A vessel exclusion barrier (VEB) is used at a port to prevent an unauthorized boat from crossing it and entering an area of vital security concern. The VEB is a floating barrier extending several thousand feet constructed out of a number of units of modular construction most often made of HDPE material. These individual units are assembled together to make a segment of about 50 ft length interconnected by several wire rope cables. A number of these segments are placed next to each other to make up the full length. The connecting wire ropes provide the primary global strength to span the barrier between the supports. The VEB is anchored to the seabed at specific intervals using chain and/or wire rope mooring and gravity or pile anchors. There could be some gates that would allow entry to the authorized vessels. Sometimes the barrier is also equipped with wire nets to capture the encroaching vessel improving the effectiveness of the barrier. The primary objective of the present study is to perform analyses for impact by a small craft of about 30 ft length trying to breach the barrier. Through these analyses mooring configuration for the floating barrier will be selected and designed. These analyses will also provide estimation of the energy absorption capacity of the VEB. The size, grade and the number of cables interconnecting the modules, the freeboard height, and the anchoring system strength, all influence the energy absorption capability of the barrier. The energy absorption capacity would limit the size of the vessel and its speed that can theoretically be stopped by the barrier. The effect of various design parameters including interconnecting wire rope breaking strength, support spacing, mooring line strength, and mooring plan radius are needed to be studied to decide on the final design configuration for optimum impact energy absorption before taking critical design decisions. A computer model of the structure is developed for a specific application and nonlinear time domain dynamic analysis is performed to address the design problem. The modeling technique used is discussed in detail. Parametric studies are carried out to quantify the effect of each design factor. The primary critical factors and their effects that emerge from the study are discussed. To the authors’ best knowledge publication covering the analytical aspects of a vessel exclusion barrier does not exist in the public domain. Therefore, general conclusions made about the characteristics of the system are expected to help a designer for the proper design of a specific application of a VEB.
- Ocean, Offshore and Arctic Engineering Division
Impact Analysis of a Vessel Exclusion Barrier
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Chakrabarti, P, Bose, K, Chawan, A, Dhaware, S, & McDole, M. "Impact Analysis of a Vessel Exclusion Barrier." Proceedings of the ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. 29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 1. Shanghai, China. June 6–11, 2010. pp. 61-73. ASME. https://doi.org/10.1115/OMAE2010-20070
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