TYPES OF STRUCTURES

The structure is a combination of structural members constructed to support the load and has a fixed position on the ground. These are a blend of various types of structures in such a way that they can hold all the members as one unit without considerable geometric alterations in the course of loading and unloading. Many factors influence the design of a structure, for instance,

Utility: the purpose of building it
Safety: the structure should be able to carry the required load safely
Economy: the structure is cost-effective in the terms of the construction process, cost, and material
Aesthetics: the structure should be attractive, good appearance.

Structures are not necessarily buildings, it is a unit or system that is designed to bear loads not necessarily occupied by humans. Structures are classified into various types based on the structural system, application, form, etc.

1. Basic Types:

Solid Structure: Bulky, big, and massy structures are solid structures. All the molecules are tightly packed keeping no hollow space. These structures resist compression, natural disasters, heavy winds, and other forces. For example, dams, doors, bridges, etc. are some of the solid structures.

Frame Structure: Different members are fabricated together to construct a frame structure, where all the members support the load. Less material is used to construct a frame structure and is more flexible. These frame structures can be seen in the construction of homes, bridges, etc. Frames for these are fabricated of beams and columns to create a two or three-dimensional rigid structure.

Shell Structure: Strong yet hollow structures are shell structures. In proportion to the size of these structures, their weight is less, in which having a curved surface makes them stronger than having a flat surface. In structures, these shells are made up of skins on frames or without frames where they undergo comparatively less deformation. The advantage of constructing such structures as a roof element is that the internal spaces become free from intermediate walls or columns thus providing a large obstruction-free space. For instance, theatres, libraries, airports, etc. have shell roofs. To prevent the shell from spreading an edge beam is provided thus making it structurally efficient. Furthermore, most of these are in-situ reinforced concrete, although timber and steel can be used for reinforced or composite shell structures.

Membrane: Membranes are made of sheet-like material that is used as members of tensile structures. Tensile structures are balanced by tension and not compression. For instance, the cloth used in the tents is under tensile force. There are other materials that are used as membranes, namely, cotton canvas, polyester, PTFE coated glass, etc. Various members are fabricated together to form a system that includes, membranes, cables, pylons, anchors, etc.

Composite: Composite structure is a combination of two or more materials or types of structures. There are various types of composites like concrete, fiber-reinforced polymer, carbon-fiber-reinforced polymer, PVC polyester, etc.

2. Based on Structural System:

Tensile Structures: Generally structures are balanced as they are held in compression by the gravitational force. On the other hand, tensile structures are balanced by tension compared to compression. However, practically structures carry both compression and tension, thus it completely depends upon the magnitude to which it is purposefully tensioned to balance that establishes whether it is a tensile structure. The force of tension is achieved using cables to pull the membrane that is held by foundations or anchors to fix and oppose by compression. Furthermore, these structures are light in weight as the material used is comparatively less than that in a compression structure and also span larger distances.

Compressive Structures: Compressive stresses are developed in compressive structures as they are suspected to instability, the possibility of their failure is taken into consideration while designing. This compressive load is applied along the length, if applied to cross-section produces stress. Compressive force pressures the structures or members inwards because of the impact of the applied force though the results may vary depending upon the position and direction of the applied force.

Shear Structure: Force that is applied perpendicular on the surface which acts in the opposite direction on a structure is a shear force. Shear force results in part of the surface being swept in one direction and the other half in the opposite direction. When the force applied results in two parts moving in different directions, it can result in failure by shear. To prepare high-rise buildings against a shear force they are provided with shear walls for resistance that might affect parallel structural elements and might result in racking.

Bending Structure: Structural systems having bending structures incorporate curved beams or shell elements which are the results of elastic deformation of an initially straight arrangement. These structures evolve chiefly bending stresses under the influence of external loads.

3. Based on their Application :

Building: A building is an enclosed structure comprising of the roof, walls, floors, openings, etc. These can be either permanent or temporary structures. Buildings create division between environments making it either inside or outside areas physically and serve various societal needs. Buildings have their own set of advantages, for instance

The internal spaces are protected from the rain, harsh sun, wind, snow, etc.
Temperature, humidity, moisture can be maintained in a closed environment
As the building is enclosed it provides occupants with privacy
Noise is obstructed creating disturbance-free interiors
The enclosed environment provides security to the occupants

Over the years versatility and style of designing a building have evolved in terms of shape, size, functions, materials as people are experimenting and coming out with new approaches and ideas.

