Why bridges are made simply supported?

Why bridges are made simply supported?

Simply Supported Bridge construction will require future removal or addition of one or more spans. ❖ They are suitable at places where uneven settlements of foundations are likely to take place. ❖ They are generally best suited for short crossings and where speed of construction is an issue.

Is bridge simply supported?

These are generally constructed for short spans or as temporary bridges. They are not useful for heavy loads. Simple bridge is like simply supported beam type which consist two supports at its ends. For shorter spans, simple bridges are suitable.

Why are the end bars of steel bridges not fixed firmly but are supported on rollers?

Q25) Why is one end of a steel girder in a bridge kept on rollers instead of fixing it in pillar? Solution: When temperature increases, the metal bridge expands and the rollers slide to allow for expansion otherwise the bridge may break the pillar.

What supports are used in bridges?

Arch. The arch bridge carries loads primarily by compression, which exerts on the foundation both vertical and horizontal forces. Arch foundations must therefore prevent both vertical settling and horizontal sliding.

What is the main purpose of bridge?

The purpose of a bridge is to allow people or cargo easy passage over an obstacle by providing a route that would otherwise be uneven or impossible.

How have bridges improved over time?

Another factor that contributed to longer, stronger bridge designs through history has been the availability of better materials, such as cast iron, wrought iron, steel and concrete. The downward forces that act on arch bridges are gravity, the weight of the bridge, and the load that it carries.

What are the advantages and disadvantages of a beam bridge?

Advantages & Disadvantages of a Beam Bridge

• Beam bridges may be costly even for rather short spans, since expensive steel is required as a construction material.
• When long spans are required to be covered, beam bridges are extremely expensive due to the piers required for holding the long beams.

Is a beam bridge simple or complex?

Beam bridges are usually placed over highways, rivers or gaps in the earth so people or cars can cross over them. Beam bridges are simple but they cannot be as long as more complex and expensive kinds.

Why are the bridges fixed with rollers at one end?

Roller supports are commonly located at one end of long bridges. This allows the bridge structure to expand and contract with temperature changes. The expansion forces could fracture the supports at the banks if the bridge structure was “locked” in place. A roller support cannot provide resistance to a lateral forces.

Why is a bridge constructed with one end resting on rollers?

The reason for providing roller support at one end is to allow contraction or expansion of bridge deck with respect to temperature differences in atmosphere. If roller support is not provided then it will cause severe damage to the banks of bridge.

Why do bridges have roller supports?

What are fixed supports?

Fixed supports can resist vertical and horizontal forces as well as a moment. Since they restrain both rotation and translation, they are also known as rigid supports. This means that a structure only needs one fixed support in order to be stable. All three equations of equilibrium can be satisfied.

What are the advantages of simply supported bridge design?

Simply supported design isolates the bridge decking from some of its supports reactions like lateral pressure of earth , sudden lateral loads generated by vehicles thus it saves the bridge from getting unwanted moments and forces which may cause a bridge to develope large number of stresses which may become concern for an bridge engineer.

Why are bridges supported on both sides of the road?

This happens because bridge is simply supported on both of it’s sides. Hence connections are not rigid which makes the movement free. This helps in durability of the bridges. Otherwise fixed connections could lead to cracks and cause failure of the bridge.

Which type of support is used in bridge?

Roller supports mainly are used in truss bridge.This type of support is provided at one end of bridge spans. Roller supports only resists perpendicular forces and they cannot resist parallel or horizontal forces and moment. It means, the roller support will move freely along the surface simply like a skate board.

What are the disadvantages of fixed supported ends?

Fixed supports are very difficult to implement (and maintain) from a practical point of view. This can cause disaster if a fixed supported end becomes simply supported over time due to some joint failure. Consider one deck of a bridge supported over two piers (see the image).