In contrast to flat room boundaries such as concrete and beamed ceilings , all vaults have in common that no bending or tensile forces occur, but the payload and dead weight only cause compressive forces and as such are transferred to abutments such as walls or pillars . The loads acting between the supports cause a horizontal vault thrust , which has to be absorbed either by buttresses (wall template), massive abutments such as soil or foundations or by tension straps between the two supports.
Structural features of vaults
Type of load distribution
In contrast to the flat wooden beam ceiling or flat ceiling , compressive stresses only occur in a vault if the vault follows the support line . If no load acts on the vault, the support line corresponds to the catenoids . So it is possible to larger spaces without bending beam or truss and without auxiliary structures such as trusses , blasting works , or a support pillar to roof.
The vault not only transmits vertically acting forces to its bearing surfaces (e.g. the wall crown ), but also horizontally acting forces that have to be absorbed by an abutment . The abutment can either absorb the horizontal forces through tension rods stretched across the vault, pass them on to neighboring supporting structures or divert them to the ground via the foundation of the walls. In the latter case, the support line or the catenoids must extend beyond the vault and through the load-bearing walls so that they can withstand not only the weight but also the vault push. In churches and other buildings with wide vaults, the vaulting was absorbed either by suitably strong outer walls, by increasing the weight on the wall vertically (e.g. by adding battlements or turrets) or by wall pillars attached to the outside of the walls . The latter were creatively developed into a buttress in the Gothic period . The vault thrust increases with the total load (dead weight plus surcharge) and the ratio of width to height of the vault cross-section (the flatter the vault is).
The thickness of a weight- and material-saving arch is reduced according to the decreasing normal force from the point of support to the vertex.
Components of a vault
If you imagine a barrel vault divided by two crossing diagonals (based on the floor plan), the triangular segments between the abutments and the apex are called “cheeks” or “hip”. The segments between the shield arch and the apex are called "caps". The diagonals projected onto the reveal , which separate the cheeks and caps, are called the "ridge arch".
These segments are the building blocks for more complex vault shapes in which two or more “imaginary” vaults penetrate one another.
Inner curve line
The arch that is visible from the interior of the vault cross-section (the reveal) is called the inner vault line .
Simple barrel vaults are usually designed as semicircular vaults , the inner curve of which forms a semicircle.
In the case of the flatter segment or arched arches , the arching line forms less than a semicircle, i.e. a circle segment of less than 180 degrees.
With basket arch vaults , the radius of curvature increases from the support to the apex.
If the arching line represents a multi-pass arch or serrated arch , the arch consists of several composite cylinder segments with a smaller radius than that of the arch as a whole (similar to the edge of a flower).
Pointed arches consist of two segmental arches that lean against each other at an angle so that an acute angle is created at the apex.
With clinoid vaults , which are used in bridge construction, the pressure is distributed straight, usually horizontally.
In hyperbolic-parabolic vaults there is a complex, three-dimensional warped shape.
Vaults with unequal legs are called asymmetrical , those with only one leg are called one -hip .
With stilted vaults - as with stilted arches - one speaks of vaults, the vault legs of which are more or less extended vertically downwards.
Barrel vault type
If a vault has two parallel abutments of equal length, it is called a "barrel vault", regardless of the vault line. In the case of a round-arched cross-section one speaks of "round barrel", in the case of an ogival cross-section of "pointed barrel". A barrel vault is “straight” if it has a rectangular floor plan, “crooked” if it is parallelogram or trapezoidal. If the walls are not parallel to each other, a cone segment results instead of a cylinder segment.
A special form of the barrel vault is the " Prussian cap ceiling ". It consists of several parallel segmental arches. The height of the bulge is usually less than 15% of the width. Prussian caps were mainly used in the 19th century to design floor ceilings, but also as cellars. Prussian caps are also known under the term "Berliner Gewölbe".
Barrel vaults, which are intended to serve as a roof structure, are more often erected than wood or steel structures and then usually referred to as barrel roofs . Examples are the hammer beam vault and the Zollinger roof .