Aqueducts and Viaducts: Aqueducts are constructed to carry water from one point to another. This is the channel where the endpoints are significantly at distances where the water is carried through an elevated masonry or brick structure. This channel resembles a bridge with arches which is often transferred through tunnels or an underground system. Overtime material and design of aqueducts have evolved and in recent times they are constructed both underground and overground using pipes, canals, tunnels, ditches, etc. Viaducts on the other hand support railway or road. These have a similar design to an aqueduct, bridge supported by arches, columns, or piers. Viaducts are primarily constructed to eliminate an obstruction like a valley, river, etc. where the endpoints are on either side of the obstruction. Though viaducts are similar to bridges the major difference between them is that viaducts are huge and comparatively bigger structures in terms of their size, width, or even height.

Bridges: Bridges connect two points on either side of an obstacle like a river, valley, road, railway, etc. These are spanning structures that are a common attribute of construction seen everywhere. Attributes that assist in bridge designs are spanning of the element, shape, materials that are used, type of support, function, budget, etc. Bridges are further classified into three major categories namely, beam, arch, and suspension bridges.

Canals: Canals are constructed to supply water or to aid water transport vehicles. There are multiple methods to construct canals, for instance, the body of the canal is excavated and external sources such as streams provide the water source. The water stream is channelized by making a navigational path making it easier to flow, these are canals.

Cooling Towers and Chimney: Cooling towers help in cooling the interiors of the building during warm weather, this is often known as comfort cooling. There are various methods to do so, for instance, evaporative cooling where water evaporates by absorbing the heat energy and making a change in the interior. Another method is by using direct evaporative cooling that can be done by using a heat exchanger that sprays water over the coils of the chiller that cool the environment. On the other hand, a chimney is also a tower structure but is made up of walls creating a flue that helps in eliminating unwanted gas. These are constructed by using brick, metal, concrete, etc. It is a passage that transfers the fumes to the outside air.

Dams: Dams are obstacles that are constructed to resist the flow of water in a river and store in a lake or reservoir. These are constructed using natural materials, concrete, etc. There are various reasons for constructing these dams few being that, the reservoir that is created by them helps in storing rainwater which is later filtered and used. Another benefit of building a dam is that the stored water can be used to generate hydroelectric power that is directed to producing electricity. Dams also help in controlling the water flow in the river and preventing floods and the stored water can be used for irrigation during the shortage of water solving a major issue in today’s time of global warming.

Railways: Railways have changed the transportation infrastructure marking the end of the canal era as trains are able to carry much more load and thus more number of people are able to travel. Trains run on tracks that are permanent, horizontal structures that aid with a surface for the train wheels to roll upon. These are classified into three major types namely, traditional tracks, ballast-less tracks, and the continuous longitudinally-supported tracks. Railways have evolved structurally over the years making them even more efficient and economical.

Road: Roads have developed a lot from ever since they were made in terms of construction method, materials, durability, efficiency, etc. Initially, road structure was made of stone and timber, now modern roads are constructed using asphalt and/or concrete. There are three broad processes that elaborate roads viz, setting out, earthworks, and paving construction. After setting out i.e. following the dimensions for the road, a profile of board is placed to define the final level of the road, excavation, etc. Following this earthwork is completed that involves eliminating the unwanted i.e. topsoil, vegetation, etc. to clear the area. Finally paving construction of the road structure is done after burying the drainage and installing all the underground services. Paving can be rigid or flexible and includes final surfacing and finishing.

Retaining Walls: As the name suggests retaining walls are structures that are constructed to retain or restrict materials on one side of it thus, prohibiting it from collapsing and preventing the material from erosion. These wall structures are vertical or near-vertical depending upon the desired design or requirement. The chief attribute of it is to be able to resist the pressure loaded on it by the material it retains which is mostly soil and prevent it from collapsing. Retaining walls are constructed to support terrain where the angle of the soil exceeds the limit and can collapse, they are also used as functional or decorative elements in landscaping. These can either be part of a building or are often constructed as an independent structure. Retaining walls are widely used in parking as well.

