Ultimate Strength Analysis of Ship Hull Girder Under Random Material and Geometric Properties

Abstract

The ultimate strength of a ship’s hull depends on its material and geometric properties, some or all of which may be random in nature. In addition, initial imperfections in the form of initial deflection and residual welding stresses in plating between stiffeners can significantly affect the hull ultimate strength. In this paper, the effect of randomness in yield strength and in the initial imperfections on ultimate hull girder strength is determined. Different levels of statistical dependence between yield strength and initial imperfection of stiffeners and plating between stiffeners have been considered. The methodology is applied on a bulk carrier and a VLCC tanker.

Comparative analysis among deterministic and stochastic collision damage models for oil tanker and bulk carrier reliability

“…Furthermore, all elements inside the damaged area, after collision or grounding events, are deleted from the structural model and the Smith method (IACS, 2015a), based on equilibrium of axial forces, is applied, disregarding the equilibrium of the horizontal bending moment, in case of asymmetrically damaged cross-sections, and neglecting the combined effects of vertical shear (Campanile et al, 2010) and non-uniform torsion (Campanile et al, 2009). Really, it is conceivable that hull girder residual strength is generally affected by several sources of uncertainties, during the entire ship lifetime, mainly due to: (i) random corrosion wastage of structural elements (Kim et al, 2014), (ii) welding residual stresses and fatigue (Paik et al, 1998;Paik and Frieze, 2001;Saydam and Frangopol, 2013;Zhu and Frangopol, 2013), (iii) randomness of geometrical (Ivanov, 1986) and material (Vhanmane and Bhattacharya, 2011) properties, (iv) randomness of damage size and location. In this respect, this is the main reason why hull girder ultimate and residual strength variation coefficients are generally affected by a certain variability, as gathered from different values proposed by several researchers in the last two decades: 0.08 (Guedes Soares et al, 1996), 0.10 (Teixeira, 1997Paik and Frieze, 2001;Fang and Das, 2005), 0.15 (Mansour and Howen, 1994).…”

An overview of maintenance management strategies for corroded steel structures in extreme marine environments

“…The marine biofouling may be comprised of flora and fauna in the form of micro and macro bio-organisms. SRBs encrusting algae, fungi, seaweeds, molluscs, barnacles, zebra mussels, worms, sea squirts, barnacles, hydroids are few common types of biofoulings in marine environment[72,127,168]. The pollutant addition in seawater aggravates the concentration of hydrogen sulphides (H2S) and nutrient content in the form of dissolved inorganic nitrogen (DIN) which significantly elevate the corrosion rate of low carbon steel[134,169,170].…”