The aim of this paper is to develop computational models for the ultimate compressive strength analysis of stiffened plate panels with nonuniform thickness. Modeling welding-induced initial deformations and residual stresses was presented with the measured data. Three methods, i.e., ANSYS finite element method, ALPS/SPINE incremental Galerkin method, and ALPS/ULSAP analytical method, were employed together with existing test database obtained from a full-scale collapse testing of steel-stiffened plate structures. Sensitivity study was conducted with varying the difference in plate thickness to define a representative (equivalent) thickness for plate panels with nonuniform thickness. Guidelines are provided for structural modeling to compute the ultimate compressive strength of plate panels with variable thickness.

The flight deck of aircraft carriers in operation is exposed to fire risks which must be mitigated by fire safety measures such as firefighting and suppression systems. To develop advanced fire safety measures, the quantitative risk assessment and management is essential, where fire hazards must be identified in a probabilistic manner considering operational conditions (e.g. sortie generation rates) and site-specific ocean environmental conditions (e.g. humidity, wave and wind profiles). In this paper, a set of realistic fire scenarios on the flight deck of a hypothetical short take-off/vertical landing (STOVL) type aircraft carrier are selected, which shall be used for the quantitative fire risk assessment and management. Potential fire hazards are formulated as a function of random parameters associated with operational and ocean environmental conditions, and probabilistic sampling technique is used to select hundred fire scenarios. Fire exceedance diagrams are established in association with fire-impacted (leak) area through the selected fire scenarios.

A literature review was conducted to examine blast load characteristics of hydrogen, and the trend of hydrogen blast load and correlations between load characteristics were analyzed and compared with those of hydrocarbons. It was empirically confirmed that hydrogen explosions tend to produce higher peak overpressures and shorter durations compared with hydrocarbon explosions. In addition, blast load scenarios for hydrogen were selected considering the examined load characteristics and applied to numerical simulations. Dynamic structural responses of a corrugated blast wall were investigated through numerical simulations and analyzed from the perspective of displacement and strain energy. The results also indicated that blast walls designed for hydrocarbon explosions might not provide sufficient structural stiffness and strength to prevent excessive deflection and fracture under hydrogen blast loads. Lastly, a new type of diagram for structural response analysis was proposed, and deformation modes of corrugated blast walls were defined based on qualitative and quantitative structural responses.

Thermo-elasto-plastic analysis using nonlinear finite element analysis is used for predicting welding-induced structural deformation; however, its application in the prediction of welding deformation in large structures, such as ships and offshore plants, is practically impossible. Therefore, in this study, an inherent strain-based thermal deformation analysis method, which can be applied to large structures, was developed; furthermore, the inherent strain-based analysis was used for predicting the welding deformation occurring during block erection welding. However, although the tendency is somewhat similar in terms of quality, it still differs from the actual measured value in terms of quantity. In this study, a regression equation was derived by analyzing the sensitivity of the variables used in the existing method, and, subsequently, the results corresponding to the measured values were obtained; finally, the accuracy improvement for the three ships was confirmed. Therefore, using the proposed method, it is possible to improve the technology of predicting and controlling hull deformation.