Diving into the thermodynamics behind structural engineering

Posted in: Bridges, Construction, Highways

When you hear “thermodynamics,” you probably don’t immediately think about bridges. For civil and structural engineers, our mind jumps to expansion joints and bearings. That’s because, surprisingly, thermodynamics plays a large role in the way we design and build transportation structures.

Thermodynamics is a branch of physics that deals with temperature and the way it affects energy. In bridge terms, thermodynamics shows us how changes in temperature can make structures “move.” When any material gets hot or cold, it expands and contracts. Common bridge structures – steel beams, cables and reinforced concrete – are all affected by temperature. Engineers design each structure with a little “wiggle room” between materials. Expansion joints give the materials just enough leeway so they have room to expand or contract without collapsing.

This video from Practical Engineering provides a good overview of how thermodynamics affects bridges. It even provides a small-scale example of what it looks like when structures don’t have enough room to move.

Civil and structural engineers quickly become aware of thermodynamics in their designs as different locations, weather systems and climates can cause varying amounts of expansion and contraction. It looks a lot different in my home in South Carolina compared to Maine or Alaska. How does the temperature in your area affect the way your bridges get built?

Tony Steffee, PE

About the Author

Tony Steffee, P.E., has more than 10 years of experience providing project management, structural design and evaluation services. He has inspected the structural integrity of both buildings and bridges alike. As a Safety Assessment Program evaluator, Tony will apply his leadership experience and volunteer when disaster strikes, helping those in need. His experience in the engineering industry will be an invaluable asset during his SAP assessments in South Carolina.

Read more posts by Tony Steffee, PE

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