Tham khảo tài liệu 'nuclear power control, reliability and human factors part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Collapse Behavior of Moderately Thick Tubes Pressurized from Outside 259 Fig. 2. Integrated primary system reactors of small size. a Westinghouse SMR-200 MWe Small Modular Reactor b SMART-90 MWe System Integrated Modular Advanced Reactor . Reproduced from http smr and from Ninokata 2006 respectively 1981 Tamano et al. 1985 Yeh Kyriakides 1988 such results are adequate in the range of interest for oil industry but become questionable for the thicker tubes required by the nuclear applications mentioned above. In this range collapse is dominated by yielding but interaction with buckling is still significant and reduces the pressure bearing capacity by an amount that cannot be disregarded when safety is of primary concern. The problem is similar to that of beam columns of intermediate slenderness which also fail because of interaction between yielding and buckling and that have been studied in detail. A simple predictive formula was proposed in this context which turns out to be reasonably accurate for any slenderness and several code recommendations are based on it . EUROCODE 3 1993 . An attempt at adapting such formula to the case of tubes was made in Corradi et al. 2008 but a direct modification was successful only in the medium thin tube range where the formula appears as a feasible alternative to other proposals. With increasing thickness the formula becomes conservative and only provides a often coarse lower bound to the collapse pressure. A correction was proposed which however is to a large extent empirical and based on fitting of numerical results. 260 Nuclear Power - Control Reliability and Human Factors In this study a different proposal is advanced which is felt to better embody the physical nature of the phenomenological behavior. Comparison shows that tubes behave essentially as columns for D 1 25 30 but differences make their appearance and grow up to significant values as this ratio diminishes. One reason is
