PSI - Issue 64

Yuan Xu et al. / Procedia Structural Integrity 64 (2024) 1865–1872 Author name / Structural Integrity Procedia 00 (2019) 000–000

1870

6

To investigate effects of strengthening parameters on the strengthening efficiency, including the CFRP layers ( n ), CFRP width ( w ), and prestressing level ( p ), a parametric study was conducted using the verified FE models. A non dimensional SCF reduction coefficient ψ was introduced, which is defined as follows: (4) where SCF pre,CFRP and SCF 0 refer to the SCFs of the prestressed CFRP-strengthened and unstrengthened joints, respectively. 3.2. Maximum hot spot stress Stress distribution in a T-joint is symmetrically distributed along the brace-chord intersection. Therefore, only results along a 90 ° polar angle from the crown point and ends at the saddle point were presented for the purpose of brevity (Fig. 6).

Fig. 6. Plan view of the chord-brace intersection area defines the 90 ° polar angle between the crown and saddle points.

Fig. 7. plots variation of the hot spot stress along the 90 degree polar angle in the scenarios with different strengthening parameters. The stress distribution at the weld toe changed with different prestressing levels. For the non-strengthened specimen, the maximum stress located in the saddle point. In the scenario with strengthening, the position of the maximum stress gradually moved from the saddle point to the crown point with increase of the prestress, which indicated that, the fatigue crack may initiate from somewhere rather than the saddle point.

a

b

c

Fig. 7. Stress distribution with variation of different strengthening parameters under 75kN axial load. (a) Prestressing level; (b) CFRP layer; (c) CFRP width

Therefore, the SCF reduction coefficient ψ at the point of maximum hot spot stress, as well as the crown point and the saddle point, were compared with different strengthening parameters. Ψ Saddle and Ψ Crown refer to the SCF ratio of the strengthened T-joint in comparison with unstrengthened T-joint at saddle and crown point respectively, and Ψ Max refers to the maximum SCF reduction in the strengthened T-joint. The three non-dimensional parameters are defined as follows:

(5) (6) (7)