Truss Hydraulic Bridge Project

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Group Members

MovableBridge draw from

Goal[edit | edit source]

The goal is to design and build a draw bridge that will use truss members and a hydraulic system.

Research[edit | edit source]

There five different types of bridge designs.

Beam bridge
Steam Across Iowa River by Douglas W. Jones

Beam Bridge- is the easy bridge to design because they are made of piers that support the horizontal beams. Very basic type of bridges that are supported by several beams of various shapes and sizes. They can be inclined or V shaped. The strength is determined by the roadway and by adding additional piers increases the strength of the bridge. Compression acts on the top of the roadway and the beam of the bridge and though the piers. Tension is pulling apart the underside of the roadway as the loads passes over the bridge is pressing down

Pros: these bridge are easy to build, inexpensive and is used in urban and rural area.

Cons: these bridge’s span between the piers are limited to a certain length, large ships and boats cannot pass underneath and they do not have an interesting appearance.

Arch bridge
Stone Arch Bridge, Kenoza Lake NY by Vonsky87

Arch bridges are one of the oldest types of bridges and have been around for thousands of years. Arch bridges have great natural strength. They were originally built of stone or brick but these days are built of reinforced concrete or steel. The introduction of these new materials allow arch bridges to be longer with lower spans. Instead of pushing straight down, the load of an arch bridge is carried outward along the curve of the arch to the supports at each end. The weight is transferred to the supports at either end. These supports, called the abutments, carry the load and keep the ends of the bridge from spreading out. Arch bridge the arch uses semicircle design that can reduce the compression forces throughout the structure of the bridge. If the semicircle of the arch is greater than there is a greater the effect of the tension on the underside of the bridge. The arch bridge strength is determine by the shape of the arch.

Pros: is that the bridge is very strong and can use many different materials to build.

Cons: the design is limited to certain sites and can be expensive.

Truss bridge

Truss bridges are one of the oldest types of modern bridges. Truss bridges are among a variety of bridge designs that are being used for road traffic. Truss bridges are made up of triangles that holds up the roadway and is set on two piers for support. Truss bridge are very strong and are support heavy loads. The triangle angle are used because they are rigid and are stable. Compression acts on the upper horizontal members of the truss structure and in the piers that support the bridge. Tension acts on the bottom horizontal members. The angular members shares both of the force.

Pros: very strong used for a draw bridge or used for railroad trains.

Cons: difficult to build and require high maintenance. Are different to widen the bridge.

Suspension bridge

Bridge with overhead cables supporting its roadway. One of the oldest of engineering forms, suspension bridges were constructed by primitive peoples using vines for cables and mounting the roadway directly on the cables Suspension bridges are one of the strongest bridges that can span for long distances. They require large amount of materials and takes a long time to build. They are usually located near harbors. Suspensions bridges commonly have cable that stretch from two towers and are attached to each end of the bridge. The smaller cables are attached to the main cable to the roadway. The compression in the bridge is carried through the cables to the two towers. Tension is always acting on the cable because the roadway is stretching them.

Pros: can span long distances, can allow large ships and bats to travel underneath.

Cons: Expensive and requires a long time to build. Requires a large amount of material.

Cable stayed bridge

Cable stayed bridge are similar to Suspension bridges but are cheaper in cost and materials. These bridges have one or more towers that have cable attached to the roadway. The tower of a cable-stayed bridge is responsible for absorbing and dealing with the compression forces. The cables attach to the roadway in various ways. Bridge that uses deck cables that are directly connected to one or more vertical columns. The compression is in the cables that are attached to the roadway and are transfer to the towers. The tension is always located in the cables because the roadway is stretching them.

Pros: can span medium distance of about 500-2800 feet, are less expensive and faster to build than suspension bridge.

Cons: are typically more expensive than the other type of bridges.

Draw Bridge design

|Basic types of truss bridges or other bridges

pdf file of an explanation of the 5 common bridges

Bridge design

Design[edit | edit source]

CAD design

This is a CAD design of the truss bridge that open at a 45 degree angle. To build the actual bridge the group will have to find the a way to operate the truss bridge to open. This truss bridge is design in autodesk inventor.

A design using Autodesk Inventor, there is also a video of this bridge opening up and closing.

The is an assembly drawing with two parts the truss bridge and the holder. First made a sketched of half of the bridge and was able to put constraints on the bridge so that it was connected with the holder. Then mirror the whole assembly to make a complete bridge. Next the bridge move up and down because of a constraint function on the parts and using the inventor studio in the Autodesk. Next was able to animate the constraints so that the bridge can open and closed at 45 degrees. A video of the truss draw bridge design

This is an updated video of the CAD design. In this design a base was added to better illustrate the movement of the bridge opening and closing. Truss draw bridge desgin 2.

This is a simple bridge in openSCAD, these are the code that were used to design the bridge.

