Chemistry · Foundation

1/3
Thermal expansionRunning
Heat bridge. Temperature swing at 90 K. Predicted growth 0.03 m, Joint allowance 0.01 m. Currently predicted growth is over by 0.015 m.TUNINGPREDICTED GROWTHJOINT ALLOWANCECONDUCTING BRIDGE90 K0.03 m
t = 0.0s

Predicted growth

0.03m

Joint allowance

0.01m

90 K

Heat bridge. Temperature swing at 90 K. Predicted growth 0.03 m, Joint allowance 0.01 m. Currently predicted growth is over by 0.015 m.

What has to balanceΔL=αL0ΔT\Delta L = \alpha L_0 \Delta T

What is happening

You arrive at a 25 m steel footbridge installed on a hot afternoon.

The joint will be torn apart by the first hot spell. It allows exactly 12 mm of growth, steel expands 12 millionths of its length per kelvin, and the assumed temperature swing is wrong.