iscarsah 10-11 - · pdf filescientiﬁcreports iscarsah newsletter n. 10-11/2015 3...

Message of the PresidentGörün Arun

isasters and HeritageLooking back on 2015, many heritagestructures in the World have sufferedmany disasters.Although historic cities and landscapes,museums, monuments and archaeologicalsites are seriously affected by natural orman-made threats, globally heritage isusually not taken into account in statis-tics. Loss of such places as a result ofearthquakes, floods, fire, armed conflictsand other hazards has become a majorconcern to heritage conservation society.In 2015, twenty earthquakes with magni-tude ranging between7.0-9.0 occurred inthe world. Many heritage buildings weredevastated in 25 April and 12 May 2015earthquakes in Nepal.Similarly many culturally importantstructures and landscapes for their userswere demolished on 30 May in Japan, on16 September in Chile and on 26 Octoberin North Afghanistan and Pakistan.Due to heavy continuous rainfall andheavy flood in river and resulting land-slides places having social values for thecommunity were affected during JanuarySoutheast Africa floods and East Malaysiafloods, and during August Argentinafloods in Buenos Aires Province.Numbers of cultural heritage assets weredamaged during February floods inGreece, June flood in Accra-Ghana andApril floods in Dar-es Salaam and otherregions of Tanzania. Downpours on 31 Julyin north-eastern Vietnam caused flooding

and toxic spills from several coal mine and power plant sites around the Ha Long Bay World Heritage Site. People were banned to visitheritage sites due to flooding after monsoon rains on September in Assam and on December in the north-east India.Among the man-made disasters fires mainly due to negligence in taking proper measures, and armed conflicts made intentionally as ashow of power may be counted. On January 14, the thatched roofs of the Royal Palaces of Abomey World Heritage complex in Beninwere burned. On June 15, fire broken at the Basilique Saint Donatien in Nantes damaged properties in the Church.And on August 20, the Palazzo del Lavoro designed by Pier Luigi Nervi, was threatened by fire after years of misuse and abandon.Heritage places are threatened by planned acts of terrorist operations in Iraq, Syria and Yemen. Intentional damage to the cultural her-itage and the targeted destruction of Islamic and Christian religious sites, damage to the architectural remains in the ancient city ofPalmyra, destruction of the Baalshamin Temple, the Temple of Bel, and tower tombs in the Valley of the Tombs and collapse of part ofthe walls of Aleppo's ancient citadel with bomb explosion are horrendous.In Yemen, bombing of the World Heritage Site of the Old City of Sana’a and the old city of Sa’adah, and the Dhamar Museum; damage tothe archaeological site of the pre-Islamic walled city of Baraqish; and destruction of the 1,200 year old mosque of Imam al-Hadi, in thecity of Saada; or damage to the 10th century BC historic castle of Al-Cairo in Taiz worrying situations are evidenced.March 19 terrorist attack at Bardo National Museum in Tunisia, June 10 suicide bomber attacks at Luxor and Pyramids in Egypt and De-

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IscarsahInternational Scientific Committee on the Analysis andRestoration of Structures of Architectural Heritage

Nepal Earthquake (photo: Dinçşahin, Umut, GEA Conference 12.12. 2015).

Argentina Flooding (photo: http://www.aljazeera.com/news/2015/08/argentina-floods-150812083646292.html).

10-11newsletterAugust-

December, 2015

INDEX

Message of the President Görün ArunDisasters and Heritage

Scientific reportsStephen J. Kelley - Dan M Worth - Al O’Bright, The Old Courthouse revealsthe Role of St Louis at the Forefront ofArchitectural Cast Iron in theUnited StatesPierre Smars, Impact of the 2016-02-05earthquake on the ArchitecturalHeritage of Tainan (Taiwan)Stefano Gizzi, Restauración de la iglesiade San Bernardino en Urbino (Italia)S. Patrick Sparks, African House: Use ofSynthetic Rope for StructuralIntervention.Melrose Plantation, Louisiana, USA

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Message of the President of ISCARSAH

cember 29 gunmen attack at Naryn-Kala fortress, the world heritage site at Daghestan,Russian Federation were targeting tourists visiting the area. Any natural or man-made damage to movable and immovable heritage and looting ofthe artefacts and antiques right after a disaster may harm the community and lead to ir-reparable loss to local social life.After each event, to protect those who have been most harmed by such disasters, the de-stroyed heritage and the people living that trauma, rehabilitation and reconstructionprocess becomes necessary. The reconstruction of living heritage site is a critical procedure that must be carried outidentifying the priorities depending on how important they are to the daily lives of thepeople with great caution. It has to take into account that physical setting that people areaccustomed to use continue to serve their functions so that they are part of the daily life.In order to avoid inappropriate interventions, reconstruction procedure must be basedupon effective collaboration between professionals from many disciplines, cooperationof government authorities, stakeholders, implementing agencies, academic researchers,private or public enterprise, and the local residents. The title of the Scientific Symposium that will be held during 2016 ICOMOS Annual Advi-sory committee Meeting on 15-21 October in Istanbul, Turkey is “Reconstructions: TheRole of Rebuilding Monuments and Urban Landscapes”.Involvement of ISCARSAH members in this Symposium with their contributions will bevery valuable.May heritage prevail in 2016.

International Scientific Committee on theAnalysis and Restoration of Structures ofArchitectural Heritage

website:https://iscarsah.org

facebook:https://www.facebook.com/pages/IS-CARSAH/263710868630

linkedin:http://www.linkedin.com/groups/IS-CARSAH-Structures-Architectural-Her-itage-3930057

Newsletter n. 10-11August, 2015 - December, 2015ISSN 2306-0182

Editor: María Margarita Segarra LagunesVia Emanuele Filiberto, 19000185 Roma (ITALY)

email: [email protected]'s ancient citadel walls (photo: http://www.bbc.com/news/world-middle-east-33499609).

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Pier Luigi Nervi. Turin, Palazzo del lavoro fire in August 2015(http://torino.repubblica.it/cronaca/2015/08/20/news/brucia_palazzo_del_lavoro_fiamme_al_primo_piano_dell_edificio_abbandonato-121315743/).

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IntroductionAt the request of the National ParkService (NPS), the authors devel-oped an archival and physical ex-amination report covering SpecialIssues for the Old Courthouse atJefferson National Expansion Me-morial (JEFF) in St. Louis, Missouri,USA. One of the identified specialissues that were the focus of thisstudy included an investigation ofthe use of structural cast andwrought iron and its specific appli-cation to the Old Courthouse.The work included review of draw-ings, specifications, historic photo-graphs, and other written andillustrative documentation aboutthe history, construction, alter-ations, and repairs to the OldCourthouse. The authors builtupon the extensive historical andarchival research performed byothers. Reference documents re-viewed for this study are from thearchival repositories at the NPSJEFF Archives in St. Louis; NPSDenver Service Center TechnicalInformation Center; Missouri His-tory Museum, St. Louis; and theSt. Louis Mercantile Library, Uni-versity of Missouri -St. Louis. Vi-sual assessment was performed ofselected metallic members whichwas facilitated by inspection open-ings. Metallurgical testing of mate-rials samples was also performedon comparative structural mem-bers.The Old St. Louis Courthouse is lo-cated in the heart of downtown St.Louis near the riverfront on a cityblock bordered by Fourth, Chest-nut, Market, and Broadway (for-

The Old Courthouse reveals the Role of St Louis atthe Forefront of Architectural Cast Iron in theUnited States

merly Fifth) streets. It is on thesite of a previous courthouse thatwas constructed in 1826-1833 andthen replaced by the “Old” Court-house in a phased construction pe-riod of 1839 to 1861. The OldCourthouse served as a center forwestern migration. St. Louis was agateway to the west for settlerstravelling along the Oregon andCalifornia trails. The city was amajor outfitting point for many ofthese emigrants and a meetingpoint for many on the trails. In1847, the first of the Dred Scotttrials was held in the first levelcourtroom in the west wing,1 andthe Virginia Minor Case was held inthe Old Courthouse in 1872 inwhich she sued the state for theright of women to vote in Missouri.The Courthouse grounds wereused for political rallies and slaveauctions as well as an area wheretroops gathered during the Mexi-can-American War and the CivilWar. The building has smooth stone andbrick masonry walls and founda-tion, painted white, with entries oneach primary facade. Formalcolonnaded porticos are located atthe east and west facades. Theseporticos are defined by monumen-tal stairs leading from grade up tothe first floor level, where massivepaired entry doors provide accessto the interior. Fluted Doriccolumns support the Classical ped-iment. The shallow pitched gableroofs intersect at the center of thebuilding, where the multi-storydome rises.Full scale use of cast and wroughtiron was introduced into the con-struction of all construction by1852. This sophisticated and utili-tarian use of cast iron in particularis comparable to east coast struc-tures of the era.It is apparent that its location onthe Mississippi River and the role inriver commerce, along with thegreat fire of 1849, provided a cat-alyst for the use and developmentof cast iron in building constructionthat placed St. Louis on the fore-front of architectural cast iron pro-duction in the United States. Of thewealth of architectural cast ironbuildings that were constructed

following the fire, the majority ofwhich were demolished circa 1940,the Old Courthouse remainsamong the earliest known exam-ples of the use of this new technol-ogy in the United States.

Historical overviewIron is the workhorse of metalsdue to its great strength, and wasused extensively for building struc-ture in this country during thenineteenth and early twentiethcenturies. Because it oxidizes rap-idly when exposed to the ele-ments, iron is rarely used today forarchitectural ornament that is ex-posed to humidity. Wrought andcast irons are both ferrous metalsbut are different in composition,methods of fabrication, and physi-cal characteristics. In the United States, wrought ironwas used for minor structuralmembers such as lintels and deco-rative elements beginning in theeighteenth century, while cast ironwas a major nineteenth-centurybuilding material of the IndustrialRevolution.2

Pig iron, which contains approxi-mately 4 percent carbon alongwith other impurities, is the initialsource used in developing wroughtiron, cast iron, and steel (Figure1).3 Metallurgically, pig iron isidentical to cast iron, but it is castinto unfinished bars (pigs) for ship-ping.4 The easy handling of pig ironallowed the smelting process to befreed from the founding (casting)process.5

Iron smelting operations needed tobe located close to iron and coalsources. By the 1850s foundriesthat produced architectural castiron were located in cities to pro-vide ready access to waterwaysand railroads for shipping of rawmaterials and fabricated products.6

Definition and ManufactureWrought Iron As suggested by its name, wroughtiron can be heated to a tempera-ture at which it becomes soft andcan be wrought (shaped by ham-mering) on a forge or rolled undergreat pressure. Wrought iron con-sists of iron with slag fibers en-trained in a ferrite matrix.7 It is

Stephen J. KelleyFAIA, SE, FAPT, FUSICOMOSHeritage Conservation [email protected]

Dan M WorthAIA, FAPT Senior PrincipalBahr Vermeer& Haecker Architects(402) [email protected]

Al O’BrightTechnical RepresentativeNational Park Service(314)842-1047al_o’[email protected]


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almost pure iron with less than 1percent carbon. Slag exists inwrought iron in a purely physicalassociation rather than as an alloy,giving the wrought iron a charac-teristic laminated structure.Wrought iron has good tensilestrength and can be shaped intomany intricate forms because of itshigh elasticity.8

Wrought iron manufacture re-quired machine forges, anvils, andhammers. The melting tempera-ture of wrought iron, 1,534 de-grees Celsius (2,793 degreesFahrenheit), could not be achievedwith machine forges of the time;however, the iron could be madehot enough to be worked. Ironmanufacturers could also make themetal in wrought iron pure by con-trolling the temperatures in theirfurnaces. By the 1840s it was un-derstood that wrought iron shouldbe free of sulfur, which made theiron brittle at high temperatures(“hot short”); should not have ex-cessive phosphorus, which madethe iron brittle at room tempera-ture (“cold short”); and should notcontain excess or poorly distrib-uted slag, which would reduce itsductility.9 It was also understoodthat phosphorus hardened other-wise pure iron more than any otheralloying element. If the carboncontent of the iron was less than0.1 percent, it would remain duc-tile with the addition of phospho-rus.10

Wrought iron provides strength intension, making it appropriate for

tension members such as truss el-ements and flexural members suchas beams and girders.

Cast IronCast Iron is an iron-carbon alloywith a higher carbon content thanwrought iron, usually averaging3.0 to 3.7 percent, and varyingamounts of silicon, sulfur, man-ganese, and phosphorus. Cast ironhas enough carbon to lower itsmelting temperature so that it canbe put into a molten state and castinto decorative or structuralshapes.11 However, cast iron is toohard and brittle to be shaped byhammering, rolling, or pressing.12

Cast iron is very brittle and inelas-tic. It is strong in compression butweak in tension; therefore, it can-not effectively take bendingstresses as a beam.13

Cast iron, with carbon content of 2percent to 4 percent by volume, ishighly fluid and can be cast into in-tricate shapes. The melting tem-perature of cast iron isapproximately 1,150 degrees Cel-sius (2,102 degrees Fahrenheit).Such a temperature was easily at-tained in a small blast furnace.14

The previously described metallur-gical understanding of wroughtiron by the mid-nineteenth centuryis also applicable to cast iron.

