Expansion and contraction problem

Due to changes in ambient temperature, steel cable trays will expand and contract with heat. Outdoor bridges are significantly affected by temperature variations. For example, if the maximum ambient temperature is 40°C and the minimum temperature is -20°C, the maximum thermal contraction of the cable tray can be calculated as follows:

ΔL = 11.2 × 10⁻⁶ × 60°C × 1000 mm

This leads to the following conclusions:

• When the temperature difference is 60°C, ΔL = 0.672 mm/m

• When the temperature difference is 50°C, ΔL = 0.560 mm/m

• When the temperature difference is 40°C, ΔL = 0.448 mm/m

In engineering design, expansion joints should be incorporated for cable trays in straight sections. The recommended spacing for expansion joints is as follows:

• 50 m when the temperature difference is 40°C

• 40 m when the temperature difference is 50°C