Page 14: of Maritime Reporter Magazine (December 2016)

EYE ON DESIGN

Hull-Structure Damage and Future Consequences

Forensic Analysis orensic analysis of hull-struc- and size, work site environmental con- areas of interest. Generating these values the total shear force capacity of the hull tures, after damaging events, ditions, original design life expectations, using both at conversion and end-of-life structure, and calculates the still water can provide critical data and nature of operations for the structure, scantlings gives the conservative answer allowables by subtracting the wave in-

Fassist in the determination of class society designation, etc. The FEA as to whether the vessel can still func- duced load component. This analysis necessary actions to ensure future safety damage assessment can be performed on tion on its last planned day of service – concludes the impact of the dent on the and feasibility of company assets. Such local FEA models created in way of the as previously decided at construction or shear ? ow through the global structure, analysis can also be requested to see areas of interest. Areas of interest are the conversion. The speci? c vessel focused and the impact on the total shear force exactly what took place to bring upon most severely damaged areas from the upon in this editorial is one that is in capacity of the hull structure.

the damage, how to ? x the damage, as damaging incident, as these ? ndings will service in a benign environment, giving For this speci? c side shell case, away well as placing blame on a party at fault. generate the most conservative answers the owner a wider range of options when from the area of interest, primary stiffen-

The following information is pulled for an owner and operator. deciding how to handle the damage and ers and minor panel breakers are mod- from work conducted on the side shell Models of both the original as built generate a solution for moving forward. eled with beam elements with cross- of a converted double-hull ? oating ship- con? guration and the damaged shape To provide further insight to the sectional moments of inertia modi? ed shape structure, damaged in multiple lo- con? guration are loaded with the origi- change in global hull strength and shear to account for the effectiveness of the cales, while in transit to its work site. nal class-required conversion loads, force, a midship section was modeled to associated plating. Material properties,

In order to conduct successful advanced damage-speci? c DLA cases designed to determine the change in hull girder ulti- such as mild steel and any high-tensile analysis in a forensic case, provider of maximize the global and local load con- mate strength by comparing the strength steel in the surrounding structure are also services must obtain the ability to assess ditions, as well as our intuitive knowl- in the as-built con? guration and dam- modeled. and interpret the situation and data with edge gained through our history of oper- aged con? guration by eliminating the As it pertains to the FEA loading de- both a quantitative and qualitative ap- ation as an engineering support services damaged members from the calculation scription for both class required cases proach. To begin advanced analysis for company. Performing a spectral fatigue of overall hull girder section properties. and additional cases, the initial analysis such situations there are many factors life calculation is also critical to show the The still water allowables for vertical of the damage to the vessel side shell to take into consideration; vessel type new minimum fatigue life values for the shear force are determined to calculate has been completed using the original 14 Maritime Reporter & Engineering News • DECEMBER 2016

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