Tunnels: Tunnels are structures that fabricate an underground passage through a hill or under cities, water, buildings, or roads. There are many aspects that need to be taken into consideration before constructing a tunnel as they would affect the tunnel’s attributes, for example, the size of the tunnel i.e the cross-section will depend on the purpose of the tunnel. The nature of the ground will decide whether it is feasible to construct a tunnel or it may develop defects to the structure. Type of tunnel, length of it, and ground conditions along with the timeline to complete construction help in determining the construction method to be used. The major process while constructing a tunnel is the removal of water which is widely done by pumping. Though tunnel structure is a hazardous process of construction, taking all the safety measures and risk assessment and its management today there are many tunnels that have been successfully built that were challenging to construct.

Coastal Defences: Coastal Defences chiefly protect the land-sea boundary which is the solution as per the coastal management. They defend from flooding, erosion, etc., and are constructed through different methods namely, soft engineering and hard engineering. Soft engineering in comparison to hard engineering is more sustainable and durable also involves functioning with natural. processes

4. Based on the Form:

One-dimensional: These are also known as ‘line supporting structure’ as the material is strenuous in a straight, curved, or angular but in a single line. One-dimensional structures are large in one direction and comparatively smaller in the other two, for example, ropes, cables, beams, columns, arches, and struts.

Two-dimensional: These are also known as surface structures and are large in two dimensions and small in the third dimension. Contradicting the one-dimensional structures, these have material that remains distributed equally along with the entire surface structure which can be either plain or curve. Few examples of two-dimensional structures are membranes, slabs, shells, plates, domes, vaults, etc.

Three dimensional: Three-dimensional structures are solid masses. These structures have all three dimensions in proportion to form a structure, for example, a room.

Composite Structures: Composite structures are a combination of two or more types of form structures mentioned above, for example, bridges, high-rise buildings, etc.

5. Based on the Material:

Timber: Humans have been using wood to construct structures ever since they started building shelters. Even though the construction process has evolved, timber still plays a vital role in architecture. Today, the world is looking for sustainable materials as everybody is concerned about the environmental impact it makes. Consumers, retailers, etc. are concerned and consider the environmental and social impact materials makeover the price, quality, and availability of them. Moreover, timber has a great performance capability and thus can be used in a wide range of applications.

Concrete: Concrete is the most widely used construction material. It is the primary material used to build structures like bridges, roads, buildings, etc. also it has structural applications in drains, pipes, curbs, etc. Concrete is a composite material comprising water, Portland cement, and aggregate in a specific proportion as per the requirement. There are several advantages of using concrete namely, concrete being cost-effective has a longer life, and not much maintenance is required. When concrete is in the form of a paste it can easily be shaped to the desired form and when hardens is stronger in compression. Moreover, it is non-combustible thus widens the scope of use.

Metals: Metals are solid materials widely used in the construction industry as they are durable and strong enough to form structural components. Steel and aluminum are metals that are extensively used in construction. Steel is an alloy that has high tensile strength and is cost-effective. Steel is used in a lot of forms for reinforcement, channeling, etc. Aluminum on the other hand is relatively expensive. It is widely used in the exteriors for wall cladding as they can be shaped as per the design thus allowing larger wall panels making it time-efficient for installation.

Masonry: Independent units often laid and bound to each other form a masonry. These individual units are chiefly of brick, cement blocks, stones, etc. that are bound together with mortar. There are a number of advantages of using masonry construction, for instance, it boosts fire protection as masonry is non-combustible. It is durable and prevents the construction from pests, weather, and natural disasters. Masonry is used to build walls and buildings.

Glass: Glass is very commonly used in construction and is made from liquid sand. Glass has a wide range of uses in construction viz, windows, cladding, facades, projections, etc. A variety of glasses are used as per the design requirement like transparent, tinted, reflective, opaque, stained, etc. Though glass is brittle it is still used in buildings as it can absorb, refract or transmit light within the building. Another advantage is that glass is weather-resistant and as it allows natural light into the building it enhances the mood of the occupants, reduces the use of electricity, and also allows the occupants to have a view of the outdoors.

Adobe: Adobe is made either of earth, clay, straw, and few more organic materials. These are basically mud bricks that have an appearance alike to rammed earth buildings. Adobe bricks are sun-dried and not kiln-fired like the traditional clay bricks are. Cement mortar is replaced with earth mortar for masonry work. The construction method, process of producing adobe bricks, and the properties of the material make them water-resistant along with the traditional properties of being durable, fire-resistant, flexible, etc.