Iron Industry Development forBuilding in the USBy the turn of the nineteenth cen-tury, blacksmiths were ubiquitousand working iron into horse shoes,

iron straps, tie rods, and nails forbuilders.15 Wrought-iron rods wereuniversally used in the mid-nine-teenth century in wood and irontrusses for buildings and bridgeswhere the structural member wasput in tension.16 By the 1840ssome foundries had developedtheir technology to fabricate largerelements that could be used inbuilding construction. The “bulb-tee,” with a flat flange on the bot-tom and a convex bulb on the top,could be used either as a railroadrail or as a beam for buildings.17

Prior to 1850 there were smallfoundries scattered throughout thecountry producing cast iron itemssuch as stoves, fireplace equip-ment, wash tubs, and cookware.Foundries at the time were locatednear the mines, as the items pro-duced were easily transportable.In building construction, by the1820s builders had adopted theBritish practice of using interiorcast iron columns. By the early1830s, cast iron columns were oc-casionally being adopted for shopfronts in American cities.18

Foundries that produced architec-tural cast iron sprang up in nearlyevery major American city of thenineteenth century, as shown bythe city directories of the period.19

By the time iron ore was beingprofitably exploited and adequatetransportation was becoming avail-able in America, Europeans werealready benefiting from the advan-tages of cast iron over wood andmasonry in building construction.20

American foundries producing ar-chitectural cast iron borrowed fromBritish and French developments inthis field, thus the advanced re-search and development in Europewere put to practical application inthe United States.21

Despite these developments andthe use of both wrought and castiron in construction, the varyingphysical qualities between thesematerials were not fully under-stood in America until well into the1870s. This is exemplified by thefact that many buildings werebeing constructed with cast ironbeams (used in flexure) andwrought iron columns (used incompression), which was not thebest use of these materials.22 Castiron was used for both columnsand beams through the first sevendecades of the nineteenth century.In the 1860s wrought iron becamecompetitive with cast iron andmore widely produced as improved

FIGURE 1. Ingots of pig iron smelted near the mine were easily handled andtransported to the foundry, where it could be cast or wrought. Source:http://equatorline.indonetwork.co.id/ 2279287/pig-iron-iron-scrap-roll-coil.htm,accessed November 2012.

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ported to the Mississippi River forshipment. In 1855 the St. Louisand Iron Mountain Railroad Com-pany’s line was constructed with itsterminus in Pilot Knob, Missouri,running directly into the heart ofSt. Louis.26 The rail line had a ter-minal at Plum Street and the river,one block south of the currentsouthern boundary of JeffersonNational Expansion Memorial.

Construction of the oldCourthouseThe first county courthouse to beconstructed on this site in 1826-1828 was designed by St. Louis ar-chitects Laveille and Morton in theFederal style. In the decade follow-ing completion of the first court-

house, the population of St. Louistripled. By 1838, the courthousewas considered inadequate to han-dle the required case load and inneed of expansion. The city held acompetition to solicit new designsfor a larger courthouse to serve in-creased demands in 1839. Ulti-mately the design of HenrySingleton of a cruciform plan witha central rotunda, which incorpo-rated the first courthouse as theeast of its four wings was selected.The building was designed in theGreek Revival style (Figure 3).Work would begin on the westwing.In 1840 the St. Louis foundry ofGaty, Coonce & Belzhoover wasgiven a contract to fabricate six

industrialized processes for rollingwere developed to meet the rail-road demand.23

Cast iron beams were capable ofcarrying light loads at shorterspans. Cast iron beam sectionswere unsymmetrical about theirhorizontal axis in profile, with thelarger areas being in the tensionzone at the bottom, revealing anunderstanding of the tension-car-rying shortcomings of this mate-rial.24 Larger areas for tensionmeant that the tensile force perarea was less.The Bessemer converter process,developed in England in 1857, wasthe first industrial process for themass-production of steel from pigiron. Steel had physical propertiesthat were superior to both wroughtand cast iron, and, when it was in-troduced to the American marketas an inexpensive alternative inthe 1880s, cast and wrought ironquickly fell from favor for struc-tural applications. By 1889 theUnited States was the largest fab-ricator of steel in the world.

Iron Industry Development inSt LouisThe era of cast iron architecture inAmerica has been defined by somearchitectural historians as lastingfrom approximately 1850 to 1880,although structural and decorativeiron elements were used in the1840s in Boston and New York,and, largely uncredited, in St.Louis.25

Wrought iron, ironsmiths, and thefoundries that fed the St. Louis ar-chitectural cast iron industry werelocated within the city and were animportant factor in the swift re-covery of the commercial districtfollowing the 1849 St Louis fire.Established fur trading familiesturned their investments to ironmining acquisitions to support thisneed.The largest source of iron ore forSt. Louis was the Precambrian corearea of the Ozark Uplift in IronCounty located about 80 milessouth of St. Louis, which beganproducing iron ore at the beginningof the nineteenth century (Figure2). There were other iron minesand forges to the southwest of St.Louis in the Rolla area. In 1843 theAmerican Iron Mountain Companynear Pilot Knob was incorporatedby the Missouri legislature. Orewas transported eastward tosmelting furnaces in the Farming-ton area. Pig iron was then trans-

FIGURE 2. Iron ore mine in Pilot Knob, Missouri, circa 1919. Source: Iron County,Missouri Genealogical Society, photo courtesy of Marcine Lohman.http://www.rootsweb.ancestry.com/~moicgs/ photos1.html, accessed November2012.

FIGURE 3. Artist rendering representing Henry Singleton’s cruciform plan court-house with the original concept for the dome and porticos at all four elevations.Source: Missouri History Museum collection.

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“Greek Doric” cast iron columns forthe southern entry to the Court-house.27 Fabrication of thesecolumns proceeded in July 1842.In 1843 this contract was cancelledfollowing an examination of thecolumns by an appointed commis-sion of Meriwether Lewis Clark andJohn Martin.28 It is not knownwhether the contract was annulleddue to the poor quality of the castiron or a change in the design atthe Old Courthouse. However, doc-umentation related to the contractreveals that architectural cast ironwas available in St. Louis as earlyas 1840.

The West WingConstruction began on the westwing and north and southtransepts of the Old Courthouse in1842. The second floor is believedto have been composed of woodframing though there is no conclu-sive archival data. In January of1843 the contractor, John Foster,was asked to make structuralchanges to the second level of thewest wing, which was noticeablysettling, although the wing was notyet completed. Foster was directedto procure iron of the best qualityfor this work by connecting thesecond floor to the timber framingof the roof above according to ascheme of his own design.29 Thework was completed with a centraldome and inclusion of the firstcourthouse by 1845 (Figure 4).

The St Louis Fire of 1849On May 7, 1849, a fire beganaboard the steamboat White Cloudwhile it was moored on the St.Louis levee at Cherry Street. Theboat, engulfed in flame, broke freefrom its moorings, drifted down-stream, and set twenty-two othersteamboats ablaze. Whipped byunusual northwesterly winds, thefire jumped over the levee from theboats to the warehouses and storesalong Wharf Street, burning its wayinland to destroy 418 buildings sit-uated in fifteen blocks of the river-front district (Figure 5). Throughthe efforts of the St. Louis volun-teer fire departments, the blazewas stopped before it consumedthe Old Cathedral or the Old Court-house.30 The process of rebuildingthe commercial heart of the citybegan immediately. Financed by in-surance claim settlements, nearlyall of the burned area was rebuiltwithin a calendar year. New con-struction reflected the latest build-

FIGURE 4. Southeast view of the courthouse in 1851, just before demolition of theprevious courthouse and construction of the east wing. The first courthouse com-pleted in 1828 is visible at right, with the south transept and west wing visible atleft. Source: Half plate daguerreotype by Thomas Easterly taken in 1851. MissouriHistory Museum collection, reference n17030.

FIGURE 5. Artist’s illustration from the east representing the Great Fire of 1849 inthe commercial district of St. Louis. The dome of the Old Courthouse can be seenin the depiction. The Old Courthouse was not damaged during the fire. Source:Missouri History Museum collection.

ing trends and materials in Amer-ica: cast iron, plate glass, shuttersof iron, and roofs of sheet metal.Thus St. Louis after the fire be-came a crucible for developmentand use of architectural cast iron.Not only did architectural cast ironcreate aesthetically pleasing store-fronts much to the taste of con-temporary business owners, but itwas also “fireproof” as mandatedby the city to prevent a recurrenceof the 1849 conflagration.31

The East WingThe first Courthouse was demol-ished in 1851-1852 and in Augustof 1852, John T. Dowdall wasawarded a contract to supply castiron girders for a new east wingbased on designs by architectRobert S. Mitchell. By 1853 theirfabrication had been completedand by June, Dowdall was awardeda contract for the cast iron girdersfor a new south wing extension aswell.32

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Dowdall had established the Wash-ington Foundry, J. T. Dowdall Pro-prietors, at the corner of Secondand Morgan Streets by 1852. Hewas the only permanent partner ofthe Washington Foundry, which ad-vertised the manufacture of“steam engines and boilers; sawand grist mill machinery; tobacco,lard and oil press screws; lard ket-tles, building castings; wool card-ing machines, etc.”33 TheWashington Foundry was closedand demolished in 1870.34

The profile of a cast iron beamused on the first floor is shown inFigure 6. Levelness measurementsand drill probes taken below thetop flange indicate that the topflange is sloped (Figure 7).On December 10, 1853, McMurray& Pauley was awarded a contractfor the wrought iron work at theeast wing roof, and by the follow-ing March the roof was under con-struction.35 The east wing wascompleted in 1856.

The South WingIn 1853 construction of the southwing extension had begun. In May1854, the firm of Dowdall Carr &Co. furnished the iron work for thesouth wing in accordance withtheir 1853 contract.36 Little isknown presently about the supplierof the wrought iron roof. The southwing was completed in 1856.The profile of a cast iron beamused on the second floor is shownin Figure 8. The beam is similar insection to iron railroad tracks ofthe time. Levelness measurementstaken below the top flange indi-cated that the top flange is notlevel however we could not deter-mine whether the top flange is ta-pered or curved.

Rehabilitation of the West WingIn May 1856 the roof of the westwing was found to be unsafe andwas ordered to be rehabilitatedand strengthened. The weight ofthe sagging floor had initially beensustained by heavy iron rods at-tached to the wooden roof trusses.Partition walls had been addedfrom below to the second floor tothe top of the foundation walls in1855. The new roof was to be ofwrought iron with cast iron fit-tings.37 The west wing roof framingwas to match that of the eastwing. The work was performed byMcMurray Winklemaier.38 The sec-ond floor was most likely replacedat this time with the cast iron

FIGURE 6. Sketch of the profile of acast iron beam at the east wing - firstfloor. This beam was likely fabricatedand installed by J. T. Dowdall circa1852.

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FIGURE 7. Sketch in elevation of a castiron beam at the east wing – first floor.

FIGURE 10. Sketch in elevation of thecast iron beam at the west wing - sec-ond floor.

FIGURE 8. Sketch of the profile of acast iron beam at the south wing - sec-ond floor. This beam was likely fabri-cated and installed by J. T. Dowdallcirca 1853. The large triangular massof iron at the bottom increasesstrength of this shape in tension ascast iron has low tensile strength.

FIGURE 9. Sketch of the profile of acast iron beam at the west wing - sec-ond floor. This beam was likely in-stalled circa 1855 and the fabricator isnot attributed. In addition, the custom-made brick that forms a spring point isdepicted.

beams but the manufacturer hasnot yet been identified.The profile of a cast iron beam onthe second floor is shown in Figure9. The beam is similar in section toiron railroad tracks of the time. Aspeculative sketch of the beam inelevation is shown in Figure 10.The North WingThe construction of the north wingextension was begun in 1856. J.G. McPheeters, owner of the Excel-sior Works at Clark Avenue andEighth Avenue (established in

1840 and expanded in 1849), wasawarded the contract for the northwing roof framing, which was to becomposed of wrought iron withcast iron fittings at the rafters. Thecontract also included the ironworkfor the stairs from the first to thirdfloors in both the north and southwings, the columns within thenorth wing, and all cast andwrought iron work for the dome. InFebruary 1858 McPheeters wasalso awarded a contract to cast, in-stall, and furnish all the cast ironfloor beams and girders requiredfor the north wing.39 The profile ofa cast iron beam from the firstfloor is shown in Figure 11. A spec-ulative sketch of the beam in ele-vation is shown in Figure 12. Thissketch compares with cast ironbeams that were depicted by ar-chitectural cast iron manufacturer

FIGURE 11. Sketch of the profile ofcast iron beam at the north wing - firstfloor. This beam was likely fabricatedand installed by J. G. McPheeters circa1858. The large triangular mass of ironat the bottom increases strength ofthis shape in tension, as cast iron haslow tensile strength. It also forms abearing surface for the spring point ofthe brick floor vault.

FIGURE 12. Sketch in elevation of castiron beam at the north wing - firstfloor.

Iscarsah newsletter n. 10-11/2015 Scientific reports

Daniel D. Badger in his 1865 pub-lication, Illustrations of Iron Archi-tecture made by the ArchitecturalIron Works of the City of New York(Figure 13).

The DomeThe first dome of the Old Court-house had been demolished in1857 leaving the rotunda open tothe elements. The new dome de-signed by County Architect T. D.P. Lanham included twenty-fourdecorative cast iron columns at thedrum.40 The hoisting of the twenty-four iron columns that would sup-port the stone cornice of the domecommenced in June and the instal-

lation was completed by Septem-ber 1858.41 Controversy over thestability of the dome as designedcaused the work to be stopped sothat the structural capacity of thedome could be evaluated (Figure14) and the previously mentionedMcPheeter contract was rescinded.After analysis it was determinedthat the dome would be composedof wrought iron rather than castiron and would be constructed inaccordance with the design ofCounty Architect William Rumbold.McPheeter & Pauley was awardedthe contract for the work, which

was begun in 1860 (Figure 15).42

The wrought iron ribs of the outerdome were fabricated by thePhoenix Iron Company ofPhoenixville, Pennsylvania, nearPhiladelphia as evidenced by themarkings on the ribs. This seemsto be the lone example of ironworkat the Old Courthouse that wasfabricated outside of St. Louis.43

The dome structure was completedin 1861.The dome ribs are radiallylaid members constructed of struc-tural T-shapes for the inner andouter flanges (3 inches in depthwith a 5-1/2 inch flange width) and

FIGURE 13. Plate LIII from the publica-tion by Daniel Badger in 1865. Thesebeams are similar to beam shapesused in the north wing of the OldCourthouse.

FIGURE 14. Controversy surroundedthe Old Courthouse dome design byWilliam Rumbold. Construction was de-layed until confidence could be estab-lished regarding the strength of thedome structure. A test loading of amodel of the dome during this periodof uncertainty illustrates a prolongedloading that is many times beyond thatwhich would have been required inconstruction. Source: Missouri HistoryMuseum collection.

