A Microplane Constitutive Model for SFRC Subjected to High Temperatures

Area of Science:

• Civil Engineering
• Materials Science
• Computational Mechanics

Background:

• High temperatures significantly degrade concrete structures, affecting material properties like strength and stiffness.
• Fiber reinforcement enhances concrete's fire resistance and fracture energy, necessitating advanced predictive models.
• Existing models often lack comprehensive temperature-dependent behavior for fiber-reinforced concrete.

Purpose of the Study:

• To develop a thermodynamically consistent, temperature-dependent microplane material model for steel fiber-reinforced concrete (SFRC).
• To simulate the mechanical behavior of preheated SFRC under residual conditions.
• To analyze the influence of high temperatures on material response and failure mechanisms.

Main Methods:

• Development of a microplane material model incorporating a smeared crack approach.
• Simulation of preheated steel fiber-reinforced concrete under varying temperature loads.
• Evaluation of stress-crack opening displacement and stress-crack slip curves.
• Numerical analysis of the acoustic tensor to predict discontinuous bifurcation and failure orientation.

Main Results:

• The model accurately predicts the temperature-dependent mechanical behavior of SFRC.
• High temperatures lead to degradation in strength and stiffness, with increased porosity.
• Failure analysis identified critical orientations for bifurcation at different temperature levels.

Conclusions:

• The developed microplane model provides a robust tool for predicting the fire performance of SFRC structures.
• Understanding temperature effects on material properties and failure is crucial for structural integrity.
• The study contributes to the advancement of computational modeling for fire-resistant concrete materials.