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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damage. The use of VI and NDT is critical in identifying bridge deterioration, planning maintenance and repair activities. b) Numerical Analysis developing a finite element model (FEM) of the bridge which involves creating a computer based model of the bridge using finite element analysis (FEA) software. The model will take into account the geometry, materials, and other relevant characteristics of the bridge. c) Instrumentation: The sensors should be carefully installed on the bridge in strategic locations, including the critical members and joints, to measure the accelerations and other relevant parameters. The sensors should be calibrated before installation. d) Test Vehicles: The test train will be selected based on the bridge's characteristics and loading conditions. The vehicles should have sufficient mass and speed to create the desired loads on the bridge. e) Testing Procedures: The testing procedure will be carefully planned to ensure that the loads applied to the bridge represent the actual loading conditions. The vehicles will be driven at the desired speed and spacing to create the desired loading patterns. The tests will be conducted at different times of the day and under different weather conditions to capture the variability in the bridge's response. f) Data Acquisition: The data acquisition system will be carefully set up to record the sensor data accurately. The data should be synchronized with the vehic le’s speed and position to facilitate data analysis. g) Data Analysis: The collected data will be analyzed to evaluate the bridge's LCC. The strains and deflections should be compared to the design values to determine if the bridge can withstand the increased axle load. The dynamic response of the bridge should also be analyzed to evaluate its dynamic behavior under moving loads. h) Interpretation: The results of the field tests will be interpreted to determine the bridge's LCC and to identify any structural deficiencies or damage. The results should be compared to the numerical models to validate the modeling assumptions and to improve the models' accuracy.

Fig. 2. Sequence of Investigating for conducting field tests to evaluate the load-carrying capacity of a railway bridge .

3. Case study 3.1. Bridge details

This study focuses on the assessment of axle load capacity in five box-type concrete RBs. Table-1 provides information about the distinct geometries, material properties, and number of tracks present in each bridge. Originally designed to support a 21-MT axle load, these bridges now require evaluation for accommodating a 25-MT load. However, to ensure safety, the maximum train speed is limited to 10 km/h. Figure 1 displays the flow chart of the methodology used in this study. Bridge geometry information collected through visual examination is shown in Fig. 3 – 7. Each bridge, labeled bridge 1 to 5, has a total length of 13.65 m, 26.7 m, 40.8 m, 42.6 m, and 92.8 m, respectively.