FIGURE 15. Photograph of the Rum-bold-designed dome with twenty-fourradially oriented wrought iron ribs setin place. The cast iron Corinthiancolumns below had been previously setfor the Lanham-designed dome, whichhad been abandoned. Source: MissouriHistory Museum collection. Photographby unknown photographer.

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FIGURE 16. The dome ribs are latticework, radially laid members con-structed of structural T-shapes for theinner and outer flanges, with platesriveted to the stems of the T-sectionsand at the intersection of the plates.The 2x6 wood purlins are fastened tothe outer T-section with metal joisthangers to provide a nailable surfacefor the wood plank sheathing belowthe sheet metal copper roofing.

FIGURE 17. View of the dome ribs andradial straps. The straps are locatedonly in the lower portion of the dome,where the outward thrust would begreatest.

FIGURE 18. Cast iron x-bracing in-stalled between the ribs near the topof the dome.

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It is apparent that its location onthe Mississippi River and the role inriver commerce, along with thegreat fire of 1849, provided a cat-alyst for the use and developmentof cast iron in building constructionthat placed St. Louis on the fore-front of architectural cast iron pro-duction in the United States.Of the wealth of architectural castiron buildings that were con-structed following the fire, the ma-jority of which were demolishedcirca 1940 as part of the JeffersonNational Expansion memorial thatwas realized in 1965, the OldCourthouse remains as one of theearliest known examples of the useof this new technology in theUnited States.

................1 “The Revised Dred Scott Case Collec-tion,” Washington University in St. Louis,www.digital.wustl.edu, accessed April 17,2012, and October 28, 2012.2 Margot Gayle, David W. Look, and JohnG. Waite, Metals in America's HistoricBuildings: Uses and Preservation Treat-ments (Washington: U.S. Department ofthe Interior, Heritage Conservation andRecreation Service, Technical Preserva-tion Services Division, 1980), 42.3 L. William Zahner, Architectural Metals:A Guide to Selection, Specification, andPerformance (New York: Wiley, 1995),186.4 Antoinette J. Lee, “Cast Iron in AmericanArchitecture: A Synoptic View,” The Tech-nology of Historic American Buildings:Studies of the Materials, Craft Processes,and Mechanization of Building Construc-tion, H. Ward Jandl, ed. (Washington,D.C.: Foundation for Preservation Tech-nology, 1983), 99.5 Smelting is producing metal from its ore.Smelting uses heat and a chemical re-ducing agent to decompose the ore andexpel gasses and slag to leave a relativelypure metal behind. The reducing agent,typically charcoal or coal, when burnedcreates carbon monoxide, thus removingoxygen from the ore and leaving behindthe elemental iron. 6 Lee, 99.7 Slag, also known as cinder, is fused andvitrified matter separated during the re-duction of a metal from its ore. In ironproduction the slag, rich in silicon, risesto the surface when the iron is moltenand can be easily removed. 8 Zahner, 187.9 Robert B. Gordon, American Iron:1607–1900 (Baltimore: Johns HopkinsUniversity, 1996), 7.10 Ibid., 13.11 Daniel D. Badger, Badger's IllustratedCatalogue of Cast-iron Architecture (NewYork: Dover Publications, 1981), reprint,5.12 Gayle, Look, and Waite, 130.13 Zahner, 185.

5 inch by 1/4 inch plates installedas a lattice and riveted to thestems of the T-sections and toeach other where they intersect(Figure 16). The ribs are set onmetalwork above the rotundacolumns at the base of the domeand are affixed to a compressionring at the top of the dome justbelow the lantern. Circumferentialstraps approximately 2-1/2 incheswide by 1/4 inch thick are fastenedto the inner flange of the ribs andare spaced at approximately 3 feet8 inches on the ribs on the lowerpart of the dome (Figure 17). Castiron x-bracing was installed be-tween ribs near the top of thedome (Figure 18). All of the major construction cam-paigns were completed with thetopping of the dome (Figure 19).Presently all of the cast andwrought iron of the Old Courthousedescribed remains in place exceptfor the roofs of the wings. Thewrought iron trusses with cast ironfittings, wrought iron lattice beamsand purlins in the wings were re-moved circa 1940 and replacedwith a system of steel beams.

Laboratory Studies of theCast IronThe difference between wroughtand cast iron components can, inmost cases, be readily seen by theexperienced eye. Cast iron can befabricated in numerous utilitarianand decorative shapes that cannotbe obtained by working iron. Castiron beams also typically have castlines. Iron production at the time was anart as well as an evolving science,and it is noteworthy that the chem-ical composition of the cast ironsamples fabricated in different fac-tories over a period of time arecomparable to one another. It is significant that the cast ironsamples from a two decade periodand three to four different fabrica-tors are chemically very similar toone another. This suggests that ac-ceptable cast iron composition waswell understood in the St. Louiscommunity of cast iron fabricators.Iron content from the samplesranges from 93 percent to 94.5percent and is within the typicalrange expected for cast iron of thisera. Carbon content ranges from3.34 percent to 4.90 percent,which is within the typical range.44

Sulfur content, except for onesample which had 0.325 percent,ranges from 0.06 percent to 0.13

percent, which is at the high end ofthe typical range.45 Manganesecontent ranges from 0.12 percentto 0.73 percent, which is wellbelow the typical range.46 Phos-phorus content ranges from0.200 percent to 0.543 percent,which is above the typical range.47

Silicon content, an indication ofslag content, ranges from 1.10percent to 2.44 percent and iswithin the typical range.48

ConclusionOur research reveals that all of thecast and wrought iron that wasused in the extant Old Courthouse,excluding portions of the dome,was smelted close to St. Louis andwas fabricated within the limits ofSt. Louis’ mid-nineteenth centurycommercial area and only blocksfrom the Old Courthouse. Further-more, this research reveals thatSt. Louis was on the frontier of ar-chitectural cast iron developmentin the United States along withNew York. Full scale use of cast and wroughtiron was introduced into the con-struction of all wings by 1852 andthereafter. This sophisticated andutilitarian use of cast iron in partic-ular is comparable to East Coaststructures of the era such as theCooper Union building (1853–1859) (Figure 20) and the Harperand Brothers Building (1854, de-molished) (Figure 21), both de-signed in part by James Bogardusand located in New York City.

FIGURE 19. The southeast courtyard,1866. This 1866 view of the southeastcourtyard illustrates the southeastcourtyard, including the fountain sur-rounded by a wrought iron fence,perimeter fence and wall, walk leadingto the south wing areaway, and streettrees set within the sidewalks edgingthe city streets. Source: JNEM Archive.“The view from the southeast in 1866,shortly after completion of the dome.

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14 Gordon, 10.15 Margot Gayle and Carol Gayle, Cast-iron Architecture in America: The Signifi-cance of James Bogardus (New York, NewYork: W.W Norton Company, Inc., 1998),34.16 Gayle, Look, and Waite, 48.17 Gayle and Gayle, 141.18 Gayle and Gayle, 35.19 Lee, 109.20 Ibid., 100, 101.21 Cast iron for non-architectural purposeshad been well developed in England,France, the Germanic states, and Swe-den. Gayle and Gayle, 34. 22 Lee, 99.23 Lee, 99.24 J. Stanley Rabun, Structural Analysis ofHistoric Buildings: Restoration, Preserva-tion, and Adaptive Reuse Applications forArchitects and Engineers (New York, NewYork: Wiley, 2000), 317.25 Bryan, “Iron in St. Louis Architecturebetween 1800 and 1900”; Lee, 97–116;Betsy Hunter Bradley, The Works: The In-dustrial Architecture of the United States,(New York and Oxford: Oxford UniversityPress, 1999), 3–53; Elaine B. Ulman,“The Eyes of the House,” Early AmericanLife August 1979, 42–45; Diane Welebit,“A Century of Pressed Glass,” Americana,July/August 1983, 55–57; Gayle andGayle; Charles E. Peterson, “Inventingthe I-Beam, Part I : Richard Turner,Cooper Hewitt and Others,” Bulletin of theAssociation for Preservation Technology12, no. 4, 1980, 3–28; “Inventing the I-Beam, Part II: William Borrow at Trentonand John Griffen of Phoenixville,” Bulletinof the Association for Preservation Tech-nology 25, no. 3/4, 1993, 17–25.26 “Missouri Mines.”http://www.miningartifacts.org/ Missouri-Mines.html, accessed November 2012. 27 1841 St. Louis City Directory, GatyCoonce & Glasby, foundry and steam en-gine manufactury, located at 210 NorthFirst Street, 1840–1841.28 Clark was the son of William Clark andnamed after his father’s fellow explorer,Meriwether Lewis. He was an architect,engineer, politician, and a general in theConfederate army during the Civil War.29 JEFF Archives, Records of St. LouisCounty Courts, Vol. III, page 285.30 Laura Wilson, “The Great Fire of St.Louis in 1849,” research report, JeffersonNational Expansion Memorial, September1938, 1–35.31 John Albury Bryan, “Iron in St. LouisArchitecture, 1800-1900,” National ParkService research report, Jefferson Na-tional Expansion Memorial, August 1961,23–28; Wilson, 23–34; Betsy HunterBradley, The Works: The Industrial Archi-tecture of the United States (New Yorkand Oxford: Oxford University Press,1999), 3–53.32 JEFF Archives.33 Cara Jensen, The History of 712 North2nd Street, City Block 26, Laclede’s Land-ing, St. Louis, Missouri (St. Louis: Sher-lock Homes, n.d.) 3,http://www.sherlock-homes.us/712.pdf,accessed November 2012, citing 1855Missouri Democrat Advertisement.

34 Ibid., citing Sanborn Fire Insurancemaps from 1872 and 1874; JEFFArchives, Mechanics' Institute of St.Louis Records, 1816–1894, RU 113.35 John D. McMurray, Iron Railing Manu-facturer, was established by 1841 at 6North 2nd Street. By 1860 the McMur-ray, Winklemaier Co. had relocated toChestnut Street between Ninth andTenth Streets. JEFF Archives. 36 JEFF Archives.37 Daily St. Louis Intelligencer, July 3,1856.38 Ibid., July 8, 1856.39 JEFF Archives. Contract between J. G.McPheeters and Thos. D. P. Lanham.40 St. Louis Missouri Republican, June17, 1858.41 Ibid., JEFF Archives, contract for fourflights of stairs in the courthouse, Sep-tember 25, 1857.42 St. Louis Democrat, June 2, 1860.43 Fabrication markings of the PhoenixIron Company were observed on the

wrought iron ribs of the outer dome dur-ing the investigation performed for thisstudy. 44 Carbon content lowers the meltingpoint of the alloy, making the moltenmaterial conducive to casting.45 High sulfur contents will make alloybrittle at high temperatures.46 Manganese was typically added tocast iron to counter the effects of sulfur,and contributes to the strength andhardness of the iron. Like carbon, man-ganese also lowers the melting point ofthe alloy and increases its fluidity in themolten state.47 Posphorus was important as an alloy-ing agent and for hardening of the iron,Excessive phosphorus content, around0.900 percent, makes iron brittle atroom temperature.48 Slag inclusions are a result of themanufacturing process in irons made byrolling or forging rather than an inten-tionally added ingredient.

FIGURE 20. View of the Cooper Union building in New York City, which used castiron construction developed by James Bogardus, as illustrated in the March 30,1861, edition of Harper's Weekly.

FIGURE 21. Harper & Brothers Building, New York, NY, circa 1870. The buildingwas demolished in 1925. Source: Albumen Print, Museum of the City of New York.

Impact of the 2016-02-05 earthquake on the Architectural Heritage of Tainan (Taiwan)

Pierre Smars - National Yunlin University of Science & Technology (Taiwan), April 2016

Figure 1: Taiwan. Star: earthquake epicentre. Left: topography (Data: NOAA ETOPO1Global Relief Model; processed with GMT); Right: major faults and tectonic elements(Data: Central Geological Survey, MOEA [1]).

IntroductionFebruary 5 2016, a ML 6.6 magni-tude [2] (MW 6.4 [3]), earthquakehit Taiwan (figure 1) [4]. The epi-centre (22.938°N 120.601°E) is es-timated [3] to be located at 46 kmNE of Kaohsiung, the secondbiggest city in Taiwan (2.8 millioninhabitants) and at 40 km ESEfrom Tainan, the sixth biggest cityin Taiwan (1.9 million inhabi-tants).It left 116 dead (114 of them in thecollapse of a 16th story building inTainan) and 550 injured [5].This short account specificallydeals with the impact of theearthquake on the historicalbuildings of Tainan, the oldest cityin the country, and the richest interms of the number of listedMonuments (131) and HistoricalArchitecture (48) [6].In Tainan, the Modified MercalliIntensity of the earthquake wasestimated to 7 (very strong) [3].

Geographical and GeologicalContextTaiwan is formed from the colli-sion of the Eurasian Plate withthe Philippine Sea Plate [7].Earthquake are frequent.September 20 1999, the Jiji earth-quake (7.6 MW) caused 2400deaths. Regularly, weaker earth-quakes hit the country: in 2006 inHenchun (7.0 MW), in 2009 inHualien (6.8 MW), in 2010 inKaohsiung (6.7 ML), in 2013 inNantou (6.2 MW), etc. In 1964, the 6.3 M Baihe earth-quake caused extensive damagein Tainan (see [8] for data and his-torical photos; [9]). Its epicentre

Figure 2: Accelerogram recorded at the TAI station (Data: Taiwan Rapid Earthquake In-formation Release System [15]; processed with GNU Octave).

was at 45 km from the city centre,about 29 km North of this year'searthquake.