This is a "smaller barrel vault", which usually cuts at right angles (less often at an angle) into a "main vault". Such “secondary vaults” are arranged, for example, above window or door openings, in niches or smaller ancillary rooms, in order to improve the lighting of the vault or to enable lateral access. "Stitch caps" are often separated from the "main vault" by the so-called "cap wreath". If the vertices of two opposite stitch caps have the same height as the vertex of the main vault, a "cross vault" is created. Lance-cap vaults are often found in church buildings from the Baroque period .
If you close the ends of a "barrel vault" with two inwardly inclined cheeks, it becomes a "hollow vault". The "hollow vault" differs from the "monastery vault" in that it still has a (shortened) apex line, while all the cheeks of the "monastery vault" converge in a common vertex.
A "mirror vault" is a "hollow vault", the curves of which terminate in a central horizontal surface - the "ceiling mirror". The vault is trimmed below its (theoretical) apex line by a horizontal plane. This design is particularly suitable for ceiling paintings .
In the “monastery vault”, four cheeks are built on the sides of a rectangular floor plan, which rise to a common vertex. The two caps of a “barrel vault” are replaced by cheeks, it has four walls as abutments, and four ridge lines run in the corners.
Bohemian cap, Platzel vault
The Bohemian cap is a form of vault related to the hanging dome. A burr-free (! Therefore not a monastery vault) shell is stretched over a mostly square floor plan. The arches delimiting the vault area, which can be read on the side walls, are not semicircular in the Bohemian Cap, but form very flat segmental arches , so the Platzel vault is much flatter in contrast to the hanging dome.
“ Domes ” can be seen as a special form of the “monastery vault” with a polygonal, circular or oval floor plan - they also have only one apex and the entire circumference of their floor plan forms the abutment. Typical examples of church architecture are octagonal so-called "monastery domes" over the crossings .
Larger domes are often built with structures made of wood and steel and then usually no longer referred to as vaults . Examples are the Schwedler domes , geodesic domes and domes in the inch-lamellar construction .
If the two cheeks of a “barrel vault” with a square floor plan are replaced by two caps with the same ridge arch, a “cross vault” with four ridges, four shields and four abutment points in the corners is created. While the ridges in the "monastery vault" are designed as inner corners, in the "cross vault" they are outer corners.
If the caps are pass instead of a uniform concave curvature towards the apex in a convex curvature, so bulged spherical (and optionally the top end in a point), one speaks of Busung or bussed vault.
The simple "groin vault" can also be referred to as a "groin vault", which is considered typical of Romanesque architecture. In the “cross rib vault”, on the other hand, the edges of the ridges are designed as decorative “cross ribs”, which represent a typical element of Gothic architecture.
If several "cross vaults" follow one another in the longitudinal axis of a "barrel vault", the arches adjoining the longitudinal wall are called shield arches, while the arches between the individual vaults are called " belt arches " or "belts". If the vaults of the central and side aisles are at the same level ( hall church ), the vaulted arches that separate the longitudinal aisles from one another are referred to as " dividing arches ".
The technique of the groin vault was developed in antiquity and brought to perfection in the Roman baths - one is still preserved in the imperial tetrapylon of Cáparra , as well as in the church of Santa Maria degli Angeli e dei Martiri in Rome, the former frigidarium of the Diocletian baths . In the early Middle Ages , this dome shape was resumed.
Groin vaults can be defined as two penetrating barrel vaults, creating four caps. Where the caps meet, there are two crossing diagonal ridges that start from the four abutment points in the corners. Since the diagonal ridges have a depressed, statically unfavorable shape when the cross vault is purely geometrically formed from two penetrating round arched barrels, most cross vaults are elevated towards the center. Because the diagonal ridge, which has a larger span than the shield arches (because the diagonal of a rectangle is longer than its edges), becomes higher than the shield arches in the statically advantageous round arch design because of its larger radius. One then says that the vault was built “with a stitch ” or “busted”. A fully closed formwork is always required to build a groin vault, as the vault only supports it after it has fully hardened.
