MODELING OF COLD-FORMED PURLIN-SHEETING SYSTEMS .2. SIMPLIFIED MODEL

A number of theoretical and experimental investigations have been made into the nature of purlin-sheeting systems over the past 30 years. Th ese systems commonly consist of cold-formed zed or channel section pur lins, connected to corrugated sheeting. They have proven difficult to model due to the complexity of both the purlin deformation and the res traint provided to the purlin by the sheeting. Part 1 of this paper pr esented a non-linear elasto plastic finite element model which, by inc orporating both the purlin and the sheeting in the analysis, allowed t he interaction between the two components of the system to be modelled . This paper presents a simplified version of the first model which ha s considerably decreased requirements in terms of computer memory, run ning time and data preparation. The Simplified Model includes only the purlin but allows for the sheeting's shear and rotational restraints by modelling these effects as springs located at the purlin-sheeting c onnections. Two accompanying programs determine the stiffness of these springs numerically. As in the Full Model, the Simplified Model is ab le to account for the cross-sectional distortion of the purlin, the sh ear and rotational restraining effects of the sheeting, and failure of the purlin by local buckling or yielding. The model requires no exper imental or empirical input and its validity is shown by its goon con e lation with experimental results. (C) 1997 Elsevier Science Ltd.