Historically, the term counter-arch was used in architecture to describe multiple types of arches that provide opposing action:
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; 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" following the works of John Smeaton; an arch that is built adjacent to another arch to oppose its forces or help stabilize it."counter arch." McGraw-Hill Dictionary of Architecture and Construction. McGraw-Hill Companies, Inc., 2003. Answers.com, 7 September 2008. The counter-arch can be used, for example, when constructing the flying buttress, buttressing arches built between the opposing building facades over narrow streets of old cities; in fortification, an arch built on the tops of counterforts behind the bastion walls intended to limit the scope of the potential wall breaching; 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.
See also Arcade (architecture) Flying arch Strainer arch
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