Fatigue Crack Propagation Properties of Ordinary Plain Concrete Under Three-Point Loading

Area of Science:

• Civil Engineering
• Materials Science
• Structural Engineering

Background:

• Fatigue crack propagation is critical for bridge durability.
• Understanding concrete's fatigue behavior is essential for structural integrity and service-life extension.

Purpose of the Study:

• To determine the fatigue crack propagation properties of C50 plain concrete used in bridge construction.
• To analyze the applicability of Paris Law and Forman Equation to concrete fatigue.
• To compare fatigue crack growth rates in C50 concrete with existing literature.

Main Methods:

• Fabrication of 48 single-edge notched beam specimens from C50 plain concrete.
• Monotonic loading for static capacity and fatigue loading under three-point bending.
• Monitoring crack length evolution using visual observation, strain gauges, and the elastic compliance method.

Main Results:

• Fatigue fracture surfaces exhibit greater zigzagging and microcrack coalescence than monotonic loading.
• The elastic compliance method accurately captures three-stage fatigue crack development.
• Paris Law applies to plain concrete, with crack growth rate and stress intensity factor range showing a linear relationship on logarithmic scales.
• C50 concrete exhibits a 46.7% faster fatigue crack growth rate than lower-strength concrete.

Conclusions:

• The study provides valuable data on fatigue crack growth properties of ordinary structural concrete.
• Findings contribute to improved fatigue assessment and service-life extension strategies for concrete bridges.
• Further research is needed to fully understand concrete fatigue behavior under various conditions.