Models and methods of analysis

Structural analysis in nowadays performed electronically with use of appropriate software. This chapter gives criteria to set up numerical models for the entire structure or parts of it. It presents analysis models for the most usual applications, such as single story industrial buildings, but also for other common types of steel structures. It gives methods to incorporate composite slabs and treat composite beams in multi-story buildings and shows how to use sub-models for parts of the structure and more elaborated models for structural details that need special investigation. It then presents methods of analysis including linear and non-linear methods in terms of non-linear material behavior and geometric non-linear behavior, possibly accounting for geometric, structural or equivalent geometric imperfections. The implications of different types of analysis are illustrated for simple structural systems. It outlines the Eurocode provisions concerning the cross-section classification that allows or not the application of plastic analysis and design for steel structures. It finally presents the types and values of geometrical imperfections provided by the Eurocode and the analysis methods prescribed by the Code as well as alternative proposals of the authors on their selection.