Finite Element Modelling of Impact Loads on Offshore Containers Conforming to DNV 2.7-1 Regulations

Impact load analysis is an essential part of structural calculations for offshore containers resulting from shocks during lifting, shipping, loading & offloading. The impact loads are classified as non harmonic dynamic loads acting in short time. Calculating the dynamic nature of impact loads requires complicated calculation; therefore, a practical quasi-static approach can be very useful in the industry. DNV based on many years of experience in marine and offshore industry, has introduced certain procedures to calculate, check and test the offshore container’s structures against the impact loads under the DNV certification standard no. 2.7-1, offshore container, issued on Apr. 2006 [1]. In this paper we will determine the maximum vertical impact load as a function of the mass for free falling motion and compare with the DNV design load factor. We will detail a method to model the impact loads in FEA programs as per DNV recommendation and we will compare the results with the conservative method of individual beam calculations. The results will determine the accuracy and speed of this improved FEA calculation method.