ClassNK releases guidelines for Direct Load Analysis and Strength Assessment
Leading classification society ClassNK has released its Guidelines for Direct Load Analysis and Strength Assessment of hull structure. These guidelines incorporate the load and structural consistent analysis structural evaluation method.
As vessels being constructed today continue increasing in size, structural strength assessments during the design stage are essential in helping ensure the safety and integrity of hull structures even in the harshest conditions of the ocean.
Direct strength calculations in structural strength assessments of hulls are one of the class requirements included in both ClassNK’s “Rules and Guidance for the Survey and Construction of Steel Ships” and the International Association of Classification Societies’ “Common Structural Rules” (IACS CSR). Simplified formulae, which calculate loads according to principle ship particulars and loading conditions, are used to carry out structural strength assessments. However, these simplified formulae were developed to cover load conditions estimated from actual ships and have not yet been evaluated for increased sizes and configurations of vessels not yet constructed. Therefore, in some cases, structural strength assessment that takes the loads of each individual vessel characteristics into account is essential.
Structural strength assessment methods based on “load and structural consistent analysis” take the influence of waves at sea into consideration when directly estimating loads and are therefore able to closely replicate actual ship conditions. As a result, shipyards and design companies are widely implementing these assessment methods.
In order to help ensure the safety of this new generation of larger and more advanced vessels, ClassNK developed guidelines for direct load analysis and direct strength assessment methods as essential elements of class requirements. They will be updated to reflect the latest findings from research and development initiatives. The class notation “PS-DA-DLA” and/or “PS-FA-DLA” is respectively affixed to the classification characters of a ship when strength assessments have been carried out for all cargo areas in accordance with the guidelines.