Photo shows a row of concrete columns and beams that compose a bridge crossing a body of water.
A concrete bridge in Dallas, TX.
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Summary
Students learn about the types of possible loads, how to calculate ultimate load combinations, and investigate the different sizes for the beams (girders) and columns (piers) of simple bridge design. They learn the steps that engineers use to design bridges by conducting their own hands on associated activity to prototype their own structure. Students will begin to understand the problem, and learn how to determine the potential bridge loads, calculate the highest possible load, and calculate the amount of material needed to resist the loads.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).
Engineering Connection
Engineers who design structures must completely understand the problem to be solved, which includes the complexities of the site and the customer needs. To design for safety and longevity, engineers consider the different types of loads, how they are applied and where. Engineers often aim for a design that is strongest and lightest possible—one with the highest strength-to-weight ratio.
Learning Objectives
After this lesson, students should be able to:
List several examples of loads that could affect a bridge.
Explain why knowledge about various loads or forces is important in bridge design.
Describe the process that an engineer uses to design a bridge, including determining loads, calculating the highest load, and calculating the amount of material to resist the loads.
Educational Standards
NGSS: Next Generation Science Standards - Science
Common Core State Standards - Math
International Technology and Engineering Educators Association - Technology
State Standards
Suggest an alignment not listed above
Worksheets and Attachments
Load Combinations Worksheet (docx)
Load Combinations Worksheet (pdf)
Load Combinations Worksheet Answers (docx)
Load Combinations Worksheet Answers (pdf)
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Pre-Req Knowledge
The students should have a familiarity with bridge types, as introduced in the first lesson of the Bridges unit, including area, and compressive and tensile forces.
Introduction/Motivation
We know that bridges play an important part in our daily lives. We know they are essential components of cities and the roadways between populations of people. Some bridges are simple and straightforward; others are amazingly complex. What are some bridges that you know that might be called simple bridges? (Possible answers: Log over a creek, bridges over streams.) What are some bridges you know that might be considered more complicated? (Possible answers: Golden Gate Bridge, other large bridges, bridges that carry both highway traffic and train traffic.) What makes some bridges simple and other complex? (Possible answers: Their size, multiple purposes, environmental conditions, environmental forces, material maintenance requirements, etc.)
One amazing example of a bridge's contribution to connecting people to other populations and places for both social and commerce reasons is the Sky Gate Bridge connecting people to Japan's Kansai International Airport, located in Osaka Bay.
It all started when the nearby Osaka and Tokyo airports were unable to meet demand, nor be expanded. To solve the problem, the people of Japan took on one of the most challenging engineering projects the world has ever seen. Since they had no land for a new airport, they decided to create the Kansai International Airport by constructing an entire island! On this new, artificial island, they built the airport terminal and runways. Then, they needed a bridge to access it. Spanning 3.7 km from the mainland in Osaka to the airport in an ocean bay, the Sky Gate Bridge is one of the longest truss bridges in the world and has an upper deck for auto transport and a lower, internal deck for rail lines.
Aerial satellite image shows urban shoreline, blue bay waters, and long bridge connecting shore to a rectangular island containing airport terminal and runways.
Satellite image of Sky Gate Bridge to Kansai Airport in Osaka Bay, Japan.
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Explanation:
