A corbel arch is an arch-like construction method that uses the architectural technique of corbeling to span a space or void in a structure, such as an entranceway in a wall or as the span of a bridge. A corbel vault uses this technique to support the superstructure of a building's roof. A corbel arch is constructed by offsetting successive courses of stone at the springline of the walls so that they project towards the archway's center from each supporting side, until the courses meet at the apex of the archway. For a corbeled vault covering the technique is extended in three dimensions along the lengths of two opposing walls. Although an improvement in load-bearing efficiency over the post and lintel design, corbeled arches are not self-supporting structures, the corbeled arch is sometimes termed a "false arch" for this reason. Unlike "true" arches, not all of the structure's tensile stresses caused by the weight of the superstructure are transformed into compressive stresses. Corbel arches and vaults require thickened walls and an abutment of other stone or fill to counteract the effects of gravity, which otherwise would tend to collapse each side of the archway inwards.
The Newgrange passage tomb has an intact corbel arch supporting the roof of the main chamber, the buildings of the monastery at Skellig Michael are constructed using this method. During the Fourth Dynasty reign of Pharaoh Sneferu, the Ancient Egyptian pyramids used corbel vaults in some of their chambers; these monuments include the Red Pyramid. The Great Pyramid of Giza uses corbel arches at the Grand Gallery. Corbel arches and vaults are found in various places around the ancient Mediterranean. In particular, corbelled burial vaults constructed below the floor are found in Ebla in Syria, in Tel Hazor, Tel Megiddo in Israel. Ugarit has corbelled constructions. Nuraghe constructions in ancient Sardinia, dating back to 1900 BC, use similar corbel techniques; the use of Beehive tombs on the Iberian peninsula and elsewhere around the Mediterranean, going back to 3000 BC, is similar. The Hittites in ancient Anatolia were building corbelled vaults; the earliest ones date to the 16th century BC. Some similarities are found between the Mycenaean construction techniques.
Yet the Hittite corbelled. The ruins of ancient Mycenae feature many corbel arches and vaults, the "Treasury of Atreus" being a prominent example; the Arkadiko Bridge is one of four Mycenean corbel arch bridges which are part of a former network of roads, designed to accommodate chariots, between Tiryns and Epidauros in the Peloponnese, in Greece. Dating to the Greek Bronze Age, it is one of the oldest arch bridges still in use; the well-preserved hellenistic Eleutherna Bridge on Crete has an unusually large span of nearly 4 m. Corbeled arches are a distinctive feature of certain pre-Columbian Mesoamerican constructions and historical/regional architectural styles in that of the Maya civilization; the prevalence of this spanning technique for entrances and vaults in Maya architecture is attested at a great many Maya archaeological sites, is known from structures dating back to the Formative or Preclassic era. By the beginning of the Classic era corbeled vaults are a near-universal feature of building construction in the central Petén Basin region of the central Maya lowlands.
Before the true arch was introduced in Indo-Islamic architecture, the arches in Indian buildings were trabeated or corbelled. In North India in the state of Orissa, "the temples at Bhubaneswar were built on the principle of corbelled vaulting, seen first in the porch of the Mukteswar and, technically speaking, no fundamental change occurred from this time onwards."It took a century from the start of the Delhi Sultanate in 1206 for the true arch to appear. By around 1300 true domes and arches with voussoirs were being built; the Adhai Din Ka Jhonpra mosque in Ajmer, Rajasthan is an example of Islamic architecture drawing on Persia and Central Asia, where builders were well used to the true arch, that prefers to stick with the corbelled arch that Indian builders were used to. The candi or temples of Indonesia which are constructed between 8th to 15th century, are made use of corbel arch technique to create a span opening for gate or inner chamber of the temple; the notable example of corbel arch in Indonesian classic temple architecture is the arches of Borobudur.