Composite: Composite material is the amalgamation of two or more materials enhancing the attributes when together than they hold individually. There are many types of composites namely, cement which is the most commonly used material in construction that is a combination of aggregate, water, and cement. Few other materials being Fiber-reinforced polymer, PVC polyester, PTFE glass, etc. Moreover, there are advantages of using composite materials like it holds greater durability and protects the structure from extreme environments. Composite materials are lightweight, eases the construction process as they can be repaired in situ, and have low maintenance. These materials can have altered colors, texture, and shape as per the design requirements.

6. Based on the Element:

Substructure: Part of the building that is under the ground is the substructure. The main function of the substructure is to transfer the entire load by the structure on it to the ground. Substructure includes foundations with a damp proof course as a part of it along with the basement excavation excluding the basement walls that are not in contact with the ground. Basement retaining walls are part of the substructure excluding those that don’t provide external walls. Thus, all the elements under the ground other than a few exceptions are a part of the substructure.

Superstructures: Superstructures are all the elements of a structure that are above the ground. The superstructure includes frames of all the elements, all the floors that include the slab, column, and beam, roof structure, staircase, etc. Finishes, furnishings, equipment, fittings are not a part of the superstructure but the doors, windows, and other openings are. To conclude, structural members above the ground level are part of the superstructure having some exceptions.

Foundations: Foundations are a part of the substructure that supports the entire structure. The primary function of a foundation is to support and transfer the load of the structure to the soil or rock that can near the load and support the structure. Foundations are classified into various types and are used as per the design and structural requirements of the building. The type of foundation to be used for a particular structure depends on a number of factors like, nature of the load that requires support by the foundation. Secondly, the condition of the ground on which the foundation will support and whether there is a presence of water. The space available, accessibility, and sensitivity to vibrations also influence the selection of the type of foundation to be constructed for a structure.

Roof: Roof is the structural member at the top that covers the building creating a closed envelope. Roof basically protects from external elements like snow, rain, extreme temperatures, wind, etc. along with providing security, insulation, and privacy by creating an enclosed space. Depending on the design requirement roofs might have openings or windows that are designed to allow light, ventilation and give an open to sky view. Roofs can be fabricated using various materials and in a variety of shapes subject to various factors like the design, local climate, skills required to build it, span to be covered, etc.

Shell and Core: Shell and core design method is most frequently used in commercial buildings. Shell refers to the component that detaches the interior from the exterior of a building, whereas the core includes services like the staircase, water pipes, elevators, electrical cables, etc. Moreover, the core makes it efficient for occupants to travel through floors and distribute services efficiently. This method is adapted to prevent wastage of materials and money due to the difference in design ideas between the developer and the tenant. The material is stacked by the developer and later the tenant completes the shell work as per his design requirements. Thus, shell and core is a practice that changed the development idea of a commercial office building.

Structural Frame: Structural frame is a skeleton that supports a structure i.e. buildings, bridges, etc. Frames made in any material are capable of standing by themselves as a rigid structure to prevent deformation. Structural frames are classified further in types like rigid frame, fixed ended rigid frame, pin ended rigid frame, etc.

Floor: A horizontal bottom surface including its finishes is a floor. The primary function of a floor is to support everything standing on it including occupants, furniture, self-weight, etc. Classified into two types solid floors from the ground and higher-level floors are supported by the walls. The floor is constructed with a variety of materials like timber, concrete, stone, metal, etc. that have finishes as per the design aesthetics. However, floors divide spaces horizontally defining different levels in a building acting as a roof to the floor beneath it enclosing the space.

Walls: Wall is a vertical structure that defines and encloses a structure. The primary function of a wall is to transfer the load on it by the members above it, along with providing security and privacy. Walls are broadly classified as external and internal walls and their thickness depends on the type and material. External walls enclose the space whereas inert al walls divide spaces to create different rooms. Walls are made of different materials and have various finishes to make the interior look aesthetically pleasing and protect the wall. Moreover, on the basis of their function walls are segregated as loadbearing, compartment, retaining walls, etc.

7. Based on Overall Building Form:

Multi-storey: Storey refers to a floor when there is just one storey i.e. the ground floor that building is a single-storey building. When a building has more than one storey and includes stairs, lifts, and ramps for the vertical situation it is known as a multi-storey building. Multi-storey buildings might include certain amenities and services essential for their working, for instance, fire safety and evacuation plan, structural design, maintenance and cleaning, and so on. These multi-storey buildings can be classified on the basis of their total height namely, low-rise, mid-rise, high-rise, skyscraper, super tall, and mega tall structures.

