Issue 48

E. Maiorana, Frattura ed Integrità Strutturale, 48 (2019) 459-472; DOI: 10.3221/IGF-ESIS.48.44 468  h' / h  = -1  = 0  = 1 k th k num k th k num k th k num 1.50 0.20 4.94 7.18 7.63 11.92 4.00 6.68 0.30 5.60 9.19 7.63 13.22 4.00 6.75 0.50 7.60 9.94 5.25 7.51 4.00 6.89 1.00 0.20 4.94 9.60 7.63 11.88 4.00 7.59 0.30 5.60 9.29 7.63 11.64 4.00 7.45 0.50 7.60 10.55 5.25 7.46 4.00 7.12 0.67 0.20 4.94 10.80 7.63 10.78 4.46 8.74 0.30 5.60 9.46 7.63 11.12 4.33 8.08 0.50 7.60 11.88 5.25 7.34 4.00 7.95 Table 8: Linear buckling coefficient for cross-section CZ7. S TIFFENER POSITIONING he optimal position of a stiffener with regard to web panel height is a function of the compressed subpanel (Fig. 7). For  = 1, pure compression, the optimal position is h  / h = 0.5, whereas for  = -1, pure bending, is h  / h = 0.2 from the compressed edge. Linear buckling analyses has been done for various positions of a longitudinal stiffener, from h  / h = 0.14 to 0.5 with step 0.01, to cover the whole area of the compressed subpanel while  was set from -1 to 1 with step 0.25. A conventional flat stiffener was chosen, i.e. cross-section OF1, the simplest section among those in Tab. 1. Figure 7: Buckling coefficient k vs. stiffener position h  / h for plate under pure bending moment. In order to analyse the variability of stiffeners geometric dimensions with respect to plate geometry, i.e., relative flexural stiffness, the relationship between stiffener thickness and width versus the elastic critical load of the plate was established. The resulting thickness/width groups were identified and four types were found (Fig. 8). In case OF1-I, the typical dimensions of the longitudinal stiffener were b st = 300 mm and t st = 10 mm, OF1-II b st = 100 mm and t st = 10 mm, OF1-III b st = 200 mm and t st = 20 mm, and OF1-IV b st = 300 mm and t st = 30 mm. Except OF1-I (very flexible), the dimensions satisfy the relationship between width and thickness given by Eqn. 9 12 355 y st st f b t  (9) 0 4 8 12 16 0 0.2 0.4 0.6 0.8 1 h' / h k T