How to Calculate Gap Between Concrete Slabs on a Bridge
Understanding the Change in Length
Where:
- ΔL is the change in length
- α is the coefficient of linear expansion of concrete
- L is the original length of the slab
- ΔT is the change in temperature from the day the slab was cast
Calculating the Gap
Given:
- Original length of the slabs (L) = 315 cm
- Coefficient of linear expansion of concrete (α) = 12 × 10⁻⁶/°C
- Temperature difference between the hottest day and 0°F (ΔT) = 115°F - 0°F = 115°F
Using the formula:
ΔL = αLΔT
ΔL = (12 × 10⁻⁶/°C) (315 cm) (115°F)
ΔL ≈ 0.423 cm
To find the gap between the slabs on a 0°F day:
Gap = Elongation - Original Length
Gap = 0.423 cm - 315 cm
Gap ≈ -0.577 cm
The negative value indicates contraction when cooling. Therefore, the gap between the slabs on a 0°F day is approximately 0.577 cm.