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http://dx.doi.org/10.3744/SNAK.2021.58.2.084

Quasi-Static Analysis of Block Impact Against the Ground Due to Sling Failure During Block Lifting  

Kim, Seon-Yeob (Dongil Shipyard Co., Ltd.)
Lee, Tak-Kee (Department of Naval Architecture & Ocean Engineering, Gyeongsang National University, Institute of Marine Industry)
Yoon, Jung-Ho (Department of Naval Architecture & Ocean Engineering, Graduate School, Gyeongsang National University)
Publication Information
Journal of the Society of Naval Architects of Korea / v.58, no.2, 2021 , pp. 84-89 More about this Journal
Abstract
Recently, shipyards are making many efforts to reduce the number of the mounted blocks by increasing the block size. This is to improve productivity and reduce related costs by minimizing block movement and shortening the building period. However, as the blocks become larger, the weight increases considerably. If the target block has a damage due to an unexpected accident during block lifting, it may seriously cause a problem of the reusability of the block. In this study, a large-sized block of the offshore structure weighing 480 tons was lifting with a total of seven sling belts, and one sling belt was broken while it was moving, resulting in a situation in which a part of the edge of the block collided with the ground. The aim of this paper is to verify the structural integrity of the block that directly collides with the ground in the form of free fall due to the sling breakage. Considering that the hook loads acting on several sling belts holding the block are redistributed when a sling belt is broken, the hook loads were recalculated at the angle just before the sling breakage. These loads were used to check the safety of the sling belts. In addition, FE analysis was performed by calculating the amount of impact from the free fall condition, obtaining the impact area by using Hertz's contact theory, and then applying the impact load to the area.
Keywords
Block lifting; Lifting lug; Sling failure; Block damage; Hook load; Structural integrity;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
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1 DNV-GL, 2016a. General Guideline for Marine Project, 0001/ND.
2 DNV-GL, 2016b. Guidelines for Marine Lifting & Lowering Operations, 0027/ND.
3 DNV, 2014. Lifting Operation, OS-H205.
4 IACS, 2020. Common Structural Rules for Bulk Carrier and Oil Tankers.
5 ISO 8792, 1986. Wire Rope Slings - Safety Criteria and Inspection Procedures for Use.
6 Jang, I.S. & Chae, D.B., 2000. The derivation of simplified vehicle body stiffness equation using collision analysis. Transactions of the Korean Society of Automotive Engineers, 8(4), pp.178-185.
7 Jang, C.H & Lee, J.S., 2017. Risk assessment of dropped object in offshore engineering through quantified risk analysis. Journal of the Society of Naval Architects of Korea, 54(2), pp.143-150.   DOI
8 Kim, U.N. & Kim, H.B., 2019. A study on the design concept and simplified analysis method in dropped object accidents by lifting crane. Journal of the Society of Naval Architects of Korea, 56(3), pp.251-262.   DOI
9 KS, 2017. Webbing Slings for Lifting Purposes, B 6241.
10 Liu, B., Pedersen, P.T., Zhu, L., & Zhang, S., 2018. Review of experiments and calculation procedures for ship collision and grounding damage. Marine Structures, 59, pp.105-121.   DOI
11 MSC, 2011, PATRAN/NASTRAN Ver.2012.
12 Richard, M., 1973. Systematic layout planning, Boston, MA: Canners Books.
13 Yeom, C.U. & Noh, I,S., 2015. Redundancy analysis of stiffened panel with plastic deformation due to collision. Journal of the Society of Naval Architects of Korea, 52(2), pp.161-169.   DOI
14 Bently, 2015, SACS Ver.5.7.
15 Cho, S.R., 2010. Ship structural damages due to collision and grounding. Journal of the Society of Naval Architects of Korea, 47(4), pp.7-10.
16 Kim, B.S., 2019. Development of transporter for marine leisure ship with safety and operation support system. Journal of Ocean Engineering and Technology, 33(5), pp.486-494.   DOI