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Bald Arch
A bald arch is an arch featuring decay on the crucial keystones in stone or masonry buildings. Left unchecked, the progression of the condition will eventually lead to the failure of the arch and any structures supported by it. Causes The structural degradation of arches can occur for a variety of reasons. The stones or masonry components that make up an arch are vulnerable to physical and chemical attack over long periods of time. Sources of damage include atmospheric conditions, human induced mechanical stress, improper design, and natural disturbances like earthquakes or wildlife. Ground shifting Movement of the ground beneath an arch will eventually destroy it by changing the mechanical relationship between stones in the arch. An arch will evenly distribute forces across the surfaces of each stone when it is properly emplaced. Moving the ground below the arch will negatively affect the distribution of stress. An arch will slump in the center if the two sides move apart. If ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keystone (architecture)
A keystone (or capstone) is the wedge-shaped stone at the apex of a masonry arch or typically round-shaped one at the apex of a vault. In both cases it is the final piece placed during construction and locks all the stones into position, allowing the arch or vault to bear weight. In arches and vaults (such as quasi-domes) keystones are often enlarged beyond the structural requirements and decorated. A variant in domes and crowning vaults is a lantern. Keystones, as a hallmark of strength or good architecture, or their suggested form are sometimes placed in the centre of the flat top of doors, recesses and windows for decorative effect, so as to form an upward projection of a lintel. Although a masonry arch or vault cannot be self-supporting until the keystone is placed, the keystone experiences the least stress of any of the voussoirs, due to its position at the apex. Old keystones can decay due to vibration, a condition known as bald arch. Architecture In a rib-vaulted c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arch
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it. Arches may be synonymous with vaults, but a vault may be distinguished as a continuous arch forming a roof. Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture, and their systematic use started with the ancient Romans, who were the first to apply the technique to a wide range of structures. Basic concepts An arch is a pure compression form. It can span a large area by resolving forces into compressive stresses, and thereby eliminating tensile stresses. This is sometimes denominated "arch action". As the forces in the arch are transferred to its base, the arch pushes outward at its base, denominated "thrust". As the rise, i. e. height, of the arch decreases the outward thrust increases. In order to preserve arch action and prevent collapse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lindisfarne Priory (8521930908)
Lindisfarne, also called Holy Island, is a tidal island off the northeast coast of England, which constitutes the civil parish of Holy Island in Northumberland. Holy Island has a recorded history from the 6th century AD; it was an important centre of Celtic Christianity under Saints Aidan, Cuthbert, Eadfrith, and Eadberht of Lindisfarne. After the Viking invasions and the Norman conquest of England, a priory was re-established. A small castle was built on the island in 1550. Name and etymology Name Both the Parker and Peterborough versions of the Anglo-Saxon Chronicle for 793 record the Old English name . In the 9th-century the island appears under its Old Welsh name . The philologist Andrew Breeze, following up on a suggestion by Richard Coates, proposes that the name ultimately derives from Latin (English: Healing sland, owing perhaps to the island's reputation for medicinal herbs. The name Holy Island was in use by the 11th century when it appears in Latin as . The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscillation
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate complex interactions, such as those between atoms. Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science: for example the beating of the human heart (for circulation), business cycles in economics, predator–prey population cycles in ecology, geothermal geysers in geology, vibration of strings in guitar and other string instruments, periodic firing of nerve cells in the brain, and the periodic swelling of Cepheid variable stars in astronomy. The term ''vibration'' is precisely used to describe a mechanical oscillation. Oscillation, especially rapid oscillation, may be an undesirable phenomenon in proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic
Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads) for travel and transportation. Traffic laws govern and regulate traffic, while rules of the road include traffic laws and informal rules that may have developed over time to facilitate the orderly and timely flow of traffic. Organized traffic generally has well-established priorities, lanes, right-of-way, and traffic control at intersections. Traffic is formally organized in many jurisdictions, with marked lanes, junctions, intersections, interchanges, traffic signals, or signs. Traffic is often classified by type: heavy motor vehicle (e.g., car, truck), other vehicle (e.g., moped, bicycle), and pedestrian. Different classes may share speed limits and easement, or may be segregated. Some jurisdictions may have very detailed and complex rules of the road while others rely more on drivers' common sense and willingness to cooperate. Organization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buttress
A buttress is an architectural structure built against or projecting from a wall which serves to support or reinforce the wall. Buttresses are fairly common on more ancient buildings, as a means of providing support to act against the lateral (sideways) forces arising out of inadequately braced roof structures. The term ''counterfort'' can be synonymous with buttress and is often used when referring to dams, retaining walls and other structures holding back earth. Early examples of buttresses are found on the Eanna Temple (ancient Uruk), dating to as early as the 4th millennium BC. Terminology In addition to flying and ordinary buttresses, brick and masonry buttresses that support wall corners can be classified according to their ground plan. A clasping or clamped buttress has an L shaped ground plan surrounding the corner, an angled buttress has two buttresses meeting at the corner, a setback buttress is similar to an angled buttress but the buttresses are set back from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Falsework
Falsework consists of temporary structures used in construction to support a permanent structure until its construction is sufficiently advanced to support itself. For arches, this is specifically called centering. Falsework includes temporary support structures for formwork used to mold concreteHardie G.M. (1995) Building Construction: Principles, Practices, and Materials. New Jersey: Prentice Hall. (Pg 116, paragraph 1) in the construction of buildings, bridges, and elevated roadways. The British Standards of practice for falsework, BS 5975:2008, defines falsework as "Any temporary structure used to support a permanent structure while it is not self-supporting." History Falsework has been employed in bridge and viaduct construction since ancient times. The Romans were renowned for its use, as at the Limyra Bridge in Turkey. Until the turn of the 20th century almost all falsework was constructed from timber. To compensate for timber shortages in different regions and to rati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Brace
Dental may refer to: * Dental consonant, in phonetics * Dental Records, an independent UK record label * Dentistry, oral medicine * Teeth See also * * Dental care (other) * Dentist (other) A dentist is a practitioner of dentistry—a branch of medicine pertaining to the oral cavity. Dentist may also refer to: * The Dentists, a British band active in the 1980s and 1990s * ''The Dentist ''The Dentist'' is a 1996 American slasher f ... * Tooth (other) {{Disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medieval Architecture
Medieval architecture is architecture common in the Middle Ages, and includes religious, civil, and military buildings. Styles include pre-Romanesque, Romanesque, and Gothic. While most of the surviving medieval architecture is to be seen in churches and castles, examples of civic and domestic architecture can be found throughout Europe, in manor houses, town halls, almshouses, bridges, and residential houses. Designs Religious architecture The Latin cross plan, common in medieval ecclesiastical architecture, takes the Roman basilica as its primary model with subsequent developments. It consists of a nave, transepts, and the altar stands at the east end (see '' Cathedral diagram''). Also, cathedrals influenced or commissioned by Justinian employed the Byzantine style of domes and a Greek cross (resembling a plus sign), with the altar located in the sanctuary on the east side of the church. Military architecture Surviving examples of medieval secular architecture mainly s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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