The city of Tainan is located on theWest coast of the island (wheremost of the population lives), in the

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Chianan plain (about 35 km wideand 60 km long) [1]. The plain isformed of a strata about 60 m thickof Holocene alluvium on top of 60to 300 m thick strata of Miocene toPleistocene sediments; consistingof poorly sorted alternating beds ofsand, silt and clay [10]. In theTainan area, the average shear-wave velocity of the upper 30 me-ters of soil profile (Vs30) isestimated to 230-250 m/s [11], thePeak-Ground Acceleration is esti-mated to 0.55g (for a 475 returnperiod) [12].UN OCHA RegionalOffice of Asia Pacific estimates to20 the probability that an inten-sity 7 or higher hits Tainan in thefollowing 50 years [13].

Earthquake EventAccording to the United States Ge-

ological Survey [3], the earth-quake: “occurred as the result ofoblique thrust faulting at shallow-mid crustal depths (20 km). Focalmechanisms indicate rupture oc-curred on a fault oriented eithernorthwest-southeast, and dippingshallowly to the northeast, or ona north-south striking structuredipping steeply to the west.”The main earthquake was fol-lowed by seven aftershocks ofmaximum 4.9 [4]. The highest PGA(344 gal) was recorded in Caoling(Yunlin county), in an area of lowpopulation density. The TAI sta-tion of the Central Weather Bu-reau recorded the acceleration inthe city centre (figure 2). The sta-tion is located at 41.3 km of theepicentre, the PGA was 23.835 %gand the PGV 29.400 cm/s [2, 4, 14].

Figure 3: Listed buildings with structuralconcerns after 2016-02-05 earthquake inTainan Municipality (Earthquake data:Tainan Municipal Administration of Cul-tural Heritage; Map data: 2016 ©Google).

Figure 4: Tie-xian-Qiao Tungi Temple (Tiexian Village, 1692, Municipality level listing): damaged acroterion (Photo: Tainan MunicipalAdministration of Cultural Heritage).

Figure 5: Wind God Temple. Left: Drum Tower (Photo: http://www.fingermedia.tw/). Right: Collapsed Bell Tower. The furnace is alsodamaged. (Photo: Tainan Municipal Administration of Cultural Heritage).


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Tainan Cultural HeritageAs stated above, Tainan is therichest city of Taiwan in terms ofarchitectural heritage. It keepsbuilt evidences of the main his-torical periods of the country,starting from 1623 when the DutchEast India Company (VOC) arrivedin Taiwan looking for a base fortheir trade activities with China

and Japan (Fort Zeelandia in An-ping District and Fort Provintia inthe West Central District, both un-damaged). It is also there that theMing commander Koxinga landedin 1661 to fight (and eventuallydefeat) the Dutch. From the Mingand then Qing presence to thepresent day, numerous templeswere built. Many buildings (ad-

ministrative building, train sta-tion, factories, etc) also witnessthe Japanese colonial period(1895-1945). Tainan remained themost important city of the islandfrom 1623 to 1887 (when Taichungand soon after Taipei replaced it).Most of the historical buildingsdamaged in the earthquake arebrick and stone masonry con-structions with wooden roofstructures.

Damages on the Cultural HeritageThe Tainan Municipal Administra-tion of Cultural Heritage, respon-sible of the listed monuments ofthe municipality (i.e., the countyand the city) [6], coordinated theactions following the earthquake.To assess the situation, the ad-ministration was helped by theexperts (usually University pro-fessors), which are their perma-nent advisers for specific areas ofthe municipality. With the sitemanagers of their area, the ex-perts surveyed the damages andrecommended actions. 43 histori-cal buildings and monumentswere damaged (list below; figure3). Buildings were classified intwo categories, whether theyraised structural concerns (14buildings) or not (29 buildings,figure 4). As far as I am aware, theeffect of the earthquake on non-listed historical buildings was notyet assessed.• Old Tainan Watercourse (Shan-shang village, 1912, National levellisting)• Sing-ji Temple (North District,1647~1683, National level listing)• Old Julius Mannich MerchantHouse (Anping District,1875~1895, Municipality level list-ing)• Huang's Residence (Houbi Vil-lage, 1923, Municipality level list-ing)

Figure 6: Official God of War Temple (Photos: P. Smars, 2016).

Figure 7: Official God of War Temple. Far, on the right side: Fort Provintia (ChihkanTower): undamaged by the earthquake (Photo: P. Smars, 2016).

Figure 8: Courtyard of the Official God of War Temple (Photos: P. Smars, 2016).


Figure 9: Temple of Confucius. Left: Stele. Right: Hall of Great Achievement (Photos: P. Smars, 2016).

Figure 10: Sing-Ji Temple (Photos: P. Smars, 2016).

pality Level listing)• Shanhua Cing An Temple(Dongkuan Village, 1709, Munici-pality Level listing)• Lutaoyang Chiang Family Shrine(Lu-Tian Village, 1906, HistoricalArchitecture level listing)• Fu Chenghuang Temple (WestCentral District, 1669, NationalLevel listing)• Old Barrack of the Second Bat-talion of Japanese Infantry in Tai-wan (East District, 1912, Nationallevel listing)Below, a few photographs illus-trate the type of damages ob-served.

Only one construction collapsed: astone tower belonging to the com-plex of the Wind God Temple, atemple founded in the 18 c. (and re-built in 1927 after the original tem-ple was demolished for urbanisticreasons by order of the Japaneseadministration). Three stone con-structions stood in front of the tem-ple: a gate of three bays and twotowers (a bell and a drum tower).The higher and slender gate did notsuffer damages but the top heavytowers did. The bell tower col-lapsed (figure 5-right) and the drumtower, heavily damaged (figure 5-left), was dismantled a few dayslater. Both of them were not expe-riencing their first misfortune. Thebell tower already collapsed in1930, following the M 6.5 xinyingearthquake (Tainan municipality),was rebuilt in 1967 and displaced in1995. And the drum tower collapsedin 1946, following the M 6.1 xinhuaearthquake (Tainan municipality)and was only rebuilt in 1995.Possibly the most common damagepattern observed in historicalbuildings is cracks appearing be-tween structural elements imper-fectly connected, especially stoneelements (columns, slabs) and


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• Tainan Confucius Temple (WestCentral District, 1665, NationalLevel listing)• Official God of War Temple(West Central District, 1647~1683,National level listing)• Grand Mazu Temple (West Cen-tral District, 1664, National levellisting)• Wind God Temple (West CentralDistrict, 1739, Municipality levellisting)• Chen Cheshing Residence (WestCentral District, 1719, Municipalitylevel listing)• Yanshui Octagonal Building(Zhongjing Village, 1847, Munici-

walls. In the Official God of WarTemple significant displacementsof columns were observed, in theentrance (figure 6) and inside thetemple complex. Provisionalstrengthening structures were in-stalled there, in the courtyard (fig-ure 8) and on the outside wall ofthe temple (figure 7). Cracks in be-tween structural elements are alsoobserved in the Singi Temple (fig-ure 10) and in the Confucius Tem-ple (figures 9-left).

AcknowledgementI thank director Lin Chia-Ping,Architect Marvun Fu and Ms Caoof the Tainan Municipal Admin-istration of Cultural Heritageand Chou Ying-Hung, masterstudent at the National YunlinUniversity of Science & Technol-ogy for their help in the prepa-ration of this short paper.

......................References[1] MOEA Central Geological Survey.Taiwan geology cloud. http://www.ge-ologycloud.tw/. Accessed: 2016-04-20.[2] Seismological Center, CentralWeather Bureau.http://scweb.cwb.gov.tw/. Accessed:

[7] S.E. Lallemand and H.H. Tsien. An in-troduction to active collision in taiwan.Tectonophysics, 274:1–4, 1997.[8] Seismological Center, CentralWeather Bureau. http://scweb.cwb.gov.tw/DisasterList.aspx . Accessed: 2016-04-20.[9] Jeen-Hwa Wang and Hung-Chi Kuo. “Acatalogue of M s ≥ 7 Taiwan Earthquakes(1900-1994)”. Journal of the GeologicalSociety of China, 38(2):95–106, 1995.[10] Brian Keith Woodall. Natural arseniccontamination in alluvial aquifers of Chi-anan Plain, Taiwan. Master’s thesis,Auburn University, 2013.[11] Chyi-Tyi Lee and Bi-Ru Tsai. MappingVs30 in taiwan. Terr. Atmos. Ocean. Sc.,19(6):671–682, 2008.[12] Cheng, Chiou, Lee, and Tsai. “Studyon the probabilistic seismic hazard mapsof Taiwan after Chi-Chi earthquake”.


Figure 11: Temple of Confucius (Photos: P.Smars, 2016).

Figure 11: Grand Mazu Temple (Photos: P. Smars, 2016).

2016-04-20.[3] The USGS Earthquake Hazards Pro-gram. http://earthquake.usgs.gov/. Ac-cessed: 2016-04-13.[4] NARLabs. February 6, 2016 (localtime) ML -6.4 Meinong Earthquake Kaoh-siung City, Taiwan. Powerpoint, Ver5.0.[5] Central Disaster Emergency Opera-tions Center. 16th Handling Report of0206 Earthquake Disaster. Technical re-port, National Fire Agency, 2016/02/13.[6] Pei-fu Ho et al. Cultural Treasure: Wit-nessing the cultural Heritage of Tainan.Tainan Municipal Administration of Cul-tural Heritage, 2013.

Journal of GeoEngineering, 2(1):19–28,2007.[13] PreventionWeb. http://www.preven-tionweb.net/. Accessed: 2016-04-20.[14] Kuo, Lin, Huang, Chang, and Wen.The strong ground motion and site effectsof the near-source region of the MeiNongearthquake. http://tec.earth.sinica.edu.tw/new_web/news_con.php?id=163, 2016.Powerpoint.[15] Taiwan Rapid Earthquake Informa-tion Release System, Seismological Cen-ter, Central Weather Bureau.http://gdms.cwb.gov.tw/rapid/. Accessed:2016-04-13.

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Restauración de la iglesia de San Bernardinoen Urbino (Italia)Stefano GizziMinistero per i Beni e le Attività Culturali e il Turismo, Italia

1. IntroducciónLa iglesia de San Bernardino deUrbino, uno de los ejemplos másperfectos y célebres del Re-nacimiento italiano, fue realizadacomo Mausoleo de los Duques deMontefeltro de Urbino1, por vo-luntad del Duque Federico, sobrelos restos preexistentes de laiglesia de San Donato y del con-vento de los frailes franciscanosconventuales2. Situada en unaextraordinaria posición paisajís-tica, dominante la ciudad deUrbino por un lado y las colinas yla campiña por el otro, integrada

en un contexto arbóreo y agrí-cola de gran belleza, su historiaha cautivado desde siempre a loshistoriadores de la arquitectura,sobre todo por la atribución, aúnincierta, que oscila entre dospersonajes de primer orden delRenacimiento italiano: DonatoBramante3 y Francesco di GiorgioMartini4.

2. Diferentes hipótesis sobrelos autores y sobre elproyecto del edificioLa iglesia se presenta como unorganismo de planta central, con

dos brazos casi iguales, forma-dos por una nave longitudinal yun transepto que se concluyecon dos ábsides que sobresalenhacia el exterior. El ábside origi-nal semicircular, correspondientea la nave principal, fue sustituidoen época imprecisada con unaterminación rectangular. Susrestos fueron estudiados y docu-mentados en los años Treinta delsiglo XX5. Externamente, comoya había observado el historiadorde la arquitectura alemán Hein-rich Strack a finales del sigloXIX, su configuración correspon-de perfectamente a la distribu-ción interior, de acuerdo a unaconcepción típica de la arquitec-tura renacentista6.Dejando a un lado las hipótesis,hoy superadas, de Carlo Promis,que atribuía el edificio a BaccioPontelli7, y de Cornelio Budinich,de inicios del siglo XX, que iden-tificaba al autor con Pippo d’An-tonio Fiorentino8 (arquitecto dela corte de Urbino mencionadopor Giovanni Santi, padre deRaffaello Sanzio), de acuerdo ala interpretación de ArnaldoBruschi9 – el mayor especialistade Bramante –, es verosímil queel proyecto haya sido preparadoentre 1472 y 1482, pero que en1491 la nueva iglesia no estu-viese todavía acabada.En efecto, algunos documentoscertifican que ésta estaba pre-vista antes de 1482 – fecha de lamuerte de Federico, «que habíadecidido que se rehiciera la igle-sia de San Donato, donde habíadesignado ser sepultado»10 – yque fue terminada después de1491, cuando aparece citada porprimera vez en un testamento. Elárea para edificar el nuevo edifi-cio (a un lado de San Donato)era, como se ha dicho, depropiedad del Duque Federico,cuya voluntad «era la de ser in-humado en esa iglesia, junto alConde Guido»11. De hecho, a sumuerte, «fue llevado su cuerpo aSan Donato, conforme a su tes-tamento»12.Sobre el autor del proyecto de laiglesia, la tradición local tiende a

El conjunto de San Bernardino de Urbino.


Vista del conjunto de San Bernardino desde la ciudad de Urbino (Foto S. Gizzi,2012).

