The cantilever bridge craze began with the development of the first cantilever bridge, built in 1855 in Coalbrookdale, Shropshire, England. Since that time, these bridges have been built all over the world and are usually seen in areas where there are few natural supports available to anchor the structure or the terrain makes it difficult to build the foundations into solid ground. This type of bridge has both advantages and disadvantages that must be considered before deciding whether this type of bridge is right for you.
What are cantilever bridges?
Cantilever bridges are bridges in which one or both ends of a span rest on abutments (or piers) rather than on a central support called a pier. The surface is supported by two cantilevers (one for each half of the bridge), though there may be additional anchored spans as well. The most famous example, not surprisingly, is New York City’s Brooklyn Bridge—the world’s first steel-wire suspension bridge. One small drawback to being able to build longer bridges: Because it’s so difficult to build these structures, they tend to be more expensive than similar-length arch bridges. But you know what they say: All things being equal, go with your strengths!
How do they work?
The formula for finding out how long it will take to construct a bridge can be broken down into: Time=(L*W)/240. This is calculated by measuring L (span) in feet, while W (depth) is in inches. The depth refers to the depth at which you are installing your supports, while L measures distance from point A to point B on your current project. Once you have these measurements, measure them along with your craze lines and then multiply that number by 240. For example: if your bridge has a span of 100 feet that is 30 inches deep with vertical craze lines each side that are 10 inches apart then your final answer would be: 6 hours + 120 minutes = 7 hours 20 minutes
Why do we need them?
Many people wonder why we need these seemingly small, insignificant bridges. In reality, these small craze lines provide a lot of value to our society. They serve as an avenue for pedestrians that would otherwise have to cross streets filled with cars, buses, and trucks. The bridge also serves as a refuge for anyone who is too tired or uninterested in continuing their trek across roads filled with aggressive drivers. Lastly, due to its small size and lack of traffic lights or stop signs, it allows a quicker transition from one place to another compared to large overpasses or bridges that can take some time with long traffic signals on them.
Pros and Cons
The major advantage of cantilever bridge dental is that they are more economical to build than suspension bridges. Also, because they can be erected from both sides of a river, at either end, rather than just at one end as in a suspension bridge, then there is less disruption to traffic. Finally, if you want a very long span, you may find it easier to construct with cantiles than with simple beams. However: Cantilevers cannot span as large an area as trusses; if you want a span wider than 9 metres (30 feet), you will need to go for trusses.
Common types of cantilevers
The most common type of cantilever is a fixed-end cantilever, in which one end of a beam or slab is anchored to a vertical surface (often a building) while gravity holds down its other end. Fixed-end cantilevers can provide support for walkways, balconies, and other architectural features; they’re also used as structural supports for building structures. In an open-ended (or balanced) cantilever, the beam or slab extends past both ends and is suspended only by its own weight—and is often used for pedestrian bridges. Open-ended cantilevers can span wider distances than fixed-end ones but require sturdy foundations on either side.
