Recent developments in the philosophy of structural steel design have led to design specifications that incorporate second-order geometric effects. The use of second-order elastic analysis (SOEA) in the design of structural frameworks may lead to more economically designed structures and increased knowledge of structural stability. The research presented here concerns economy of design between the available steel design specifications as they apply to the metal building industry. Since these buildings are primarily for industrial use, their optimization suggests the use of gabled rigid frames with tapered elements to provide the required load carrying capacity. Results of the research indicate that elastic stability considering geometric nonlinearity is not a primary concern for these types of frames. Rather, the fully-stressed design approach leads to the optimally designed frame. / Master of Science

Experiments were conducted to measure the three-dimensional static and free vibrational response of two graphite-epoxy, thin-walled, open section frames. The frames are semi-circular with a radius of three feet, and one specimen has an I cross section and the other has a channel cross section. The flexibility influence coefficients were measured in static tests for loads applied at midspan with the ends of the specimens clamped. Natural frequencies and modes were determined from vibrational tests for free and clamped end conditions. The experimental data is used to evaluate a new finite element which was developed specifically for the analysis of curved, thin-walled structures. The formulation of the element is based on a Vlaysov-type, thin-walled, curved beam theory. The predictions from the finite element program generally correlated well with the experimental data for the symmetric I-specimen. Discrepancies in some of the data were found to be due to flexibility in the â clamped' end conditions. With respect to the data for the channel specimen, the correlation was less satisfactory. The finite element analysis predicted the out-of-plane response of the channel specimen reasonably well, but large discrepancies occurred between the predicted in-plane response and the experimental data. The analysis predicted a much more compliant in-plane response then was observed in the experiments. / Master of Science