Transient Nonlinear Heat Conduction in Concrete Structures: A Semi-Analytical Approach

Area of Science:

• Civil Engineering
• Materials Science
• Thermal Engineering

Background:

• Concrete structures face durability challenges from thermal loading, particularly during fires.
• Analytical solutions for heat conduction in concrete are complex due to nonlinear thermophysical properties.

Purpose of the Study:

• To develop a semi-analytical approach for transient nonlinear heat conduction in concrete structures.
• To account for temperature-dependent thermal conductivity, mass density, and specific heat capacity.

Main Methods:

• Utilized Boltzmann transformation and mean value theorem for Taylor series approximation.
• Employed Bernstein polynomial to extend the solution across the entire domain.
• Validated the approach against Finite Element Method simulations and experimental measurements.

Main Results:

• The semi-analytical method demonstrated high accuracy, with relative errors below 5% compared to FEM.
• Predictions for a scaled subway station model under fire conditions showed good agreement with experimental data.
• The approach effectively captured the influence of temperature-dependent properties on heat conduction.

Conclusions:

• The developed semi-analytical method is accurate and stable for analyzing heat conduction in concrete under thermal loading.
• This provides valuable insights into the thermophysical behavior of concrete during fire events.
• The method enhances the safety and durability assessment of concrete structures exposed to fire.