Types, Advantages and Disadvantages of Cantilever Bridges
What are Cantilever Bridges?
Due to their adaptability and ability to span significant lengths across rivers and other bodies of water, cantilever bridges are one of the most often used today. Both steel and concrete can be used to construct cantilever bridges, which are made up of two cantilevers, which are substantial extensions of a supporting beam. Due to its strength and adaptability, this kind of bridge is appropriate for a variety of settings and purposes.
Types of Cantilever Bridges
The simple, through, and box girder cantilever bridges are the three primary varieties of cantilever bridges. Two cantilever arms that extend from the fixed end and are connected at the centre make up the simple cantilever bridge. Two cantilever arms make up the through cantilever bridge, one of which extends beyond the point of support and the other of which extends out from the opposite side. The box-shaped beam of the box girder cantilever bridge is attached to supports at both ends.
Due to their low cost and excellent use of available space, cantilever bridges are frequently chosen for use in bridge construction. As they frequently result in physically magnificent bridges, they are also appreciated for their aesthetic appeal.
Simple Span Cantilever Bridge
A Simple Span cantilever bridge is a form of a bridge that spans a single gap of open water or land using cantilever construction. The bridge’s deck is normally supported by two or more cantilever arms that extend from the foundations on either side of the gap.
The adaptability of a basic span cantilever bridge is one of its main benefits. It can cross distances that other bridge types cannot, making it useful in a number of circumstances. It is very simple to construct and affordable as well.
However, there are certain disadvantages to simple-span cantilever bridges as well. Its low load-bearing capacity is one of the major issues. The strength of the cantilever arms and their connections to the foundations limit the span even though the arms can hold a lot of weight. This indicates that carrying large loads is not appropriate. The requirement for lateral force resistance is another area that needs development. A basic span cantilever bridge offers little defence against seismic or wind pressures.
Simple-span Cantilever bridges are appropriate for light weights and relatively short spans. They are a fantastic option for bridges that don’t need to support huge weights or span great distances because they are reasonably cheap and simple to construct.
Cantilever Through Bridge
Two cantilever arms are used to create a cantilever through the bridge; these arms are attached at their ends and support one another. A continuous unobstructed span across a vast area is made possible by the bridge’s lack of piers. For crossing over rivers, significant bodies of water, and other lengthy distances, this sort of bridge is frequently employed.
Cantilevers through bridges have a number of benefits, including their strength and adaptability. They are capable of spanning a wide range of lengths and widths because of the several ways in which they may be built. Cantilever arms are the best option for high loads since they also offer a sturdy, solid framework.
If the bridge is constructed over a river or lake, the pierless design also prevents any interference with the natural flow of the water. Cantilever-through bridges also cost less than other bridge styles because they require fewer piers and supports.
The difficulty of the building is cantilevering across bridges principal drawback. The construction process can be labour- and time-intensive if the arms aren’t tightly linked. Furthermore, the additional complexity may result in expensive design modifications or mistakes during construction.
Due to their design, cantilevers through bridges are inadequate for supporting heavy weights. Long arm spans may result in less stability, and as a result of the extra weight, the entire structure may weaken.
Cantilever bridges provide a variety of benefits, including their strength, adaptability, and capacity for long spans. However, because of their intricate design, high cost, and potential unsuitability for bearing heavy weights, these bridges are only appropriate in certain situations.
Cantilever Truss Bridge
A type of bridge that uses cantilevers in both the structural design and construction is cantilever truss bridges. A projecting beam or structure known as a cantilever is held up by just one end. Cantilever bridges typically cross wide expanses of water, including rivers, canals, and other bodies of water.
Cantilever construction works particularly well with truss bridges because of its inherent structural stability. Truss bridges are made up of triangle pieces, which are typically made out of steel rods or beams. The truss’ triangular design can offer more strength than a straight beam bridge, enabling it to span much farther.
The cantilever truss Bridges typically consist of two primary components: the truss, which is the triangular structure that supports the bridge, and the cantilever arm, which is a rigid beam attached to the bridge’s main structure. The truss is built with a set of vertical columns known as cantilever arms and horizontal beams joining them to support the arm.
