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.
