طاق قوسی

تاق قوسی سازه‌ای است که برای انتقال بار عمودی وزن به تکیه‌گاه‌ها در یک دهانه ایجاد می‌شود. قدمت تاق‌های قوسی به دو هزار سال پیش از میلاد و به منطقه میان‌رودان باز می‌گردد. تاق قوسی از لحاظ شکل هندسی به انواعی همچون نیم‌دایره، قوس گوتیک، قوس نوک‌تیز، بیضوی، سهموی و زنجیروار تقسیم می‌شود. شکل‌های سهموی و زنجیروار به دلیل تغییر جهت تقریبا کامل بارهای عمودی به بار در امتداد قوس(بار محوری) قوی‌ترین انواع تاق قوسی شناخته می‌شوند. چنین تاق‌هایی معمولا برای پوشش دهانه به اجزای اضافی نیازی ندارند.[۱]

از آنجا که بسیاری از مصالح ساختمانی قدیمی(مانند سنگ و آجر) علیرغم مقاومت مناسب در برابر تنش فشاری مناسب، توانایی کمی برای تحمل تنش کششی داشتند، طرح قوسی شکل تاق می‌توانست بسیار مفید واقع شود. در یک تاق قوسی، بخش بسیار زیادی از بار عمودی فاقد لنگر خمشی بوده و بنابراین هیچ عضوی از تاق، تحت تنش کششی قرار نخواهد گرفت. اشکال تاق‌های قوسی آن است که نیروی افقی دور کننده به تکیه‌گاه‌های خود وارد می‌کند که در قوس‌های بزرگ می‌تواند مخرب باشد. گاهی این نیرو توسط یک عضو کششی در پائین قوس خنثی می‌شود.[۲]

شرط عملکرد قوس سختی جانبی کافی هر دو تکیه گاه قوس است به منظور ایجاد جفت نیروی واکنش افقی تکیه گاه‌ها. در مورد بعضی پل‌ها، جناحین پل قوسی یا همان تکیه گاه‌های آن کوه و صخره بوده و این سختی کاملا تامین می‌شود. در مورد قوس‌های کوچک هم سختی دیوار‌های تکیه گاهی این نیاز را برآورده می‌کند. در صورت وجود تکیه گاه‌های نامناسب (انعطاف پذیر) از یک عضو کششی استفاده شده که دهانه قوس یا جناحین را کاملا به یکدگیر می‌بندد.

این یک نوشتار خُرد معماری است. با گسترش آن به ویکی‌پدیا کمک کنید.
منابع [ویرایش]

↑ Wikipedia, the free encyclopedia →Arch (بازدید: ۲۵ شهریور ۸۹)
↑ Wikipedia, the free encyclopedia →Arch (بازدید: ۲۵ شهریور ۸۹)
رده‌های صفحه: مهندسی عمران طاق و قوس
قس عربی
القوس هو شکل هندسی قادر على الدوران فی الفراغ وفی نفس الوقت حمل وزن.
القوس ،فی الهندسة المعماریة، هو عنصر هیکلی على شکل منحنی یرکز عادة على دعاماتین ویتألف من قطع من الحجارة أو الطوب التی مفاصلها ترتب على شکل شعاعی.
[عدل]وصلات خارجیة

