Different Components And Elements That Can Be A Part Of A Metal Bridge

FOUNDATION
An integral part of basically any regular metal bridge, the foundation is pretty much every part of a bridge that is placed below the ground level. There can be multiple different foundation types depending on circumstances and bridge type – with pile foundation, well foundation, and open foundation being some of the biggest examples.

 

PILE CAP
Some of the foundation types would have to have an additional element added to them called a cap (well and pile foundations are good examples of these cases). The main purpose of a cap is to serve as a connection between the bridge components that are placed above the ground level, transmitting weight loads from the highest elements of a metal bridge to the lowest – such as the aforementioned foundation.

 

DECK
A deck is one of the main parts of a bridge – its surface. A deck can not only be made using steel, but there can also be other materials in its place, such as wood, concrete, or open grating. A deck is where all of the specialized covering goes, be it asphalt concrete for cars/pedestrians, railroad bed for trains, and more.

A deck can act as one of the primary structural elements in some specific cases – mostly with cable-stayed and tied-arch bridges – supporting the entire bridge span by carrying compressive or tension forces. A concrete deck can also be supported by other elements instead – these supporting elements can be girders, I-beams, etc.

 

BEAM
The biggest use case for beams is to act as supporting structures, but they can only be used for smaller bridges with relatively short bridge lengths since beams do not have built-in supports for themselves. The main deciding factor for any beam bridge is what is the distance between support elements since this distance has a direct correlation to how strong this bridge is going to be.

As such, some of the more common examples of beam bridges usually go for about 80 meters or less. However, this does not mean that it is impossible to build longer bridges with this structure – it only means that you would have to use multiple beam bridge segments that are connected to each other (the term "continuous span" is used for these kinds of bridges).

 

GIRDER
A girder is a variation of a regular steel beam that shares a lot of its characteristics – but there are also differences. For example, a girder can be made of both steel and concrete (and the variation of a girder that uses a steel beam enclosed into a concrete box is incredibly popular in rural areas that have a lot of corrosion-friendly environments). However, a lot of the similarities are still there, with the girder's strength being mainly decided using parameters such as the girder's height, material type, girder weight, girder shape, and so on.

 

BEARING
A specific element that provides a resting surface between the bridge deck and that bridge's piers is called a bearing. The main purpose of a bearing is to reduce the potential stress by allowing for controlled movement of the entire bridge's structure. There can be many sources of stress that a bearing can help with, be it internal stress (fatigue, contraction, shrinkage, etc.) or external (seismic activity, ground settlement, thermal expansion, and so on).

 

PIER
A pier is an element that has only one purpose – to transfer either horizontal or vertical loads from the superstructure to the foundation and below. Piers are also used to accommodate for several other factors, be it water, wind, or vehicle collision. Piers can be made in several different shapes, ranging from relatively simple to rather complex and composite.