Misplaced Pages

#417582

62-490: An arch is a curved structure capable of spanning a space while supporting significant weight. Arch , Arches , or The Arch may also refer to: Arch An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC , but structural load-bearing arches became popular only after their adoption by

124-567: A four-centred arch is made of two circle segments with distinct centers; usually the radius used closer to the springing point is smaller with a more pronounced curvature. Common in Islamic architecture ( Persian arch ), and, with upper portion flattened almost to straight lines ( Tudor arch ), in the English Perpendicular Gothic . A keel arch is a variant of four-centred arch with haunches almost straight, resembling

186-409: A proscenium arch in theaters used to frame the performance for the spectators, but is also applied to corbelled and triangular arches that are not based on compression. A typical true masonry arch consists of the following elements: A (left or right) half-segment of an arch is called an arc , the overall line of an arch is arcature (this term is also used for an arcade ). Archivolt

248-459: A catenary is often misclassified as a parabola (per Galileo , "the [hanging] chain fits its parabola almost perfectly" ). González et al. provide an example of Palau Güell , where researchers do not agree on classification of the arches or claim the prominence of parabolic arches, while the measurements show that just two of the 23 arches designed by Gaudi are actually parabolic. Three parabolic-looking curves in particular are of significance to

310-514: A collapse (the oldest arch still standing is at Ramesseum ). Sacred buildings exhibited either lintel design or corbelled arches. Arches were mostly missing in Egypt temples even after the Roman conquest , even though Egyptians thought of the arch as a spiritual shape and used it in the rock-cut tombs and portable shrines. Auguste Mariette suggested that this choice was based on a relative fragility of

372-405: A decorative pattern, primarily at the top of window openings. The corbel (also corbelled ) arch, made of two corbels meeting in the middle of the span, is a true arch in a sense of being able to carry a load, but it is false in a structural sense, as its components are subject to bending stress. The typical profile is not curved, but has triangular shape. Invented prior to the semicircular arch,

434-407: A fixed arch, a two-hinged arch, or a three-hinged arch. The fixed arch is most often used in reinforced concrete bridges and tunnels, which have short spans. Because it is subject to additional internal stress from thermal expansion and contraction, this kind of arch is statically indeterminate (the internal state is impossible to determine based on the external forces alone). The two-hinged arch

496-402: A given load, the best solid structures are compression-only; with the flexible materials, the same is true for tension-only designs. There is a fundamental symmetry in nature between solid compression-only and flexible tension-only arrangements, noticed by Robert Hooke in 1676: "As hangs the flexible line, so but inverted will stand the rigid arch", thus the study (and terminology) of arch shapes

558-898: A number of civilizations in the ancient Near East including the Levant , but their use was infrequent and mostly confined to underground structures, such as drains where the problem of lateral thrust is greatly diminished. An example of the latter would be the Nippur arch, built before 3800 BC, and dated by H. V. Hilprecht  (1859–1925) to even before 4000 BC. Rare exceptions are an arched mudbrick home doorway dated to c.  2000 BC from Tell Taya in Iraq and two Bronze Age arched Canaanite city gates, one at Ashkelon (dated to c.  1850 BC ), and one at Tel Dan (dated to c.  1750 BC ), both in modern-day Israel . An Elamite tomb dated 1500 BC from Haft Teppe contains

620-671: A parabolic vault which is considered one of the earliest evidences of arches in Iran. The use of true arches in Egypt also originated in the 4th millennium BC (underground barrel vaults at the Dendera cemetery). Standing arches were known since at least the Third Dynasty , but very few examples survived, since the arches were mostly used in non-durable secular buildings and made of mud brick voussoirs that were not wedge-shaped, but simply held in place by mortar , and thus susceptible to

682-433: A positive bending moment in the arch, while the inward-directed horizontal reaction from the spandrel/abutment provides a counterbalancing negative moment. As a result, the bending moment in any segment of the arch is much smaller than in a beam with the equivalent load and span. The diagram on the right shows the difference between a loaded arch and a beam. Elements of the arch are mostly subject to compression (A), while in

SECTION 10

#1732787938418

744-473: A rounded, not pointed, top. Common in Islamic architecture and Romanesque buildings influenced by it, it later became popular in the decorative motifs of the Late Gothic designs of Northern Europe. Each arc of an ogee arch consists of at least two circle segments (for a total of at least four), with the center of an upper circle being outside the extrados. After European appearance in the 13th century on

