Trans RINA, Vol 154, Part A2, Intl J Maritime Eng, Apr-Jun 2012
B0 for the C3 and C4 condition as shown in Figure 19. This illustrates that the width of the panels B0 affect slightly the ultimate strength of the stiffened panels when symmetric boundary condition is applied on the AB and A1B1 edges in the transverse direction. Hence, the narrow model A with the C3 and C4 condition for three bays can reduce the influence by the lack of the effectiveness in lateral plating edges. The mean value of the ratio of the C4 to C3 is 0.96 which means the ultimate strength is close between the clamped and restrained boundary condition at direction.
the end of panels in the longitudinal
0.0 0.2 0.4 0.6 0.8 1.0
C3
Figure 21 presents a comparison of the ultimate strength for different configurations. The ultimate strengths of the stiffened
panels with different
configurations are
different which depends on the stiffener type to some degree. For the stiffened panels under consideration, the FS series is the most sensitive to the boundary condition in the longitudinal direction whose standard deviation is 0.05 for different FE models and boundary conditions in Figure 22. The LS series have the smallest modelling uncertainty whose standard deviation is 0.01. The mean values of the ratio of the C5 /C3 and C6 /C4 are 1.02 and 1.00 between the 3 and 1/2+1+1/2 bays model, namely the ultimate strength of the 1/2+1+1/2 bays model bigger slightly than the 3 bays model with the same boundary condition. The mean values of the ratio of the C4/C3, C6/C5 and C8/C7 are 0.96, 1.00 and 0.96 respectively. This indicates that the clamped or restrained boundary conditions in the longitudinal direction have only a minor influence on the panel strength.
FS2-A3 BS2-A3 LS2-A3 US2-A3
300 600 900 1200 1500 Width(mm)
Figure 19 Ultimate strength for 3bays-C3
0.0 0.2 0.4 0.6 0.8 1.0
C4 -0.05
FS2-A BS2-A LS2-A US2-A Stiffener type
Figure 22 Influence of the stiffener configurations
FS2-A3 BS2-A3 LS2-A3 US2-A3
300 600 900 1200 1500 Width(mm)
Figure 20 Ultimate strength for 3bays-C4
0.0 0.2 0.4 0.6 0.8 1.0
3Bay-C1 3Bay-C2 3Bay-C3 3Bay-C4 2Bay1-C5 2Bay1-C6 2Bay2-C7 2Bay2-C8 1Bay-C9
FS2-A BS2-A LS2-A US2-A Stiffener type
Figure 21 Ultimate strength of the stiffened panels with different configurations (B0= 300 mm)
A-74
Figure 23 - 31 show the equivalent stress distributions of the FS series at the ultimate limit state with different configurations for the narrow model A. The collapse shapes of the stiffened panels are different with different FE models and boundary conditions. For the narrow model A, the collapse shapes are similar between the 3bay-C1 and 3bay-C2 independently of whether or not the displacement in the z direction on intersection nodes between the plate and the frames is constrained as shown in Figure 23 and 24. It shows that the symmetric boundary condition in the transverse direction affects significantly the collapse shapes in Figure 24 and 25. The collapse modes of the three and 1/2+1+1/2 bays model are similar when their boundary conditions are the same, but their equivalent stress distributions are different in Figure 25 - 28.
The asymmetrical collapse shapes occur for the 1+1 bays model with clamped or restrained boundary condition in the longitudinal direction as shown in Figure 29 and 30. To reduce the uncertainty of modelling for the 1+1 bays model, the periodical symmetric or symmetric boundary condition should be adopted in the longitudinal direction. The collapse shape of the 1 bay model in Figure 31 is
0.00 0.10 Standard deviation 0.05
©2012: The Royal Institution of Naval Architects
Su/Syp
Su/Syp
Su/Syp
Su/Syp
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