PSI - Issue 42

Fatih Kocatürk et al. / Procedia Structural Integrity 42 (2022) 1206–1214 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1212

7

14 15 16

2.82 2.86 2.86

1.94 2.01 1.96

30.09 30.12 29.42

The experimental tensile test results of bolts with different socket depths were introduced in Table 1. As described, each socket depth of the bolts was measured before and after the actual tensile test to determine the exact and values, as described in Section 3. During tensile tests, load was applied until bolts were fractured and the final fracture load was recorded. The values with respect to fracture load was plotted in Fig. 5. In Eq. (4), total stress occurring on the FC formed in head and the tensile stress acting on thread are compared to find the minimum residual floor thickness that results failure in thread region. In order to obtain the minimum value, i.e. , ( . ) value was used. The ( . ) value for the bolts used in this study was obtained from ISO 898-1 (2004) standard, given as the minimum ultimate tensile load. According to ISO 898-1 (2004), the ( . ), i.e. the minimum ultimate tensile load for M8x1.25 for 8.8 grade was 29.2 kN. Therefore, the value was obtained as the value satisfying the fracture load of 29.2 kN. Based on the experimental fracture loads given in Fig. 5, the value was obtained as 2.73 mm. . ℎ > . (4) where is the compound of tensile stress and shear stress acting on the head, ℎ is the surface area of the FC.

Fig. 5. Experimental fracture load obtained for different y values. The critical y value, i.e. y min was obtained as 2.73 mm. The analytical formulation proposed in Kocatürk et al. (2020) estimated value of the chosen bolt specimen as 2.82, and the numerical studies were determined value as 2.78 mm. In this study, the experimental studies revealed the value of as 2.73 mm. Taking into account the three methods, the analytical model estimation for the MSD was on the safe side, that is, the value of the MSD estimated by the analytical formulation was greater compared to the numerical model and the experimental results (Table 2). The difference between the analytical and experimental results was 3.2%. Therefore, the analytical and experimental results were found to be in good agreement.

Table 2. Obtained y min values from analytical model, numerical model and experiments. y min (mm) % difference Analytical model 2.82 - Numerical model 2.78 1.4 Experiments 2.73 3.2