Classification society ClassNK has released its Guidelines for Vehicles Carrier Structures. The Guidelines specify the technical requirements specifically related to the structural strength assessments of vehicles carriers by using direct calculation.
Vehicles carriers are designed with a minimum number of transverse bulkheads and partial bulkheads in order to increase cargo handling efficiency as well as to permit more vehicles to be loaded on board. This, however, means that the structures of such ships are fairly susceptible to racking deformation.
New Types of Vehicles Carriers
In recent years, new types of vehicles carriers have been entering service in increasing numbers, including post-panamax and bulkhead-free designs. In consideration of such circumstances, ClassNK released its Guidelines for Racking Strength Assessment of Vehicles Carriers and Guidelines for Evaluation of Yielding Strength in November 2016 in order to clarify unified evaluation procedures for vehicles carriers with various structural design types.
Strength Assessments
As its next step, ClassNK has decided to develop its own set of technical requirements related to strength assessments for bottom structures and fatigue strength assessments due to racking deformation. After the development of technology requirements for strength assessments had been completed, ClassNK included the latest knowledge acquired through R&D into the guidelines and renamed them as “Guidelines for Vehicles Carrier Structures”.
Direct Strength Analysis and Evaluation of Yielding Strength
The guidelines consist of “Guidelines for Direct Strength Analysis” as well as “Guidelines for Racking Strength Assessment—Evaluation of Yielding Strength—”. The first specify requirements related to the use of direct strength analysis to evaluate the structural arrangements and scantlings of the primary structural members of bottom structures in cargo hold areas. The latter outline requirements related to the use of direct strength analysis to evaluate the structural arrangements and scantlings of primary support members that support racking deformation in cargo hold areas.
Research into Fatigue Strength Assessments
ClassNK is carrying out research on the requirements for fatigue strength assessments of racking deformation and will update the guidelines upon completion.
The guidelines are available via ClassNK’s website.
Picture: The car carrier Coral Leader of the Japanese company NYK inbound on the River Weser and heading for Bremerhaven.