806-548: A section view of a capsized ship. Popular in Islamic architecture, it can be also found in Europe, occasionally with a small ogee element at the top, so it is sometimes considered to be a variation of an ogee arch. Curtain arch (also known as inflexed arch , and, like the keel arch, usually decorative ) uses two (or more) drooping curves that join at the apex. Utilized as a dressing for windows and doors primarily in Saxony in

868-459: A semicircle, is associated with Islamic architecture and was known in areas of Europe with Islamic influence ( Spain , Southern France , Italy ). Occasionally used in Gothics, it briefly enjoyed popularity as the entrance door treatment in the interwar England. A pointed arch consists of two (" two-centred arch " ) or more circle segments culminating in a point at the top. It originated in

930-497: A vault: "what would remain of the tombs and temples of Egyptians today, if they had preferred the vault?" Mycenaean architecture utilized only the corbel arches in their beehive tombs with triangular openings. Mycenaeans had also built probably the oldest still standing stone-arch bridge in the world, Arkadiko Bridge , in Greece. As evidenced by their imitations of the parabolic arches, Hittites most likely were exposed to

992-405: Is also highly recommended to prevent the aforementioned creaking and other problems as well. Subfloor isn't load bearing in residential construction. Although the use of steel joist hangers to support floor joists is recommended over a ledger supporting the joists because of house settling and nail separation, they are not required by code in most municipalities. However, toe nailing & end nailing

1054-511: Is inextricably linked to the study of hanging chains, the corresponding curves or polygons are called funicular . Just like the shape of a hanging chain will vary depending on the weights attached to it, the shape of an ideal (compression-only) arch will depend on the distribution of the load. There are multiple ways to classify an arch: A sequence of arches can be grouped together forming an arcade . Romans perfected this form, as shown, for example, by arched structures of Pont du Gard . In

1116-443: Is most often used to bridge long spans. This kind of arch has pinned connections at its base. Unlike that of the fixed arch, the pinned base can rotate, thus allowing the structure to move freely and compensate for the thermal expansion and contraction that changes in outdoor temperature cause. However, this can result in additional stresses, and therefore the two-hinged arch is also statically indeterminate, although not as much as

1178-436: Is nowhere near as effective as using hangers to support flooring systems. Twist straps provide a tension connection between two wood members. They resist uplift at the heel of a truss economically. When the strengthening is being done from the inside, the ideal connector to use is one that connects rafters or trusses directly to wall studs. This can only be done where the rafter or trusses are immediately above or immediately to

1240-417: Is the exposed (front-facing) part of the arch, sometimes decorated (occasionally also used to designate the intrados). If the sides of voussoir blocks are not straight, but include angles and curves for interlocking, the arch is called " joggled ". A true arch, due to its rise, resolves the vertical loads into horizontal and vertical reactions at the ends, a so called arch action . The vertical load produces

1302-626: Is the most common form of the pointed arch, with the centers of two circles forming the intrados coinciding with the springing points of the opposite segment. Together with the apex point, they form a equilateral triangle , thus the name. If the centers of circles are farther apart, the arch becomes a narrower and sharper lancet arch that appeared in France in the Early Gothic architecture ( Saint-Denis Abbey ) and became prominent in England in

SECTION 20

#1732787938418

1364-599: Is the one that frames the internal side of an opening in the external wall. Structurally, relieving arches (often blind or containing) can be used to take off load from some portions of the building (for example, to allow use of thinner exterior walls with larger window openings, or, as in the Roman Pantheon , to redirect the weight of the upper structures to particular strong points). Transverse arches , introduced in Carolingian architecture , are placed across

1426-517: Is the only one of the symmetric wedge shape), and that efficiently uses the compressive strength of the masonry in the same manner as a curved arch and thus requires a mass of masonry on both sides to absorb the considerable lateral thrust. Used in the Roman architecture to imitate the Greek lintels, Islamic architecture, European medieval and Renaissance architecture. The flat arch is still being used as

1488-400: Is therefore statically determinate. It is most often used for spans of medial length, such as those of roofs of large buildings. Another advantage of the three-hinged arch is that the reaction of the pinned bases is more predictable than the one for the fixed arch, allowing shallow, bearing-type foundations in spans of medial length. In the three-hinged arch "thermal expansion and contraction of

1550-433: Is what supports the flooring systems in residential homes and buildings built using lumber, from dropping and twisting thus creating an uneven walking surface. This is known as floor sagging. It is important to note that when laying wooden subfloor to apply adhesive to the joists which the subfloor will lay on to help prevent creaking & lateral movement and separation of the joists and subfloor. Using screws instead of nails

1612-490: The Ancient Romans in the 4th century BC . Arch-like structures can be horizontal, like an arch dam that withstands the horizontal hydrostatic pressure load. Arches are normally used as supports for many types of vaults , with the barrel vault in particular being a continuous arch. Extensive use of arches and vaults characterizes an arcuated construction , as opposed to the trabeated system, where, like in

