PSI - Issue 47

Muhammad Imaduddin Hanif et al. / Procedia Structural Integrity 47 (2023) 125–132 Hanif et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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[Dabit et al., 2020; Prabowo et al., 2019; Ansori et al., 2022; Nubli et al., 2022; Smaradhana et al., 2021; Yusvika et al., 2022]. Ship emerges as one of the solution which one of them is bulk carrier type. Considering the important roles of bulk carriers in the global transportation modes to deliver cargo, the safety analysis of buck carriers should be continuously progressed by the fact that many accidents on bulk carriers were still reported [Shu and Moan, 2011]. According to published data by Nwigwe et al. [2022], until the end of July 2022, there had been a total of 34 accident cases on bulk carrier. In the effort to increase the structural safety of the bulk carrier, it is necessary to carefully analyze Hull Girder Ultimate Strength (HGUS). According to Adiputra et al, [2023], the ship can be ensured safe if the HGUS value exceeds the total bending moment value at the specified margin. Various approaches to calculating HGUS have been carried out previously. Lenthall [1991] was the first to perform analytical calculations to calculate bending moment and shear values. This was continued by Caldwell [1965] through Caldwell's method, where in theory, the analysis was carried out by considering the buckling plate on the stiffened hull longitudinally before reaching the ultimate strength value. However, Caldwell's method has not been able to obtain the post-buckling strength of the stiffened panel. Then, Smith [1977] formulated a new method to determine the relationship between moment and curvature in which progressive failure and post-buckling of stiffened panels can be considered. This method was then adopted by the IACS-CSR [2022]. In the Smith method, the analysis will be carried out by dividing and categorizing the ship hull into elements, including stiffened plate elements, hard corners, and plate elements. The load-shortening curve calculations for each respective element category are carried out. However, in actual circumstances, several parameters need to be considered in conducting an HGUS analysis. One factor to note is the initial imperfection geometric. This factor is very influential on the ultimate strength value and determining the collapse behaviour of the stiffened panel. Usually, the geometric imperfection is assumed as a single value based on the plate’s slenderness, as has been done by [Khan and Zhang, 2011] and followed by [Anyfantis, 2020]. To enhance the analysis, this present paper varies the degree of initial geometric imperfection into several categories, namely standard imperfection and severe imperfection. Standard imperfection relates to the condition of a newly built and good-maintained ship, and severe imperfection relates to a poor-maintained ship. 2. Analysis Environment 2.1. Stiffened panel model In this study, the stiffened panel models are selected from the typical b ulk carrier’s hull. The reference for the bulk carrier model itself is obtained from ISSC-2000, as seen in Figure 1.

Figure 1. Hull girder cross-section of the ISSC-2000 bulk carrier.

2.2. Stiffened panel’s ultimate strength based on IACS-CSR The load-shortening formulation of stiffened panels based on IACS-CSR were derived based on the possible buckling mode, including column buckling, torsional buckling, and local buckling as listed in Eqs. 1-3 [IACS-CSR, 2022].