A Process of Bridge Designing

When designing a bridge there are multiples of different things that make if function correctly. From the actual structure of the bridge to the material that is used. All of these things come into play at some point. There are many different types of structures bridges can be those are Arch, Girder, Truss, and Suspension. There are also many types of materials like steel, wood, and plastics. There are many ways to make good bridges and every company or place that builds a bridge does it with a different reason for that particular structure or material. If we were to build bridges the same way every single time we built a bridge there wouldn't be any because it takes different kinds to fit certain areas. All of the areas I will go over will somewhat lap over each other because with a bridge everything is interdependent meaning that if one side of the bridge fails it is all going to fail because everything is particularly placed.

Joints are also a big factor in bridge design joints are what holds all of the individual pieces together there are multiple different ways to do this. When using cables on a bridge the amount of tension or if using beams the amount of stress that can be put on certain parts is critical. If there is too much tension of stress that can cause bridges to collapse. The five stages of the design process can also help to make sure bridges are built with precision and that it will hold what it is supposed to. Bridges are used thousands and thousands of times a day all over the world. One reason bridges are able to hold so much weight and their structure designs only have gotten better over the years because of benchmarking company's use existing bridge designs to then make their bridges even stronger and are able to use even more amazing structures because everyone has a different way of building bridges all over the world.

What kind of structure makes a good bridge. There are many different types of structures bridges can be those are Arch, Girder, Truss, and Suspension. Arched bridges have a curved shape to them. These bridges are very durable and can hold a lot of weight. They are a limited length bridge making them harder to build in large places without more anchor points. Girder bridges have the roads on top of them and are supported by columns or girders giving them the name. Truss bridges are made of different connected elements to for triangular shapes. Suspension bridges have cables ran to the top of suspenders therefore giving the road below extra support using its own structure.

All of these bridges can be made of different materials some are made of concrete like girder bridges. But others are usually made of steel like arch, truss, and suspension giving it more ability to support itself in different shapes. Over passes and most railway and city highways are made with the girder structure. While the Brooklyn Bridge and the Manhattan bridge use the suspension structure. These bridges are lightweight and strong meaning they can handle a lot of weight and stretch a lot further than the regular bridge. The disadvantage of this bridge is that they are expensive to build and  move in the wind which can be a problem when people pass over them thinking the bridge might fall or not be sturdy. Permanent bridge structures are usually made out of steel with concrete anchoring the ends and center points they are maintained at a high level so that they have the ability to last a long time.

Through Bridges have the structure above formation level while semi-through bridges have the super structure only partly above the formation level. There are also structured bridges on flood level submersible bridge structures make it able that water can go over the bridge on unimportant roads and they are low cost. Out of all of these bridge structures suspension bridges are the best structure because of their ability to hold a lot of weight. That's why they are some of the most used structures for large bridges like the Manhattan. The strength of the structure also depends on the quality of the material being used if you are using cheap steel then your bridge might be prone to stress cracks in the steel especially if it is being used in a very cold environment. All of this can be solved by using the steps in the design process when brainstorming you could make your bridge with steel and a truss or suspension structure giving it great strength.

There are hundreds of different kinds of bonding fastening and joining methods used on bridges. This is what the bridge depends on most for its support if the bridge can't stay together properly then it's not a bridge. One major way to hold wood bridges together or anything wood are screws they come in different lengths and sizes to hold all your pieces together. Soldering is an option used on smaller pieces of metal mostly in electronics and circuit boards. Most of the bridges use welds when needing to join two or more pieces of steel together. But there are other choices like riveting which is taking two pieces of metal and punching through them and adding a metal fastener, but this is usually used on sheet metal and would be difficult for large pieces of steel.  On a truss bridge the pieces push against each other to add support these pieces of steel would be welded together. On a smaller scale of bridge that we are building we will be using glue. There are multiple different types of glue.

White craft clue being the most common found in school classrooms and is somewhat flexible. Wood glue is more rigid and a stiffer hold than craft glue but isn't as flexible. The next glue is super glue, this glue has very strong adhesive properties and works good for Bolsa wood projects. Next is hot glue this is a better version of the white craft glue sets up strong and holds good strength. There are many more glues but those are the most used for small projects and shows which you should use for what you need. Out of all these methods superglue and got glue will work best for our project because they have the strong adhesive abilities along with the strength needed to hold everything together.

