LOCAL BUCKLING IN THE ANALYSIS OF CYLINDRICAL MEMBERS
Abstract
When thin-walled circular tubular members are subjected to extreme loading conditins, the circular cross section of these members does not remain circular. There is a local buckling or distortion of the cross section. The local buckling or distortion of the cross section significantly reduces the load-carrying capacity of the thin-walled tubular members. The local buckling of the cross section can be considered in the analysis by shell theory. However, the shell theory, especically in the elastic-plastic regime, will make the analysis of the members of the tubular tower structures very complicated and time consuming. Threrefore, in the past, the effect of the local buckling has not been considered in the analytical studies of the tubular members. In this thesis, a simple analytical method is proposed to include the local buckling of the cross section in the analytical study of tubular members. The method is developed in three stages. In the first stage, a simple kinematic model is proposed to describe the geometry of the distorted or locally buckled cross sections of the tubular members. In the second stage, on the basis of this kinematic model, a computer code is developed to determine the moment-curvature behavior of the sections of the tubular members. The computer moment-curvature relationship is confirmed by the experimental results. The computer code is extended to obtain the cyclic behavior of the sections. In the final stage, the section behavior is used to develop the load-deflection expressions for the behavior of the tubular members under monotonic and cyclic loadings. These load-deflection expressions are useful for the study of the behavior of tubular towers and their individual members. The study of the behavior of individual members shows that the effect of the local buckling on the maximum strength and the behavior of the tubular members, increases with the increase in their diameter-to-thickness ratio and with the decrease in their slenderness ratio. The local buckling effect must be included in the design and analysis of the tubular tower structures under the extreme loadings.
Degree
Ph.D.
Subject Area
Civil engineering
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