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, New York City ]] A Barrel vault, also known as a '''tunnel vault''' or a '''wagon vault''', is an architectural element formed by the extrusion of a single curve (or pair of curves, in the case of a pointed barrel vault) along a given distance. The curves are typically circular in shape, lending a semi-cylindrical appearance to the total design. The barrel vault is the simplest form of a placed side by side, i.e., one after another. As with all arch-based constructions, there is an outward thrust generated against the walls underneath a barrel vault. There are several mechanisms for absorbing this thrust. One is, of course, to make the walls exceedingly thick and strong - this is most primitive and sometimes unacceptable method. A more elegant method is to build two or more vaults parallel to each other; the forces of their outward thrusts will thus negate each other. This method was most often used in construction of churches, where several vaulted Nave s ran parallel down the length of building. However, the outer walls of the outermost vault would still have to be quite strong or reinforced by Buttress ing. The third and most elegant mechanism to resist the lateral thrust was to create an intersection of two barrel vaults at right angles, thus forming a Groin Vault . Barrel vaults are known from Ancient Egypt , and were used extensively in Roman Architecture . They were also used to replace the Cloaca Maxima with a system of underground sewers. Early barrel vault designs occur in northern Europe , Turkey , Morocco and other regions. In Medieval Europe the barrel vault was an important element of stone construction in Monasteries , Castle s, Tower House s and other structures. This form of design is observed in Cellar s, Crypt s, long Hallway s, Cloister s and even Great Hall s. THEORY AND EARLY HISTORY Barrel vaulting was known and employed by early civilisations, including of the vault was only two meters. In these early instances, the barrel vault was chiefly used for underground structures such as drains and Sewer s, though several buildings of the great Late Egyptian Mortuary Palace - Temple of Ramesseum were also vaulted in this way.Dietrich Wildung, ''Egypt, From Prehistory to the Romans'', Taschen, 2001. Recent Archaeological evidence discovered at the Morgantina site (in the province of Enna ) shows that the aboveground barrel vault was known and used in Hellenistic Sicily in third century BC, indicating that the technique was also known to Ancient Greek s. Ancient Romans most probably inherited their knowledge of barrel vaulting from Etruscans . Romans were the first to use this building method extensively on large-scale projects, and were probably the first to use Scaffold ing to aid them in construction of vaults spanning over widths greater than anything seen before. However, Roman builders gradually began to prefer the use of Groin Vault ; though more complex to erect, this type of vault did not require heavy, thick walls for support (see bellow), and thus allowed for more spacious buildings with greater openings and much more light inside, such as Thermae . After the fall of the Roman Empire , few buildings large enough to require much in the way of vaulting were built for several centuries. In the early Romanesque period, a return to stone barrel vaults was seen for the first great cathedrals; their interiors were fairly dark, due to thick, heavy walls needed for support of vault. One of the largest and most famous churches enclosed from above by a vast barrel vault was the church of Cluny Abbey , built between eleventh and twelfth century. In thirteenth and fourteenth century, with the advance of the new Gothic style, barrel vaulting became almost extinct in constructions of great Gothic cathedrals; Groin Vault s reinforced by stone ribs were mostly used in the beginning, and later on various types of spectacular, ornate and complex medieval vaults were developed. However, with the coming of Renaissance and Baroque , and revived interest in art and architecture of antiquity, barrel vaulting was re-introduced on a truly grandiose scale, and employed in constructions of many famous buildings and churches, such as Basilica Di Sant'Andrea Di Mantova by Leone Battista Alberti , San Giorgio Maggiore by Andrea Palladio , and perhaps most glorious of all, St. Peter's Basilica in Rome, where a huge barrel vault spans the 27 meters wide nave.http://www.stpetersbasilica.org/Interior/Nave/Nave.htm ENGINEERING ISSUES With a barrel vault design the vectors of pressure result in a downward force on the crown while the lower portions of the arches realise a lateral force pushing outwards. Mount Holyoke college, The Art of Cathedrals: Stresses in barrel vaulted design As an outcome this form of design is subject to failure unless the sides are anchored or buttressed to very heavy building elements or substantial earthwork sidings. For example, at 2006 ] The inherent difficulty of adequately lighting barrel vaulted structures has been widely acknowledged.Friedrich Ragette, ''Traditional Domestic Architecture of the Arab Region'', American University of Shadah (2003) The intrinsic engineering issue is the need to avoid Fenestration punctures in stonework barrel vaults. Such openings could compromise the integrity of the entire arch system. Thus the Romanesque medieval builders had to resort to techniques of small windows, large buttresses, or other forms of interior wall cross-bracing to achieve the desired lighting outcomes. In many of the monasteries a natural solution was cloisters which could have high barrel-vaulted construction with an open courtyard to allow ample lighting. Since 1996 Method'', CRC Press (2003) These analyses have typically used a Finite Element algorithm to calculate gravity induced stresses from the self weight of an arched system. In fact, for structural engineers, analysis of the barrel vault has become a benchmark test of a structural engineering Computer Model "because of the complex membrane and inextensional bending states of stress" involved. In terms of comparison to other vaulting techniques the barrel vault is inherently a weaker design compared to the more complex Groin Vault . The barrel vault structure must rest on long walls creating less stable lateral stress, whereas the groin vault design can direct stresses almost purely vertically on the apexes.Robert A. Scott, ''The Gothic Enterprise: A Guide to Understanding the Medieval Cathedral'' University of California Press (2003) EARLY OCCURRENCES sewer in Rome. Construction started ca. 600 BCE ]]
MODERN EXAMPLES There are numerous contemporary examples of barrel vault design in Victorian and Modern Architecture , including:
THE BARREL VAULT IN UNCONVENTIONAL USAGE Beyond the classical use of the barrel vault in macro-architectural design (e.g. as a major structural roofing element), there are a variety of derivative applications clearly based on the original concept and shape of the barrel vault. These applications arise in the fields of Surgery , Skylight design, children's toys and micro-structure design (such as bus shelters). While none of these applications rival the majesty of the ancient and Classical predecessors, they demonstrate the pervasiveness of the barrel vault as an architectural concept in contemporary times. In the field of bone surgery the technique of a "barrel vault" shaped incision is not only a well defined in 91 such operations. SEE ALSO REFERENCES EXTERNAL LINKS |
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