Arches and Lintels

Arches and Lintels

Contents

Define the term Arch 1

Recall the following terms related to Arch: i. Intrados , ii. Extrados iii. Skewback iv. Springer 3

Recall the classification of Arch according to the Shape: i. Flat arch, ii. Segmental arch, iii. Semi-circular arch iv. Semi-elliptical arch, v. Inverted arch 4

Recall the classification of Arch according to the number of centres: i. One-centred arch, ii. Two-centred arch iii. Three-centred arch iv. Four-centred arch, v. Five-centred arch 5

Recall the classification of Arch according to materials of construction: i. Stone arch ii. Brick arch, iii. Concrete arch 6

Recall the Stability of an arch: i. Crushing of the masonry ii. Sliding of voussoir iii. Uneven settlement of abutment or pier 7

Define the term Lintel, and Recall the following types of Lintel: i. Wood lintels ii. Stone lintels, iii. Brick lintels iv. RCC lintels 8

Define the term Arch

An arch is a curved structure that is used to span an opening or support weight above it. The arch is a fundamental element of architecture that has been used for thousands of years to construct a wide range of buildings and structures, such as bridges, aqueducts, and arches.

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An arch can be composed of a variety of materials, including stone, brick, concrete, and steel, and it can take on a variety of forms and shapes. The key characteristics of an arch is that it is a curved structure that relies on compression to support the weight above it. This is different from a beam, which relies on tension to support weight.

There are different types of arches, each with its own characteristics. Some examples include:

  1. The semicircular arch, which is the most common type of arch and it has a curved shape that forms a half circle.
  2. The pointed arch, which is an arch with a pointy top and its sides are made up of two curves that meet at the top.
  3. The lancet arch, which is similar to the pointed arch, but it is more elongated and has a more pointed top.
  4. The four-centred arch, which has a curved shape that forms a four-centred arch with a flattened centre.

Arches can be used in many different types of structures and architectural styles, such as Gothic, Romanesque, and Renaissance styles, they are also widely used in various applications in modern architecture as well. They are often used to create openings, such as doorways and windows, as well as to support vaults, domes, and other architectural elements.

In summary, the arch is a fundamental element of architecture that has been used for thousands of years to construct a wide range of buildings and structures. It is a curved structure that relies on compression to support weight and has different types such as semicircular, pointed, lancet and four-centred arch that can be used in different types of structures and architectural styles.

Recall the following terms related to Arch: i. Intrados , ii. Extrados iii. Skewback iv. Springer

  1. Intrados: The intrados is the inner curved surface of an arch. It is the part of the arch that faces into the structure or opening that the arch is spanning. It is the concave surface of the arch and the one that forms the bottom surface of the arch. It is often considered as the most decorative and visible surface of the arch, as it forms the visible surface of the arch when viewed from inside.
  2. Extrados: The extrados is the outer curved surface of an arch. It is the part of the arch that faces out of the structure or opening that the arch is spanning. It is the convex surface of the arch and the one that forms the top surface of the arch. It is the surface where the keystone is located. The extrados is subjected to compressive forces and its curve is determined by the stresses in the arch.
  3. Skewback: The skewback is the inclined surface on either side of an arch that connects the intrados and extrados of an arch. It is the surface that helps to transfer the weight and forces of the arch to the supporting structure. Skewbacks are typically formed by the intersection of two planes that form the angle at the top of the arch. The skewbacks are an important structural element of the arch as they help to prevent the arch from buckling and ensure its stability.
  4. Springer: The springer is the lowest voussoir of an arch, the voussoir is a wedge-shaped block used in the construction of an arch. The springer is the stone that is placed at the base of the arch on either side, it is the first stone to be laid and establishes the correct curve of the arch. The springer is a keystone that is important for the stability and support of the arch, it transfers the load of the arch to the supporting structure.

In summary, these terms are related to the arch and its elements. The intrados is the inner curved surface of an arch that faces into the structure or opening, while the extrados is the outer curved surface of the arch that faces out of the structure or opening. The skewback is the inclined surface on either side of an arch that connects the intrados and extrados, it is the surface that helps to transfer the weight and forces of the arch. The springer is the lowest voussoir of an arch, it is the first stone to be laid and establishes the correct curve of the arch and it is important for the stability and support of the arch.