If the vault rises sharply towards the middle, so that the apex or the keystone of the vault is significantly higher than the apex of the shield arches, one speaks of the domical vault . This can be found in the Middle Ages especially in the western French regions of Anjou and Maine ( Angers Cathedral , Saint Serge in Le Mans, Le Mans Cathedral ) and in Germany in Westphalia ( Münster Cathedral , Cistercian Church Marienfeld ) as well as in the Mecklenburg regions, which were built according to Westphalian models late Romanesque-early Gothic village churches with busted vaults. Often domical vaults are formed by longitudinal and transverse ribs as eight-part vaults.
Cross rib vaults are similar in shape to the groin vaults, but have diagonal arches made of stone on the crossing ridges, the cross ribs. There is a keystone at the intersection of the ribs .
The vault is formed and held by the self-supporting ribs. The ribs cross each other like the diagonals in a rectangle; they divert the pressure and shear forces of the vault onto the pillars . Each cross rib is made up of several profiled stones .
The ribbed vault is a typical element of Gothic architecture . It made high church spaces possible. Compared to the barrel vault , the walls were relieved and could be provided with larger window areas.
The aisle vaults of Durham Cathedral are considered to be the first rib vaults , shortly before 1100 and thus 40 years before the beginning of the Gothic period with the ambulatory of the abbey church of Saint-Denis . In the transept vaults of the Speyer Cathedral , the construction time of the ribs is questionable, as the neighboring crossing dome was stabilized in the Baroque period.
If a rib vault is divided into six caps in the transverse direction by a rib going from the keystone to the outer walls, one speaks of a six-part vault , which is typical for early Gothic church buildings. When using the six-part vault, the so-called bound system is created , in which a central nave vault is assigned two aisle vaults on each side. If there is also a crown rib in the longitudinal direction, an eight-part vault is created.
Cross rib vaults can be supported by further ribs, so that rib fans, rib stars, rib nets or other patterns can arise. Then the vaults are named accordingly (fan vaults, star vaults, net vaults, loop rib vaults, etc.). The shapes of the rib vaults experienced a significant variation. Fan vaults were particularly influential in the English Gothic, and loop rib vaults in the late Gothic in Upper Saxony and Bohemia , for example in the parish churches in Annaberg , Kuttenberg and Königswiesen or in the Albrechtsburg Castle in Meißen .
Radial rib vault
A radial rib vault is present when ribs extend from a centrally located keystone, for example at the same angles, to the wall of the (for example round or semicircular) room. Such a vault can be found in the shell tower above the chapel in Hinterglauchau Castle . The example mentioned can be classified between 1485 and 1534.
The "star vault" is a cross vault in which the vault caps are subdivided again. If ribs of the second order are raised from the three corner points in each such triangular vault cap, which unite in an apex, another small vault is created. This creates the star shape of the ribs that gave it its name. Examples of star vaults can also be found in the brick Gothic , including in the Dominican church in Kulm and in the Cistercian abbey church in Pelplin .
"Cell vaults" (also "diamond vaults") are a special form of the late Gothic vaults. Instead of walling the triangles between the ribs (or ridges) of a star vault as continuous, curved caps, these were formed from three straight surfaces as pyramidal cavities, so that a multi-fold ceiling is created. The net of the supporting struts was filled with small vaulted "cells" without any falsework. Cell vaults are (compared to the other Gothic vault forms) relatively little common. Examples can be found in the Albrechtsburg in Meißen , in the Marienkirche in Danzig , in the Göglhaus in Krems and in Greinburg Castle in Grein on the Danube.
"Fan vaults" (palm vaults, radiated vaults) arise when more than three ribs extend from supports or services on the wall, which means that per yoke unit, not the cross shape of the cross rib vault, but two fan-shaped fans running towards each other. English fan vaults consist of conical, masonry shells rising from the rib base, the spaces between which are covered by horizontal panels in the middle of the vault.