1674-630: The Roman builders since the 4th century BC . It is considered to be the most common arch form, characteristic for Roman, Romanesque , and Renaissance architecture. A segmental arch , with a rounded shape that is less than a semicircle, is very old (the versions were cut in the rock in Ancient Egypt c. 2100 BC at Beni Hasan ). Since then it was occasionally used in Greek temples , utilized in Roman residential construction, Islamic architecture , and got popular as window pediments during

1736-426: The dead load increases with a distance from the center. Unlike regular arches, the flat arch (also known as jack arch , lintel arch , straight arch , plate-bande ) is not curved. Instead, the arch is flat in profile and can be used under the same circumstances as lintel . However, lintels are subject to bending stress, while the flat arches are true arches, composed of irregular voussoir shapes (the keystone

1798-466: The nave to compartmentalize (together with longitudinal separating arches) the internal space into bays and support vaults . A diaphragm arch similarly goes in the transverse direction, but carries a section of wall on top. It is used to support or divide sections of the high roof. Strainer arches were built as an afterthought to prevent two adjacent supports from imploding due to miscalculation. Frequently they were made very decorative, with one of

1860-528: The 13th-14th centuries their appeared as parts of flying buttresses used to counteract the thrust of Gothic ribbed vaults . A central part of an arch can be raised on short vertical supports, creating a trefoil -like shouldered arch . The raised central part can vary all the way from a flat arch to ogee. The shouldered arches were used to decorate openings in Europe from medieval times to Late Gothic architecture , became common in Iranian architecture from

1922-526: The 14th century, and were later adopted in the Ottoman Turkey . In a stilted arch (also surmounted ), the springing line is located above the imposts (on "stilts"). Known to Islamic architects by the 8th century, the technique was utilized to vertically align the apexes of arches of different dimensions in Romanesque and Gothic architecture. Stilting was useful for semicircular arches, where

Arch (disambiguation) - Misplaced Pages Continue

1984-564: The Egyptian designs, but used the corbelled technique to build them. The Assyrians , also apparently under the Egyptian influence, adopted the true arch (with a slightly pointed profile) early in the 8th century. In ancient Persia , the Achaemenid Empire (550 BC–330 BC) built small barrel vaults (essentially a series of arches built together to form a hall) known as iwan , which became massive, monumental structures during

2046-480: The Islamic architecture, arrived in Europe in the second half of the 11th century ( Cluny Abbey ) and later became prominent in the Gothic architecture . The advantages of a pointed arch over a semicircular one are flexible ratio of span to rise and lower horizontal reaction at the base. This innovation allowed for taller and more closely spaced openings, which are typical of Gothic architecture. Equilateral arch

2108-409: The Late Gothic and early Renaissance buildings (late 15th to early 16th century), associated with Arnold von Westfalen  [ de ] . When the intrados has multiple concave segments, the arch is also called a draped arch or tented arch . A similar arch that uses a mixture of curved and straight segments or exhibits sharp turns between segments is a mixed-line arch . The popularity of

2170-480: The Renaissance. A basket-handle arch (also known as depressed arch , three-centred arch , basket arch ) consists of segments of three circles with origins at three different centers (sometimes uses five or seven segments, so can also be five-centred , etc.). Was used in late Gothic and Baroque architecture . A horseshoe arch (also known as keyhole arch ) has a rounded shape that includes more than

2232-448: The advantages of the arch, the vault and the dome. Tie (engineering) In wood-frame construction ties are generally made of galvanized steel . Wood framing ties generally have holes allowing them to be fastened to the wood structure by nails or screws . The number and type of nails are specific to the tie and its use. The manufacturer generally specifies information as to the connection method for each of their products. Among

2294-517: The arch design: parabola itself, catenary , and weighted catenary . The arches naturally use the inverted (upside-down) versions of these curves. A parabola represents an ideal (all-compression) shape when the load is equally distributed along the span, while the weight of the arch itself is negligible. A catenary is the best solution for the case where an arch with uniform thickness carries just its own weight with no external load. The practical designs for bridges are somewhere in between, and thus use

2356-581: The arch will cause vertical movements at the peak pin joint but will have no appreciable effect on the bases," which further simplifies foundational design. The arch became popular in the Roman times and mostly spread alongside the European influence, although it was known and occasionally used much earlier. Many ancient architectures avoided the use of arches, including the Viking and Hindu ones. True arches, as opposed to corbel arches , were known by

