RELIABILITY ANALYSIS OF BUCKLING OF RETICULATED SINGLE LAYER ROOFS OF GENERAL FORM UNDER VERTICAL LOADS

This paper discusses a new formulation to evaluate reliability of elasto-plastic buckling load required in design of metal reticulated shells of general form under dead and snow loads. Several roofs of different geometries with a span around 50 meters are first analyzed to evaluate their buckling load considering both elastic buckling load and plastic strength. Then, for reliability analysis, general formulas for the evaluation of the elastic buckling load and plastic strength are formulated based on a perturbation-like method. The proposed formulation is applied to evaluate the reliability index of free form reticulated shells under dead and snow loads. For the reliability index, not only external loads but also Young's modulus, yield strength, sectional area of members, knockdown factor for elastic buckling load, and several related structural factors are treated as probabilistic parameters. The global load factor is also evaluated in terms of reliability index using 100-year reference period for safety evaluation and 100-year return period for member proportioning. Finally, conclusions are drawn for future development of the present scheme for reticulated shells of free form.