Spa

(1952); the small Sports Palace in Rome (1957, with

Antonio Vitellozzi, Fig. 9); the Leverone Field House andThompson Arena at Dartmouth College in Hanover, NH(1962, with Campbell and Aldrich, and 1976); the NorolkScope Arena in Norolk, VA (1965-71, with Williams andTazewell & Associates)at the time, the largest dome inthe world with a diameter o 135 m (443 ); and St. MarysCathedral in San Francisco, CA (1963-71, with Pietro

Belluschi, Fig. 10). In this last work, the errocement tilesand the mesh o concrete ribs adapt to the elegant hyper-bolic paraboloid suraces o the dome.

In the Gatti Wool Mill (Rome, Italy, 1951), the precasttiles are used to build a fat foor. The design o the ribpattern on the ceiling is derived rom the lines o theprincipal bending moments, again resulting in a partic-ularly rened ormal eect that is ound in a number oNervis subsequent projects.

Later WorksNervis rst important work outside Italy was the

UNESCO Headquarters in Paris, France (1953-58, in

Fig. 9: The small Sports Palace in Rome, Italy, 1957, P.L. Nervi with

Antonio Vitellozzi. The elegant pattern of the concrete ribs seems

to be inspired by the geometrical network of a sunflower core

Fig. 7: Sports Palace in Rome, Italy, 1958-60, P.L. Nervi with

Marcello Piacentini

Fig. 8: Hall C of Turin Exhibition Complex, Turin, Italy, 1950, while

hosting the International Nervi Exhibtion, 2011


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cooperation with Marcel Breuer and Bernard Zehruss). Thesignature eature o this building is the ascinating oldedstructure o the exposed concrete o the walls and roo. Aseries o other prestigious commissions ollowed. Besidesthose mentioned previously, the list includes: GeorgeWashington Bridge Bus Terminal in New York, NY (1962);Montreals Victoria Square Tower, Canada (1961-66, withLuigi Moretti, Fig. 11)at the time, the tallest reinorcedconcrete building in the world at 145 m (475 ); Australia

Square and MLC Center Towers in Sydney (1964-72, withH. Seidler); the hyperbolic paraboloid umbrella roos orNewark International Airport, NJ (1971); the B.I.T. head-quarters building in Geneva, Switzerland (1972); and theItalian Embassy in Brasilia, Brazil (1979).

Fig. 12: Pirelli Tower, Milan, Italy, 1955-58, Pier Luigi Nervi with

Arturo Danusso and Gio Ponti

Fig. 10 (left and right): St. Marys Cathedral, San Francisco, CA, 1963-71, Pier Luigi Nervi with Pietro Belluschi, Mc Sweeney, Ryan &Leew and Leonard F. Robinson (structural engineer)

Fig. 11: Victoria Square Tower, Montreal, QC, Canada, 1961-66,

Pier Luigi Nervi with Luigi Moretti


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In Italy, the most celebrated works o his later periodinclude: the 135 m (443 ) tall Pirelli Tower in Milan(1955-59, with Arturo Danusso and Gio Ponti, Fig. 12); theacilities or the 1960 Rome Olympics, including, besidesthe two mentioned Sports Palaces, the Flaminio Stadium,and the Corso Francia Viaduct; the Palazzo del Lavoro inTurin (1959-61) (Fig. 13), with its geometrically ascinatingcolumns eaturing striped slanting suraces covered by asteel umbrella-like structure (designed by Gino Covre);the Ponte Risorgimento in Verona (1963-68); and thePapal Audience Hall in the Vatican (1963-71, with Anto-nio Nervi, Fig. 14). The latter project recalls the themes othe Turin Exhibition Hall (rom 20 years earlier) whileenhancing them to create an imposing composition also

characterized by the sculpturally highly efective shapes othe main supporting columns and o the ribbed ceilingso the proscenium.

ExperimentationExperimentation, including scale models and ull-scale

prototypes and constructions, continued to play a majorrole in Nervis work. The scientic collaboration betweenNervi and Oberti, initiated at the Laboratory o the Poli-tecnico di Milano beore the war, continued aer 1950within the new research laboratory oIstituto SperimentaleModelli E Strutture (ISMES), ounded by Danusso in

Bergamo with the support o Italcementi, the leadingItalian cement corporation.

Nervi and Oberti considered experimentation to be thebest strategy to overcome the practical impossibility, at thattime, o basing saety checks o complex constructions onadequately accurate and computationally easible theoreti-cal models.4 This strategy was also ollowednot coinci-dentallyby other leading exponents o structural architec-ture in the 20th century, including Eduardo Torroja, FranzDischinger, Antoine Tedesko, Felix Candela, Heinz Hoss-dor, and Heinz Isler, to name a ew.

While the numerical modeling techniques that increas-

ingly appeared in the late 1960s would have gradually

Fig. 13 (left and right): Palazzo del Lavoro in Turin, Italy, 1959-61, Pier Luigi Nervi with Antonio Nervi and Gino Covre

Fig. 14 (upper and lower): Papal Audience Hall, Vatican City,

Rome, Italy, 1963-71, Pier Luigi Nervi with Antonio Nervi


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opened new rontiers, its air to say that experimentationusing models became an extremely rened art orm andan essential phase o the design path or Nervi and othereminent protagonists. Creating physical models was an artorm that required, almost in the same way as in realconstruction, the designer to be able to combine techno-logical expertise and imaginationperhaps justiyingObertis requent citation o the adage attributed to

Michelangelo by Vasari: The most blessed monies thatare spent by those who would build are on models.