The interlocking andesite stone blocks creating the corbel arch, is notable for its "T" formed lock on the center top of the corbel arch. All the temples in Angkor made use of the corbel arch, between 12th centuries. Beehive house Beehive tomb Catenary arch Corbelling Parabolic arch Coe, Michael D.. The Maya. London: Thames & Hudson. ISBN 0-500-27455-X. Harle, J. C; the Art and Architecture of the Indian Subcontinent, 2nd edn. 1994, Yale University Press Pelican History of Art, ISBN 0300062176 An illustrated glossary of the terms used masonry construction
A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member; the term column applies to a large round support with a capital and a base or pedestal, made of stone, or appearing to be so. A small wooden or metal support is called a post, supports with a rectangular or other non-round section are called piers. For the purpose of wind or earthquake engineering, columns may be designed to resist lateral forces. Other compression members are termed "columns" because of the similar stress conditions. Columns are used to support beams or arches on which the upper parts of walls or ceilings rest. In architecture, "column" refers to such a structural element that has certain proportional and decorative features. A column might be a decorative element not needed for structural purposes. All significant Iron Age civilizations of the Near East and Mediterranean made some use of columns.
In Ancient Egyptian architecture as early as 2600 BC the architect Imhotep made use of stone columns whose surface was carved to reflect the organic form of bundled reeds, like papyrus and palm. Their form is thought to derive from archaic reed-built shrines. Carved from stone, the columns were decorated with carved and painted hieroglyphs, ritual imagery and natural motifs. Egyptian columns are famously present in the Great Hypostyle Hall of Karnak, where 134 columns are lined up in 16 rows, with some columns reaching heights of 24 metres. One of the most important type are the papyriform columns; the origin of these columns goes back to the 5th Dynasty. They are composed of lotus stems which are drawn together into a bundle decorated with bands: the capital, instead of opening out into the shape of a bellflower, swells out and narrows again like a flower in bud; the base, which tapers to take the shape of a half-sphere like the stem of the lotus, has a continuously recurring decoration of stipules.
Some of the most elaborate columns in the ancient world were those of the Persians the massive stone columns erected in Persepolis. They included double-bull structures in their capitals; the Hall of Hundred Columns at Persepolis, measuring 70 × 70 metres, was built by the Achaemenid king Darius I. Many of the ancient Persian columns are standing, some being more than 30 metres tall. Tall columns with bull's head capitals were used for porticoes and to support the roofs of the hypostylehall inspired by the ancient Egyptian precedent. Since the columns carried timber beams rather than stine, they could be taller and more widerly spaced than Egyptian ones; the Minoans used whole tree-trunks turned upside down in order to prevent re-growth, stood on a base set in the stylobate and topped by a simple round capital. These were painted as in the most famous Minoan palace of Knossos; the Minoans employed columns to create large open-plan spaces, light-wells and as a focal point for religious rituals.
These traditions were continued by the Mycenaean civilization in the megaron or hall at the heart of their palaces. The importance of columns and their reference to palaces and therefore authority is evidenced in their use in heraldic motifs such as the famous lion-gate of Mycenae where two lions stand each side of a column. Being made of wood these early columns have not survived, but their stone bases have and through these we may see their use and arrangement in these palace buildings; the Egyptians and other civilizations used columns for the practical purpose of holding up the roof inside a building, preferring outside walls to be decorated with reliefs or painting, but the Ancient Greeks, followed by the Romans, loved to use them on the outside as well, the extensive use of columns on the interior and exterior of buildings is one of the most characteristic features of classical architecture, in buildings like the Parthenon. The Greeks developed the classical orders of architecture, which are most distinguished by the form of the column and its various elements.