This is a simple beam bridge using OpenSCAD.

cube(size =[10,21,1],center=true);


cube(size =[1,21,1],center=true);


cube(size =[1,21,1],center=true);

union(){ translate ([4.5,9,-3])

cylinder(h=5, r=1, center=true, $fn=100);

translate ([-4.5,9,-3])

cylinder(h=5, r=1, center=true, $fn=100);

translate ([-5.5,9,-1.5]) rotate ([90,0,90]) cylinder (r=1, h=11,$fn=100);



translate ([4.5,-9,-3])

cylinder(h=5, r=1, center=true, $fn=100);

translate ([-4.5,-9,-3])

cylinder(h=5, r=1, center=true, $fn=100);

translate ([-5.5,-9,-1.5])

rotate ([90,0,90]) cylinder (r=1, h=11,$fn=100);


some ideas that the has came up with is to use:

Servo Motors [1] This is a video of a project that uses servo motors.

Hydraulic Systems [2] This is a video that uses a hydraulic system with syringes. We plan on using Hydraulic get our draw bridge to go up

Bill of Materials[edit | edit source]

The bill of materials for the project will include the prices of the wood for the base and the sides of the truss. The syringes and plastic tubing for the hydraulic system. Here is the link to the Bill of Materials Spreadsheet

Tools glue box cutter scissors

Prototype[edit | edit source]

First Prototype

First Design[edit | edit source]

The very first design was a concept of want the group plans to move further during this project. The first prototype used very little materials and still provided a clear idea of the function of the bridge. The truss member was a frame of cut cardbroad and the roadway was a block of wood. They were glue together with hot glue.

First Prototype idea

Next Steps[edit | edit source]

  • Finalize the design using other materials like wood for the truss members
  • Figure out how to use servo motor to open and close the bridge with at least a 45 degree angle.
  • Figure out how to use hydraulic power and determine if a hydraulic system have provide enough force to open the bridge.
Second Prototype

How We Made The New Bridge[edit | edit source]

After we reconstructed the first prototype gave us an idea of how we were gong to get the bridge to go up so instead of using the old prototype we create a new frame made out of white foam light material because it was easier to cut out than the cardboard, and instead of using a wooden block we decided to use a foam. After building the base, the frames for the bridge will support the roadway. There will be four frames (one for each side).

First Design for the Hydraulic system[edit | edit source]

From the Engineering Lab the group found a long white broad that will be the base to place provide the bridge and the hydraulic system support. The group than cut out stands that will held up the bridge. The stands will have to be high enough so that the syringes will be placed underneath the roadway of the bridge. When the syringes are pressed the water inside the system will be carried through the system and because of the pressure within the system will enter the syringes underneath of the bridge and force up the bridge. Similar to this design [3] But we had to find a syringe that would provide enough force to push the bridge upward at an angle of at least 45 degrees. The group did found a 60 ml syringe which can contain enough water to force the bridge upward.

We installed the bridge onto the white base and but we had to figure out what was going to hold the syringe in place so our group member, Melissa Chaput, suggested that we take piece of foam that could hold the syringe together.

Melissa pointed out that a rode will be needed to help move the bridge up and down and not get stuck in just one place like what would happen if glue was used. We decided to pierce a hole into the side of the stands to allow the rode to go through, and allow the bridge move up and down freely. Here are the picture of the finish second prototype.

Our Next Steps[edit | edit source]

  • The syringe that are used for the hydraulic system does not have water, for testing the bridge the group has been using air. With the air the bridge can since be force upward at an angle of at least 45 degrees. The groups wants to test with water to determine if using water will be more efficient.
  • The group want to make the stands large so that there will be more space underneath the bridge. The group plans to position the syringes so that the bridge will open at a large angle of degree.
  • The bridge right now have a basic idea of how the frame of the truss members will look like. The next steps is to measure and cut out the a frame that will appear like a truss and still be light to move.

Final Prototype

Improvements Made[edit | edit source]

The stand that provide support for the frames and is used to rotate the bridge was remove. Four pink foam was glue to the white wooden board and the stands were glue onto the top of the foam. This improve always for more space between the roadway of the bridge and the syringes to allows the bridge to open at a higher degree of angle.

The next improvements was to redesign the truss member design. This new design provides the concept of a truss bridge. However truss bridges using many member of metal for support. For our bridge the truss design was cut out of the same sheet of poster broad. This allow for the bridge to be light so that the hydraulic system will be able to force that bridge upward at an angle of greater than 45 degrees.

Melissa decorated the bridge by spray printing the bridge a silver color, added toy pine trees, and added blue play dough under the bridge for a water look. Then she made a control panel that store the syringes. When the control panel was pressed both syringes released the store water and pushed open the bridge. However the force require to closed the bridge is more and takes more time.

Our Next Steps[edit | edit source]

  • Design an actural truss bridge with truss memebers.
  • Test to see if the hydraulic system will be able to open the bridge if it was make of wooden truss members
  • Add LEDs lights to blink when the bridge is opening and closing.

Final Presentation[edit | edit source]

Truss Hydraulic Bridge Presentation