Bridges come in all shapes and sizes longer bridges are harder to handle because it relies on more man power and more mechanical power. On bridges that are 50 to 250 meters the Balanced cantilever method. Which is building the bridges in segments and casting it in place. This is great on cable-stayed bridges because they are attached with strong piers that are usually concrete. Cast-in-situ bridge construction is a flexible method where shapes that are irregular or are unusual can be constructed. These pieces are made at a different place then installed once they are in the exact place they are meant to be in. Turning large complex bridges into something that can be handled with less mechanical and man power. Precast construction methods are pre made parts that are then assembled once they are at the location.

A lot like cast-in-situ method these parts are usually beams, decks, or segmental decks. These are set in place by a crane once transported many parts are only small sections of a much larger piece. Span by Span method of construction is where decks are began at one point and piece by piece are laid throughout making one whole bridge. This is the most economically beneficial method and is used all over the world. This method is also safer and has had many advancements in the way they are constructed. The Incremental Launching Method of construction is for continued segments of bridges that are usually concrete or steel. These bridges are longer than 250 meters and can be even longer than that. The bridge is built section by section putting pressure on each anchor point making this a very strong design. There are many things that can affect a bridge like the scale, nature of the soil and also local weather. These can make all the difference by making sure the anchor points are all strong. If the soil erodes the bridge could collapse causing major issues. Beam bridges are a very simple design two vertical beams are put into the ground while one horizontal beam is then put on top. The only issue with a bridge like this is it must be a short bridge because force is applied to the middle of the horizontal beam causing tension. They are in expensive and easy to build but must only be built in short segments.

The super structure of a bridge is what holds it all together. It is your trusses for your truss bridges or girder for girder bridges. The super structure of the bridge all begins with what bridge you are wanting to design. The superstructure is what holds all of the weight that will be crossing over it. The deck of the bridge is what is used for the road. This can be concrete or wood whatever the preferred material being used is. Most of the larger bridges are made with concrete decks because they are able to hold more weight over longer periods of time. The decks are supported by large beams which are usually anchored into the piers. Bearings are a large part of a bridges structure they help evenly disperse the load through the bridges anchor points or piers. The bearings help the bridge move horizontality with the way the decks are facing giving for a smoother structure. The type of bearing depends on multiple things like weight, geometry, and tolerances. Piers are the structures that hold the bridge up they are vertical to the bridge usually places either under or in between the decks supporting the load above them. Piers are made from steel with concrete surrounding into the soil giving it added structural support. The type of pier depends on structural connectivity, and the shape of the section. The structural connectivity of the pier is labeled as monolithic or cantilevered. When talking about shape they are labeled as hexagonal, hollow, solid, round , octagonal or, rectangular. Abutments control the earth behind the bridges structure. Usually placed under the oncoming point of the bridge.  Wingwalls are extensions of the abutments and also help retain the earth coming from beneath the bridge. Guardrails and hand rails are added to bridges to help from cars driving off the side or for walk ways over the bridge for people to grab.

These are all ways of different structures and designs and ways to build bridges when bringing this into a wooden model bridge isn't much harder the same designs can be used. From these designs a truss bridge will be best for this project. With each individual piece pushing against the other force helps the bridge stay strong. The pros of working with balsa wood on this project is that its flexible and can support a bit of weight for being wood. This will help with the force that is applied to the top. Fishing sting can also be applied to the bridge adding a suspension like structure. This also supports the down force by pulling down on the vertical supports adding a helping force. With having multiple piers in this case will help the bridge from collapsing from the middle this force will be absorbed by the piers. Using the different types of bridge structures and designs will add extra support to the bridge. For joining and bonding methods wood glue will be the best for the deck because it is very strong and the pieces won't break from each other.

Using the craft glue for points that have great forces helps the flexibility of the bridge giving added support to the forces. If we were able to use metal in this project the strengths of the bridge could be much better if we used steel the joints could be welded together. The bridge could also have even more options of support like cables. if we were to use a stacking pattern of balsa wood sticks for the deck that would be greater support because the forces of the stacked pieces would push outwards towards the force that is applied. The cons of using balsa wood are also that it is inconsistent in density which can lead to the bridge breaking in certain places just because of the density of the wood. Bass wood could be a better alternative to balsa wood because it is heavy, and is also stronger and does better with tests of force. Lateral bracing is also a great way to keep the bridge from twisting because of the properties of balsa wood it is flexible which is a pro and a con in itself. With shorter pieces used in the construction of the bridge can handle more applied force because it is a shorter piece and the weight can be more evenly distributed without sagging. The more triangles that can be used in the structure will be better because they are able to bear more weight. Triangles also hold their shape better than squares because they only have 3 supporting points that push on each other.

