HRISHIRAJ SARMA | A.P.I.E.D | 2014 1

AN INTRODUCTION TO ARCHES

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What is an Arch? An Arch may be defined as mechanical arrangement of wedge-shaped blocks of stones or bricks mutually supporting each other and supported at the end by piers or abutments. An arch is a structure that spans a space and supports structure and weight below it. Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture and their systematic use started with the Ancient Romans who were the first to apply the technique to a wide range of structures.Function of an

Arch The function of an Arch is to carry weight of the structure above the opening. Because of their shape, the blocks support each other by mutual pressure of their own weight. Hence, the structure remains in the position by the resistance from the support.

HRISHIRAJ SARMA | A.P.I.E.D | 2014 3

Basic conceptAn arch is a pure compression form. It can span a large area by resolving forces into compressive stresses and, in turn eliminating tensile stresses. This is sometimes referred to as arch action. As the forces in the arch are carried to the ground, the arch will push outward at the base, called thrust. As the rise, or height of the arch decreases, the outward thrust increases. In order to maintain arch action and prevent the arch from collapsing, the thrust needs to be restrained, either with internal ties, or external bracing, such as abutments. 1.

Keystone

2. Voussoir

3. Extrados 4. Impost 5. Intrados 6. Rise

7. Clear span 8. Abutment

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1. Flat Arch.2. Semi-circular Arch.3. Segmental Arch.4. Relieving Arch.5. Dutch of French

Arch.6. Elliptical Arch.7. Parabolic Arch.8. Four centered Arch.9. Five centered Arch.10. Seven centered

Arch.11. Tree foil Arch.12. Moorish Arch.13. Ogee Arch.14. Multifoil Arch.15. Tudor Arch.

Type of Arch

Materials of Construction

Geometry

1. Stone Arch. Rubble Arch, Aslar Arch.2.Brick Arch. Rough Arch, Axed Brick Arch,

Gauged Brick Arch, Arch of Brick bonds.

3. Concrete Arch Concrete block Arch Monolithic Concrete Arch R.C.C Arch4. Wooden Arch.5. Metal Arch.

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Flat Arch

Types of Arches on Geometry

French of Dutch Arch

Semi circular ArchSegmental Arch

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Relieving Arch

Types of Arches on Geometry

Different Types of Arches

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Types Of Arches on Geometry

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Types Of Arches on Geometry

Different Types of Arches

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Types Of Arches on Geometry

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Types Of Arches on Geometry

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Types Of Arches on Material of Construction

Rough Brick Arch Axed Brick Arch

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Types Of Arches on Material of Construction

Rubble Arch AshlarArch Monolithic Concrete Arch

R.C.C Arch Metal Arch Wooden Arch

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Uses of Arch Arches with a circular form, also referred to as rounded arch, were commonly employed by the builders of ancient history, heavy masonry arches. Ancient Roman builders relied heavily on the rounded arch to span large, open areas. Several rounded arches placed in-line, end-to-end, form an arcade, such as the Roman aqueduct.

Roman aqueduct near Nimes, France

Horseshoe arches (9th century) in the Mosque of Uqba, in Kairouan, Tunisia

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Uses of Arch Pointed arches were most often used by builders of Gothic-style architecture. The advantage to using a pointed arch, rather than a circular arch, is that the arch action in a pointed arch produces less thrust at the base. This innovation allowed for taller and more closely spaced openings, typical of Gothic architecture

Cathedral of St. Michael and St. Gudula in Brussels, Belgium, with its central, pointed arch window, typical of Gothic architecture.

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Uses of Arch The parabolic arch employs the principle that when weight is uniformly applied to an arch, the internal compression resulting from that weight will follow a parabolic profile. Of any arch type, the parabolic arch produces the most thrust at the base, but can span the largest areas. It is commonly used in bridge design, where long spans are needed.

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Uses of Arch Vaults are essentially "adjacent arches are assembled side by side.“ If vaults intersect, complex forms are produced with the intersections. The forms, along with the "strongly expressed ribs at the vault intersections, were dominant architectural features of Gothic cathedrals."

Interior vaulted ceiling of Notre Dame de Paris, showing the ribs at the intersection of several arches.

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History of Arch 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.

Arch of the Near East

Arch of Levant Mayan Corbel Arch

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History of Arch A rare exception is the bronze age arched city gate of Ashkelon (modern day Israel), dating to ca. 1850 B.C. An early example of a voussoir arch appears in the Greek Rhodes Footbridge. 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

City gate of Ashkelon

Greek Rhodes Footbridge

Arch-roofed passageway underneath the Pyramid of Quetzalcoatl

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History of Arch 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. Throughout the Roman empire, their engineers erected arch structures such as bridges, aqueducts, and gates.

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History of Arch 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.

Arch of Constantine, Rome

Arch of Triumph in Genoa, Italy

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Examples of Arches

Muslim Arch Gothic Arch

Roman Arch Hindu Arch

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Why Arch is Important The arch is important because it is a marvelous way to structurally support the mass of a building roof, a railway line, or an aqueduct, like the ones the Romans built. Some of the arches built by Ancient Romans still stand today, and they offer a mute testament to the effectiveness of the arch in engineering. The arch is still in wide use today, and we even see big glue-lams (wood glued to laminate it to make large beams) in the shape of arches. The arch has a long history in structures man has built