PSI - Issue 57

Qingyang Wei et al. / Procedia Structural Integrity 57 (2024) 262–270 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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As shown in Fig. 7, one cracked case with 60 mm crack and one uncracked case are used. The four pairs of typical nodes marked with white oval dotted line, which are the cracked edge, the cracked zone, the cracking tip, and the uncracked zone, are selected. The normal strains of these nodes in the y -direction evoked by random excitation applied on the bridge’s deck are collected and presented in Fig. 8. The duration of the strain responses has no significant effect on the CCSC values after several validations, the final duration of the analyzed strain responses is set as 0.2 s.

Fig. 8. Paired of strains in y -direction, (a) cracked pair 1; (b) uncracked pair 1; (c) cracked pair 4; (d) uncracked pair 4; (e) cracked pair 7; (f) uncracked pair 7; (g) cracked pair 10; (h) uncracked pair 10.

As shown in Fig. 8 (a) and (c), the stresses at the nodes below the crack are released to small values due to the existence of the crack. In Fig. 8 (e), the stress values at the crack tip return to a higher level, but it showed a different trend from the stress on the opposite side. As shown in Fig. 8 (g), the nodes in the uncracked area show a similar trend. In Fig. 8 (b), the two nodes at the cracked edge show basically the same change trend for the uncracked zone, even though their curves do not coincide completely. As shown in Fig. 8 (d), (f), and (h), the closer the location is to the constraint end, the higher the degree of coincidence of the strain curve becomes. In Fig. 7, the 16 nodes highlighted with yellow are numbered 1 to 16 from left to right. The CCSC values of these nodes are extracted and marked with “Excitation 1” in Fig. 9 (c). Similarly, the other cases with different crack depths are also investigated. As shown in Fig. 9, the CCSC values of the crack tips are the negative values while the CCSC values of the uncracked zones are close to 1. In Fig. 9 (c), (d), and (e), the CCSC values of the cracked zones that located on the left of the crack tips are generally lower than 0.5 except the first points on the left of the crack tips. Considering the effect of different excitations, the other two random excitations are also applied and the results are marked with “ Excitation 2” and “ Excitation 3” are also presented in Fig. 9. The other two curves also showed a sudden