How does thermal expansion affect bridges?
Thermal expansion can affect bridges with either expanding or contracting the bridge (or, by essentially distorting it's shape).
If a bridge gets very heated, the road bed will expand. On the other hand, if the bridge is cooled, the road bed will retract. These changes in the bridge may seem initially insignificant, but with constant temperature changes, there will be constant and pervasive changes in the bridge length. Consequently, the bridge may eventually start to get distorted. Think of someone continuously pulling and squishing an eraser- eventually, the eraser might crack or form bumps.
One way to counteract this problem is by using expansion joints. Expansion joints fill gaps within the bridge and act as a flexible, variable filler that help the bridge adapt to temperature changes without distorting.
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