Fan vault in Bath Abbey , England
Rib vault made of wood, St. Bavo's Church , Haarlem, Netherlands
Rib vault in San Baudelio de Berlanga (12th century)
Due to its complex geometry, this type of construction only found widespread use in modern architecture. It is a surface that is warped in all three dimensions and that follows the force curves in the case of roof surfaces that are not flat. Early forms were realized with flat brick vaults ("Catalan vault"), today they are often made of concrete or as a glue-truss construction, as "flying roofs" they can also consist of textile fabrics .
Since vaults usually only become stable when the keystone or keystones have been set (exception e.g. Santa Maria del Fiore in Florence), they must be built up using falsework that define the inner reveal from below . After the keystones have been set, the falsework can be removed. In contrast, steep cantilever vaults and certain Nubian vaults can also be erected without falsework. See also cantilever structures made of dry masonry .
Vaults were mainly made of house stone , brick or quarry stone , more rarely in cast mortar . Particularly light vaults were made from tufa limestone or tuff stone or hollow, burnt potted stone (tuff vault, pot vault).
As an aid in the square cross vault, belt arches are often drawn in beforehand , which rest on pillars. Semicircular templates are used to create the belt arches. Then the cross vault can be placed on the belt arches.
More recently, especially since the 1920s, thin-shell reinforced concrete has also been used as a stable building material for vaults.
Cantilever vaults , also known as false vaults , with horizontally joined layers of stone have been used since prehistoric times; in the 14th century BC Chr. Z. B. from Mycenae . They were built regionally until modern times.
The real vault construction with radially joined stones was already known to the Egyptians and Assyrians and was introduced into the building practice of the West by the Etruscans . The Romans in particular developed vaults and built barrel, cross and domed vaults. Some outstanding examples have survived in Rome, such as: B. the Pantheon and the Maxentius basilica .
In Egypt, brick vaults have been used since the early 3rd millennium BC. Often used and from the end of the 8th century BC. Vaulted vaults were built. Monumental temple buildings of the Pharaonic culture in the Nile Valley managed without the use of vaults, as even the huge portals with widths of more than 7 meters were spanned with ashlar beams.
The early Christian basilicas were usually not vaulted, but flat-roofed. Significant late antique vaulted buildings can be found in Ravenna , for example San Vitale . In Byzantine architecture, the domed churches flourished. The most important example is the Hagia Sophia in Istanbul .
With the conquest of Rome by the Teutons , the construction of vaults in western Europe declined sharply from the 5th century onwards. One of the few exceptions was the after Byzantine model built Aachen Cathedral with its high dome.
The dome vaults received their highest training in Islamic architecture and the cross vaults in medieval and Renaissance architecture . Initially, only the narrower and lower aisles were arched, the wide, high central aisles remained flat. This did not change until around the year 1000. At first the barrel vault was the main form of construction. In Burgundy, the pointed barrel vault was created when the church of Cluny III was built. The first fully vaulted structure was Durham Cathedral . The ribbed vault developed into the standard Gothic vault shape . By reinforcing the vault abutments with the help of buttresses and buttresses, the builders achieved vault heights of up to 48 meters ( Beauvais Cathedral ). The late Gothic formed decorative rib figures, especially in England and Germany, the star, net and fan vaults.
With the end of the Gothic period, the renaissance of church construction returned to barrel vaulting, which was often opened by side stab caps to the windows. Large-span mirror vaults were often used for the Baroque ceiling paintings, for example Balthasar Neumann's vault above the stairwell of the Würzburg Residence . In addition, the Renaissance ushered in a new heyday of dome construction, which the dome of St. Peter's Basilica in Rome stands for.
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- About vault
- www.Stuck-Katalog.de: vault
- Lexicon construction technology: vaults
- Clay tube vault in Landsberg (Fusée céramique)
- Bohemian cap. Retrieved September 24, 2019 .
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- Information from the Speyer cathedral builder Coletto
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- Announcement of the lecture by Prof. Ulrike Fauerbach " Vaults in Ancient Egypt. Origins, Development, Meaning and Alternative " in Momentum Magazine, April 12, 2017