Editing Arch (section)

{{Short description|Curved structure that spans a space and may support a load}}
{{About|the architectural construct|other uses of ''arch'' or ''arches''|Arch (disambiguation)}}
{{Use dmy dates|date=August 2020}}
{{Use Oxford spelling|date=August 2016}}
[[File:St Louis Gateway Arch.jpg|thumb|[[Gateway Arch]]]]

An '''arch''' is a curved vertical [[structure]] [[span (engineering)|spanning]] an open space underneath it.{{sfn |Gorse|Johnston|Pritchard| 2020 | loc=arch}} 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 the [[Ancient Romans]] in the 4th century [[Anno Domini|BC]].{{sfn | Woodman | Bloom | 2003 | loc=History }}

Arch-like structures can be horizontal, like an [[arch dam]] that withstands the horizontal [[hydrostatic pressure]] load.{{sfn |Gorse|Johnston|Pritchard| 2020 | loc=arch dam}} Arches are usually used as supports for many types of [[Vault (architecture)|vaults]], with the [[barrel vault]] in particular being a continuous arch.{{sfn | Clarke | Clarke | 2010 | loc=vault}} Extensive use of arches and vaults characterizes an '''arcuated construction''', as opposed to the [[trabeated]] system, where, like in the architectures of ancient Greece, China, and Japan (as well as the modern [[steel-framed]] technique), [[Post and lintel|posts and beams]] dominate.{{sfn | Lyttleton | 2003 | p=}} 

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.<ref name=britannica/> Their role in construction was diminished in 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.