انواع الاقواس
هذه بذرة مقالة عن الریاضیات تحتاج للنمو والتحسین، فساهم فی إثرائها بالمشارکة فی تحریرها.
شاهد المزید من الصور والملفات فی ویکیمیدیا کومنز حول: قوس (عمارة)
بوابة الریاضیات
تصنیفات: عناصر معماریةأشکال هندسیةهندسة وصفیة
قس آذربایجانی
Tağ - Memarlıqda divarlarda pəncərə və qapı yerlərinin, yaxud iki dayaq (sütun, dirək və s.) arasındakı boşluğun üstünü örtmək üçün əyrixətli örtük konstruksiyası. Yarımdairə, çatma, nalvarı və s. formalarda olur. Daşdan hörülür və ya metal, ağac və dəmir-betondan hazırlanır. Tağ, əsasən, sıxılmaya işləyir və üzərinə düşən şaquli yükləri dayaq, kontrfors və dartqılara (iki dayağa söykənən və dartılmaya işləyən millərə) ötürür. Tağdan binalarda örtüklərin, körpülərdə aşırımların yüksaxlayan elementi kimi istifadə edilir. Konstruktiv sisteminə körə tağ şarnirsiz (oynaqsız) və iki-üç şarnirli (oynaqlı) olur. Layihələndirilmə zamanı tağın əyriliyi, oxları elə götürülür ki, daimi yük altında (tağın öz çəkisi, ona söykənən örtüyün, damın və s. ağırlığı) tağda ancaq sıxıcı qüvvə yaransın. Bu halda onun en kəsiyinin ən az ölçüsü alınır.
Tağ ilk dəfə Qədim Şərq memarlığında (daşdan) meydana gəlmiş, sonralar antik Roma tikililərində (binalarda, akveduklarda, zəfər tağlarında) geniş istifadə edilmişdi. Müsəlman Şərqinin, o çümlədən Azərbaycanın orta əsr memarlığında əsasən çatma tağlar tətbiq olunmuşdur. Çatma tağlar seysmik təsirlərə böyük müqaviməti, aşırma qüvvəsinin azlığı və s. ilə səciyyələnir. Çatma tağların əyriləri iki, üç və dörd-mərkəzli olur. Tağa dekorativ forma vermək üçün şərqr memarlığında ellips əyrisi hissələrindən də istifadə edilirdi. Bu da tağ əyrisinin axıcı, ahəngdar və möhkəm olmasını təmin edirdi (Sultaniyyədəki Ölcaytu Xudabəndə türbəsinin, Bakıdakı Şirvanşahlar sarayı ansamblının çatma tağları). Formasına, quruluşuna, təyinatına, tikinti materialına və s. əlamətlərə görə orta əsrlərdə Azərbərbaycan memarlığında 90-dək tağ növü tətbiq olunmuşdur.
[redaktə]Həmçinin bax

Arkada
Memarlıq portalı
Memarlıq ilə əlaqədar bu məqalə qaralama halındadır. Məqaləni redaktə edərək Vikipediyanı zənginləşdirin.
Kateqoriyalar: Memarlıq qaralamalarıMemarlıq elementləri
قس انگلیسی
An arch is a structure that spans a space and supports a load. Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture [1] and their systematic use started with the Ancient Romans who were the first to apply the technique to a wide range of structures.
Contents [show]
[edit]Technical aspects

The arch is significant because, in theory at least, it provides a structure which eliminates tensile stresses in spanning a great amount of open space. All the forces are resolved into compressive stresses. This is useful because several of the available building materials such as stone, cast iron and concrete can strongly resist compression but are very weak when tension, shear or torsional stress is applied to them. By using the arch configuration, significant spans can be achieved. This is because all the compressive forces hold it together in a state of equilibrium. This even applies to frictionless surfaces. However, one downside is that an arch pushes outward at the base, and this needs to be restrained in some way, either with heavy sides and friction or angled cuts into bedrock or similar.
This same principle holds when the force acting on the arch is not vertical such as in spanning a doorway, but horizontal, such as in arched retaining walls or dams.
Even when using concrete, where the structure may be monolithic, the principle of the arch is used so as to benefit from the concrete's strength in resisting compressive stress. Where any other form of stress is raised, it has to be resisted by carefully placed reinforcement rods or fibres. (See Arch bridge.)
[edit]History



