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Range analysis determines allocation of fixed-point integer bit-widths, which is critical for arithmetic on fixed-point representations. The traditional methods, either simulation-based or static, can be time-consuming and produce coarse bounds, potentially leading to large error bounds and unnecessary bits. In this paper, we propose a new static method to perform fixed-point range analysis towards obtaining the tighter ranges efficiently. The hybrid method, ICAT, combines four techniques, including Interval arithmetic, consistency checking, affine arithmetic and arithmetic transform and is the only method that is aware how far it is from the exact solution. For the benchmarks available with comparable methods, we show that the bit-width allocation can be obtained with better results, and in shorter execution time.

Rectangular concrete-filled steel tubular (RCFST) columns can be designed to have unequal wall thickness to maximize their resistance to combined axial and uniaxial bending loads. However, there is very little published research on their local–global interaction buckling behavior. This paper presents an efficient fiber-based simulation model for analyzing the inelastic interaction buckling of eccentrically loaded RCFST slender columns with unequal wall thickness. The model considers the progressive local–global interaction buckling, distributed plasticity, concrete cracking and crushing, second-order effects, and geometric imperfections. The mathematical model is programmed to compute not only the axial load–displacement responses but also the interaction curves of axial load and moment of slender RCFST columns. The simulation modeling is validated by experimentally measured data. The validated computer model is used to parametrically study the interaction local–global buckling responses of RCFST columns while the range analysis is conducted to identify the relative significance of key parameters. It is demonstrated that the proposed computer model accurately simulates experimentally measured responses. Hence, it can be used with confidence in practice to analyze and design RCFST slender columns fabricated with steel plates of unequal thickness. The existing design standard AS/NZS 2327:2017 provides acceptable strength predictions of RCFST slender columns and beam-columns while the procedure specified in Eurocode 4 overestimates their capacities.