| Because of its high bearing capacity, good ductility, convenient construction and otheradvantages, concrete-filled steel tube structure has been widely used in the field of civilengineering construction. However, compared with reinforced concrete columns, in general,concrete-filled steel tube also has its own disadvantages. For example, its fire resistance ispoor; the steel pipe wall of the burden column is too thick to guarantee the welding quality.Therefore, based on the concrete-filled steel tube, this paper puts forward a new type ofembedded cross I shaped steel-reinforced and concrete-filled steel tubular column. Thecolumn not only has high bearing capacity, good ductility and deformation ability, but alsobecause of the inner cladding steel, its refractory performance is good, and the difficulty canbe avoided that the thick wall pipe welding quality is hard to guarantee, and it can greatly cutdown the column section size, improve the building layout, increase the the effective use ofspace of construction. In order to get the stress mechanism of the section of the pole and therelated calculation formula, this paper mainly focuses on the following aspects:(1) There are nine test specimens in the test. Among them, three of all are the shortcolumn specimens under axial compression, two of all are the short column specimens undereccentric compression, and two of all are the slender high column specimens under axialcompression. The experimental results show that: with the increase of eccentricity, the limitedbearing capacity of columns decreases; with the increase of internal steel ratio, the limitedbearing capacity of columns appears upward trend; with the increase of the external steel ratio,the limited bearing capacity of columns rises; with the increase of the slenderness ratio, thelimited bearing capacity of columns decreases. The confinement effect of steel pipe is closelyrelated to the concrete state. In the big pressure side, the constraint effect is stronger; in thesmall compression (or tension) side, the constraint effect is weaker. The related parameters(eccentricity ratio, steel ratio, internal external steel ratio, slenderness ratio) effect on thebearing capacity, ductility and fracture morphology of size are studied.(2) The test piece M1~M9are simulated and analyzed by finite element softwareABAQUS. Through the comparison of analysis results and experimental results, the finiteelement analysis method is verified reasonable and effective. At the same time, choose the typical specimen for stress analysis, then discuss its working mechanism. The results showthat: the steel ribs in different conditions of transverse stress are all tensile, but tensile stress isrelatively large under axial pressure; steel tubes in different conditions of hoop stress is alltensile, but the short column in the axial compression reflects strong constraint. The coreconcrete longitudinal stress increase faster than the transverse and hoop stress; until thespecimen failure, longitudinal stress is maximum, and exceed the peak stress of theconstitutive relation.(3) The bearing capacity formulas of the steel-reinforced and concrete-filled steel tubularshort column, long column under eccentric compression and slender high column under axialcompression are put forward. Based on analyzing the previous research results, make theregression analysis of the experiment data, and finite element analysis of the large number ofparameters. After analyzing the calculation results of the regression equation, and the resultsof experiment and finite element analyzing results, the reliability and generally adaptivity ofthe formulas are verified. |
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