Recall the classification of Arch according to the Shape: i. Flat arch, ii. Segmental arch, iii. Semi-circular arch iv. Semi-elliptical arch, v. Inverted arch

  1. Flat Arch: A flat arch is a type of arch that has a flat or horizontal top surface, rather than a curved or pointed top. This type of arch is often used in post-and-lintel construction where the arch serves to transmit the load of the structure to the abutments or supports. A flat arch is relatively simple to construct and can be made of a variety of materials, such as stone, brick, or concrete. It is often used in modern architectural designs.
  2. Segmental Arch: A segmental arch is a type of arch that has a curved top surface that is less than a semicircle. This type of arch is often used in bridges, where the span of the arch is relatively short and the arch does not need to be as strong as a semicircular arch. A segmental arch is relatively simple to construct and can be made of a variety of materials, such as stone, brick, or concrete.
  3. Semi-circular Arch: A semi-circular arch is a type of arch that has a curved top surface that forms a semicircle. This type of arch is considered to be one of the strongest and most stable types of arches and it is often used in ancient and traditional architecture, such as the Roman and Gothic styles. It is also popular in modern architecture for decorative purposes.
  4. Semi-elliptical arch: A semi-elliptical arch is a type of arch that has a curved top surface that forms a half ellipse. This type of arch is considered to be a more elegant and aesthetically pleasing version of the semicircular arch. It is less common than the semicircular arch in traditional architecture, but it is sometimes found in Renaissance architecture.
  5. Inverted Arch: An inverted arch is a type of arch that has its curve facing downward, instead of upward. This type of arch is used in underground structures, such as tunnels, mines and other underground excavations, and is also sometimes used in bridges, where the arch is inverted to increase the height of the bridge’s clearance. The inverted arch is less common than the other types of arches.

In summary, these are different types of arches classified according to their shape. A flat arch is a type of arch that has a flat or horizontal top surface, a segmental arch is a type of arch that has a curved top surface that is less than a semicircle, a semi-circular arch is a type of arch that has a curved top surface that forms a semicircle, a semi-elliptical arch is a type of arch that has a curved top surface that forms a half ellipse and an inverted arch is a type of arch that has its curve facing downward, instead of upward. The choice of which type of arch to use will depend on the specific requirements of the structure and the design aesthetic.

Recall the classification of Arch according to the number of centres: i. One-centred arch, ii. Two-centred arch iii. Three-centred arch iv. Four-centred arch, v. Five-centred arch

An arch is a curved structure that spans an opening, such as a doorway or window, and is used in the construction of buildings and bridges. The classification of arches according to the number of centres refers to the number of points that determine the shape of the arch.

  1. One-centred arch: A one-centred arch has a single point, called the centre, that determines the shape of the arch. This type of arch has a semicircular shape, with the centre of the circle located at the apex of the arch.
  2. Two-centred arch: A two-centred arch has two points, or centres, that determine the shape of the arch. These points are located at the base of the arch, and the arch forms a shape that is slightly flattened at the top, known as a pointed arch.
  3. Three-centred arch: A three-centred arch has three points, or centres, that determine the shape of the arch. These points are located at the base of the arch, and the arch forms a flattened shape with a curved top, known as a segmental arch.
  4. Four-centred arch: A four-centred arch has four points, or centres, that determine the shape of the arch. These points are located at the base of the arch and forms an arch with a shape that is flattened at the top and bottom, known as a Tudor arch
  5. Five-centred arch: A five-centred arch has five points, or centres, that determine the shape of the arch. These points are located at the base of the arch and form an arch with a complex shape. It’s not a popular choice but it could be used for educational purposes.

It’s important to note that the classification of arches is not exclusive and sometimes arches can be combined to form different shapes and variations, but the number of centres is the main way to classify them.

Recall the classification of Arch according to materials of construction: i. Stone arch ii. Brick arch, iii. Concrete arch

The classification of arches according to materials of construction refers to the types of materials that are used to construct an arch. The main materials used for building arches include stone, brick, and concrete.

