How and Why Bridges Are Made to Move
Practical Engineering took a look at how the weather affects everything, even something as simple as walking down the street.
Intentional cracks in the sidewalk are a perfect example of how engineers deal with thermal expansion. By filling these gaps with a flexible material, the engineers create what’s known as a “expansion joint,” something that’s meant to help a structure keep its form even with shifting temperatures.
Expansion joints come in all shapes and sizes, from clay bricks to molded rubber. Some forms of construction, like railways or air ducts, have specialized breather joints meant to deal with their unique thermal stresses. Copper is often seen as a good one-size-fits-all solution for an expansion joint, given its durability and ability to take a wide variety of forms.
Some researchers are looking at 3D printing to find a way to make a material that doesn’t react to heat at all. That’d be a game changer in terms of large civil engineering projects. But until they do, expansion joints will fill the gaps the best they can.
From: Popular Mechanics
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Joseph Olson
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Solids, liquids and gases respond to temperature increases in varying ways based on their ‘degree of freedom’. Solids have a Linear Coefficient of Expansion, and by happy coincidence, steel and concrete have nearly the same expansion rate, preventing sprawling and allowing concrete protection of steel reinforcement during fires.
Liquids form thermal barriers, known as Thermoclines and gases for the planet wide Lapse Rate. Energy flows within solids by conduction, between solids and liquids/gases by convection and into space by EM radiation. Climaclownology myths ignore Thermodynamic realities.
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