Bridge Building-Scranton Preparatory School - The Jesuit Prep School of Northeast Pennsylvania

The intention of the Scranton Preparatory Bridge Building Competition is designed to introduce students to the field of engineering and to motivate them to investigate careers in math and science when they enter college. In addition the participant should be able to: (A) identify the engineering principles behind bridge building; (B) identify different types of bridges; (C) become aware of a process outlining how bridges are designed and built; (D) understand some of the physics important for designing, building and using bridges (E) understand some of the preliminary events that takes place before construction, and finally (F) design and build a bridge that adhere to specific criteria and applications.

Even though bridges have different styles and designs, they all are constructed to support their own weight (dead weight) and the weight of the traffic that must go across them. Bridge designers or civil engineers must also consider other factors such as the weather, strong winds and earthquakes when designing bridges. There are several elements that all bridges have in common. All bridges consist of piers that hold up the center of the bridge and abutments that support the end of the bridge. The distance between the two supports is identified as the span. Each support is a foundation that transfers forces into the substrata of the earth. Civil engineers decide which type of bridge to build based on the weight or load that the bridge must support, the distance the bridge has to span, and the forces of nature that the bridge will have to endure. According to which source that you read, there are three or four different types of bridges, the beam bridge, suspension bridge, arch bridge and the truss bridge. Some sources categorize the truss bridge as a type of beam bridge. A truss bridge is classified as a type of beam bridge. Therefore, the major difference between the three types of bridges is the distance that they can cover in a single span. For example, a beam bridge can span up to 200 feet, if trusses are added it can span as far as 1200 feet. The arch bridge can span up to 1800 feet, whereas a suspension bridge can span up to 7,000 feet. Each of the different types of bridges holds weight in different ways.

The engineering process is an extension of the scientific method. Teaching students to use this process when they begin to build their bridges will provide them with valuable skills to use when it comes to solving problems or creating a project. The engineering process includes basic procedures that engineers use to identify the problem and determine an adequate solution to the challenge they have undertaken. The engineering process can be broken down into the following eight simple steps:
(1) Identify the Problem - Before the engineer can begin work, the problem or task that is going to be undertaken must be known.
(2) Determine the Constraints - Constraints are the limitations that must be considered before you begin designing your bridge. Even though they are not limited to the materials, size, and money, you have to consider them the problem or task.
Preliminary Design
____(A) Brainstorming- Once both the problem or task has been determined and the constraints have been identified the group needs to think of as many ways to possible to solve the problem. The ideas should be broad enough to allow for unique solutions to arise. The class, meeting in smaller groups, may find that rough sketches are extremely helpful to stimulate a lot of different ideas. Even though all of the ideas may not be good ones, but they may inspire another idea that may lead to a solution to the problem.

____(B) Focus- Once all reasonable ideas are listed and the sketches are drawn, the group should choose the best two or three ideas for further development. The rough sketches should be converted to scaled or measured drawings.
(3) Analysis of Design - During this step, the designs are studied based on their merit in relationship to strength, cost, market appeal, and manufacturability. Models, drawings and calculations can be presented at this stage. A decision should be made at this point on which design to use or rather to begin a new design.
(4) Design Refinement - This step begins after a design has been analyzed. Any problems or unresolved considerations with the design should have been made apparent by now. Each design team should attempt to rectify the problems by making improvements in the design. After the corrections have been made, then each team should go back and analyze the design once again.

(5) Implementation Plan - Once the final design has been approved, it must be translated from an idea on paper to the real thing. Before the plan can be implemented, plans need to be made outlining the construction process. The methods of construction together with the strategy for scheduling involved a list of the tools; machinery and materials needed to complete the project. A listing of the parts and the dimension of the project are drawn up. The order in which the bridge is to be built is also written down and the specifications are compiled.
(6) Modify for Implementation - Any obstacles that may arise during the building of the bridge must be analyzed in order to find out if it is a big enough problem to cause a change in the original plan.
(7) Implementation - The final step is to manufacture the individual parts as prescribed in the implementation plans. Even though the steps are listed in a specific order, in real life two or more of these steps maybe combined or done in a different order. In the field of engineering, sometimes one person may specialize in a certain step, but the method is always followed in one respect or the other.