• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.629-644
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• 2013

This paper concerns about the raking damages on the ultimate residual hull girder strength of bulk carriers by applying the modified R-D diagram (advanced method). The limited raking damage scenarios, based on the IMO's probability density function of grounding accidents, were carried out by using sampling technique. Recently, innovative method for the evaluation of the structural condition assessment, which covers the residual strength and damage index diagram (R-D diagram), was proposed by Paik et al. (2012). This concept is applied in the present study and modified R-D diagram, which can be considered vessel size effect, is then proposed. Four different types of bulk carrier structures, i.e., Handysize (37K), Supramax (57K), Kamsarmax (82K) and Capesize (181K) by Common Structural Rule (CSR), were applied to draw the general tendency. The ALPS/HULL, intelligent supersize finite element method, was employed for the ultimate longitudinal strength analysis. The obtained empirical formulas will be useful for the condition assessment of bulk carrier structures. It can also cover different sizes of the bulk carriers in terms of ultimate longitudinal strength. Important insights and findings with useful guidelines developed in this study are summarized.

• Structural Engineering and Mechanics
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• v.42 no.4
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• pp.531-549
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• 2012

Numerous oil tanker losses have been reported and one of the possible causes of such casualties is caused by the structural failure of aging ship hulls in rough weather. In aging ships, corrosion and fatigue cracks are the two most important factors affecting structural safety and integrity. This research is about effect on hull girder ultimate strength behavior of double hull oil tanker according to corrosion after Part I: stiffened panel. Based on corrosion data of Part I (time-dependent corrosion wastage model and CSR corrosion model), when progressing corrosion of fourtypes of double hull oil tankers (VLCC, Suezmax, Aframax, and Panamax), the ultimate strength behavior of hull girder is compared and analyzed. In case of the ultimate strength behavior of hull girder, when occurring corrosion, the result under vertical and horizontal bending moment is analyzed. The effect of time-dependent corrosion wastage on the ultimate hull girder strength as well as the area, section modulus, and moment of inertia are also studied. The result of this research will be useful data to evaluate ultimate hull girder strength of corroded double hull oil tanker.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.476-484
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• 2017

The purpose of this paper is to verify the structural integrity of a region with numerous penetration-holes in offshore structures such as semi-submersible rig and FPSO. In order to effectively check the yielding and buckling strength of plate members with penetration-holes, a screening analysis program was developed with the FE analysis tool to generate fine meshed model using the theoretical and analysis methods. When a hole is appeared in the plate structure members, the flow of stress is altered such that concentrations of stress form near the hole. Stress concentrations are of concern during both preliminary and detail design and need to be addressed from the perspectives of strength. To configure the geometrical shape, very fine meshed FE analysis is needed as the most accurate method. However, this method is practically impossible to apply for the strength verifications for all perforated plates. In this paper, screening analysis method was introduced to reduce analysis tasks prior to detailed FE analysis. This method is applied to not only the peak stress calculation combined stress concentration factor with nominal stress but also nominal equivalent stress calculation considering cutout effects. The areas investigated by very fine meshed analysis were to be chosen through screening analysis without any reinforcements for penetration-holes. If screening analysis results did not satisfy the acceptance criteria, direct FE analysis method as the 2nd step approach were applied with one of the coarse meshed model considering hole or with the very fine meshed model considering the hole shape and size. In order to effectively perform the local fine meshed analysis, automatic model generating program was developed based on the MSC/PATRAN which is pre-post FE analysis program. Buckling strength was also evaluated by Common Structure Rule (CSR) adopted by IACS as the stress obtained from very fine meshed FE analysis. Due to development of the screening analysis program and automatic FE modeling program, it was able to reduce the design periods and structural analysis costs.