Fatigue Failure Mechanism Of Reinforced Concrete Bridge Deck Slabs: Experimental And Analytical Insights.pdf

This study investigates the fatigue failure mechanism of reinforced concrete bridge deck slabs under moving wheel loads, addressing a growing concern in Japan where several instances of slab damage and collapse have been reported.

Methods:

- Seven slabs with full-scale dimensions were tested under static, pulsating, and moving pulsating loads.
- Four test slabs were sawn from distressed bridge decks to simulate real-world conditions.
- Three-dimensional stress analysis was performed on a model slab with grid-like cracks to understand crack growth under alternating transverse and twisting shearing stresses.

Key Findings:

1. Crack Formation and Growth:
- Moving loads cause crack faces to rub against each other, forming a slit in the cracked section over time.
- This process reduces flexural and shear rigidities, leading to premature surface collapse.

2. Stress Analysis:
- A 10-stage crack penetration process was observed: initial flexural cracks at the bottom surface, followed by twisting cracks at the top surface as the wheel load moves away.

3. Field Observations:
- Similar rubbing and slit formation were confirmed in actual damaged deck slabs exposed to rolling and moving wheel loads.

4. Implications:
- The study highlights the significance of moving wheel loads on fatigue strength and failure of bridge deck slabs, which has not been adequately considered in previous tests based on static loading.

Conclusion:

The research provides valuable insights into the fatigue failure mechanism of reinforced concrete bridge deck slabs under moving wheel loads, offering crucial data for more conservative design codes and improved structural integrity.