PSI - Issue 66

B. (Bo) van Schuppen et al. / Procedia Structural Integrity 66 (2024) 412–418 Author name / Structural Integrity Procedia 00 (2025) 000–000

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cross-section critical. For components loaded in tension, in each cross-section, the design value of the applied tension force N Ed shall satisfy: �� � , �� � 1.0 (1) where N t,Rd is the design tension resistance that, in the case of cross sections containing holes, should be taken as the smaller of the design plastic resistance of the gross cross-section �� , �� � � �� (2) and the design ultimate resistance of the net-cross section at the hole � , �� � 0.9 ��� � �� (3) where A is the gross cross-section area, f y is the nominal value of the yield stress, f u is the characteristic value of the ultimate tensile strength, A net is the net cross-section area, and γ M0 and γ M2 are partial factors. When a capacity design is requested, then it should be that N pl,Rd < N u,Rd . For the calculation of the design ultimate resistance of the net-cross section, the factor 0.9 is based on tension tests and fracture mechanics safety assessments, as explained in Sedlacek et al. (2008). After omitting the partial safety factor, the resistance function is obtained: � � 0.9 ��� � (4) Concerning the factor 0.9, the applicability and conservativism of the design rule presented in Eurocode 3 have been studied previously by previous authors. This factor is partially due to the potential presence of cracks around the hole, which can reduce the net cross-sectional resistance of the steel element. Rombouts et al. (2014) investigated 28 specimens with different configurations of bolts where the net cross-section failure is decisive. It was concluded that the additional safety value of 0.9 can be omitted, for both plates with- and without bolts. Snijder et al. (2017) investigated net cross-sectional resistance of additional bolt-hole configurations and plates of different steel grades by validating a finite element model with test results and subsequently using it to generate additional numerical results. They found that the current partial factor in Equation 3, γ M2 =1.25 in the Netherlands, is over-conservative and could be lowered to 1.05 overall, as a combined factor for both factor 0.9 and the partial factor. However, the study proposed to omit the factor of 0.9 and keep γ M2 as a partial factor. Baarssen et al. (2022) conducted a study to investigate the applicability of the net cross-sectional resistance rule of the Eurocode 3 to steel plates with the presence of cracks nucleated due to fatigue at the bolt hole. The specimens used were made of S275 plates with a single hole at the center. The specimens were cyclically loaded until relatively short cracks, i.e. having a length < 1 mm, nucleate from the root of the bolt hole. The ultimate cross-sectional resistance is then obtained by performing tensile tests. As a result, they reported that the presence of cracks lowered the ultimate strength as compared to the specimens without cracks. However, the rule of Eurocode 3 is still deemed applicable to the pre-cracked specimens. This research aims to provide additional evidence concerning the applicability of the design rule for tension members in Eurocode 3, by investigating the ultimate strength of specimens with different bolt-hole configurations in the presence of cracks induced by fatigue. The bolt-hole configurations investigated in this paper are presented in Fig. 1, including their corresponding failure modes: single-centric bolt hole (type A), single eccentric bolt hole (type B), and double staggered bolt holes (type D). In addition, the failure assessment diagram is used to predict the experimental results, hence potentially providing a parametric modeling framework for taking into account additional parameters.