PSI - Issue 52

Govardhan Polepally et al. / Procedia Structural Integrity 52 (2024) 487–505 Govardhan Polepally/ Structural Integrity Procedia 00 (2019) 000 – 000

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have created job opportunities and supported the development of local towns, as noted by Agrawal et al. (2019) and, these bridges facilitate connection, economic development, and regional expansion. However, the design, construction, and maintenance of RBs in India present significant challenges. Singh et al. (2018) identify several obstacles that must be addressed to improve RB performance and functional life. In addition to that, some of the authors stress the importance of addressing challenges and identifying research opportunities, necessitating further studies to enhance RB performance and longevity in design, construction, and maintenance. During the service life, bridges are subject to various types of stresses and loads, sometimes this can lead to structural damage and distress. Identifying and mitigating these challenges is essential, as noted by Zhang et al., (2021). The most common damages observed in RBs are fatigue cracking, corrosion, deformation, and joint failures, as reported by Wang et al. (2020). Visual inspections, non-destructive testing, and finite element analysis are among the methods used to detect and assess these defects. Addressing these damages is critical to ensuring the long-term performance and safety of RBs, as highlighted by Karavasilis et al., (2019) and O'Connor et al., (2018). Sairam et al (2022) studied special studies on Rail-structure interaction using wireless sensors. The Load-Carrying Capacity (LCC) of RBs is another crucial factor in their safe and dependable operation, particularly as demand for railway transit grows. Huang et al., (2020) emphasize the need for evaluating the LCC of RBs designed for lower loads but required to support higher axle loads. Increased loads can result in changes in bending, shear, and deflection, as pointed out by Bhandari et al. (2019). Bridge LCC is assessed using various methods, including analytical methods, numerical modeling, and field testing. Accurate evaluation of LCC is required to ensure the safe operation of RBs under increased load circumstances, as studied by Gao et al., (2018). Robust methods are still under development and simultaneously research is being carried. Several studies have been conducted to investigate the LCC of RBs that are built to withstand specific loads but have to support increased axle loads. Huang and Zhang (2021) conducted field experiments and numerical simulations on the bridge, detecting substantial changes in its behavior under higher loads, such as increased bending moment and deflection. Bhandari and Barai (2019) investigated the LCC of existing RBs under moving loads, illustrating the significant effect of structural component influences on bridge capacity. When assessing LCC, Gao and Wang (2018) emphasized the need of taking into account train-bridge dynamic interaction and found it crucial for accurately predicting the bridge's behavior under increased loads. Huang and Zhang (2020) evaluated a reinforced concrete RB using finite element modeling. They proposed combining field testing and computational simulations to determine the bridge's LCC more precisely. Furthermore, Bhargava et al. (2019) evaluated the effect of increasing axle loads on a steel girder RB, concluding that it could take the increased loads without substantial damage but recommending continuous monitoring. Prakash and Kumar (2018) emphasized the need of using field testing and numerical modeling to address dynamic loads in the design and assessment of RBs. Jadhav et al. (2017) investigated the LCC of a steel girder RB and discovered that it can handle increasing loads without sustaining major damage. Shukla et al. (2019) used a mix of field testing and numerical simulations to evaluate a reinforced concrete RB, determining that it could take higher loads but required constant monitoring. Finally, Reddy et al. (2016) studied a RB's LCC under static and dynamic loading conditions, recommending frequent inspections and repairs to tolerate growing loads. Overall, these studies emphasize the need to precisely evaluate and maintain the LCC of RBs confronting rising axle loads by taking into account numerous elements such as dynamic loading, structural conditions, and frequent monitoring. The study evaluated the load-carrying capacity of box-type concrete bridges designed for a 21 MT load, when subjected to an increased 25 MT axle load. Operational Modal Analysis (OMA) and finite element analysis were used to assess the bridges. Vibration data from wireless accelerometers were collected to estimate dynamic properties, and finite element analysis was conducted based on Visual Inspection and Non-Destructive Test (NDT) results. The methodology was tested on five real-time bridges at a constant train speed of 10 kmph. Results indicated that all five bridges could withstand the increased load at that speed. Thus, the study demonstrated the effectiveness of this technique in predicting structural behavior under increased dynamic loads. 2. Methodology In this study, an effective approach for evaluating bridges' LCC is proposed, in Fig. 1. The two-step proposed methodology consists, to analyze a bridge under dynamic loads, first a test train applies a moving live load to the bridge's structure to measure the acceleration caused by the vibration of the bridge. The inherent frequencies and