Their Doric and Corinthian orders were expanded by the Romans to include the Tuscan and Composite orders. Columns, or at least large structural exterior ones, became much less significant in the architecture of the Middle Ages; the classical forms were abandoned in both Byzantine architecture and the Romanesque and Gothic architecture of Europe in favour of more flexible forms, with capitals using various types of foliage decoration, in the West scenes with figures carved in relief. Furing the Romanesque period, builders continued to reuse and imitate ancient Roman columns wherever possible. Where new, the emphasis was as illustrated by twisted columns, they were decorated with mosaics. Renaissance architecture was keen to revive the classical vocabulary and styles, the informed use and variation of the classical orders remained fundamental to the training of architects throughout Baroque and Neo-classical architecture. Early columns were constructed of some out of a single piece of stone. Monolithic columns are among the heaviest stones used in architecture.
Other stone columns are created out of multiple sections of mortared or dry-fit together. In many classical sites, sectioned columns were carved with a centre hole or depression so that they could be pegged together, using stone or metal pins; the design of
A machicolation is a floor opening between the supporting corbels of a battlement, through which stones or other material, such as boiling water or boiling cooking oil, could be dropped on attackers at the base of a defensive wall. A smaller version found on smaller structures is called a box-machicolation; the word derives from the Old French word machecol, mentioned in Medieval Latin as machecollum from Old French machier'crush','wound' and col'neck'. Machicolate is only recorded in the 18th century in English, but a verb machicollāre is attested in Anglo-Latin. Both the Spanish and Portuguese words denoting this structure, are composed from "matar canes" meaning "killing dogs", the latter word being a slur referring to infidels. In Italy and countries which were influenced by the Italian language, such as Malta, it was known as piombatoio. Similar to a machicolation is a smaller version which opens similar to an enclosed balcony from a tower rather than a larger structure; this is called a box-machicolation.
The design of a machicoulis originates from the Middle East, where they are found on defensive walls. The original Arabian design is rather small, similar to the domestic wooden balcony known as mashrabiya. However, different from the domestic balcony, for defense purposes the Middle-East version of the machicoulis prominently features a wide opening at the bottom; the opening allows the dropping of hot water and other material intended to cause harm to the enemy below. The otherwise enclosed opening adapted from that of a closed balcony provides cover from enemy attack while using it. Machicolations were more common in French castles than English, where they were restricted to the gateway, as in the 13th-century Conwy Castle. One of the first examples of machicolation that still exists in northern France is Château de Farcheville built in 1291 outside Paris; the origins are from Syria and the Crusaders brought their design to Europe. Machicolations were a common feature in many towers in Rhodes, which were built by the Knights Hospitallers.
After the Knights were given rule over Malta, machicolations became a common feature on rural buildings, until the 18th century. Buildings with machicolations include Cavalier Tower, Gauci Tower, the Captain's Tower, Birkirkara Tower and Tal-Wejter Tower. A hoarding is a similar structure made of wood temporarily constructed in the event of a siege. Advantages of machicolations over wooden hoardings include the greater strength and fire resistance of stone. Machicolation was used for decorative effect with spaces between the corbels but without the openings, subsequently became a characteristic of many non-military buildings. Battlement Defensive walls Arrow slit Bretèche Jettying Murder hole Glossary of Medieval Art and Architecture: machicolation. Machicolation
A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, furnace, incinerator or fireplace from human living areas. Chimneys are vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect; the space inside a chimney is called the flue. Chimneys are adjacent to large industrial refineries, fossil fuel combustion facilities or part of buildings, steam locomotives and ships. In the United States, the term'Smokestack industry' refers to the environmental impacts of burning fossil fuels by industrial society including the electric industry during its earliest history; the term smokestack is used when referring to locomotive chimneys or ship chimneys, the term funnel can be used. The height of a chimney influences its ability to transfer flue gases to the external environment via stack effect. Additionally, the dispersion of pollutants at higher altitudes can reduce their impact on the immediate surroundings.
