James Rhodes Students Get a Lesson in Bridge Engineering

On Wednesday, December 15 the James Rhode students learned about several bridge engineering principles using simple materials.  Divided into teams of four the students tackled the task of constructing models of an arch bridge, beam bridge, suspension bridge, and cable-stayed bridge. The students were asked to consider the forces acting on each type of bridge and prepare diagrams to document their findings.

 For the arch bridge the students used a piece of cardboard for the arch and textbooks for abutments. By pushing on the top of the cardboard and removing one of the textbooks the students learned the importance of the abutments in transferring the load to the ground and maintaining the structural integrity of the bridge. The arch was found to be under compression transmitting the force to the abutments.

For the beam bridge the students used an eraser for a beam. The students made notches in the top and bottom of the eraser and placed it between two textbooks. By pushing on the top of the eraser the students learned how the top notch tried to squeeze together in compression and the bottom notch tried to spread apart under tension.

For the suspension bridge the students used string for cables, and textbooks for piers and anchorages. By pushing on the string between two piers without using anchorages, then doing the exercise again with anchorages, the students learned how the loads were transferred in the bridge. The cables were found to be in tension, transmitting compression to the piers and tension to the anchorages.

For the cable-stayed bridge the students used string for cables and volunteered one of their team members to act as a pier! One string was placed over the lucky team member’s head and tied to each elbow, and another string was placed over the team member’s head and tied to each wrist. The students were asked to describe where they felt a pushing force, or compression. Each person quickly responded that they felt compression on the top of their head, demonstrating that the pier is in compression and the cables are in tension.

Additional information on this activity can be found at http://www.pbs.org/wgbh/nova/bridge/build.html, and additional information on tension and compression can be found at http://science.howstuffworks.com/engineering/civil/bridge.htm.

John Hay Seniors and Construction Methodologies



Design Build Team



Design Bid Build Team
Constructing from Another's Design



The John Hay Seniors learned first hand the pros and cons between the Design-Bid-Build and Design Build construction methodologies.  After an overview of both arrangements, four teams were created to construct a bridge out of toilet paper rolls, foam board, stryo foam blocks, tooth picks, scotch tape and wire, in an hour time limit! All teams also needed to draw their design to scale.  Two teams were the Design Builders and they were permitted to design and construct simultaneously.  The two Design-Bid-Build teams were only permitted to draw their bridge during the first 30-40 minutes.  A surprise was thrown into the mix because after 40 minutes, the two Design-Bid-Build teams had to trade designs and were required to construct the other team's design based on the drawings.  That caused some heartburn because the teams were really connected to their own drawings and wanted a chance to build to them.



Careful Construction of a Design
Build Team



All teams finished their bridge construction approximately the same time and each group had a chance to talk about the process.  Both Design Build teams were initially happy with their group, but soon realized that it was more difficult than they first thought.  As they were constructing, new ideas would be presented, but they could not always incorporate them because it didn't go with what was already built.  Constructing and doing the design at the same time added pressure to who was doing the drawing to make sure it matched what was built.



Design Bid Build Team Finishes Construction and
Even Runs a Load Test



Both Design-Bid-Build bridges were constructed very closely to the intent of the design, and both teams thought it was because their designs were superior.  These teams realized the importance of having someone who was familiar with the design participate in the construction process (as the mentor helping the drawing team moved to the constructing team).  They were frustrated that they couldn't make design changes even if they thought of something that would make an improvement.

James Threalkill, Sr. Director, Human Resources from Skanska was visiting from Nashville, Tennessee and he commended the students on their performance, skill set and teamwork.  In his six years of working with ACE students, he said the John Hay Seniors and the Cleveland program as a whole was one of the best.  He encouraged the students, with particular emphasis to the girls, to continue in the construction field.