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atribuirlo a Donato Bramante.Entre los historiadores de laRegión de las Marcas, MicheleAngelo Dolci, en la segundamitad del siglo XVIII, daba porcierta la paternidad del arqui-tecto urbinate: «Iglesia de losPadres menores reformadosfranciscanos. Fuera de la ciudad.[…] La iglesia fue diseñada por elcélebre Bramante y por ellomerece una observación espe-cial, tanto por la construcción ysolidez de la fábrica, como por lamagnificencia y esbeltez delpresbiterio»13. Esta afirmación esretomada por el abad AndreaLazzari a principios del siglo XIX:«la iglesia fue diseñada pornuestro famoso arquitecto Bra-mante»14. En la opinión de Ar-naldo Bruschi, es posible queBramante hubiese preparado,antes de partir hacia Milán, un

proyecto posteriormente reela-borado y ejecutado porFrancesco di Giorgio Martini y, deacuerdo a una hipótesis de Co-rrado Maltese15, que la soluciónde éste último hubiera sido dis-cutida por ambos arquitectos enMilán en un posible encuentrohacia 149116.Entre los autores más acredita-dos que consideran la iglesiacomo proyecto de Bramante, noslimitaremos solamente a citar alos más conocidos. Entre losprincipales se encuentran AdolfoVenturi – sólo en una primerafase17, ya que posteriormente laatribuirá a Francesco di GiorgioMartini18 – y Gustavo Giovannonique, por afinidades estilísticas yconstructivas con otros organis-mos bramantescos, la da comoposible obra del arquitecto deFermignano, aunque, escribe,

«todo esto es, naturalmente,hipótesis, basada en compara-ciones de conjunto y de de-talles», por ejemplo de las«ventanas geminadas, con dintely una columnilla al centro, enforma de puntal», parecidas alas «de Santa María de las Gra-cias en Milán»19; sin embargo,aclara, «no creo que en el estadoactual del conocimiento se puedadecir algo más»20. Quien se in-clinaba enérgicamente a favor deBramante era el abogado e his-toriador de Urbino FrancescoCanuti21, quien a mediados delos años Cincuenta del siglo XXllevó a cabo numerosas investi-gaciones, muy influenciadas porla mentalidad de la época y porlos estudios de Roberto Papinisobre Francesco di Giorgio, pu-blicados a finales de la décadade los Cuarenta. En la opinión dePasquale Rotondi, Superinten-dente de Urbino a partir de1939, la iglesia en 1482 noexistía o estaba en construcción,pero fue terminada antes de149822. Por su parte, el historia-dor y archivista de Urbino, Mon-señor Franco Negroni, pensaba aun inicio posterior a la muerte deFederico y el mismo Bruschi, enla segunda edición de su Bra-mante23, ya consideraba inciertala atribución a Bramante. Sinembargo, de nuevo en forma du-dosa, en uno de sus últimos tex-tos, Bruschi afirmaba: «la iglesiafue construida (1482-95 ca.)después de su muerte [delDuque Federico], bajo la super-visión de Ottaviano Ubaldini ypor obra de Francesco di Giorgio.Un dibujo de este último24 puedeidentificarse con un proyectopara la iglesia. Otro dibujo, con-tenido en el mismo códice, talvez copiado de un original deMartini, muestra el interior enperspectiva. Ambos dibujos,publicados y estudiados porHoward Burns, conciernen unafase del proyecto que podríahaberse iniciado antes de lamuerte del Duque y antes de lapartida de Bramante hacia Lom-bardía»25.Pero veamos los puntos en losque las hipótesis de Canuti – quelo atribuye a Bramante – sondiscutibles: Francesco di GiorgioMartini (1439-1501) llega aUrbino en 1475, cuando se dis-tancia del pintor Neroccio enSiena, o bien en 1476, visto que


Exterior de la iglesia a principios del siglo XX.

Planta de la iglesia de San Bernardino de Urbino.

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en la primavera de 1477 firma yapara Federico de Montefeltrodocumentos notariales para laconstrucción del revellín deCostacciaro, que habría de rea-lizarse conforme a su diseño.Debe recordarse que Bramante(1444-1514) parte hacia Lom-bardía en 1476-1477, pues en1477 está ya documentado enBergamo, en donde realiza unaserie de pinturas murales en elPalacio del Podestá26. Por lotanto ha ya dejado Urbino ytiene treinta y dos o treinta ytres años. No sabemos si hayaregresado a Urbino desde Ber-gamo o desde Milán, aunque es-tudios recientes sobre sufamilia27 confirman que el arqui-tecto volvió a aparecer en suslugares de origen para ocuparsede sus propiedades inmobiliarias.Un legado efectuado en 1473 afavor del «Convento de San Do-nato» no confirma que la nuevaiglesia estuviese ya en construc-ción, sobre todo porque en elcuerpo del convento podría fácil-mente identificarse un núcleomás antiguo, que podría habersido precisamente el objeto de ladonación; por otra parte Canutiafirma que la tardía denomi-nación de San Bernardino «noprueba que la iglesia de SanBernardino no hubiese sido edifi-cada antes de 1482»28; pero ladoble negación no puede consti-tuir una prueba de que la nuevaiglesia fuese erigida antes de1482; y, en todo caso, antes de1477, año de la partida de Bra-mante.Se cuenta con la noticia de unCapítulo general que se llevó acabo en Urbino en 1475, cuandose reunieron en la ciudad losProvinciales de la orden, en elcual, un no precisado arquitecto«hunc locum magnifice satis acpro tanti Principis splendore om-nibus satis numeris absolvit»29;ello sin embargo no constituyeuna prueba fehaciente, ya quepodría al contrario haber urgidola edificación de la nueva iglesia.Algunos documentos de 1476«pro fabrica» de la nueva iglesiaparecen sufragar esta hipótesis ytodavía en 1483 un documentoanálogo cita San Donato y noSan Bernardino30.En el volumen De origine sera-phicae religionis…, FrancescoGonzaga31 – franciscano y obispo– narra de Federico «ac fratispijs votis satisfacturus inchoa-


Interior de la iglesia en los años Treinta del siglo XX (publicada en L. Serra, op. cit.).

El conjunto de San Bernardino en la tela de Girolamo Caldieri (primera mitad delsiglo XVII).

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tum hunc locum magnificefatis»32, usando el tiempo futuro,y por lo tanto mencionando quela iglesia y la nueva parte delconvento habrían de ser cons-truidas.Ninguna mención a Francesco diGiorgio (ni a Bramante) comoautor de San Bernardino hace elespecialista Enrico Rocchi en suamplio discurso, pronunciado enSiena en 1900 sobre la actividadde Martini33. A favor de la atribu-ción a este último, como autordel proyecto, se pueden consi-derar los siguientes elementos:un dibujo descubierto porHoward Burns en la BibliotecaLaurenziana de Florencia34, en unfascículo de bosquejos proce-dentes de Urbino claramentecopiados de Francesco di Giorgio,que representan un estado deelaboración cercano pero noidéntico a cuanto realizado, y porello considerados estudios ante-riores de proyecto35. Otro ele-mento es el hecho que la iglesiade San Bernardino tenga carac-teres (basamento, «ricinti» –como los definía el mismoFrancesco di Giorgio –, y unarelación entre paramentos ypartes esculpidas) muy parecidosa los de la iglesia de Santa Maríade las Gracias al Calcinaio en C

ortona, obra cierta de Martini,con cúpula posterior de Pietro diDomenico di Norbo (1509), quese apoya sobre un tambor reali-zado, como toda la iglesia, apartir del diseño de Martini ysobre todo con una concepciónde conjunto que bien se colocaen la arquitectura de Francescodi Giorgio y de sus estudiossobre la antigüedad. Y, final-mente, el testimonio de GiovanniSanti (padre de Raffaello) queofrece, entre 1484 y 1494, unacronología de la fábrica en suvolumen dedicado al Duque Fe-derico36. En conclusión, dejando a un ladolas consideraciones estilísticas deCanuti, que evidentemente noera un experto en los años deformación de Francesco di Gior-gio, ni podía conocer los docu-mentos descubiertosposteriormente a su texto, puedequedar la duda que la iglesia deSan Bernardino haya sidocomenzada antes de la muertedel Duque Federico – aunqueparece imposible colocar su ini-cio antes de 1476 – y, si asífuese, atribuirla sin pruebas aBramante, que ciertamente par-ticipa de esa cultura figurativa,como por otra parte, toma tam-bién parte Francesco di Giorgio. Uno de los mayores historiadoresde la arquitectura italianos,Leonardo Benevolo, se inclina,con cautela, hacia Martini: «fal-tan documentos sobre el autor ysobre la época de construcción.La arquitectura pareceríareferirse a Francesco di Giorgio yla edificación a los últimos añosdel Quattrocento»37.Algunos autores sostienen queun dibujo de Bramante, el céle-bre Templo en ruinas – conocidoa través del grabado de BernardoPrevedari – realizado en 1481 yhoy conservado en el British Mu-seum, sea una referencia per-sonal de una de sus solucionespara San Bernardino o bien de laiglesia de San Bernardino ya ter-minada por Francesco di GiorgioMartini. De cualquier manera, se notanalgunas analogías con la soluciónarquitectónica de la capilla delPerdón del Palacio Ducal deUrbino (realizada antes de 1480,probablemente alrededor de147638) tal vez por el mismoBramante o por Baccio Pontelli39,aunque últimamente algunos es-pecialistas tienden a atribuirla

también a Martini40.La excepcionalidad de la iglesiafue reconocida casi inmediata-mente. Rafael Sanzio conocía yapreciaba la solución arquitec-tónica y los detalles decorativosde San Bernardino. La repre-senta (con ligeras variaciones)en el fondo de algunas de suspinturas, como el de la pequeñaMadonna Cowper (1504-1505) oen los estudios arquitectónicospresentes en el verso de uno delos bocetos preparatorios de laVirgen del Jilguero41, en donde,en la parte alta a la derecha,muestra un fragmento de plantade iglesia con coro y transeptocon ábsides y columnas en lasesquinas de grandes dimen-siones y, en el margen inferiordel folio, el mismo transeptorepetido y ligado a una navecentral, referibles a SanBernardino. El mismo Rafaelvuelve a proponer el modelo delportal de San Bernardino en lasescuderías Chigi en Roma,proyectadas entre 1512 y 1513 yhoy desaparecidas. De 1495 a1503 el párroco de San Donatoen Urbino es un tío de Rafael,don Bartolomé de Sante. ¿Habráido Rafael desde Roma a visitar asu tío a Urbino y podría habervisto la nueva iglesia ya termi-nada?

3. Materiales constituyentes yfenómenos de deterioro:problema de restauración yconsolidaciónA continuación se examinan losmateriales constitutivos de laiglesia y los problemas relaciona-dos con su acentuado deterioro.Los paramentos exteriores sonde ladrillo aparente, formadospor elementos no homogéneoscon diferente grado de al-teración, dispuestos en hiladashorizontales, con juntas demortero de diferentes espesores,a menudo faltante o que ha sidomanipulado. En la fachada, lascornisas son en bloques depiedra arenisca, empotrados enel muro, así como los elementosque constituyen el tímpano, lasventanas y la columnilla centralde la ventana superior. Son enpiedra caliza compacta blanca loselementos del portal de acceso ala iglesia, es decir las dos colum-nas con basas y capiteles, elarco y el dintel. Las ventanasson especialmente elegantes ensu simplicidad. Así las describió


Detalle de la Madonna Cowper deRafael, en cuyo fondo se distingue unaiglesia parecida a San Bernardino.

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Egidio Calzini, historiador deUrbino (que había mantenidouna extensa correspondencia conCamillo Boito) en 1897: «Otrocarácter típico de Bramante loencontramos en las graciosasventanas rectangulares con jam-bas cuyas partes simples y conpoco relieve están en perfectaarmonía con la columna de enmedio, también muy simple»42.Para llevar a cabo la investi-gación histórica y los análisis di-agnósticos preliminares a laintervención, la Superintenden-cia de Monumentos de las Mar-cas, por iniciativa de quienescribe, proyectista y director delas obras43, firmó un conveniocon el Departamento de Historia,Dibujo y Restauración Arquitec-tónica de la Universidad de Roma“La Sapienza”44, y para las obrasde restauración, recientementeterminadas, contó con la ase-soría del Instituto Superior deConservación y Restauración delMinisterio de Bienes y Activi-dades Culturales, que propor-cionó una valiosa orientación45.Ya los terremotos de 1695 y es-pecialmente el de 1703 (devas-

tador en gran parte del centro deItalia, sobre todo en el Abruzzo)habían causado daños significa-tivos en la iglesia y en el con-vento: «En 1704 fueronreparadas las tumbas de losDuques, dañadas por el terre-moto. Se rehízo entonces el re-mate del campanario que,aunque deteriorado, por un mila-gro no cayó sobre la iglesia. Lacúspide fue reconstruida entravertino del Monte Nerone»46.Hoy en día se conservan todavíalos contrafuertes de mam-postería, no empotrados, sinduda posteriores a la construc-ción original de la iglesia y colo-cados como elementos deconsolidación, quizá provisional,muy probablemente en sigloXVIII (éstos ya habían sido nota-dos por Serra en 1932: «huboque proceder con la realizaciónde contrafuertes para apunta-larla»47), aunque los ladrillos,por tamaño y disposición, sonsimilares a los del resto de laiglesia, siendo probablementereutilizados. Por otra parte, ob-servando una pintura del sigloXVII48, en la que se representa

en el fondo la iglesia de SanBernardino con la cúspide de latorre del campanario y cuatropequeñas torres en las es-quinas49, se nota que el contra-fuerte no está presente. Como ellienzo es de la primera mitad delsiglo XVII, ello confirmaría lahipótesis que los mencionadosrefuerzos sean posteriores, pro-bablemente del siglo XVIII y,según algunas conjeturas, in-cluso posteriores al terremoto de1781.Después de este sismo se regis-tran también diversos desperfec-tos: «un daño no indiferente seprodujo en la iglesia y convento,tanto que la primera estuvo sinpoder oficiar durante casi todoun año; sirviendo para las fun-ciones sagradas la iglesia lla-mada de San Donato [...]. Elnuevo Guardián [...] presentóuna súplica a esta Ill.ma Comu-nidad para que concediera al-guna ayuda pecuniaria y solicitóla asignación de 25 escudos. [...]Se supo que el Papa Pío VI [...]había repartido entre los lugaresmás dañados [...] la suma dedoce mil escudos romanos y,

Levantamiento e interpretación diagnóstica efectuados por el Departamento de Diseño, Historia y Restauración de la Facultadde Arquitectura de Roma “La Sapienza”.


Fachada sureste con contrafuertes(Foto S. Gizzi, 2012).

Detalle de los contrafuertes en mam-postería (Foto S. Gizzi, 2012).

Torre campanaria con cornisas origi-nales y de restauración (Foto S. Gizzi,2012).

