Post_tensioned_Concrete_Presentation_Expanded.pptx

Post-tensioned concrete

1. Modelling of the Behavior of Post-Tensioned Concrete Structures Subjected to Long-Term Thermal Loads Fernando Medina Reguera, Héctor Cifuentes Bulté, Fernando Medina Encina Third International Conference on Mechanical Models in Structural Engineering University of Seville, June 24-26, 2015

2. Introduction - Post-tensioned concrete structures are widely used in engineering. - High temperature affects concrete strength, deformations, and stress levels. - Objective: Develop a model to evaluate the coupled effects of temperature on post-tensioned concrete.

3. Effects of Temperature on Concrete - High temperatures reduce compressive and tensile strength. - Non-uniform temperature distribution causes differential thermal expansion. - Resulting thermal stress field can lead to unexpected cracking and larger global displacements.

4. Temperature Dependent Parameters - Tensile Strength: \( f_{ctm}(T) \) - Compressive Strength: \( f_{cm}(T) \) - Modulus of Elasticity: \( E(T) \) - Fracture Energy: \( G_{f}(T) \) References: [1], [2]

5. Uniaxial Behavior Characterization - Stress-strain relationship for concrete in tension and compression. - Pre-peak and post-peak behavior. - Sensitivity to strain softening and damage parameters.

6. Fracture Mechanics Approach - Fracture energy: \( G_f(T) \) - Crack propagation modeling - Temperature effects on crack growth

7. Material Model for Steel - Steel reinforcement behavior under temperature variations - Yield strength \( f_y(T) \) - Modulus of elasticity \( E_s(T) \)

8. Uniaxial Behavior Temperature Dependency - Experimental data on temperature effects - Stress-strain curves at various temperatures - Calibration of the model parameters

9. Geometrical Description - Description of the concrete specimen - Dimensions and boundary conditions - Loading conditions

10. Pre-Design Assumptions - Initial assumptions for material properties - Design criteria and safety factors - Environmental conditions considered

11. Post-Tensioning Details - Post-tensioning force application - Tendon layout and profile - Anchorage and stressing sequence

12. Model Setup and Simulation - Finite element model setup - Mesh generation and refinement - Simulation parameters

13. Impact of Temperature on Post-Tensioning Force - Variation of post-tensioning force with temperature - Analysis of force loss and redistribution - Temperature profiles considered

14. Damage and Cracking Analysis - Identification of damage zones - Crack initiation and propagation - Comparison with experimental data

15. Stress-Strain Relationships at Different Temperatures - Stress-strain curves from simulations - Comparison with experimental data - Interpretation of results

16. Conclusion - Summary of findings - Implications for design and optimization - Recommendations for future research