Editing Arch (section)

=== Variations ===
Few transformations can be applied to arch shapes.

If one [[Impost (architecture)|impost]] is much higher than another, the arch (frequently [[pointed arch|pointed]]) is known as ''[[ramping arch]]'', ''raking arch'',{{sfn | Davies | Jokiniemi | 2008 | p=305}} or ''rampant arch'' (from {{langx|fr|arc rampant}}).{{sfn | Woodman | Bloom | 2003 | loc=Ramping}} Originally used to support inclined structures, like stairs, in the 13th-14th centuries they appeared as parts of [[flying buttress]]es used to counteract the thrust of Gothic [[ribbed vault]]s.<ref name=treccani1991/> 

A central part of an arch can be raised on short vertical supports, creating a [[trefoil arch|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 the 14th century, and were later adopted in the [[Ottoman Turkey]].{{sfn | Woodman | Bloom | 2003 | loc=Shouldered}}

In a [[stilted arch]] (also ''surmounted''<ref>{{M-W|surmounted arch}}</ref>), 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.{{sfn | Woodman | Bloom | 2003 | loc=Stilted}} Stilting was useful for semicircular arches, where the ratio of the rise fixed at {{frac|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 form an oblique angle in the horizontal plane with respect to the (parallel) springings,{{sfn | Woodman | Bloom | 2003 | loc=Skew}}{{sfn | Calvo-López | 2020 | p=265}} 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 the wall is larger than the exterior one), the intrados of a round splayed arch is not cylindrical, but has a [[conical]] shape.<ref>{{MW|splayed arch}}</ref>{{sfn | Calvo-López | 2020 | p=265}}

<gallery>
File:Palau Dalmases.jpg|Ramping arches at {{ill|Palau Dalmases|ca}} in [[Barcelona]]
File:Frauenstein Lorenziberg Filialkirche hl Laurentius Vorlaube Schulterbogenportal 25042017 7964.jpg|Shouldered arch around the door of {{ill|Filialkirche Lorenziberg|de|lt=Lorenziberg church}}. The raised portion is a flat arch.
File:Doges Palace 5 (7243239310).jpg|Shouldered arch above the main entrance of [[Doge's Palace]] in [[Venice]]. The vertical supports separate the segments of an ogee arch.
File:St John's Chapel, Tower of London.jpg|The smaller arches at the lower level are stilted to match the wider arches on the left ([[St John's Chapel, London]])
File:Nave and left aisle - Cathedral of Monreale - Italy 2015.JPG|Stilted pointed arches at the [[Monreale Cathedral]])
File:Sickergill Skew Bridge in 1898.jpg|Skew arch (Sickergill Bridge) with [[helicoidal]] [[masonry course]]s
File:All Saints Church - splayed tower window - geograph.org.uk - 1361830.jpg|Splayed arch over a window opening in the All Saints Church in [[Chedgrave]]
</gallery>

A wide arch with its rise less than {{frac|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'''<ref>{{M-W|surbased}}</ref> (sometimes also a ''depressed arch''{{sfn | Woodman | Bloom | 2003 | loc=Surbased}}). A '''drop arch''' is either a [[Basket-handle arch|basket handle arch]]{{sfn | Woodman | Bloom | 2003 | loc=Drop}} or a blunt arch.<ref>{{M-W|drop arch}}</ref>