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después de haber asignado a laCiudad Arquidiócesis de Urbino lacantidad de mil escudos, [...]benignamente fue beneficiadacon el favor de cincuenta escu-dos [...]. El día 8 de abril del añosiguiente 1872, el mismoGuardián [...] dio inicio a larestauración de la Iglesia [...] yen el curso de cinco semanas diofin a la obra»50.A finales del siglo XIX se llevarona cabo otras restauraciones,como nos informa la Relación deGiuseppe Sacconi, entonces Di-rector Regional para la Conser-vación de los Monumentos de lasMarcas y Umbría51: «Este temploimportantísimo para el arte y lahistoria desde hace muchotiempo se encuentra en estadode deterioro, tanto que requierereparaciones rápidas y eficaces.Para ello, la Oficina elaboró unaestimación con fecha 21 deagosto de 1898 por la suma de2,000 liras. [...] Las obras con-sisten en la reconstrucción deltecho y de las cornisas exterio-res».En 1932, escribe Serra: «El es-tado de conservación esmediocre. Los marcos y las cor-nisas se han renovado en granparte debido a las heladas. Fuerestaurada, devolviéndole en loposible su severa majestad origi-nal, en 1927-1929»52. En estecaso, parecería que la reinte-gración de las cornisas, más quepor razones de conservación, sehaya debido a factores estéticos,enfocados al “retorno” a unasupuesta antigua gloria.Al año siguiente, el Municipio deUrbino, en una carta enviada a laSuperintendencia el 8 de juniode 1933, señalaba que «en elalzado lateral de la iglesia deSan Bernardino, que mira haciael norte, se derrumbó una partede la cornisa del tímpano porcasi cuatro metros, y la caída delos materiales ha dañado la cor-nisa horizontal subyacente delmismo tímpano y también deltecho que cubre el espacio semi-circular, en el que está colocadoun altar lateral» (firmado elPodestá).Un cuarto de siglo más tarde, el1 de julio de 1959, el Superin-tendente Vittorio Mesturino in-forma al Ministerio que «laSuperintendencia ya desde algúntiempo se está ocupando del in-signe monumento, en especial

Tambor con evidente deterioro de las cornisas en piedra arenisca.


Una cornisa de reintegración con lafecha grabada: 1933 (Foto S. Gizzi,2015).

Deterioro de las cornisas del frentenoroeste (Foto S. Gizzi, 2015).

Deterioro de las cornisas del frente noroeste. Nótense las partes reintegradas conpiedra arenisca (Foto S. Gizzi, 2012).

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para la conservación de los per-files de piedra arenisca que eltiempo está deteriorando. Por lotanto, prepara un presupuestopor un importe de 1.000.000 deliras para la renovación de algu-nas secciones de cornisas, ar-quitrabes, frisos etc., y paraobtener un modelo para la re-hechura completa de todas lascornisas, frisos, dinteles». Y enla estimación de los costes,preparada por el prof. Belli y re-frendada por el SuperintendenteMesturino, en la partida 2 sepreveía el suministro, fabricacióne instalación de cornisas enpiedra arenisca gris [...] deacuerdo con los diseños queserán proporcionados por la Di-rección de Obras»53.La iglesia y el convento, ademásde haber sufrido daños por laguerra, también fueron utilizadoscomo refugio bélico: «todo eledificio por la larga permanenciade las tropas alemanas, aliadas yde muchas personas desplazadasnecesita con urgencia serlimpiado y encalado»54.En 1959, el Superintendente, enun comunicado al SacroGuardián del Convento (12 denoviembre 1959), señala que haincluido en el programa decenaluna serie de intervenciones enSan Bernardino, que incluyen «larestitución de las cornisas enpiedra arenisca en sustitución lasviejas piezas desgastadas por eltiempo». De esta manera, la ideaera proceder a través de la susti-tución de elementos y no através de la consolidación de losexistentes.Similares a los de la iglesia sonlos problemas relativos a ladegradación de los arquitrabesdel claustro55, también en piedraarenisca; con el tiempo, algunosde ellos han sido reemplazadoscon una serie de elementos dehormigón armado, que hoymuestran plenamente su avan-zada decadencia.En la intervención actual, efec-tuada a partir de 2012, la colum-nilla en piedra arenisca de laventana principal de la fachadade la iglesia – fisurada por unaerrada restauración precedenteen la que se utilizó un núcleo dehierro – se ha consolidado deacuerdo al siguiente iter: pre-consolidación de las lagunaslenticulares través de mi-croinyecciones de resina acrílica;desmontaje y montaje de las

piezas desprendidas con unsellador especial; inserción demicropernos en acero inoxidablecon rosca antes del desmontajey de la eliminación de los refuer-zos inadecuados (realizados an-teriormente con un simplealambre); corte y remoción delcapitel; eliminación de elemen-tos en hierro oxidado del fustede la columna; protección delfuste con policloruro de vinil du-rante el desmontaje; montajedel basamento; consolidaciónpor aspersión hasta rechazo desilicato de etilo; preparación deun soporte adecuado al sucesivomontaje de la columna; reposi-cionamiento de la base e inser-ción de una barra de aceroinoxidable con rosca en lugar delhierro oxidado; montaje delcapitel con mortero a base decal, polvo de piedra arenisca grisy puzolana adicionada con fila-mentos de fibra de vidrio56.Las restauraciones anteriorespueden identificarse – no sincierta dificultad – comparandolos diversos tipos de materiales;en la fachada se notan, enefecto, morteros diferentes delos originales, aplicados a travésdel tiempo para efectuar repara-ciones y reintegraciones. Son, enespecial, de dos tipos: morterorosado o de color cemento apli-cado para sellar lagunas dediferentes tamaños, como lacúspide del tímpano o el para-mento del tambor de la cúpula;mortero de cemento, aplicadocomo una espesa lechada sobre

elementos de piedra muy deteri-orados, que ya no conservan laslíneas de su perfil original.También se observan otras inser-ciones de restauraciones ante-riores: pernos y fajillas de metalpara la columnilla de la ventanadel orden superior y elementosde piedra, en el dintel de la por-tada, en la ventana del primerorden y en el resalte por debajode la cornisa del segundo orden.La presencia de elementos desustitución ha afectado los para-mentos de todo el monumento;en las cornisas en piedraarenisca, constituidas por blo-ques casi completamente des-truidos – de tono oscuro, con


Detalle de las cornisas originales y de sustitución en el frente noroeste (Foto S.Gizzi, 2013).

Monitoreo del frente principal (Foto S.Gizzi, 2013).

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Proyecto de consolidación de los añosNoventa del siglo XX, efectuado conresinas sintéticas.

Efectos negativos de la consolidación efectuada con resinas sintéticas en los añosNoventa del siglo XX (Foto F. Lanari, 2013).

depósitos negros y pátinas bio-lógicas, carentes de definiciónformal – destacan bloques decolor más claro, con talla neta,mucho más dura con moldurascontinuas y regulares con unasuperficie lisa.En especial, en el lado lateral,intercalados con los de recienteintegración, se pueden ver otrosbloques que se caracterizan porfenómenos de exfoliación y muymarcada erosión: su diferentegrado de alteración, intermedioentre la completa destrucción delos elementos de la fachada y losmás recientes, prácticamente in-tactos, sugeriría una reposiciónparcial repetida en el tiempo.Difíciles de fechar son algunasreintegraciones, tales como lasconstituidas por fragmentos deladrillo insertados en los resi-duos de los elementos de piedraarenisca o introducidas a lo largode las líneas de empotramientode los bloques de piedra areniscaen los muros o incluso en loscortes del paramento a los ladosde las columnillas del portal deacceso.Como se ha dicho, los problemasmás significativos se producenpor la degradación progresiva delos elementos constructivos.Entre ellos, la corrosión piedraarenisca es uno de los más in-tensos en la zona de las Marcasy de la Umbría y son numerososlos casos en los que se manifi-esta: de Camerino, a Fano, hastaCittà di Castello, Castiglione delLago y Gubbio. En la iglesia deUrbino se trató de resolver laerosión a través de numerososintentos, no del todo exitosos, alo largo del siglo pasado.Algunos importantes historia-dores del arte contemporáneo,como Corrado Maltese y HowardBurns, señalaron en su momento

el deterioro de las molduras. Elprimero hizo hincapié en que «sila intemperie no hubiese co-rroído de esta manera esas cor-nisas exteriores, la similitud conlas cornisas típicas de Francesco


Deterioro de la piedra arenisca en elPalacio Papal de Camerino (Foto S.Gizzi, 2012).

Deterioro y reintegraciones de la piedraarenisca de la iglesia de Santa María delas Gracias al Calcinaio en Cortona(Foto S. Gizzi, 2012).

bloques, que deben ser reem-plazados con superficie lisa, vistoque no quedan restos de la orna-mentación y de los relieves», su-giriendo, como solución, «larenovación de las reintegracionesen las bases de las columnas ydel dintel»60.Sólo en algunos de estos bloquesde reintegración se ha anotadola fecha de la restauración. Enuna cornisa en piedra areniscadel tímpano se lee la fecha deuna de esas sustituciones: 1933.En la fachada principal y en laslaterales se perciben numerososfenómenos de deterioro tanto delos materiales pétreos como delladrillo. En el portal, tan admi-rado y citado por Rafael Sanzio,

di Giorgio sería sin lugar a dudasmuy fuerte»57; el segundo ob-servó cómo «las cornisas depiedra arenisca» son de «unapiedra que al aire libre se dete-riora considerablemente y, hoyen día, de hecho, se estádesmoronando o ha sido susti-tuida por reformas reciente»58.Ciertamente, en las partidas dediversas estimaciones elaboradasentre los años Treinta y los añosNoventa del siglo XX, casi siem-pre se menciona «el suministrode cornisas de arenisca (piedraserena) de cualquier espesor yaltura»59. E incluso en las esti-maciones de los canteros se sub-raya que «por razones estáticasque requiere la renovación de los

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en piedra caliza blanca, se ad-vierte la presencia de una colo-nización generalizada delíquenes, pero el estado de con-servación es bueno, sin exce-sivos fenómenos dedisgregación, a excepción de pe-queñas zonas de dintel, dondeson muy evidentes algunos des-prendimientos.Acerca de los materiales y ele-mentos de piedra, en el interiorde la iglesia se conservan lashuellas que el compás y el cinceldejaron impresas sobre las carassuperiores de los capiteles delorden interno; tales huellasfueron descubiertas después dehaber removido una ligera capa

de encalado. Estos capiteles sonsimilares a algunos prototiposproto-renacentistas que se con-servan en el Museo Nacional Ro-mano61.En la fachada, todos los elemen-tos en piedra arenisca (a excep-ción de algunos segmentos delas cornisas de evidente sustitu-ción) se encuentran en condi-ciones de avanzada destrucción.Fragmentos residuales de laslíneas arquitectónicas sólopueden apreciarse en las partesterminales de las cornisas delfrontón. Como es bien sabido, anivel general, los tratamientosde restauración habituales parala consolidación de areniscas dis-

gregadas requieren una mano deobra altamente cualificada y pro-ductos de compleja aplicación(silicato de etilo, nanosílices; mi-croemulsiones acrílicas;morteros hidráulicos con granu-lometrías muy finas para las in-yecciones), con operacionesdelicadas y laboriosas, que de-mandan un control muy precisopara minimizar la incertidumbresobre el resultado final y en elcorto o mediano plazo (eficacia;inercia química, ausencia decambios de color).Existe además un problema con-siderable en lo relativo al sumi-nistro del material dereintegración: varias canteras depiedra arenisca presentes enUrbino – ahora casi todas aban-donadas o agotadas –, eran tanricas que fomentaron una extrac-ción muy intensa durante el Re-nacimiento, tanto en Umbríacomo en las Marcas, al gradoque el hijo de Federico,Guidobaldo, para evitar que fal-tase material útil para la cons-trucción del Palacio Ducal deUrbino, promulgó una ordenanzacon la que limitaba la comercial-ización de la piedra, que podía ll-evarse a cabo sólo después deobtener una licencia ducal62.Para la arenisca, la solución ac-tual es o bien la consolidación delo que quedaba de la materiaoriginal, casi completamente in-forme, o bien la sustitución conmaterial nuevo, con un aspectomás duro, como se ha hecho enotras iglesias (por ejemplo,Santa María delle Grazie al Calci-naio, en Cortona, del mismoFrancesco di Giorgio Martini, quepresenta los mismos problemasde desintegración gradual delapiedra arenisca). La tendencia

Claustro del convento de SanBernardino (Foto S. Gizzi, 2013).

Tipos de ladrillo y deterioro de loscapiteles en el claustro del Convento(Foto S. Gizzi, 2013).

Tipos de los ladrillos y deterioro de loscapiteles en el claustro del Convento deSan Bernardino (Foto S. Gizzi, 2013).

Detalle del deterioro del capitel enpiedra arenisca en el claustro (Foto S.Gizzi, 2013).

Ladrillos con restos de revocos policro-mados y esgrafiados (Foto S. Gizzi,2015).

Pruebas de consolidación de los ladrillosy test de tratamiento del mortero (FotoS. Gizzi, 2015).

