One cannot enter a constructed building if there are no openings. It is the constructor’s responsibility to extend such a provision in the form of a door creating a passage. Again, while doors may let us in, we need windows and other openings to ensure good ventilation and natural light inside the building. It is not an easy task to make an opening in a building as it involves various factors, from balancing the structure to distributing the load. To ensure such delicacy, either an arch or lintel is used in construction. Both arches and lintels are situated above the openings, supporting and transmitting the loads to the adjacent walls to balance the vacuum down below. Understanding arches and structural dimensions is essential to distributing loads and enhancing the aesthetics of the building. This article looks into the definition of an arch in the construction sector and the various types that shape the outlook of today’s buildings.
What is Arch?
It is a mechanical structure made up of wedge-shaped blocks, either bricks or stones. This arrangement provides mutual support to the bricks or stones. Piers or abutments are used to provide stability to this structure. The curved line of the arch is arranged with wedge-shaped units to balance their weight. This exerts a vertical pressure that can be sustained safely by the supports below. In layman’s terms, it is a curved structure that supports loads from above to span an opening. This is a construction marvel as it covers a wide span without additional support. The inclusion of arches as a design in buildings will create visually striking designs ensuring structural integrity as well.
Types of Arches
We don’t have a single set of arch designs to fit all architectural designs. For years, people have been using different arches for different purposes. Arch types play a crucial role from supporting loads to beautifying spaces. Some of the different types of arches in construction are,
Round Arch: Also called Roman arch, they are the most common type of arch in construction. It is preferred by the constructors for its strong and stable structure providing a semicircular shape. Even today, it is very common to see an old building having such arch designs. This stands as testimony to their durability and timeless appeal.
Pointed Arch: This pointed apex appears to be common in Gothic architecture. They add a visually stunning element to castles and cathedrals. The higher capacity to distribute weight makes it a smart choice for larger structures.
Segmental Arch: While it appears similar to a round arch, it has a shallower curve. It is very common to see this type of arches in bridges and construction buildings. As they require less vertical space, they are compact in height-constrained spaces.
Horseshoe Arch: This finds its origin in Islamic architecture, where the arch takes an extended curve that goes beyond the semicircle. As they enhance the aesthetic appearance of buildings, they are mostly used in doorways and windows to add a decorative look.
Ogee arch: This type consists of a mirror image, forming an S-shape. The double-curved shape made it popular in several architectural designs. They can bear heavy loads with full efficiency without diminishing their beautiful appearance.
Relieving Arch: It is seen to be a clever engineering solution as it decreases the weight of the lower arch. This distributes the load to the adjacent walls managing the stress of the building. They increase the longevity and structural stability of the building.
Triangular Arch: They stand distinct from the traditional arches with their straight lines and sharp, angular shape. This type is said to be the oldest form of arches finding its traces in ancient Mesopotamian civilisations. They offer a minimalistic approach with their modest designs.
Benefits of Arch Construction
· The arch can provide structural efficiency as it needs minimal material to support significant weight.
· Their iconic structural visuals increase the aesthetic appeal of the building designs.
· Their flexibility in adapting various materials and styles provides architects with a choice to choose of versatile designs.
· The cost is lessened as the arches reduce the need for external or additional support systems to manage the loads.
Step-by-Step Process of Arch Construction
There are three main steps in the construction of arches, they are,
Installation of centring: In this process, a temporary setup is made to support the structures. These temporary structures are called centring or formwork. During the construction, the formwork maintains the weight and ensures the shape of the arches retains its intended shape. The supporting structure can be made of timber, metal or any sturdy material to handle the load till the time the structure can support itself.
Laying or casting the actual arch: Following the setup of centring, the construction of the arch begins. Based on the requirement, one could lay bricks or stones or cast concrete into the desired shape. Keystone placement is very crucial in this stage. This central stone is placed at the highest point that locks the other stones in position.
Striking or removal of centring as formwork: Completion of arch construction is determined after the materials are hardened. Ensuring this, the centring is removed. The removal of formwork is called striking.
Materials Used in Arch Constructions
The materials vary depending on the type, purpose and load-bearing requirements of the arch. Some of the common materials are natural stones, cut stones, clay bricks, engineering bricks, reinforced concrete, precast concrete, prestressed concrete, structural steel, cast iron, laminated timber, and solid timber. In common, materials must be strong and durable with a capacity to handle forces and weight that arches must support.
Structural Analysis and Stability of Arches
Any infrastructure needs to undergo a structural analysis to ensure the safety and maintenance of its shape over time. Likewise, the structural analysis and stability of arches are important. The arches function by transferring loads through compression spreading them across the curve. They are designed in such a way as to minimise bending effort by converting the load into compressive stresses. The position of the line of thrust is essential for an arch to be stable. Even within the design of arches, there are different types of loads. To ensure the stability of an arch, the shape of the arch, thickness of the arch, abutment strength, and keystone position are important.
Conclusion:
The magnificent curves and the ultimate efficiency in structure have shaped cities and cultures across the globe. From ancient Rome’s aqueducts to Gothic cathedrals during the Middle Ages, arches developed and inspired successive generations. With knowledge of the different types of arches and methods of construction, architects and engineers can devise something new, innovative, and sustainable. Thorough material selection and proper load calculation can guarantee sustainability and aesthetic appeal in designs supported by arches. Today, as we keep breaking limits in creating architectural designs, arches seem to be the never-ending iconic sign of might, beauty, and human creativity.