Analysis of bridge dynamic load test based on millimeter wave radar.

Area of Science:

• Civil Engineering
• Structural Health Monitoring
• Radar Technology

Background:

• Traditional dynamic strain measurement methods have limitations for bridge monitoring.
• Accurate assessment of bridge dynamic deflection is crucial for structural integrity.
• Existing methods may be sensitive to environmental conditions, impacting data reliability.

Purpose of the Study:

• To propose and validate a millimeter-wave radar telemetry method for measuring bridge dynamic deflection.
• To compare the performance of the proposed method against traditional approaches.
• To assess the accuracy of impact coefficient calculations and analyze bridge dynamic behavior.

Main Methods:

• Implementation of a millimeter-wave radar telemetry system for non-contact measurement.
• Conducting dynamic load tests on a bridge structure.
• Analyzing modal frequencies, forced vibration responses, and impact coefficients.
• Comparing measured dynamic strain and deflection amplification coefficients.

Main Results:

• The measured first-order modal frequency (5.664 Hz) exceeded the theoretical value, indicating higher structural stiffness.
• Forced vibration frequencies consistently matched the measured modal frequency across different vehicle speeds.
• Measured impact coefficients averaged 0.135, lower than the theoretical 0.258, suggesting favorable driving conditions.
• A ratio of 1.12 was found between dynamic strain and deflection amplification coefficients.

Conclusions:

• The millimeter-wave radar method provides accurate measurement of bridge dynamic deflection and impact coefficients.
• The proposed method is robust and less sensitive to environmental variations compared to traditional techniques.
• This technology offers a precise and comprehensive tool for assessing bridge structural dynamics.