2418-535: The arches using segments of a circle is due to simplicity of layout and construction, not their structural properties. Consequently, the architects historically used a variety of other curves in their designs: elliptical curves , hyperbolic cosine curves (including catenary ), and parabolic curves . There are two reasons behind the selection of these curves: The hyperbolic curve is not easy to trace, but there are known cases of its use. The non- circumferential curves look similar, and match at shallow profiles, so

2480-411: The architectures of ancient Greece, China, and Japan (as well as the modern steel-framed technique), posts and beams dominate. Arches had several advantages over the lintel , especially in the masonry construction: with the same amount of material it can have larger span, carry more weight, and can be made from smaller and thus more manageable pieces. Their role in construction was diminished in

2542-406: The beam a bending moment is present, with compression at the top and tension at the bottom (B). In the past, when arches were made of masonry pieces, the horizontal forces at the ends of an arch caused the need for heavy abutments (cf. Roman triumphal arch ). The other way to counteract the forces, and thus allow thinner supports, was to use the counter-arches , as in an arcade arrangement, where

Arch (disambiguation) - Misplaced Pages Continue

2604-761: The best examples provided by the Wells Cathedral . Strainer arches can be " inverted " (upside-down) while remaining structural. When used across railway cuttings to prevent collapse of the walls, strainer arches may be referred to as flying arches . A counter-arch is built adjacent to another arch to oppose its horizontal action or help to stabilize it, for example, when constructing a flying buttress . The large variety of arch shapes (left) can mostly be classified into three broad categories: rounded , pointed , and parabolic . "Round" semicircular arches were commonly used for ancient arches that were constructed of heavy masonry, and were relied heavily on by

2666-524: The corbel arch was used already in the Egyptian and Mycenaean architecture in the 3rd and 2nd millennium BC . Like a corbel arch, the triangular arch is not a true arch in a structural sense. Its intrados is formed by two slabs leaning against each other. Brick builders would call triangular any arch with straight inclined sides. The design was common in Anglo-Saxon England until

2728-786: The crucial connections in a structure, that would otherwise fail under the pressures of high winds, have a corresponding type of tie, generally made of galvanized or stainless steel , and intended to resist hurricane-force and other strong winds. "Hurricane clip" has two meanings in building construction: Seismic ties are used to securely fix cabinets, bookcases, desks, appliances, machinery & equipment to walls and/or floors to constrain their movement during earthquakes. Top mount, face mount, sloped/skewed, and variable pitch hangers for dimensional lumber, engineered wood I-joists, structural composite lumber and masonry wall. To give added strength in increase various load requirements over wood only. Joist hangers are used to prevent floor joists, which

2790-400: The curves that represent a compromise that combines both the catenary and the funicular curve for particular non-uniform distribution of load. The practical free-standing arches are stronger and thus heavier at the bottom, so a weighted catenary curve is utilized for them. The same curve also fits well an application where a bridge consists of an arch with a roadway of packed dirt above it, as

2852-628: The facade of the St Mark's Basilica , the arch became a fixture of the English Decorated style , French Flamboyant , Venetian , and other Late Gothic styles. Ogee arch is also known as reversed curve arch , occasionally also called an inverted arch . The top of an ogee arch sometimes projects beyond the wall, forming the so-called nodding ogee popular in 14th century England ( pulpitum in Southwell Minster ). Each arc of

2914-405: The fixed arch. The three-hinged arch is not only hinged at its base, like the two-hinged arch, yet also at its apex. The additional apical connection allows the three-hinged arch to move in two opposite directions and compensate for any expansion and contraction. This kind of arch is thus not subject to additional stress from thermal change. Unlike the other two kinds of arch, the three-hinged arch

2976-438: The front of the panels. The clips provide a secure mount for wall panels, partitions, frames, cabinets, and more. Once installed, clips wedge together to lock panels in place. To disengage panels, simply lift and remove. See Rafter ties are designed to tie together the bottoms of opposing rafters on a roof, to resist the outward thrust where the roof meets the house ceiling and walls. This helps keep walls from spreading due to

3038-408: The horizontal thrust of each arch is counterbalanced by its neighbors, and only the end arches need to buttressed . With new construction materials (steel, concrete, engineered wood ), not only the arches themselves got lighter, but the horizontal thrust can be further relieved by a tie connecting the ends of an arch. When evaluated from the perspective of an amount of material required to support

3100-621: The interior of hall churches , arcades of separating arches were used to separate the nave of a church from the side aisle, or two adjacent side aisles. Two-tiered arches , with two arches superimposed, were sometimes used in Islamic architecture , mostly for decorative purposes. An opening of the arch can be filled, creating a blind arch . Blind arches are frequently decorative, and were extensively used in Early Christian , Romanesque , and Islamic architecture. Alternatively,