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Urbino, Convento de Santa Clara deFrancesco di Giorgio Martini (Foto S.Gizzi, 1972).


es, en general, la de conservar lomás posible la materia original:en otras consolidaciones llevadasa cabo por el Instituto Central dela Restauración, por ejemplo, enLecce, en la iglesia de SantaCroce, con otro tipo de piedra (la

llamada piedra leccese), se evi-taron las sustituciones de mate-rial y se procedió con laimbibición de productos quími-cos, con un resultado que, sinembargo, ya no es satisfactorio adistancia de poco más de una

década. En el caso concreto, seobservó que algunas zonas delparamento son sede de colo-nización de líquenes, mientrasque otros aparecen completa-mente exentos. Existen nu-merosas lagunas einterrupciones: los ladrillosaparentes, dispuestos en hiladashorizontales – con juntas demortero faltantes, desintegradaso alteradas –, presentan discon-tinuidades en las proximidadesde los elementos de piedra. Losladrillos se diferencian por color,tamaño e integridad y presentanvarias formas de alteración condiferentes niveles de gravedad;muchos parecen ser elementosreemplazados. Las operacionesúltimamente realizadas (no es-pecialmente complejas y condiferentes niveles de proble-máticas) consistieron en ladesinfección, la eliminación delos depósitos y de piezassueltas, la reconstrucción pun-tual de las juntas faltantes y laconsolidación de los ladrillos enestado de pulverización.En las cornisas horizontalesfueron, en el pasado, colocadosladrillos con pendiente ade-cuada, unidos para formar unasuperficie adecuada para laeliminación del agua de lluvia.Pero hoy en día estos elementosde protección están incompletos,por faltar muchos de los ele-mentos constituyentes. La opor-tuna reparación de lacontinuidad y de la funcionalidadde esas superficies, en larestauración en curso, se ha lle-vado a cabo reintegrando laspartes faltantes y los huecos conmorteros tradicionales con ele-vada cualidad hidráulica.Los problemas que plantea elmonumento en su conjunto sonde gran importancia y estimula-ron muchas reflexiones; en laperspectiva de una intervencióngeneral, el primero está rela-cionado con la dimensión de losparamentos, con la extensión delos elementos a ser tratados y asu accesibilidad en ausencia deandamios. A esto se conecta unsegundo tema, el de la elabo-ración de metodologías aplica-bles ampliamente, realizadasfácilmente por trabajadores noespecializados. Un tercer as-pecto está relacionado con lahistoria de la conservación, paraentender mejor – además de laincidencia de los factores

Detalle de la prueba elegida (Foto S. Gizzi, 2015).

Estado de deterioro de la columnilla de la ventana bifora del frente principal antesde la intervención (Foto S. Gizzi, 2014).

25

climáticos – las causas y ladinámica de una degradación tanpronunciada. Un nuevo elementode complejidad está ligado a laexistencia de piezas ya tratadasdurante las restauraciones re-cientes, con características es-téticas y de rendimiento distintosde los materiales pre-existentes.Existe, además, un tema muy in-teresante e intrigante de tipohistórico, que consiste en laidentificación y colocación tem-poral de un paramento de ladrillosimulado con el revoco (¿Es ori-ginal? ¿Es del siglo XVIII ? ¿Fue

propuesto por Valadier, que tra-bajó también en la catedral deUrbino? ¿Se remonta al sigloXIX?), presente en varias zonasde la fachada resguardadas porlos aleros, que fue realizado conuna capa de mortero muy ligero,aplicado con técnica pictórica nodemasiado refinada y que mues-tra esgrafiados horizontales queimitan las juntas de ladrillo.Desde el punto di vista estruc-tural, dentro del edificio se haninstalado algunas espías paraevaluar y monitorear los acen-tuados fenómenos de desplome

y las grietas de muros, que semanifiestan sobre todo en lafachada principal, con respecto alas demás paredes. Es un pro-blema que apareció ya a finalesdel siglo XIX, como señalabanlos eruditos locales (véaseCalzini «desde hace algunosaños el abultamiento ohundimiento de la tierra [...] hacomenzado a desprender la partefrontal del templo, y las rendijasse amplían sin interrupción. ¿Nosería un crimen, por descuido opor otra cosa, dejar que muerala más justa y más genial obrajuvenil de Bramante?»63).Pero los problemas más gravesse deben a las imbibiciones re-cientes, de los años Noventa,realizadas con resinas sintéticasque han alterado por completo,en pocos años, desde el puntode vista cromático y material, lapiedra.Las lesiones estructurales tam-bién conciernen otros elementos,como por ejemplo las lápidassepulcrales (la tumba estaba encornu epistulae, o sea en el ladoderecho del altar): así tambiénla del Duque Guidantonio deMontefeltro – padre de DuqueFederico – (representados con elhábito franciscano y con una es-pada y el signo de la caballeríaen el lado derecho) en la antiguaiglesia de San Donato, fracturaday en fuerte estado dedegradación. La intervencióndebe ser incluida en un pro-grama más amplio de revisióngeneral que incluya también lapavimentación.La restauración actual estuvo di-rigida a una consolidación gen-eral de las mamposterías y delas decoraciones, para una mejorapreciación y conservación delmonumento.

Notas

1 Urbino, ciudad de la Región de lasMarcas, fue Ducado de la familiaMontefeltro y su época de esplendorse coloca en la segunda mitad delsiglo XV, en tiempos del Duque Fe-derico, cuando numerosos artistasfueron llamados a trabajar en lacorte: Piero della Francesca, LucianoLaurana, Francesco di Giorgio Mar-tini. Fue cuna de Bramante (quenació en una pequeña localidad cer-cana llamada Fermignano) y deRafael Sanzio.2 A partir de una idea inicial de ubi-carlo en el interior del Palacio Ducal.

Desmontaje del capitel de la columnilla de la ventana bifora del frente principal(Foto Gamma s.r.l. Fano, 2015).

Detalle de la fisura de la columna (Foto Gamma s.r.l. Fano, 2015).


26

pelkirchen der Renaissance in Italien,Ernst & Korn, Berlin 1882, I-II.7 C. Promis, Vita di Francesco diGiorgio Martini architetto senese delsecolo XV. Aggiuntovi il catalogo de’codici, Tipografia Chirio e Mina,Torino 1841, p. 23: «De Federico [deMontefeltro] son también la iglesia yel claustro de’ Zoccolanti, en las in-mediaciones de Urbino, por tradiciónatribuidas a Baccio Pontelli».8 C. Budinich, Il Palazzo Ducaled’Urbino. Studio storico-artistico il-lustrato da nuovi documenti, Stabili-mento Tipo-Litografico Emilio Sambo,Trieste 1904, p. 126.9 A. Bruschi, Bramante Architetto,Laterza, Roma-Bari 1969, pp. 732-739, espec. p. 734.10 V. da Bisticci, Vite di uomini illustridel secolo XV, rivedute sui mano-scritti da Lodovico Frati, RomagnoliDall’Acqua, Bologna 1892.11 Ibidem.12 Ibidem.13 M. A. Dolci, Notizie delle pittureche si trovano nelle chiese e neipalazzi di Urbino, ms., Bologna 1775,edición a cura di L. Serra, Tip. G.Federici, Pesaro 1933, pp. 310-311.y, en la p. 317: en «la iglesia de losZoccolanti fuera de la ciudad, elpresbiterio es diseño de Bramante».14 A. Lazzari, De’ vescovi d’Urbinocon alcuni aneddoti concernenti il do-minio temporale de’ conti e duchi,presso Giovanni Guerrini, Urbino1806.15 C. Maltese, Opere e soggiorniurbinati di Francesco di Giorgio, en P.Rotondi (ed.), Studi artistici urbinati,Istituto d’Arte per il Libro in Urbino,Urbino 1949, vol. I, pp. 59- 83.16 C. Maltese, Opere e soggiorniurbinati..., cit.. En efecto, Maltesesupone que «Francesco di Giorgio vaa Milán en 1490, encuentra casi cier-tamente a Bramante, visita aLeonardo, a quien regala una copiade su Tratado. ¿No podría en esabreve estancia haber tenido lugar unintercambio entre Bramante yFrancesco di Giorgio?» C. Maltese,op. cit., p. 81. En la opinión de Ar-naldo Bruschi «Maltese […] pospone[…] exageradamente, la construccióna 1490-91, después del viaje a Milánde Francesco di Giorgio»: cfr. A.Bruschi, Bramante, ed. UniversaleLaterza, Roma-Bari 1977, nota 21,pp. 735-736. La hipótesis de un en-cuentro en Milán entre Bramante yFrancesco di Giorgio para discutirsobre San Bernardino es retomadaexplícitamente por F. Mazzini, en suGuida di Urbino, Eretenia, Vicenza1959, pp. 264-265.17 A. Venturi, Il luogo di nascita diBramante e i suoi esordi, en “L’Arte.Rivista di storia dell’arte medievale emoderna”, n. 21, 1918, pp. 210-219,espec. pp. 218-219: «todos los de-talles de la construcción se encon-trarán en obras posteriores ciertasdel arquitecto de Urbino».

18 A. Venturi, Storia dell’arte italiana,VIII, L’ architettura del Quattrocento,I, Hoepli, Milano 1923, pp. 779-787,espec. pp. 779-782: «Otra obra, enla capital de los Montefeltro, se debea Francesco di Giorgio: la discutidaiglesia de San Bernardino, que noofrece suficientes analogías con edifi-cios conocidos de Bramante, el pre-sunto arquitecto [...]. Las bellascornisas extendidas y las ovas conrelieve muy pronunciado, casi sepa-rados, como en un efecto pictórico;las ventanas rectangulares, con tím-pano muy saliente, tan altas que al-canzan, como en la iglesia deCortona, las cornisas del entabla-mento, siendo profundas y parecidasa tabernáculos luminosos, con unapuerta rica y esbelta, con el arco en-marcado por columnas apoyadas enun pedestal y por el alto y liso troncodel entablamento, preferido paracoronar puertas y ventanas por

3 Arquitecto urbinate (Fermignano1444-Roma 1514). Entre sus obrasprincipales se cuenta el proyectopara la reconstrucción de la Basílicade San Pedro, el templete de SanPedro in Montorio, el claustro deSanta María de la Paz, todas enRoma.4 Arquitecto e ingeniero militar(Siena 1439-Fighille 1501), conocidopor sus fortificaciones y castillossituados en Italia central y por variosproyectos llevados a cabo en elPalazzo Ducal de Urbino, en el deGubbio y por muchas iglesias, comola de Santa María de las Gracias alCalcinaio en Cortona (Toscana).5 Las excavaciones fueron dirigidaspor el ingeniero Enrico Cardelli, poriniciativa de Luigi Serra. Cfr. L.Serra, Nota sulla chiesa di SanBernardino a Urbino, en “RassegnaMarchigiana”, enero-febrero 1932.6 H. Strack, Central- und Kup-

Fases de la restauración de la colum-nilla (Foto Gamma s.r.l. Fano, 2015).

La columna después de la restauración(Foto Gamma s.r.l. Fano, 2015).


27

Espías para monitorear las fisuras en elinterior de la iglesia (Foto Gamma s.r.l.Fano, 2015).

Francesco di Giorgio, los granos per-láceos de los ornatos que adornan losfrisos, las volutas invertidas que seenganchan como articulacionesmetálicas a los vértices del ábaco,orientan claramente hacia el Maestrode Siena, arquitecto de la bella igle-silla, sepulcro de los Duques deUrbino».19 G. Giovannoni, Commenti e recen-sioni. S. Bernardino di Urbino, en“Belle Arti”, año I, n. 2, noviembre-di-ciembre 1946, pp. 121-122, espec. p.12120 Ibidem, p. 121.21 F. Canuti, Chi fu l’architetto di S.Bernardino d’Urbino, en Lo storicoconvegno di Castel della Pieve,Urbino, STEU, Urbino, 1952, pp. 31-41.22 P. Rotondi, Quando fu costruita lachiesa di San Bernardino in Urbino?,en “Belle Arti”, n. 1, 1947, pp. 191-202.23 A. Bruschi, Bramante, op. cit.24 Firenze, Biblioteca Laurenziana,Codice Ashburnham 1828, App., ff63v-64r.25 A. Bruschi, L’architettura religiosadel Rinascimento in Italia daBrunelleschi a Michelangelo, in H. Mil-lon - V. Magnano Lampugnani, Ri-nascimento da Brunelleschi aMichelangelo. La rappresentazionedell’architettura, Bompiani, Milano1994, pp. 123-181, espec. p. 151.26 O. H. Förster, Bramante, A. Schroll,Wien-München 1956.27 A. Falcioni, La famiglia Bramante.Fonti archivistiche urbinati, Depu-tazione di Storia Patria per le Marche,Ancona 2014.28 F. Canuti, Chi fu l’architetto di S.Bernardino d’Urbino…, op. cit.29 Trad. «Llevó a cabo este lugar enmodo bastante magnífico y, a gloria desemejante Príncipe, lo completó sufi-cientemente en todos sus detalles».

