PSI - Issue 52

Govardhan Polepally et al. / Procedia Structural Integrity 52 (2024) 280–292 Govardhan Polepally/ Structural Integrity Procedia 00 (2019) 000 – 000

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5.2. SSI results The same acceleration data of each HJ, has been used to estimate the dynamic properties with the help of SSI which is the TD method. Figure 10 shows the comparison of the first bending frequencies within the spans for three HJ excitations. From the comparison, it has been noticed that in the first HJ excitation, almost 80% of frequencies matching within the span, it also gives piece of evidence that no stiffness changes within the span. Remaining two cases, the deviation is about form 30% to 65% which might be due to damage or deterioration.

Fig. 10. Comparison of first bending frequency within the span using SSI subjected to human jump; (a) For human jump-1; (b) For human jump 1; (c) For human jump-3. A comparative study was conducted to select the optimal method for evaluating masonry bridges. Table-3 and Table-4 present the FDD and SSI outcomes for all the spans. From the tables, it has been noticed that the range of frequency of girder-1 for all the spans using FDD and SSI where in the range from 7.5 to 9 Hz and 5.39 to 9.02 Hz respectively, similarly for girder-2 the frequency range is observed between 7.5 to 8.5 Hz and 6.87 to 9.76 Hz.

Table 3. Comparison of first bending frequency of girder-1 between FDD and SSI subjected to HJ-1 to 3. Span Number Girder-1 Frequencies (Hz) using FDD Girder-1 Frequencies (Hz) using SSI HJ-1 HJ-2 HJ-3 HJ-1 HJ-2 HJ-3

2

8.00

8.00

8.00

8.87

7.94

8.56

3

8.50

8.25

8.25

8.60

8.25

8.54

5

8.25

8.25

8.25

8.92

8.18

8.28

7

8.50

8.50

8.50

8.62

8.79

8.77

9

8.25

8.50

8.50

8.63

8.68

8.57

11

8.50

8.00

8.50

9.02

8.41

8.70