Low-rise: Low-rise buildings as the name suggest proposes is not a tall structure that is usually below 35mts of total height. These buildings do not need elevators to aid occupants in reaching their destination. The total height of these buildings is within the reach of the fire-fighting equipment making it easier to put off the fire. Moreover, these buildings offer more privacy and security to the occupants. Although these buildings might not provide many amenities they attract people with low rents and negotiable utilities.

Mid-Rise: Mid-rise structures have a total height between 18m and 30m constituting storey in-between 5 and 10. The buildings require an elevator for the occupants to reach their destinations. As the fire-fighting norms suggest mid-rise buildings need to have fire-fighting shafts and fire-fighting lifts as well. These buildings have a good scale and thus the relationship with the street is better than a high-rise.

High-Rise: High-rise buildings have floors in-between 7-10 and a total height of 23-30m. As the number of floors is more the building requires a lift for the occupants to reach their destination. Fire-fighting equipment and refuge areas are compulsory as the height is beyond the reach of the extinguisher. Depth of evacuation also changes proportionately depending on the height. These buildings are mostly occupied as residential, office, hotel, or multipurpose.

Ground-Scraper: Contrasting to the low, mid, and high rise structures, ground scrapers are structures that extend horizontally while having a low to medium height. These buildings occupy a greater amount of land if compared to a skyscraper which can be expensive in terms of land prices. Though there are advantages of constructing a ground scarper, for instance, they do not impact the skyline. They are energy efficient and also create socially inclusive spaces as the relationship with the open spaces is much better. There are many renowned offices that are ground scrapers.

Sky-Scraper: Sky-scarpers are tall impressive buildings of 40 floors or more. These structures massively affect the skyline of the city and also showcases urbanization. As the cities are getting denser, growing vertically has become efficient in terms of maximizing floor spaces. As these structures are tall, design considerations include factors like weight i.e. the load that it can support, resistance to wind and earthquake, and the major concern of fire-fighting. These are the most complex structures to design and construct as they have many factors to be taken care of and create a balance between design, construction, engineering, and the comfort of occupants.

Supertall: Supertall buildings are taller than 300m having pedestrian entrance till the top. All the factors need to be taken into consideration like the wind pressure, earthquake, fire-fighting, etc. as these affect the structure enormously. Over the years structure-mounted cranes have assisted in lifting structural members to construct buildings with desirable heights thus motivating them to build more supertall structures.

Mega tall: Mega tall buildings are taller than 600m that exceeds supertall structures. Till 2020 only three buildings are classified as mega tall namely, Burj Khalifa, Shanghai Tower, and Abraj Al-Bait Clock Tower. There are a few under construction and dozens of mega tall structures are proposed. Burj Khalifa is the world’s tallest man-made structure that stands 828m tall and is the tallest mega tall skyscraper. These buildings not only affect the skyline of a city but become iconic buildings and tourist attractions for the country. As the project size is magnificent, sustainability is one of the major attributes that need to be taken care of while designing as it might affect the environment on a very large scale.

Super-Slender: Super –slender skyscrapers are super-slim and as tall as 50-90+ floors. These are mostly residential towers that use the design strategy of slenderness and pile the apartments. These apartments have maximum floor area making them luxurious and have breathtaking views. A slender tower is accounted to be a super-slender skyscraper on the basis of how slender it is and is not the height of it. Super- slender skyscrapers are recently trending in New York by providing ultra-luxury residential towers.

Mega-Structures: Mega-structure was a term used in the 1960s for futurist structures. These structures consist of a single structure considered as a core or frame to which utilities and spaces are clutched and thus create a self-contained city. These mega structures are more theoretical than practical yet have to fall under a certain classification, for instance, they should be flexible to reduction and extension of spaces. Secondly, they should have repetitive components, smaller elements to have clutched on them and the structure should be durable.

References:

https://www.designingbuildings.co.uk/wiki/Types_of_structure
https://mocivilengineering.com/types-of-structure/
https://edu.glogster.com/glog/structures/28pf7mpgmnm?=glogpedia-source#:~:text=Solid%20structures%20are%20mass%20structures,resist%20compression%20and%20other%20forces.&text=A%20frame%20structure%20is%20made%20of%20different%20parts%20assembled%20together.,-All%20of%20the

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