30 A. Festa, La chiesa e il convento diSan Bernardino in Urbino, en“Quaderni dell’Istituto di Storia del-l’Architettura”, n.s., 41, 2003, pp. 17-38.31 F. Francisci Gonzagae, De origineseraphicae religionis franciscanae,eiusque prograssibus, de regularisobservantiae institutione, forma, ad-ministratione ac legibus, ad-mirabilique eius propagazione,Typographia Dominici Basae, Romae1587), p. 213. Dedicado a Sixto V, enel párrafo De Conventu S. BernardiniUrbini Conv. LII.32 Trad. «Que habría de dar satisfac-ción a los píos deseos expresados porsu hermano, llevando a cabo magnífi-camente este lugar ya iniciado».33 E. Rocchi, L’opera e i tempi diFrancesco di Giorgio Martini, Confe-rencia 31 marzo 1900, CommissioneSenese di Storia Patria nella R. Ac-cademia dei Rozzi, en “Bullettinosenese di Storia Patria”, a. 7., fasc.2., Tip. E Lit. Sordomuti di L. Lazzeri,Siena 1900.34 Firenze, Biblioteca Laurenziana,codice Ashburnham 1828.35 M. Tafuri, Ricerca del Rinascimento.Principi, città, architetti, Einaudi,Torino 1992, nota 20 en la p. 219. 36 G. Santi, La vita e le gesta di Fe-derico di Montefeltro duca d’Urbino.Poema in terza rima, Codice Vat.Ottob. Lat. 1305, edición a cargo deL. Michelini Tocci, Biblioteca Apo-stolica Vaticana, Istituto Salesiano PioXI, Città del Vaticano 1985, I, pp. 1-96.37 L. Benevolo - P. Boninsegna,Urbino, Laterza, Roma-Bari 1986, piede foto de la fig. 95 en la p. 116.38 A. Bruschi, Bramante architetto…,cit., pp. 730-731.39 F. P. Fiore, Il Palazzo Ducale diUrbino, en F. P. Fiore - M. Tafuri (ed.),Francesco di Giorgio architetto,Electa, Milano 1993, pp. 164- 179,espec. p. 169.40 G. De Zoppi, La cappella del Per-dono e il tempietto delle Muse nelPalazzo Ducale di Urbino. Analisi eproposta d’attribuzione a Francesco diGiorgio Martini, en “Annali di architet-tura”, n. 16, 2004, pp. 9 - 24.41 Oxford, Ashmolean Museum, f. 517 v.42 E. Calzini, Urbino e i suoi monu-menti, Licinio Cappelli Editore Libraio,Rocca San Casciano 1897, p. 102.43 Soprintendente per i Beni Architet-tonici e Paesaggistici delle Marche,entre 2012 y 2015. ResponsabileUnico del Procedimento arq. BiagioDe Martinis, colaboración del arq.Paolo Mazzoli.44 Responsable científico FrancescoPaolo Fiore, grupo formado por FlaviaCantatore, Carlo Inglese, LeonardoBaglioni, Francesco Borgogni, Elisa-betta Giorgi, Marco Di Giovanni.45 G. M. Fazio, Relazione per contodell’Istituto Superiore per la Conser-vazione ed il Restauro del 28/1/2014,a seguito del sopralluogo del

15/11/2013, prot. ISCR 530 del28/1/2014.46 B. Ligi, Le chiese di Urbino, STEU,Urbino 1937.47 L. Serra (a cura di), Catalogo dellecose d’arte e di antichità d’Italia.Urbino, La Libreria dello Stato, Roma1932, p. 104.48 Que en el texto del siglo XIX deEgidio Calzini se atribuía a Antonio Vi-viani «el sordo de Urbino».49 Más recientemente atribuida porManfredo Tafuri a Girolamo Cialdieri,conservada en el Museo Albani enUrbino Madonna y niño con los santosGregorio y Antonio abad.50 Archivo del Convento de SanBernardino en Urbino, Cronaca, cc.69, 70, 71, citada en la tesis de licen-ciatura de J. Montanari, La chiesa diSan Bernardino in Urbino, director detesis Marcello Fagiolo, co-directorAmedeo Belluzzi, a.a. 1989-1990,Università degli Studi di Firenze, Fa-coltà di Architettura, Dipartimento diStoria dell’Architettura e Restaurodelle Strutture Architettoniche, all. n.23.51 G. Sacconi, Relazione dell’UfficioRegionale per la Conservazione deiMonumenti delle Marche e dell’Umbria1891-1892–1900-1901, TipografiaGuerriero Guerra, Perugia 1901, pp.321-322, espec. p. 322.52 L. Serra (ed.), Catalogo delle cosed’arte e di antichità d’Italia. Urbino,cit., p. 104.53 Archivo de la Soprintendenza delleMarche, Perizia di spesa SanBernardino di Urbino, 1959.54 Lettera dei Conventuali Padre Naz-zareno Ruffini (Superiore) e di P.Francesco Angeletti (Sostituto) al So-printendente, fechada Urbino 29 dejulio 1947.55 Análogo al Convento de Santa Clarade Urbino, obra cierta de Francesco diGiorgio.56 Restauración llevada a cabo por laempresa Gamma s.r.l. de Fano, deGiovanna Macchi.57 C. Maltese, Opere e soggiorniurbinati di Francesco di Giorgio, cit.,p. 79.58 H. Burns, San Bernardino a Urbino,en F. P. Fiore - M. Tafuri (ed.),Francesco di Giorgio architetto, cit.,pp. 230-243, espec. p. 230.59 Por ejemplo en la Perizia di spesaper il restauro dei danni da guerra econsolidamento della chiesa di SanBernardino a Urbino, con un importede 1.000.000 de liras, del 14 deenero 1954, capítulo 3. 60 Ibidem.61 C. Martini, scheda en A. Giuliano,Museo Nazionale Romano. Le Scul-ture, Roma 1978.62 Carta al Podestà de Fossombronedel 22 del septiembre 1568, conser-vada en los Registri delle Riformanzedel Archivo Histórico Municipal deFossombrone.63 E. Calzini, Urbino e i suoi monu-menti, cit., p. 110.

Lápida funeraria del Duque Guidantoniode Montefeltro, existente en la antiguaiglesia de San Donato colindante conSan Bernardino, afectada por los asen-tamienteos estructurales del edificio(Foto Stefano Gizzi, 2012).


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African House: Use of Synthetic Ropefor Structural InterventionMelrose Plantation, Louisiana, USA

S. Patrick Sparks, PE

Sparks Engineering, Inc., San Antonio, Texas USA

he “African House” was built c. 1820 on the Melrose Plantation, which was founded by Louis

Metoyer, a free person of color. The unusually proportioned roof suspended over modest walls (Fig-

ure 1) has captured the imaginations of artists and architects for generations. Its original purpose is

unknown, as are the names of its builders. In the early 20th century the African House was used for

storage, but for the past few decades, the building has been interpreted primarily in reference to life

on the Cane River and to the life and works of American folk artist Clementine Hunter, who lived on

the plantation and whose important murals are protected and displayed in the upper story. For more

information on Clementine Hunter and Melrose Plantation, see

http://www.melroseplantation.org/blog/

The lower story of the building is constructed of low-fired clay brick in lime mortar. The upper-story

walls are constructed of squared cypress timbers with interlocking dovetail ends in the traditional Cre-

ole style. As identified by timber-framing expert Rudy Christian, the timber in the African House was

produced by the method known as ‘mixed conversion’, meaning the logs were squared with axes first,

then sawn by hand lengthwise. Sustained efforts in recent years have stabilized the soft-brick lower

walls, and the timber walls of the second level have remained in good condition.

It was actually the perceived similarity of the roof shape to indigenous houses in Africa that prompted

a visiting artist in the mid-20th century to assign the nickname “African House”.

In fact, the wide overhanging roof structure is in many ways characteristic of the regional French Cre-

ole style of construction, with the rather startling exception that it has no columns on the perimeter.

In lieu of columns, inclined struts made of cypress poles laterally brace the roof edge against the build-

ing core. Documentary evidence suggests that this lack of columns was purposeful (Figure 2).

In early 2015 a conservation plan for the building was developed by the author through a process of

review, assessment, and collaboration with the Association for the Preservation of Historic Natchi-

toches, the U.S. National Park Service, and historic timber framing experts.

StructureClearly, the roof framing represented the main structural challenge. Over the years after its 1940

restoration, the roof framing had deformed badly, and by 2008 during our initial assessment tempo-


29

Figure 1 The African House as it appeared in 1940 after a restoration campaign (Historic American Building Survey, Library ofCongress) (left), and in 2008 with temporary supports at the roof corners (right).

T

30

rary supports had been added, as shown in Figure 1. The 2015 detailed inspection showed that the roof

had failed structurally: rupture of the first common rafters at each of the building corners and of the

‘flying’ eave plates. Despite the appearance of considerable decay, after the investigation we concluded

that many of the original timbers were still sound.

The failure was intuitively seen as being due to decay and to the intrinsic limitations of the column-

less design. But we also found that the pole struts that support the eaves had slipped or fallen in the

past, and also that the first common rafters had slid down approximately eight inches from their orig-

inal bearing position on the timber walls, exposing the original iron spikes that had anchored them.

Calculations using a three-dimensional computer model confirmed the general behavior (Figure 3) and

verified that the pole struts that support the eaves are particularly critical, as is the connectivity at the

various other timber joints. So long as the struts remain in place the roof structure is capable of sup-

porting its dead weight. Historically, however, the struts, like the other frame members, were fastened

in no other way than a few iron nails at each end. Minor wind loads were sufficient to dislodge the

struts. Loss, or even slippage, of one strut would be enough to overload the rafter and eave plate. Sim-

ilarly, slippage of one or more rafters from its bearing could induce overload elsewhere. It was also clear

from the analysis that under full design loads, the other primary areas of structural deficiency re-

mained: in the high bending stress in the first common rafters and in the inadequate stiffness of the

eave plates.

Of course, a simple and important improvement was to add positive mechanical connections at all

joints, to provide resistance to tensile and shear forces. This would assure that the pole struts would

stay in place, even during wind storms. Strengthening of the various joint connections was done with

small diameter stainless steel rods and specialty timber screws, and these were largely hidden.

Due to their structural damage, the decision was made to replace the eave plates and the first com-

mon rafters with hand-hewn and hand-sawn cypress timber. As a first alternative for strengthening

these timber elements, we considered using embedded stainless steel flitches, but that level of inter-

vention was deemed excessive. The idea was floated of adding cables or stays from the eaves to the

second story timber walls to provide a suspension effect. Initial calculations showed, counter-intu-

itively, that a single suspension stay from each corner actually caused an increase in stress in the ad-

jacent, perpendicular eave plate. But adding two stays at each corner, as shown in Figure 4, cut the

stress in half.

Still, even with the stays at each corner supporting the eave plates, the permanent stress in the first

common rafters was too high for long-term performance. And in the event of damage to other mem-

bers, these rafters would need to have excess capacity. It seemed, then that tensile-only strengthen-

ing of the rafters, also using cables could be a simple solution.

Figure 2 Documentary evidence for the lack of columns at the roof edge: Left, as remembered by artist Clementine Hunter, andright, as seen in the earliest known photos.


31

Ropes for StrengtheningInitially, stainless steel cable was identified as the material of choice. Calculations showed that a 7mm

stainless steel aircraft cable would meet the requirements of the rafter strengthening. However, the

minimum allowable radius of bends (~150mm) would not be possible to achieve. Looking for options,

we considered high-strength synthetic ropes, as are now used in sailing and other industries. Among

the strongest of these advanced rope materials

are Vectran™ and Dyneema®.

The table below gives comparative strengths of

these two synthetics against stainless steel cable,

all for a 6mm diameter.

Dyneema® is made from ultra-high molecular

weight polyethylene and is the world’s strongest

fiber. It is used extensively in the shipping indus-

try for mooring and anchor lines, for example.

It has extremely good abrasion resistance, does

not absorb water, and has a specific gravity of

0.97. Unfortunately, Dyneema® will creep under

sustained load, making it a poor choice for this

project.

Vectran™ is a liquid crystal aromatic polyester

somewhat similar to the aramid ropes. It toler-

ates bends, exhibits good knot holding proper-

ties, has excellent chemical resistance and low

moisture absorption. Resistance to ultra-violet

radiation is achieved by coating the Vectran™

fibers

Moreover, Vectran™ has no measurable creep when loaded with up to 50% of the breaking load, even

at elevated temperatures (Beers & Ramirez 1990). A 12-strand, single-braid rope by New England

Ropes would have sufficient strength for the project in 6mm diameter, with no practical limitation on

bend radius (Petrina et al., 1995).

This is the rope that was finally chosen for the project.

Figure 5 shows how the common rafters were reinforced with the 6mm Vectran™ rope.

Figure 5 shows the rope installed, captured in a groove along the top of the rafter, and anchored with

stainless steel bolts. Only the bolt head is visible to the public.

Figure 3 Rendering of the African House framing, left, and deflected shape under dead load, right (deflections magnified).

First commonrafter

“Flying” eave plate

Figure 4 Stay cables added at the building corners to allevi-ate stress in roof framing.deflected shape under dead load,right (deflections magnified).

Stay cables: 6mmVectran™ braidedrope


32

Splicing and End TerminationsTypically, the high-strength synthetic ropes are terminated in the field with some variation of the eye-

splice (usually long-bury or locked), which can achieve 95% or more of the rope strength. Mechanical

end-fittings are expensive specialty shop-fabrications and are not available for many of the higher per-

forming rope fibers. Even if available, they require pre-planning for exact lengths and allowance for

manufacturing time. The rope manufacturers generally provide

splicing guidance (e.g. New England Ropes Splicing Guide:

www.neropes.com/Resources/84906_NEROPE.pdf). In the

African House ropes, Brummel (locked and buried) eye-splices were

used with stainless steel thimbles. It is recommended to set the rope

after making up the end terminations by a brief period of tension-

ing prior to installation. Also, making up the rope a bit short of the

anchor points will assure that the rope will accept load during serv-

ice. As a reference point, applied strain at installation was targeted

at about 0.40% to achieve 15% of breaking stress.

ConclusionThe structural conservation of the unusual roof system of the African

House was made possible through careful investigation, analysis,

and especially by multidisciplinary collaboration. Though initially

perplexing, the challenge of strengthening the roof framing was met

by a simple solution of selectively adding tensile elements. A state-

of-the art synthetic fiber rope, Vectran, was found to be a good

choice because of its high strength, flexibility, and absence of creep.

With the roof now permanently stabilized, this fascinating structure can continue to protect the valu-

able paintings of Clementine Hunter, and live on as a unique model of Creole building traditions.

AcknowledgementsRudy Christian, timber-framing consultant; Alicia Spence and Gerald David, timber-framing restoration team lead-

ers; Sarah Marie Jackson of the National Center for Preservation Technology & Training; the National Trust for His-

toric Preservation and the Association for the Preservation of Historic Natchitoches.

ReferencesBeers, D. E., and J. E. Ramirez. "Vectran high-performance fibre." Journal of the Textile Institute 81, no. 4 (1990):

561-574.

Petrina, Petru, S. Leigh Phoenix, Frank A. Leban, and Vincent J. Pappas. "Lifetime studies of synthetic cables sub-

jected to lateral contact loads from sheaves." In OCEANS'95. MTS/IEEE. Challenges of Our Changing Global Envi-

ronment. Conference Proceedings, vol. 2, pp. 1319-1330. IEEE, 1995.

Figure 5 Scheme for improving flexural strength of the first common rafters by adding high-strength rope along the top edge.

Run rope in groovealong top of rafter

Radius through-hole

Anchor each endwith loop splice &thimble at stainlesssteel bolt

Strengthen rafterswith synthetic rope

Figure 6 Synthetic rope used for flex-ural strengthening of the first commonrafters. A stainless steel bolt anchorsthe end-loop, and the rope is recessedin a small channel along the top of thetimber (photo by Sarah Marie Jackson).


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