The dispersion of pollutants over a greater area can reduce their concentrations and facilitate compliance with regulatory limits. Romans used tubes inside the walls to draw smoke out of bakeries but chimneys only appeared in large dwellings in northern Europe in the 12th century; the earliest extant example of an English chimney is at the keep of Conisbrough Castle in Yorkshire, which dates from 1185 AD. However, they did not become common in houses until the 17th centuries. Smoke hoods were an early method of collecting the smoke into a chimney. Another step in the development of chimneys was the use of built in ovens which allowed the household to bake at home. Industrial chimneys became common in the late 18th century. Chimneys in ordinary dwellings were first built of plaster or mud. Since chimneys have traditionally been built of brick or stone, both in small and large buildings. Early chimneys were of a simple brick construction. Chimneys were constructed by placing the bricks around tile liners.
To control downdrafts, venting caps with a variety of designs are sometimes placed on the top of chimneys. In the 18th and 19th centuries, the methods used to extract lead from its ore produced large amounts of toxic fumes. In the north of England, long near-horizontal chimneys were built more than 3 km long, which terminated in a short vertical chimney in a remote location where the fumes would cause less harm. Lead and silver deposits formed on the inside of these long chimneys, periodically workers would be sent along the chimneys to scrape off these valuable deposits; as a result of the limited ability to handle transverse loads with brick, chimneys in houses were built in a "stack", with a fireplace on each floor of the house sharing a single chimney with such a stack at the front and back of the house. Today's central heating systems have made chimney placement less critical, the use of non-structural gas vent pipe allows a flue gas conduit to be installed around obstructions and through walls.
In fact, most modern high-efficiency heating appliances do not require a chimney. Such appliances are installed near an external wall, a noncombustible wall thimble allows a vent pipe to run directly through the external wall. On a pitched roof where a chimney penetrates a roof, flashing is used to seal up the joints; the down-slope piece is called an apron, the sides receive step flashing and a cricket is used to divert water around the upper side of the chimney underneath the flashing. Industrial chimneys are referred to as flue gas stacks and are external structures, as opposed to those built into the wall of a building, they are located adjacent to a steam-generating boiler or industrial furnace and the gases are carried to them with ductwork. Today the use of reinforced concrete has entirely replaced brick as a structural component in the construction of industrial chimneys. Refractory bricks are used as a lining if the type of fuel being burned generates flue gases containing acids. Modern industrial chimneys sometimes consist of a concrete windshield with a number of flues on the inside.
The 300 m chimney at Sasol Three consists of a 26 m diameter windshield with four 4.6 metre diameter concrete flues which are lined with refractory bricks built on rings of corbels spaced at 10 metre intervals. The reinforced concrete can be sliding formwork; the height is to ensure the pollutants are dispersed over a wider area to meet legal or other safety requirements. A flue liner is a secondary barrier in a chimney that protects the masonry from the acidic products of combustion, helps prevent flue gas from entering the house, reduces the size of an oversized flue. Since the 1950s, building codes in many locations require newly built chimneys to have a flue liner. Chimneys built without a liner can have a liner added, but the type of liner needs to match the type of appliance it services. Flue liners may be concrete tile, metal, or poured in place concrete. Clay tile flue liners are common in the United States, although it is the only liner that does not meet Underwriters Laboratories 1777 approval and they have problems such as cracked tiles and improper installation.
Clay tiles are about 2 feet long, available in various sizes and shapes, are installed in new construction as the chimney is built. A refractory cement is used between each tile. Metal liners may be stainless steel, aluminum, or galvanized iron and may be flexible or rigid pipes. Stainless stee
A bracket is an architectural element: a structural or decorative member. It can be made of wood, plaster, metal, or Mardi Norton, it projects from a wall to carry weight and sometimes to "...strengthen an angle". A corbel and console are types of brackets. In mechanical engineering a bracket is any intermediate component for fixing one part to another larger, part. What makes a bracket a bracket is that it is intermediate between the two and fixes the one to the other. Brackets vary in shape, but a prototypical bracket is the L-shaped metal piece that attaches a shelf to a wall: its vertical arm is fixed to one element, its horizontal arm protrudes outwards and holds another element; this shelf bracket is the same as the architectural bracket: a vertical arm mounted on the wall, a horizontal arm projecting outwards for another element to be attached on top of it or below it. To enable the outstretched arm to support a greater weight, a bracket will have a third arm running diagonally between the horizontal and vertical arms, or the bracket may be a solid triangle.
