Counter-arch

Historically, the term counter-arch was used in architecture to describe multiple types of arches that provide opposing action:Template:Sfn Template:Sfn

A diagram of the Moseley bridge design. Counter-arches are designated by t's

an inverted arch used opposite of a regular one. For example, an inverted arch in an open spandrel or in "Moseley bridges", a popular American Civil War-era design by Thomas William Moseley, where the counter-arches were intended as a low-cost alternative to diagonal bracing;Template:Sfn
any relieving arch;
outer "rings" of compound arches overlaying the one forming the intrados, used in old English bridges since medieval times, are called "counter-arches"Template:Sfn following the works of John Smeaton;
an arch that is built adjacent to another arch to oppose its forces or help stabilize it.^[1] The counter-arch can be used, for example, when constructing the flying buttress,Template:Sfn
buttressing arches built between the opposing building facades over narrow streets of old cities;Template:Sfn Template:Sfn
in fortification, an arch built on the tops of counterforts behind the bastion walls intended to limit the scope of the potential wall breaching;Template:Sfn
when a pier of the Old Westminster Bridge started sinking during the construction, Charles Labelye was forced to retrofit the bridge with open spandrels using the counter-arches springing off haunches of the two adjacent arches of the bridge thus relieving the pier.Template:Sfn

References

↑ "counter arch." McGraw-Hill Dictionary of Architecture and Construction. McGraw-Hill Companies, Inc., 2003. Answers.com, 7 September 2008.
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