The fact that cantilever bridges require minimum maintenance is one of its key advantages. The bridge can endure heavy loads without requiring extensive maintenance or refurbishment because it is supported just on one end. Cantilever bridges are also quite simple to build, which reduces their cost for many bridge projects.
However, there are disadvantages to cantilever truss bridges. They are particularly susceptible to wind damage, which can result in truss bending or breaking. They are also prone to fatigue because of their length, which can be a major problem if the bridge is put under a lot of stress. Due to these factors, it’s crucial to make sure that cantilever truss bridges are constructed using sturdy materials and periodically checked for signs of wear and tear.
Cantilever truss bridges provide a sturdy and dependable bridge structure overall. They are an excellent choice for many bridge projects since they offer the advantages of being weatherproof and rather simple to build.
Advantages of Cantilever Bridges
- Construction projects frequently use cantilever bridges considering their numerous advantages. In order to increase stability, tension rods or substantial cables are frequently used to reinforce the cantilever bridge, which is constructed on two supports at a perpendicular angle. These bridges often have a single span yet can span great distances and carry large loads. Cantilever bridges have a long lifespan, a straightforward design, and resistance to earthquakes and wind.
- The longevity of cantilever bridges is one of their main advantages. They are often long-lasting and require little upkeep, making them a good investment. A typical cantilever bridge can handle enormous loads and withstand seismic and wind pressures because of its sturdy design. This type of bridge can be built in coastal regions and other areas with harsh weather because it is also corrosion-resistant.
- Additionally, building cantilever bridges is affordable. Cantilever bridges can be built more rapidly and with fewer materials than conventional bridges, depending on the span. A cantilever bridge’s structure is also significantly simpler than that of other bridges, which can lower the labour force required for its construction. This may lead to a shorter build time and less expensive labour.
- Cantilever bridges are built to withstand earthquakes and wind as well. Cantilever bridges’ enormous cables and tension components work together to lessen the structure’s overall vibration and absorb the shock of seismic activity. As a result, cantilever bridges are dependable and secure in regions vulnerable to these natural calamities.
- Cantilever bridges have various benefits overall. They are an affordable option for bridge construction because they are simple to build and require little upkeep. Additionally, they are long-lasting, sturdy buildings that can withstand wind and earthquakes and are appropriate for coastal and extreme weather conditions.
Disadvantages of Cantilever Bridges
- Due to their strength and flexibility, cantilever bridges are among the most often used designs, yet they have drawbacks. The expense of constructing cantilever bridges is one of the major challenges. The price of building and maintenance can be rather significant because they are quite massive structures and the cantilever arms require complex engineering.
- The challenge of building cantilever bridges across water is another drawback. It can be difficult to align and secure the various parts of a cantilever bridge since they are built in several pieces. Complexity can cause building to take longer and cost more money.
- Cantilever bridges may also be subject to adverse weather, such as strong winds, heavy rain, or snow. This is because their height raises the possibility of structural damage. High traffic volumes can also put stress on the bridge because its stabilising cantilever arms might not be able to withstand the added weight.
- Finally, the size and type of vehicles that can traverse the cantilever bridge are restricted by its design. Large trucks and buses may need assistance to safely traverse cantilever bridges because they are typically only designed for light and medium-sized vehicles.
Overall, cantilever bridges have numerous benefits, but there are also some drawbacks that must be taken into account when choosing the design of the bridge. To be sure a cantilever bridge is the best option for the work, careful planning, taking into account the cost and construction complexity, should be done.
In conclusion, cantilever bridges are a widely used design of bridges. They are utilised in a variety of applications and offer an efficient and affordable means of spanning enormous distances. Cantilever bridges provide a number of benefits, including the ability to support greater spans, allow space for higher ships, and be constructed fast.
The necessity to maintain their high foundation costs, the requirement for pricey specialised equipment, and the limited design flexibility are some of the drawbacks of cantilever bridges. Cantilever bridges, however, are a common option and a useful tool for building bridges.