Roman arch architecture in Ostia Antica, Italy
True arches, as opposed to corbel arches, were known by a number of civilizations in the Ancient Near East, the Levant, and Mexico, but their use was infrequent and mostly confined to underground structures such as drains where the problem of lateral thrust is greatly diminished.[2] A rare exception is the bronze age arched city gate of Ashkelon (modern day Israel), dating to ca. 1850 B.C.[3] An early example of a voussoir arch appears in the Greek Rhodes Footbridge.[4] In 2010, a robot discovered a long arch-roofed passageway underneath the Pyramid of Quetzalcoatl which stands in the ancient city of Teotihuacan north of Mexico City, dated to around 200 AD.[5]
The ancient Romans learned the arch from the Etruscans, refined it and were the first builders to tap its full potential for above ground buildings:
The Romans were the first builders in Europe, perhaps the first in the world, fully to appreciate the advantages of the arch, the vault and the dome.[6]
Throughout the Roman empire, their engineers erected arch structures such as bridges, aqueducts, and gates. They also introduced the triumphal arch as a military monument. Vaults began to be used for roofing large interior spaces such as halls and temples, a function which was also assumed by domed structures from the 1st century BC onwards.
The segmental arch was first built by the Romans who realized that an arch in a bridge did not have to be a semicircle,[7][8] such as in Alconétar Bridge or Ponte San Lorenzo. They were also routinely used in house construction as in Ostia Antica (see picture).
The semicircular arch was followed in Europe by the pointed Gothic arch or ogive whose centreline more closely followed the forces of compression and which was therefore stronger. The semicircular arch can be flattened to make an elliptical arch as in the Ponte Santa Trinita. Both the parabolic and the catenary arches are now known to be the theoretically strongest forms. Parabolic arches were introduced in construction by the Spanish architect Antoni Gaudí, who admired the structural system of Gothic style, but for the buttresses, which he termed “architectural crutches”. The catenary and parabolic arches carry all horizontal thrust to the foundation and so do not need additional elements.
The horseshoe arch is based on the semicircular arch, but its lower ends are extended further round the circle until they start to converge. The first known built horseshoe arches are known from Aksum (modern day Ethiopia and Eritrea) from around the 3rd–4th century, around the same time as the earliest contemporary examples in Roman Syria, suggesting either an Aksumite or Syrian origin for the type of arch.[9][page needed]
[edit]Construction

An arch requires all of its elements to hold it together, raising the question of how an arch is constructed. One answer is to build a frame (historically, of wood) which exactly follows the form of the underside of the arch. This is known as a centre or centring. The voussoirs are laid on it until the arch is complete and self-supporting. For an arch higher than head height, scaffolding would in any case be required by the builders, so the scaffolding can be combined with the arch support. Occasionally arches would fall down when the frame was removed if construction or planning had been incorrect. (The A85 bridge at Dalmally, Scotland suffered this fate on its first attempt, in the 1940s[citation needed]). The interior and lower line or curve of an arch is known as the intrados.
Old arches sometimes need reinforcement due to decay of the keystones, forming what is known as bald arch.
The gallery shows arch forms displayed in roughly the order in which they were developed.

Triangular arch



Round arch or Semi-circular arch



Segmental arch or arch that is less than a semicircle



Unequal round arch or Rampant round arch



Lancet arch



Equilateral pointed arch



Shouldered flat arch -see also jack arch



Three-foiled cusped arch



Horseshoe arch



Three-centered arch



Elliptical arch



Inflexed arch



Ogee arch



Reverse ogee arch



Tudor arch



Parabolic arch


[edit]Construction of adobe arches
Below a set of pictures of various stages of construction of Arches made of adobe- mud- bricks using local materials and local labor in Merzouga, Morocco. They rest upon concrete pillars and have a concrete bar across them for strength.

Adobe Arches in Merzouga Morocco



Ready for final touches



Notice the adobe bricks



Bricks made from local mud.



Arches supported by concrete pillars



Similar to Arches in the Mosque in Cordoba,Spain


Completed Arches

Construction in Merzoura Morocco



Arches are made of Adobe and have to be protected from the rain. Roof is being constructed and is partially finished|







[edit]Other types



The Delicate Arch, a natural arch near Moab, Utah
A blind arch is an arch infilled with solid construction so it cannot function as a window, door, or passageway.
Natural rock formations may also be referred to as arches. These natural arches are formed by erosion rather than being carved or constructed by man. See Arches National Park for examples.
A special form of the arch is the triumphal arch, usually built to celebrate a victory in war. A famous example is the Arc de Triomphe in Paris, France.
[edit]Gallery


The dry stone bridge, so called Porta Rosa (4th century BC), in Elea



Arch of Constantine, Rome, Italy commemorating a victory by Constantine I in 312 AD



The Gateway Arch in Saint Louis, Missouri; a sculpture based on a catenary arch



Doubled round archivolts – Igreja de Nossa Senhora da Assunção, Linhares da Beira, Portugal.



Stonework arches seen in a ruined stonework building – Burg Lippspringe, Germany



Several arches at the Casa Simón Bolívar in Havana, Cuba



Arches in the Armenian monastery of Geghard.



Arches in the nave of the church in monastery of Alcobaça, Portugal



The Arc de Triomphe, Paris; a 19th-century triumphal arch modeled on the classical Roman design



The Second Wembley Stadium, in London, built in 2007



Catenary arches inside Casa Milà in Barcelona, Spain by Antoni Gaudí



Arches in one of the porticos of Mosque of Uqba also known as the Great Mosque of Kairouan, city of Kairouan, Tunisia



Lucerne railway station, Switzerland



Arcade at Campeche, Mexico.

