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

海洋结构物作为海洋开发的前沿基地，由于其在结构强度、抗风浪能力等方面的优势，被设计成空间刚架结构。为了确保大型框架结构在地震和碰撞等恶劣环境中的安全，使用计算系统对结构完整性进行分析和设计是不可避免的。虽然已有有限元程序用于框架分析，但弹塑性分析的计算效率还不够高，不能满足初始设计的需要。为了显著提高框架结构非线性有限元分析的计算效率，首席研究员提出了一种新的计算方法，称为自适应位移加强技术(简称ASI技术)。将该方法应用于各种框架结构…的塑性倒塌、弹塑性屈曲和动力倒塌分析。本研究的目的是在上述基础研究成果的基础上，开发出适用于实际海洋结构物的分析与设计系统。主要研究成果有：(1)基于ASI技术的框架结构有限元碰撞分析方法的发展及其验证；(2)框架结构与网格尺寸无关的弹塑性损伤分析方法的发展及其验证。在(1)中，提出了用基于Bernoulli-Euler假设的三次梁单元和两个线性Timoshenko梁单元组成的LCL模型进行动力碰撞分析的方法。文[2]提出了用塑性转角表示的新的损伤演化方程进行弹塑性损伤分析的方法。两者都是传统ASI技术的高级形式。通过大量的数值算例验证了它们的计算效率和精度。它们有望成为包括海洋结构在内的各种大型框架结构的结构分析和设计的强大计算工具。较少

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