ANALYSIS AND DESIGN OF FABRICATED TUBULAR BEAM-COLUMNS
Abstract
Recent increase of using fabricated tubular members requires more information about the strength and behavior of fabricated tubular column. It contains imperfections that are far more complicated than the hot-rolled members. The current design codes, such as AISC, however, do not consider fabricated tubular members. To fill this lack, the analytical investigation is carried out here to establish analytical models for studying the strength and behavior of fabricated tubular members and to develop design formulas for practical use. The work in this report consists of four parts. In PART I, the basic behavior of tubular section and the strength of tubular beam-column are studied considering the effects of residual stresses, out-of-roundness and out-of-straightness. Design formulas for the sectional capacity and the column strength are also derived. The fabricated tubular members are commonly used in offshore structures. An additional consideration is necessary for hydrostatic pressure when the structure is used in deep water. In PART II, the effect of external pressure on the strength and behavior of fabricated tubular members is investigated. If was found that the external pressure reduces the load carrying capacity of the section and column to some degree when the pressure is large. Further, the offshore structures are so designed that the structures can resist the extreme environmental loading conditions, such as earthquake or wave. In other words, the offshore structures are usually designed by their ultimate strength. In this respect, the strength and behavior of each component of the structure must be known in advance to study the strength of the structure. In PART III, the post-buckling behavior is studied using simplified method, so-called assumed deflection method, which is found not only simple to use but also reasonably accurate and suitable for parametric study. Also, in PART IV, the cyclic behavior of fabricated tubular columns is studied for both pin-ended and fix-ended beam-columns under 1-cycle of loading. In the studies, comparisons are made between the theoretical results and tests and other analytical solutions to verify the developed analytical models by using the computer program. It was found that the developed analytical models can predict the behaviors of tubular beam-columns with good accuracy. Also, numerous data are obtained to present typical behavior of fabricated tubes loaded monotonically and cyclically.
Degree
Ph.D.
Subject Area
Civil engineering
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