What makes bridges work

Traffic and construction accidents, boats hitting abutments, and explosions can lead to significant bridge stress and sometimes, failure. Builders can leverage strong, fire-retardant materials and isolating elements to limit the impact extreme events have on the balance of forces affecting a bridge. Some of the forces outlined above may cause immediate catastrophic damage to bridges or ultimate failure. These stressors also wear away at bridges over time, leading to long-term damage. Inspectors, managers, and engineers must look for these signs.

It can help them keep existing structures safe and provide them with the information they need to design even more durable and responsive structures in the future. Bridge Masters takes your privacy seriously and will never sell or share your information. The gravity dilemma The most profound force affecting bridges is gravity, which is constantly pulling at them, trying to drag them down to earth.

The answer is pretty much the same no matter the type of structure: Compression a force that pushes or squeezes inward is carefully balanced with tension a force that stretches and pulls outward.

This balancing happens by channeling the load the total weight of the bridge structure onto the abutments the supports at either end of the bridge and piers the supports that run under the bridge along its length.

These forces are distributed in a variety of ways on different types of bridges: Beam Bridge A beam bridge has its deck beam in tension and compression. Arch Bridge An arch bridge supports loads by distributing compression across and down the arch. Suspension Bridge The towers piers of a suspension bridge are in compression and the deck hangs from cables that are in tension. Cable-stayed bridge A cable-stayed bridge is similar to a suspension bridge. Truss bridge A truss bridge is a variation of a beam structure with enhanced reinforcements.

Cantilever bridge A cantilever bridge is one of the simpler forms to understand. Check out these bridges that manage forces in unique ways: The Rolling Bridge, London This sculptural structure is a type of bridge commonly referred to as a curling bridge. Stressors beyond gravity The complicating factor is that compression and tension on a bridge are constantly shifting because of stressors like: Changing loads It would be easy to build bridges if the loads on them stayed static. Environmental forces Bridges constantly react to Mother Nature.

Environmental sources of stress include: Tides, waves, and water back-ups. Water is one of the most powerful forces on earth. Engineers often insert openings into bridge abutments to allow water to flow through rather than push against them. Large gusts of wind can cause bridges to sway and twist. Modern ones are lighter and more aerodynamic, allowing wind to pass through them, which prevents them from moving.

Seismic forces cause bridge sections to shake and crash into each other, which can make them crumble. Hi this is my first time on this website. I love what guys do. I also love how you choose a random subject of sorts, and make a kid friendly article. Keep up the great the great work. May 14, Skylar May 8, Layazmin Mar 16, Testing, 1,2,3? Thanks for joining the conversation, Hunter c.!

Mar 19, Hi, Layazmin! Wonderopolis Sep 14, Why are there are a ton of people pretending to be me. Sep 17, Nov 29, We're glad you enjoyed this Wonder, marayah! Katherine Hope Jun 25, Most of what you're speaking about at the start is a cable-stayed bridge. Cable-stayed bridges are held up by towers with stay-cables directly linking to the deck, and suspension bridges are held up by towers linked with main cables, using upright suspenders. You defined this as a 'typical suspension bridge', but what you were actually describing was the definition of any suspension bridge.

Most of the pictures that you have used are of cable-stay bridges, as well. Jun 29, May 29, Micheal Fisher May 20, May 20, Wonderopolis May 20, Shaun Evergreen May 3, May 5, Nov 11, We're glad to have helped!

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See your results. Share Results. Retake The Quiz. Be the first to know! Share with the World Tell everybody about Wonderopolis and its wonders. Share Wonderopolis. Add widget. You Got It! Not Quite! It's just that the real ones are bigger. And one of our viewers, 6 year old Hannah from the UK, wanted to know how some of the things that we build stay standing. So she sent us a really great question, "Why are bridges so strong?

Sometimes when a road or railroad track needs to go across something big like a river or a deep valley, experts called engineers design and build bridges to do that job. And bridges can be really busy. Look at all those cars and trucks! It has to be pretty sturdy to carry so many people and cars. For a bridge to carry that much weight, it has to be built of special material, like iron and steel. But it takes more than tough materials to make a strong bridge.

So let's look at how bridges work. One very simple kind of bridge is called a beam bridge. When we say simple, we really do mean simple. A beam bridge can be just a log that you use to walk across a stream. Or put a long strip of cardboard between two short blocks. That's a beam bridge too. All bridges can hold a certain amount of weight, but what happens if we put too much weight on a beam bridge? Let's find out. It collapses. So a bridge that carries trucks and cars, which are very heavy, would have to be stronger than a bridge that carries bikes or people on foot, which are lighter.

So how do we make stronger bridges? Well, over time, people have learned that certain shapes can be used to make stronger bridges. Take a look at this railroad bridge. It has to be strong because it carries trains. What shape do you see? That's right, triangles. And that's not by accident.