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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3.3.1. Location of Sensors The location of sensors plays a vital role in getting the actual condition of the bridge in terms of its natural frequency. Even though it depends on the span of the bridge, better locations of the sensors can be known through preliminary numerical modal analysis. But in this case, the bridge is minor, so the location of the sensors is equally spaced as shown in the fig-10. And only one segment is considered for the study out of two and the same procedure has been carried for all bridges.

Fig. 10. Location of Sensors Deployed on the bridge-1.

3.3.2. Testing and Response Ambient vibration methodology has been considered for deriving the modal parameters of the bridge. The test is conducted in two ways, one with human jumping and the second with the actual movement of the train (Fig 8 (e) and (f)).

Table 2. Specifications of Locomotive Considered

Specifications of Locomotive Considered Gauge 1676 mm Wheel Diameter 1092 mm No of Wheels 3 X 4 = 12 No’s Wheel Base 12.834 m Length 17.12 m Loco Weight 112.8 MT Axial Load on Each Wheel

112.8/12 = 9.4 MTes = 94 kN

3.4. Numerical modeling

The box-type bridge seen in figure 11 was created as a complicated 3D model using the finite element application ANSYS Workbench. The material and geometrical characteristics determined by Visual Inspection and NDT testing. Figure 11 shows the shapes of twenty global vibration modes of the structure and their associated natural frequencies,