What are Bridge Gaps used for?

Question

What are Bridge Gaps used for, how do they work. If possible explain using the terms paricles,kinetic energy, heat, and thermal expansion

Answer 1

Gaps are there to allow for thermal expansion of the bridge.  In the summer when heat from the atmosphere is absorbed by the materials in the bridge (mostly the metal), individual particles of iron and other elements in the steel gain kinetic energy at the atomic level.  As they react with the particles around them, more force is applied across the length of the bridge member and it expands.  If the gap wasn't there, there would be enough force to actually bend the metal bridge member and possibly break some of the bonds that hold it to the next member.

In the winter the opposite happens and the metal shrinks.  The gaps should be set to their maximum width for the coldest possible temperature the bridge will encounter and for their minimum width for the hottest possible temperature.

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