Integrated Risk Classification and Buckling Resistance Prediction in Timber Piles Using Ultrasonic Wave Velocity and Dynamic Modulus of Elasticity

This study presents a comprehensive, non-destructive evaluation framework for assessing the structural integrity and buckling resistance of submerged timber piles. In situ ultrasonic wave velocity measurements, recorded using a FNIRSI 1014D digital oscilloscope, were processed in MATLAB R2023a to filter noise and remove outliers, using median values per pile for robust analysis. The relationship between ultrasonic velocity and dynamic modulus of elasticity (MOE) was analyzed to validate their combined use in characterizing internal condition and mechanical stiffness. Based on ASTM D2555 reference values, risk classification thresholds were established to categorize piles as “Safe,” “At Risk,” or “Significant Risk” using ultrasonic velocity and MOE independently. To address the limitations of single-parameter assessments, a dual-criteria risk classification system combining both ultrasonic velocity and MOE was developed, yielding improved accuracy in identifying structurally vulnerable piles by accounting for the complex interactions between material degradation and stiffness reduction. Furthermore, pile length was incorporated as a slenderness parameter to enhance buckling susceptibility predictions. A second-order polynomial regression model incorporating ultrasonic velocity, MOE, and pile length was formulated to estimate critical buckling loads, achieving a high coefficient of determination (R² = 0.87). The model reveals that piles exhibiting lower stiffness and increased slenderness are significantly more prone to buckling failure. This integrated framework offers a robust, practical tool for infrastructure monitoring and maintenance prioritization, with potential applicability across diverse timber species and environmental conditions.