The truss bridge structure also is great for a project like this because it is a short bridge and a simple design doing what it's supposed to, hold force that is applied to the top. Balsa wood is also different in different climates. If the wood is wet it is going to be more flexible but the glue might not stick. If the wood is dry it is more sturdy but is also prone to cracking under force. Building different bridges and testing them will also help find the best design and strengths. Stage four of the design process uses prototypes to find which one best fits what you are designing also eliminating failures when the final product is made. If we were to make our bridge a beam bridge it would not support the weight as much as another bridge because all the force is applied to the center causing breaking in the middle. Hot glue will also help hold all of the deck pieces together and the piers adding flexibility in the joints when the force is applied. All of this is applied to everyday bridges when one piece is pushing the other it is supporting the force above it which are usually cars or people walking over the top of them. The structure of these bridges haven't changed a lot over time because these structures support the most weight. Bridges that have irregular shapes or are bent are usually more for aesthetic purposes meaning that those bridges don't

usually carry a lot of weight over the top of them this would be a bad design to use in our project because they have no functional purpose. Aesthetics have no use in function therefore don't have a big place in the design of bridges that need to function more than they need to look good. After looking at everyone's designs taking the strongest points from each will help our bridge be the strongest. In stage two of the design process concepts and ideas are thrown out by taking the strongest parts of each of these concepts or ideas you can find what makes the strongest bridge.

When building the supports or anchors for the wooden bridge they should be made out of short pieces to keep force applied to all parts as should the bridge. With force applied to all parts it is going to handle more weight over all. If the bridge can be supported in the middle it will have the best chance of not breaking because that is where most of the force will be applied. Super glue will not be a good use in this project because it can break easily when force is applied to the joint. A better alternative to this would be using wood glue. The popsicle sticks are strong and should be used for the deck as support to the force because they are stronger than the balsa wood. If the fishing line is twisted together it can be used as cable for suspending  which helps take away some of the pressure that is also coming from the ends of the bridge. This is used on bridges like the Manhattan bridge because it is a long segment of bridge and has a lot of everyday traffic and force that is applied. It is also flexible and helps with strong winds. End posts won't really help in this project because the force is being applied to the center of the bridge if the force was being applied evenly throughout the whole bridge then this would be a good way to add support.

This helps in other bridges that are used for everyday purposes because cars are going from one end to the other when the force is applied to the center you don't get the same effect and the results will not be the same. Having a good base structure before adding the deck because this will be the main structure that takes the force. The overall design of the bridge should have a truss design on the side using triangle to keep the force equal through the bridge. There should be a lateral brace or anchoring point in the middle so that the applied force isn't just flat wood. This is taking the basic design aspects of normal truss bridges and arch bridges. Keeping all of the pieces shorter will help by not snapping the pieces and keeping the overall length shorter. There should be three anchoring points or more throughout the bridge so that there are multiple points supporting the bridge and not just all the force on one point. Overall the bridge should be able to hold more than the minimum force of 30lbs. the weight of the bridge should also be very low if only using glue in the necessary joints and not using excess wood where it will not help the force. If there were one material that would be better to do this project with I believe it would be steel because it has better strength properties and shows what kinds of stress that real bridges go through with the forces of everyday wear. There would also be more ways of joining the materials other than glue because most glues used on projects do not reflect the glues or other bonding or joining methods in actual bridge design.

After the research of different joining and bonding methods and different types of structures to use for bridges. Truss and arch bridges because they can hold an ideal amount of weight. These are also basic bridge designs that have been perfected thought-out the years. These designs have the best possible outcome of strength to weight ratio. Using the triangles on the side as trusses and multiple lateral braces and anchor points we will be able to disperse the force throughout the whole bridge. Using the popsicle sticks as the deck of the bridge there will also be more surface area for force to be dispersed. Also using the hot glue and the wood glue will give us the best joining and bonding methods with the hot glue flexibility and the strength of the wood glue for the lateral bracing. By not using super glue the bridge will be less prone to cracking at the joints with the force applied. By possibly using the fishing line we can have suspension to the major points of force keeping these points from snapping with the applied force. If all of these techniques are used in the design process then the bridge will be successful if multiple different designs are not used and the wrong structure and bonding methods are used then the bridge will be unsuccessful. These same steps are followed with everyday bridges multiple different designs are researched and hand-picked to fit the project guidelines If the steps aren't followed then the same outcome will show. Testing of a mock bridge will also help find spots of failure before the final product is tested.

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