Cantilever Bridge | Cantilever Bridge Advantages and Disadvantages | Cantilever Bridge Information

Introduction of Cantilever

A Cantilever Bridge is a type of Bridge built with horizontally projecting Cantilever members or structures.

This article will teach you about cantilever bridges, the different types of cantilever bridges, and the benefits and drawbacks of cantilever bridges.

What Does Cantilever Means?

Cantilevers are long projecting beams or girders usually fixed at one end and free at the other.

What Is Cantilever Support?

Cantilever support is a rigid structural element that extends horizontally and is supported only at one end. In most cases, the cantilever supports extend from a vertical flat surface, such as a wall or other firmly attached element.

Cantilever Bridge

Cantilever bridges are widely used in the construction of major bridges all over the world. Cantilever bridges are created because there is a need for bridges that do not require any support. It is not possible to build continuous bridges with multiple supports.

In some cases, the number of supports cannot be specified; in these cases, Cantilever Bridges are appropriate.

A Steel Truss cantilever Bridge can span up to 1500 feet with the help of proper construction materials and the perfect design of the Bridge. This Bridge is typically used by pedestrians, vehicles, and trains.

Cantilever bridges are best suited for constructing bridges that must span a waterway without being divided by river piers.

To avoid shear stress, cantilever bridges must be firmly attached to one side to carry the total superimposed load from the free-standing side.

Cantilever bridges should withstand tensile stresses in the upper Support and compression stresses in the lower Support.

Sometimes, the distance between two supports where a bridge must be built is too great to bridge with a single cantilever on each side.

In this case, a special Beam Bridge or truss Bridge is placed between the arms of two cantilevers, combining them into one Bridge. A Suspended Span Bridge is the name given to this type of Bridge.

Iron, structural steel, and prestressed concrete are used to construct the cantilever bridge.

The bending moment of the cantilever structure is maximum at the Support and zero at the free end. As a result, the section at the Support should be as large as possible to withstand the bending moment.

Another method for spanning long distances between two points is the Balance Cantilever Bridge. In this case, the engineer builds the year in the center of the river or span.

The arms of the cantilever Bridge are connected to the shore during the first stage of construction.

Steel tubes with thin walls are used as piers in constructing cantilever bridges. When building long-span cantilever bridges, it is necessary to meet both the strength and weight criteria.

Lightweight concrete is sometimes used in the construction of Cantilever Bridges to reduce the total weight of the long-span cantilever bridges.

The cantilever bridges also allow pedestrians, trains, and vehicles to pass from one end to the other.

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Type of Cantilever Bridges

The cantilever bridges are mainly classified into two types.

• Balance Cantilever Bridges

• Continuous Cantilever Bridges

1. Balanced Cantilever Bridges

The Balanced Cantilever Bridge is one of the best bridges that do not require falsework. When a longer span is required, balanced cantilever bridges are built.

Balance cantilever bridges are appropriate where simple supports or continuous frame structures are insufficient. A stronger foundation is required to build continuous or simply supported bridges with a longer span, which is more expensive.

Balanced Cantilever Bridges are a hybrid of simply supported and continuous structures.

The construction of the cantilever structure with only one cantilever length should be kept as short as possible to avoid uplift at the other end.

Cantilever balance bridges have the advantage of being both simply supported and continuous structures. Like a continuous bridge, a cantilever balance bridge requires only one line of bearings over the piers.

This method of Balanced Cantilever Bridges is more beneficial than other construction methods where temporary showings can disrupt traffic.

2. Continuous Cantilever Bridges

Continuous cantilever bridges are unique types built by attaching two gantries from opposite ends of the abutments in the center to complete the structure.

The Abutments should be made heavy to compensate for the lack of a balanced cantilever. Continuous Cantilever bridges function as continuous beam feet spanning between two supports, with the Bending moment and Shear Strength remaining constant throughout the beam.

Advantages of Cantilever Bridges

• Falsework is not required in the construction of Cantilever bridges.

• Cantilever bridges are more resistant to the effects of thermal expansion.

• Cantilever bridges are ideal for long spans.

• Cantilever bridges have multiple cantilever spans and can be started from any of the columns at any time.

• Because Cantilever Bridges do not have supporting piers, the style and geometry of the highway supported by this Bridge are more flexible.

• Cantilever bridges are ideal for deep Rocky valleys and flood-prone areas where falsework is not an option.

• Cantilever bridges require only one side of their cantilever to be supported during construction.

Disadvantages of Cantilever Bridges

• Cantilever Bridges experience high tension during construction, known as a Negative moment.

• Cantilever bridges must maintain stability by balancing compressive and tensile forces acting on them.

• Because cantilever bridges are heavy, they require larger and more robust Support.

• Cantilever bridges should not be used in earthquake-prone areas.

• Cantilever bridge construction is not appropriate for extreme weather conditions.

• Cantilever bridge construction and maintenance are difficult.

Cantilever Bridge Facts

• The world's first cantilever bridge was 38 meters long, also known as a modern cantilever. In the year 1867, the engineer Heinrich Gerber built this Bridge.

• The Forth Bridge is the most well-known cantilever bridge in the world. For 29 years, this Bridge held the world record for the longest pen.

• The 549-foot-long Quebec Bridge is the world's longest span cantilever bridge. It has the world's longest cantilever structure.