  1. Stone arch: A stone arch is an arch that is constructed using natural stone materials. Stone arches have been used for centuries in the construction of buildings and bridges, and are known for their durability and strength. The natural properties of the stones used, such as their texture, colour and pattern, give them an unique aesthetic appeal.
  2. Brick arch: A brick arch is an arch that is constructed using bricks. Brick arches have been used extensively in the construction of buildings, especially in regions where bricks are readily available. Brick arches have the advantage of being relatively easy to construct, and are known for their durability and fire resistance. The colour and pattern of bricks can also be used to create different aesthetics.
  3. Concrete arch: A concrete arch is an arch that is constructed using concrete. Concrete arches are known for their strength and ability to span large openings. This material is very versatile and it can be cast in different shapes and forms, including the arch shape. In addition, Reinforced concrete arches are able to support heavy loads and are often used in the construction of bridges and other large structures.

It’s important to note that the classification of arches according to materials of construction is not exclusive and sometimes a combination of materials could be used to construct an arch, but the main material used is what classifies it.

Recall the Stability of an arch: i. Crushing of the masonry ii. Sliding of voussoir iii. Uneven settlement of abutment or pier

Stability of an arch refers to the ability of the arch to maintain its shape and support the loads placed on it without collapsing or deforming. There are three main factors that can affect the stability of an arch: crushing of the masonry, sliding of the voussoirs, and uneven settlement of the abutment or pier.

  1. Crushing of the masonry: An arch is made up of individual units of masonry, such as stone or brick, called voussoirs. The voussoirs are placed together to form the arch shape, with the keystone at the top and the springers at the bottom. If the masonry is not strong enough or is not laid properly, it can become crushed under the load of the arch. This can cause the arch to collapse or deform.
  2. Sliding of voussoirs: The stability of an arch also relies on the voussoirs being held in place by friction and compression. If the voussoirs are not securely in place, they can slide out of position, causing the arch to lose its shape and potentially collapse. This can occur if the voussoirs are not properly cut or dressed, or if the mortar holding them in place is not strong enough.
  3. Uneven settlement of abutment or pier: An arch is supported by its abutments or piers, which are the walls or posts at either end of the arch. If one of the abutments or piers settles unevenly, it can cause the arch to become destabilised. This can happen if the foundation of the abutment or pier is not strong enough or if the soil beneath it is not stable. Uneven settlement can also cause the arch to crack or warp, which can weaken the overall structure.

Overall, In summary, for an arch to be stable, the masonry must be strong enough to support the load and must be properly laid, the voussoirs must be securely in place, and the abutments or piers must be stable and evenly settled.

Define the term Lintel, and Recall the following types of Lintel: i. Wood lintels ii. Stone lintels, iii. Brick lintels iv. RCC lintels

A lintel is a horizontal structural element that spans an opening in a wall, such as a door or window, and bears the weight of the structure above it. It is used to transfer the load of the above structure to the walls on either side of the opening. Lintels are a common architectural feature in both traditional and modern buildings.

  1. Wood Lintels: Wood lintels are made of timber and are most commonly used in residential and commercial buildings, as well as in certain traditional architectural styles. They are relatively inexpensive and easy to work with, but they have lower load-bearing capacity and may not be suitable for larger or more heavily loaded openings.
  2. Stone lintels: Stone lintels are made of natural stone such as granite, limestone or marble, and are often used in traditional and historical buildings. They are very durable and have a high load-bearing capacity. However, they are also more expensive and more difficult to install than other types of lintels.
  3. Brick lintels: Brick lintels are made of brick and are most commonly used in residential and commercial buildings. They are relatively inexpensive and easy to work with, but they have lower load-bearing capacity and may not be suitable for larger or more heavily loaded openings.
  4. RCC lintels: RCC (Reinforced Cement Concrete) lintels are made of steel-reinforced concrete and are often used in modern and high-rise buildings. They are extremely strong and have a high load-bearing capacity. RCC lintels are precast and can be used in large openings. They also have good fire resistance properties and have a long lifespan. They are more expensive to install than other types of lintels.

In summary, Lintel is a horizontal structural member that spans over an opening in a wall, to transfer the load of the structure above it to the walls on either side. The four types of lintels are: Wood lintels, Stone lintels, Brick lintels, and RCC lintels. Each type has its own advantages and disadvantages, and the choice of lintel will depend on the specific requirements of the building and the loads it will need to bear.