Development of Structural Design System of Large-Scale Offshore Structures by the Adaptive

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Offshore structures as frontal bases of ocean developments are designed as space framed structures, as they have advantages in structural strength against wave and wind forces. The use of computational systems for the analysis and design of space frames of structural integrity is inevitable in order to assure the safety of large-scale framed structures in severe environments including earthquakes and collisions. The finite element codes for frame analysis have been used, however, the computational efficiency for inelastic analysis is not high enough for a daily use for the initial design. The head researcher proposed a new computational method identified as the Adaptively Shifted Intenration Technique (abbreviated to the ASI technique) to considerably increase the computational efficiency of the nonlinear finite element analysis of framed structures. The ASI technique has been applied to the plastic collapse, elasto-plastic buckling and dynamic collapse analysis of various framed struc … More tures.The purpose of the present study is to develop the analysis and design system applicable to actual offshore structures, based on the results of the above-mentioned basic research. The main results are (1) the development of the method of finite element crash analysis of framed structures using the ASI technique and its validation, (2) the development of the method of mesh size-independent, elasto-plastic damage analysis of framed structures and its validation. In (1), the method of dynamic crash analysis has been proposed, using the LCL model composed of a cubic beam element based on Bernoulli-Euler hypothesis and two linear Timoshenko beam elements. In (2), the method of elasto-plastic damage analysis has been proposed, using a new damage evolution equation expressed in terms of a plastic rotational angle. Both are the advanced forms of the conventional ASI technique. Their computational efficiency and accuracy have been demonstrated through lots of numerical examples. They are expected to become powerful computational tools for the structural analysis and design of various large-scale framed structures including offshore structures. Less