Innovative methodology for longitudinal crack detection in prestressed concrete sleepers through modal identification and updating

Abstract The operational and regional conditions to which the prestressed concrete sleeper (PCS) is subjected in a railway track significantly contribute to its performance and durability. Maintaining the health of PCS poses challenges, and one of these issues involves the potential occurrence of longitudinal cracks in reinforcing bars, which can be caused by various constructional, functional, and environmental factors. Longitudinal cracks in PCS compromise the structural performance, resulting in a reduced capacity to withstand the loads exerted by moving vehicles. The current evaluations not only fail to yield a precise parameter for estimating the behavior and response of the PCS, but they also overlook the specific conditions of the PCS, such as prestressing, and only provide limited information regarding existing damage. Balancing the need for accurate evaluation with consideration of costs and resources, and making informed decisions about maintenance and track performance enhancement, has become a multifaceted challenge in ensuring a robust PCS assessment. This research introduces a novel methodology to improve the evaluation of mechanical and geometrical parameters of PCS over their operational lifespan. The objective is to enhance the accuracy of PCS performance estimation by concentrating on detecting longitudinal cracks. The suggested approach seamlessly integrates model updating methods and the finite element (FE) approach to achieve an accurate and timely assessment of PCS conditions. This comprehensive examination scrutinizes the methodology by applying artificial cracks to the PCS. In addition to introducing this assessment approach, a detailed examination is conducted on a laboratory-simulated PCS featuring various combinations of longitudinal cracks measuring 40, 80, and 120 cm in length. This systematic and rigorous approach ensures the reliability and robustness of the methodology. Ultimately, the parameters of cross-sectional area, moment of inertia, and modulus of elasticity, which significantly impact the performance of this sleeper, are explored and demonstrated through functional methodologies. The findings suggest that assessing and addressing damage should be conducted through a comprehensive and integrated procedure, taking into account the actual conditions of the PCS. Longitudinal cracks lead to a substantial decrease in the performance of these components in railway tracks. By applying the proposed methods, it is anticipated that the evaluation error for these components will be reduced by approximately 30% compared to visual inspections, particularly in predicting the extent of damage for cracks measuring up to 120 cm. This research has the potential to significantly enhance the evaluation of PCS performance and mitigate the impact of longitudinal cracks on the safety and longevity of ballasted railway tracks in desert areas.