One o the most complex models produced and testedwithin the ISMES acilities was o the reinorced concreterame o the Pirelli Tower in Milan, Italy, (modeled in1955-56). The nearly 10 m (33 ) tall, 1:15-scale model(Fig. 15) was produced in microconcrete o pumice stoneand portland cement and tested beyond service conditionsup to ailure, aer a series o tests in the dynamic eld tocheck the eects o wind.

Other ISMES testing programs included models o theVictoria Tower in Montreal, QC, Canada, and St. Marys

Cathedral in San Francisco, CA. In the latter case, a small-

scale (1:100) model was used or the wind tunnel tests, twomedium-scale (1:40 and 1:37) resin models were used orstatic and dynamic tests in the elastic eld (with special

attention to seismic tests due to the buildings location),

Fig. 15: Microconcrete large-scale model (1:15) used for tests to

failure for the Pirelli Tower, Milan, Italy

Fig. 16: St. Marys Cathedral, San Francisco, CA: (above) elastic

model (1:37) under dynamic test; and (below) microconcrete

model (1:15) shown following the ultimate limit state tests


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and a large-scale (1:15) model constructed in microconcretewas used or tests to ailure (Fig. 16). Its o interest to notethat the elastic tests or St. Marys were accompanied bychecks using numerical models based on early applications

o elastic nite elements analysis, made by the U.S. engi-neering studio o Leonard Robinson, the rm responsibleor the nal design.

Nervis concrete towers in Sydney were tested in Australianlaboratories and were the only two structures or which modeltesting was perormed outside o ISMES.

Philosophy o StructuresNervis most amous book was published in 1945.5 Its

titleScienza o Arte del costruire? (Is Building an Artor Science?)is also a undamental question. With hisproound knowledge o construction techniques, Nervisanswer to the question emphasizes the priority o theintuitive moment on the conception o structural architec-ture, yet it does so without underestimating the impor-tance o the mechanics o structural systems: The concep-tion o a structural system is a creative action only partlybased on scientic data; static sensitivity entering in thisprocess, although deriving rom equilibrium and strengthconsiderations, remains, in the same way as aestheticsensitivity, an essentially personal aptitude. His vision wasshared by Torroja, the other great master o structuralarchitecture o the 20th century, who declared inRazn ySer de los Tipos Estructurales (Philosophy of Structures)6 that,the birth o a structural complex, the result o a creative

process, the usion o art and science, talent and research,imagination and sensibility, goes beyond the realm o purelogic to cross the arcane rontiers o inspiration. In thisvision, Nervi essentially expresses his ear that orcedrequirements to use analytical models or reliabilityassessments o structures might limit a designers inven-tiveness. He believed that structural imagination requentlytranscends the possibilities o analytically rigorous veri-cation (which was then conned by the lack o moderncomputerized structural analysis tools). This struggle or adesign reedom was also the principal justication or hiskeen interest or experimental research on mechanical-

scale models.These concepts were at the base o Nervis extensive and

interesting writings ocusing especially on the language oarchitecture and the relationship between structure andorm, and on the ethical value o building in a correctmanner. These were also the typical themes o the univer-sity teaching he regularly carried out at Romes School oArchitecture and o some o his important speeches andlectures at prestigious universities rom Buenos Aires (1951)to Harvard (Norton Lectures, 1961-62).7 They also charac-terized his exchanges o ideas and proessional collabora-tion with those who shared his culture and mindset, such

as Mario Salvadori, Structural Engineer and Proessor atColumbia University.

The true art o Nervi is the ability to close the gapbetween art and technology to create spaces that border

on poetry without renouncing, in the conversion o theinspiration into a design and o the design into a construc-tion, the modus operandi o engineers, but rather empha-sizing engineering procedures with original and inno-vative contributions.

References

1. Levi, F., and Chiorino, M.A., Concrete in ItalyA Review o a

Century o Concrete Progress in Italy, Part 1: Technique and Archi-

tecture, Concrete International, V. 26, No. 9, Sept. 2004, pp. 55-61.

2. Chiorino, M.A., Experimentation in the Work o Pier Luigi

Nervi,Pier Luigi Nervi: Architecture as Challenge, C. Olmo and

C. Chiorino, eds., Silvana Editoriale, Cinisello Balsamo, Italy, 2010,

pp. 61-83.

3. Pemberton, J.M., Ferro CementAn Insight and Review

So What is New?Ferrocement 6: Lambot Symposium, Proceedings

o the Sixth International Symposium on Ferrocement, A.E.

Naaman, ed., University o Michigan, Ann Arbor, MI, June 1998,

pp. 75-83.

4. Nervi, P.L., Le ricerche statiche sperimentali su modelli,

Costruire Correttamente, Ulrico Hoepli, Milan, Italy, 1955, pp. 105-114.

(in Italian)

5. Nervi, P.L., Scienza o Arte del costruire? Edizioni della Bussola,

Rome, Italy, 1945, 162 pp.

6. Torroja Miret, E.,Razn y Ser de los Tipos Estructurales, Instituto

Tcnico de la Construccin y del Cemento, Madrid, Spain, 1957,403 pp. (in Spanish)

7. Nervi, P.L.,Aesthetics and Technology in Buildings, The Charles

Eliot Norton Lectures, Harvard University Press, Cambridge, MA,

1965, 210 pp.

Selected or reader interest by the editors.

Mario A. Chiorino, FacI, is Eeitus Po-

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Art and Science of Building in Concrete; The Work of Pier Luigi Nervi by Mario a. Chiorino

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