By extension any object that performs this function of attaching one part to another component is called a bracket though it may not be L-shaped. Common examples that are not L-shaped at all but attach a smaller component to a larger and are still called brackets are the components that attach a bicycle lamp to a bicycle, the rings that attach pipes to walls. Brackets can support many architectural items, including a wall, parapets, the spring of an arch, pergola roof, window box, or a shelf; the term is used to describe a shelf designed to hold a statue. In adjustable shelving systems, the bracket may be in two parts, with the load-bearing horizontal support fitting into a wall-mounted slotted vertical metal strip. Brackets are an element in the systems used to mount modern facade cladding systems onto the outside of contemporary buildings, as well as interior panels. Architectural sculptures Brackets are in the form of architectural sculptures with reliefs of objects and scrolls. Depending on their material, decorated ones cast, or molded.
They can be of cast stone or resin-foam materials with faux finishes for use on new buildings in historic revival styles of architecture. Some brackets and corbels are only ornamental, serve no actual supporting purpose. Corbel Dougong, wooden brackets found in East Asian architecture Index: Architectural elements Media related to Brackets at Wikimedia Commons
Royal Palace of Ugarit
The Royal Palace of Ugarit was the royal residence of the rulers of the ancient kingdom of Ugarit on the Mediterranean coast of Syria. The palace was excavated with the rest of the city from the 1930s by French archaeologist Claude F. A. Schaeffer and is considered one of the most important finds made at Ugarit; the palace, located in the north-west corner of the city, spanned an area of 6,500 square metres. The palace area was surrounded by a fortified wall that dates back to the 15th-century BC; the palace's main gate was protected by an array of towers, dubbed the Fortress, with 5 metres thick walls. The palace consisted of ninety rooms divided between two floors; the rooms were built around four smaller ones. The western end of the palace had a large garden. In the north side of the palace, three underground burial chambers were constructed; the ground floor was used for administrative purposes and included offices, archives and staff dwellings. The second floor housed the family quarters, was accessed through twelve staircases.
The palace had three entrances: the main gate on the northwest near the Fortress, two smaller entrances in the northeast and the southwest. The palace was built in four major stages between the 15th and 13th-century BC, it was built out of ashlar stone blocks and wooden crossbeams, with a thick coat of plain plaster covering the walls. The fortified wall, which dates back to the 15th-century BC, was built with packed stones at the bottom and had an outward slope of 45 degrees; the layout is typical of palaces of the Ancient Near East. The irregular outline of the palace and the asymmetrical layout are evidence of constant additions and alterations; the burial chambers had corbelled vaults which show a connection with Hittite and Mycenaean architecture. After the chance discovery of Ugarit by local peasants in 1929, French archaeologist, Claude F. A. Schaeffer led ten excavation campaigns at the site which only covered the northwest corner. Excavations stopped with the advent of World War II and only resumed in 1948.
Between 1950–1955 Schaeffer led concentrated excavations at the palace which unearthed a vast corpus of tablets and artefacts. Objects found at the site included ivory carvings, stone stelae, figurines. An Egyptian-made alabaster vase was found damaged; the ornamentation on the vase depicts the wedding of Ugarit King Niqmaddu II to an upper-class Egyptian woman. Other vases of Egyptian origin found at the site include ones carrying the cartouches of Egyptian Kings Ramesses II and Horemheb. Eight archives of cuneiform tablets were excavated in the palace complex; the corpus included more than a 1,000 tablets written in Akkadian and Ugaritic. A small corpus of Hurrian and Hittite tablets were discovered as well; the tablets were organized by subject in different wings. They included administrative reports about Ugarit's dependencies, judicial records, official correspondence with other rulers and practice tablets that new scribes used to learn writing; the tablets included about 36 hymns, known as the Hurrian songs