Justification of the Specified Wear of Structural Elements of Floating Docks in the Overall Strength and Stability Requirements of the Rules of the Russian Maritime Register of Shipping by Probabilistic Modeling

BACKGROUND: According to Part II (Hull), Para. 3.12 (Floating Docks) of the Rules of the Russian Maritime Register of Shipping (RMRS Rules), permissible stresses for overall longitudinal bending of the dock and calculated compressive stresses in the requirements to the stability of longitudinal frame are standardized as of the end of the estimated service life of the dock and determined on the assumption that the specified wear of all girder elements is 100%. However, such case is unlikely in real-life conditions. AIM: To improve the RMRS Rules in relation to overall longitudinal strength and stability under overall longitudinal bending state of the dock, it is required to assess the specified permissible wear of floating dock hull structures as the estimated ratios regulating the overall strength and stability to reasonably relax these requirements. METHODS: To achieve the set task, it is proposed to use a special method to assess the average wear of the longitudinal hull frame of the dock at the end of its service life by random modeling of corrosion-related dimension reduction of each girder element using random number generators. The method will allow to build bar graphs of wear allowance distribution for the girder parameters (sectional area, lowest section modulus, central moment of inertia), approximate them with a certain theoretical law, determine the expected value and values of these parameters with a given probability. CONCLUSIONS: The estimates presented in this paper show that corrosion allowances should be taken at about 65%–70% of the values provided by the Rules as of the end of the standard service life of the dock. This will result in a significant relaxation of the requirements to overall longitudinal strength and stability under overall longitudinal bending state of the dock hull.