3162-439: The late 11th century ( St Mary Goslany ). Mayan corbel arches are sometimes called triangular due to their shape. Few transformations can be applied to arch shapes. If one impost is much higher than another, the arch (frequently pointed ) is known as ramping arch  [ fr ] , raking arch , or rampant arch (from French : arc rampant ). Originally used to support inclined structures, like staircases , in

SECTION 50

#1732787938418

3224-617: The late 12th and early 13th centuries ( Salisbury Cathedral ). If the centers are closer to another, the result is a wider blunt arch . The intrados of the cusped arch (also known as multifoil arch , polyfoil arch , polylobed arch , and scalloped arch ) includes several independent circle segments in a scalloped arrangement. These primarily decorative arches are common in Islamic architecture and Northern European Late Gothic, can be found in Romanesque architecture . A similar trefoil arch includes only three segments and sometimes has

3286-519: The later Parthian Empire (247 BC–AD 224). This architectural tradition was continued by the Sasanian Empire (224–651), which built the Taq Kasra at Ctesiphon in the 6th century AD, the largest free-standing vault until modern times. An early European example of a voussoir arch appears in the 4th century BC Greek Rhodes Footbridge . Proto-true arches can also be found under

3348-458: The middle of the 19th century with introduction of the wrought iron (and later steel ): the high tensile strength of these new materials made long lintels possible. A true arch is a load-bearing arc with elements held together by compression. In much of the world introduction of the true arch was a result of European influence. The term false arch has few meanings. It is usually used to designate an arch that has no structural purpose, like

3410-420: The most common wood framing ties used is the hurricane tie or seismic tie used in the framing of wooden structures where wind uplift or seismic overturning is a concern. A hurricane tie (also known as hurricane clip or strip) is used to help make a structure (specifically wooden structures ) more resistant to high winds (such as in hurricanes ), resisting uplift, racking, overturning, and sliding. Each of

3472-411: The opening can be filled with smaller arches, producing a containing arch , common in Gothic and Romanesque architecture. Multiple arches can be superimposed with an offset, creating an interlaced series of usually (with some exceptions) blind and decorative arches. Most likely of Islamic origin, the interlaced arcades were popular in Romanesque and Gothic architecture. Rear-arch (also rere-arch )

3534-417: The ratio of the rise fixed at 1 ⁄ 2 of the span, but was applied to the pointed arches, too. The skew arch (also known as an oblique arch ) is used when the arch needs to turn in the horizontal plane, for example, when a bridge crosses the river at an angle different than 90°. A splayed arch is used for the case of unequal spans on the sides of the arch (when, for example, an interior opening in

3596-436: The side of studs below. In that case a twist strap connector can be used. A connector for connecting wall studs of two adjacent floors in a light frame building structure, the connector having a first attachment tab, a seat member, a diagonally slanted support leg, and a second attachment tab, all substantially planar. The connector is intended to be paired and the paired connectors joined by an elongated tie member that pierces

3658-402: The sill plates of the intervening floor structure. Sometimes referred to as an angle brace. The Angle tie is used to prevent displacement of building elements due to thrust. A brace/tie across an interior angle of a wooden frame, forming the hypotenuse and securing the two side pieces together. Similar to a French cleat, a Z-Clip allows for the installation of wall panels without screwing into

3720-485: The stairs of the temple of Apollo at Didyma and the stadium at Olympia . . The ancient Romans learned the semicircular arch from the Etruscans (both cultures apparently adopted the design in the 4th century BC ), refined it and were the first builders in Europe to tap its full potential for above ground buildings: The Romans were the first builders in Europe, perhaps the first in the world, to fully appreciate

3782-463: The wall is larger than the exterior one), the intrados of a round splayed arch is not cylindrical, but has a conical shape. A wide arch with its rise less than 1 ⁄ 2 of the span (and thus the geometric circle of at least one segment is below the springing line) is called a surbased arch (sometimes also a depressed arch ). A drop arch is either a basket handle arch or a blunt arch. The practical arch bridges are built either as

SECTION 60

#1732787938418

3844-452: The weight of the roof and anything on it, notably wet snow. In many or most homes, the ceiling joists also serve as the rafter ties. When the walls spread, the roof ridge will sag. A sagging ridge is one clue that the home may lack adequate rafter ties. Rafter ties form the bottom chord of a simple triangular roof truss. They resist the out-thrust of a triangle that's trying to flatten under the roof's own weight or snow load. They are placed in

#417582