Week 11 Challenge
To calculate the temperature load for the RC bridge in Delhi as per the Indian Road Congress (IRC) guidelines, we need to consider the IRC specifications for thermal expansion. The IRC recommends a temperature gradient of 35°C for calculating the temperature load.
Given:
Span of the bridge (L) = 9 m
Box girder dimensions: 1500 mm x 1500 mm
Web thickness (t) = 300 mm
Diameter of circular pier (D) = 2.5 m
Width of deck slab (Wd) = 7 m
Width of pier cap (Wp) = 6 m
Thickness of deck slab (td) = 550 mm
- Box Girder: The expansion of the box girder will occur in both the length and width directions. The IRC recommends considering a temperature gradient of 35°C.
Length expansion = Length × Coefficient of Thermal Expansion × Temperature Gradient
Width expansion = Width × Coefficient of Thermal Expansion × Temperature Gradient
The coefficient of Thermal Expansion for concrete is typically around 10 x 10^(-6) per degree Celsius (μm/m°C).
Length expansion = 9 m × 10 x 10^(-6) /°C × 35°C = 0.00315 m = 3.15 mm
Width expansion = 1.5 m × 10 x 10^(-6) /°C × 35°C = 0.000525 m = 0.525 mm
- Pier: The expansion of the circular pier will occur in the diameter direction. The IRC recommends considering a temperature gradient of 35°C.
Diameter expansion = Diameter × Coefficient of Thermal Expansion × Temperature Gradient
Diameter expansion = 2.5 m × 10 x 10^(-6) /°C × 35°C = 0.000875 m = 0.875 mm
- Deck Slab: The expansion of the deck slab will occur in both the length and width directions. The IRC recommends considering a temperature gradient of 35°C.
Length expansion = Length × Coefficient of Thermal Expansion × Temperature Gradient
Width expansion = Width × Coefficient of Thermal Expansion × Temperature Gradient
Length expansion = 9 m × 10 x 10^(-6) /°C × 35°C = 0.00315 m = 3.15 mm
Width expansion = 7 m × 10 x 10^(-6) /°C × 35°C = 0.00245 m = 2.45 mm
- Pier Cap: The expansion of the pier cap will occur in both the length and width directions. The IRC recommends considering a temperature gradient of 35°C.
Length expansion = Length × Coefficient of Thermal Expansion × Temperature Gradient
Width expansion = Width × Coefficient of Thermal Expansion × Temperature Gradient
Length expansion = 6 m × 10 x 10^(-6) /°C × 35°C = 0.0021 m = 2.1 mm
Width expansion = 1.5 m × 10 x 10^(-6) /°C × 35°C = 0.000525 m = 0.525 mm
Therefore, the temperature load for the RC bridge in Delhi as per the IRC guidelines is as follows:
-
Box Girder:
Length expansion: 3.15 mm
Width expansion: 0.525 mm
-
Pier:
Diameter expansion: 0.875 mm
-
Deck Slab:
Length expansion: 3.15 mm
Width expansion: 2.45 mm
-
Pier Cap:
Length expansion: 2.1 mm
Width expansion: 0.525 mm
These values represent the expected expansion due to temperature changes in each component of the bridge according to the IRC guidelines.