Study On The Optimal Design About Concrete Filled Rectangular Steel Tube Members

The researchers and engineers pay more attention to concrete filled rectangular steel tube for its characteristic, such as good mechanic performance, simple formation, constructing convenience and so on. But concrete filled rectangular steel tube mechanism is complicated, and the relationship between the design parameters such as slenderness ratio, the ratios of width to thickness, and the mechanic indexes such as load-carrying capacity, shearing property are difficultly described by analytic formula, but semi-analytic formula and the semi-empirical formula are limited to the experimental parameters range, so it does not do favor to the concrete filled rectangular steel tube extension and application. Therefore, based on the formers' study and summarization on theories and experiments about concrete filled rectangular steel tube in the world, the ultimate load-carrying capacity of axial compress, eccentric compress and bended concrete filled rectangular steel tube members were studied in this paper by MATLAB.For the axial compress members, the variety of the load-carrying capacity increased range with the thickness t and the confinement coefficient ζ was separately analyzed on the condition of the unaltered section. A coefficient is introduced and an adjusted formula is put forward considering to the ratios of width to height which effected to the ultimate load-carrying capacity. Based on the analysis of the theory, a neural network model was set up which can be used to analyze the ultimate load-carrying capacity of concrete filled rectangular steel tube members under axial compress. The analysis results of the model are better agreement with the experimental results than the codes of DBJ and GJB. The analytic model of ANSYS was also set up based on the unified theory, the limitation of the neural network sample space can be solved and the formula application range is extended. For eccentric compress members, based on the analysis of axial crash theory and the plastic hinge theory, a neural network model about eccentric compress members is set up using the experimental data. The results show this model can also predict the load-carrying capacity of eccentric compress members correctly comparingit with the experimental and countable data. For the bended members, the relationship between the parameters' variety and the ultimate moment was studied. The moment-curvature model was set up using the fiber model method based on the unified theory. The relationship between the moment and the curvature can be simulated well by the model.The mathematical model about section optimized of the axial loading concrete filled rectangular steel tube columns was set up and the optimal design program of the cross-section was compiled, and the section of the components which economic index is the best can be gotten by optimizing, and it can reduce the cost about 6.2% comparing the codes.The study on the concrete filled rectangular steel tube in this paper can be referred to studying the concrete filled rectangular steel tube behavior further and application to the engineering for the researchers.