[edit]See also

Arcade (architecture)
Arch bridge
Corbelled arch
Blind arch
Natural arch
Order moulding
Skew arch
Suspension bridge
Triumphal arch
Golden Arches
[edit]References

Wikimedia Commons has media related to: Arch
^ "Ancient Mesopotamia:Architecture". The Oriental Institute of the University of Chicago. Retrieved 16 May 2012.
^ Rasch 1985, p. 117
^ Oldest arched gate in the world restored
^ Galliazzo 1995, p. 36; Boyd 1978, p. 91
^ Teotihuacan ruins explored by a robot, AP report in the Christian Science Monitor, November 12, 2010
^ Robertson, D.S.: Greek and Roman Architecture, 2nd edn., Cambridge 1943, p.231
^ Galliazzo 1995, pp. 429–437
^ O’Connor 1993, p. 171
^ Stuart Munro-Hay, Aksum: A Civilization of Late Antiquity. Edinburgh: University Press. 199
Notes
Boyd, Thomas D. (1978), "The Arch and the Vault in Greek Architecture", American Journal of Archaeology 82 (1): 83–100 (91), DOI:10.2307/503797
Galliazzo, Vittorio (1995), I ponti romani, Vol. 1, Treviso: Edizioni Canova, ISBN 88-85066-66-6
O’Connor, Colin (1993), Roman Bridges, Cambridge University Press, ISBN 0-521-39326-4
Rasch, Jürgen (1985), "Die Kuppel in der römischen Architektur. Entwicklung, Formgebung, Konstruktion", Architectura 15: 117–139
Roth, Leland M (1993). Understanding Architecture: Its Elements History and Meaning. Oxford, UK: Westview Press. ISBN 0-06-430158-3. pp. 27–8
[edit]External links

DIYinfo.org's Constructing Brick Arches Wiki - A wiki on how to construct brick arches around the house
DIYinfo.org's Constructing Timber Framed Arches Wiki - Similar to the brick arches but extra information for timber arches
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Categories: Arch bridgesArches and vaults
قس اردو
فن تعمیر میں محراب (arch) نصف یا چوتھائی تقریباً دائرے کے تعمیری سی ساخت کو کہتے ہیں جو دو فاصلوں کے درمیان کی دوری کو پورا کرتا ہے اور اپنے اوپر وزن برداشت کرتا ہے. جیسے پتھر کی دیوار میں دروازے کے لئے بنایا گیا ڈھانچہ. ویسے تو محراب کا استعمال دو ہزار سال سے بھی پرانا ہے لیکن ایسا مانا جاتا ہے کہ اس کا باقاعدہ استعمال قدیم رومیوں کے دور سے شروع ہوا۔
زمرہ: تعمیرات
قس ترکی
Kemer (Farsça: کمر ,kamar), mimarlıkta iki sütun veya ayağı birbirine üstten yarım çember, basık eğri, yonca yaprağı vb. biçimlerde bağlayan ve üzerine gelen duvar ağırlıklarını, iki yanındaki ayaklara bindiren tonoz bağlantıdır.[1] Kemerler ilk olarak MÖ 2. binyılda Mezopotamya mimarisinde görülmüş, sistematik kullanımı ise bu tekniği çeşitli mimari yapılara ilk kez uygulayan Romalılarla başlamıştır.[2]
Köken bilimi [değiştir]

Kemer sözcüğü Türkçeye Farsçadan geçmiştir.[1] Kökeninin Farsça کمر (kamar) sözcüğü veya Zentçe kamarā sözcüğü olduğu düşünülmektedir.[3]
Ayrıca bakınız [değiştir]

Su kemeri
Tonoz
Kaynakça [değiştir]

^ a b "TDK Güncel Türkçe Sözlük". 19 Aralık 2009 tarihinde erişildi.
^ Robertson, D.S. (1943). Greek and Roman Architecture (İngilizce), 231, Cambridge.
^ "Çağdaş Türkçenin Etimolojik Sözlüğü - kemer". 3 Şubat 2010 tarihinde erişildi.
Mimarlık ile ilgili bu madde bir taslaktır. İçeriğini geliştirerek Vikipedi'ye katkıda bulunabilirsiniz.
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