Cantilever vault
As corbelled , corbelled or false vault a preform is genuine vault referred to as upper closure of a space. Parallel to this, there have been cantilever domes , corbel domes or false domes since the earliest times .
Construction engineering
"Cantilever arches" or "domes" are based on the cantilever arch . Cantilevered, horizontal bricks, i.e. pushed towards one another, form an arch shape that tapers towards the top to a mostly larger terminal stone without a stabilizing function. This taper can be elongated or circular, depending on whether the rooms are rectangular or round. Unlike real vaults, which stabilize themselves like an arch , a cantilever vault must be secured by applying vertical pressure to the outside of the vaulting stones. Cantilever vaults are therefore always steep and massive.
Examples
The German scholar Gerhard Rohlfs researched rural cantilever vaulted structures made of dry stone in Europe for more than 30 years . In 1957 he published the result in the book Primitive Kuppelbauten in Europa . The building history differentiates between linear cantilever vaults, cantilever arches and cantilever domes, which differ in the shape and inclination of the stones and were only replaced with the use of brick and finally the invention of concrete by the Romans.
Western Europe
The oldest preserved examples of cantilevered buildings are the tholos-like chambers in the cairn of Barnenez in Brittany (4500-4000 BC). How old this type of building can be in Western Europe can be seen from the Cairn Er-Mané near Carnac . The megalithic structures of the Newgrange type in Ireland , Wales and Scotland are also examples of this technique (around 3150 BC). In Irish and Scottish basements , the corbel technique was also used in some cases.
This suggests that the technique originated in the Western European megalithic culture and spread from north to south. In the north-east and in Central Europe, a lot of work was done with wood very early on, so there has been no evidence to date. It can be assumed, however, that due to cultural contacts one had knowledge of it early on.
European Mediterranean
The oldest Mediterranean buildings with linear corbel roof constructions are probably the Maltese temples of Tarxien , which were built between 3000 and 2500 BC. Were erected. Cantilever vaults can also be found in Iberian dome tombs ( Los Millares ) and Sardinian giant tombs . The Navetas of the Balearic Islands and the Sardinian Nuraghi (approx. 1800–500 BC) are the last culture-defining structures in which the cantilever vault technique (partly) with megaliths was used.
The dome tombs on Crete or in the treasury of Atreus , which dates from around 1250 BC, are a little younger . Was built in Mycenae . The Cypriot tholoi of Chirokitia , which have not been preserved, could be from the same period . This knowledge probably also reached west of Anatolia and the Mediterranean coast of the Levant through the Minoan and Mycenaean expansion during the Iron Age.
The technical advancement of these corbel arches are conical vaults, round arches and stone domes, which were created during Roman times, which then culminated in what was then the largest cantilever dome of the Roman pantheon around 128 AD. These modern round arches and domed vaults also came to the Orient via the Romans, where they became a stylistic element of typical Islamic buildings.
Cantilever vaults in an old country house on Gozo - the horizontal finishing stones are supported by wooden beams
North africa
The technique of building with linear cantilever constructions can be found in the Egyptian pyramids , e.g. B. in the bent pyramid of the pharaoh Snefru (approx. 2600 BC) and in the Great Gallery of the Great Pyramid of Cheops , next to simultaneous gable roof constructions.
Asia
The pre-Islamic architecture of Asia has no real vaults or domes; The temple buildings of Indian or Indian architecture are also preferably flat-roofed. Only the pyramid roofs and Shikhara towers of some Indian temples ( Naresar ) show the gradual emergence of stone cantilever structures, which, however, were initially not visible inside the temple. The spread is apparently related to the Vedic religion and its temple buildings. With the emergence of Buddhism, this was spread to other regions of Far Asia.
It was only relatively late (around the 7th / 8th centuries) in India and other regions of South Asia ( Angkor ) that “false vaults” or “false domes” using cantilever technology also became visible inside the buildings. How long the Hindu craftsmen - even under Islamic rule - held on to the traditional corbel technique is shown by the portal arches and the corrugated stone dome over the entrance to the Quwwat-ul-Islam mosque in the Qutb complex in Delhi . Some corrugated domes in later Hindu ( Khajuraho ) or Jain temples ( Mount Abu , Ranakpur ) are among the unsurpassed masterpieces of their kind.
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Central America
The cantilever vault is also a typical stylistic element of Mayan architecture and an example of an elongated (i.e. rectangular) “false vault”. The inner wall of the “vault” was often formed by almost uncut long stones or stone slabs, which were plastered on the inside; only in the classical period (approx. 600–900 AD) were the stones of the false vault in some cases ( Uxmal , Kabah , Labná ) carved smooth. When it is filled with rubble, its weight exerts a force on the rear part of the corbels, holding them in position. In this way the Maya could build "vaults" up to a maximum of about 6 meters wide and any length. This was paid for by the fact that the ceilings of the rooms were steep and the roof structures were very heavy and very high. Other cultures in Mesoamerica did not know such constructions and on the entire American continent the principle of the "real vault" remained unknown until the arrival of the Europeans.
Mayan vaults inside the Temple of the 7 Dolls in Dzibilchaltún (around 600 AD)
literature
- Renate Löbbecke: Cantilever dome buildings. Verlag der Buchhandlung König, Cologne 2012, ISBN 978-3-86335-100-7 .