Nonlinear Analysis in Limit States Design

为了修复现有的钢结构建筑，有必要根据其承载能力来评估结构的强度。还需要对风的影响进行进一步分析，以确定结构在其原始状态下的适用性，并在必要时进行加固。目前的分析方法不足以确定结构体系的全部承载力，因为它们忽略了主梁和柱的几何尺寸变化的影响。本项目将探讨几何和材料特性的非线性效应在二维和三维框架系统分析中的重要性。所研究的设计方法是塑性分析法和极限状态法。该项目将制定详细的程序，以估计几何效应对塑料设计框架的刚度和强度的影响。此外，还将开发用于确定何时需要进行二阶分析的简化规则。

To rehabilitiate an existing steel-framed building, it is necessary to evaluate the strength of the structure in terms of its load-carrying capabilities. A further analysis for wind effects is also required to determine the suitability of the structure in its original condition and after strengthening, if required. Current methods of analysis are inadequate to determine the full capacity of the structural system because they neglect the effect of the geometrical changes in dimensions of the main beams and columns. This project will investigate the significance of nonliner effects of geometry and material properties in relation to the analysis of two-and three-dimensional frame systems. The design methods to be studies are the plastic analysis and the limit state methods. The project will develop detailed procedures to estimate the influence of geometric effects on the stiffness and strength of plastically designed frames. In addition, simplified rules to determine when a second order analysis is needed will be developed.