MODAL ANALYSIS OF A HORIZONTAL SHALL STRUCTURE UNDER BLAST LOADING

• Datum: 2026
• Hauptverfasser: KUCHERENKO, O. Ye., BLAZHKO, V. A.
• Format: Artikel
• Veröffentlicht: текст 3 2026
• Online Zugang: https://journal-itm.dp.ua/ojs/index.php/ITM_j1/article/view/172
• Назва журналу: Technical Mechanics

This article addresses the problem of modal analysis of a horizontal steel tank with a capacity of 50 m³ on concrete saddle supports. The structure is modeled as a cylindrical shell of length 8.15 m, radius 1.4 m, and wall thickness 5 mm. The geometric model of the tank is presented in a three-dimensional form. To model the horizontal shell, eight-node shell finite elements (SHELL281) are employed. The saddle supports are modeled using three-dimensional twenty-node second-order finite elements (SOLID186). The horizontal shell is reinforced with stiffening beams and a diaphragm. The bottom surfaces of the supports are fixed. Contact interaction between the shell and supports is modeled as well. We use a refined mesh in the contact zones. To model the stiffening beams, nonlinear three-node beam elements based on Timoshenko’s beam theory are utilized. The natural frequencies and mode shapes are computed using the finite-element method. The boundary conditions considered in the modal analysis include the assumption of no contact loss. The calculated modal participation factors show that the first mode plays a dominant role in evaluating dynamic behavior of the structure in the Y-axis direction. This mode is also a torsional one about the vertical Z-axis, thus indicating the possibility of resonance effects under seismic loading. From an energy standpoint, beam elements of the diaphragm exhibit an excessive concentration of specific strain energy; such elements require some reinforcement to prevent resonance-induced excitations. Under blast loading, the extent of structural damage depends on the response rate of the structure to the blast wave. Small, stiff structures respond significantly faster than large ones. When the duration of the blast wave exceeds the natural vibration period of the structure, the critical factor is the overpressure. Conversely, if the blast wave duration is short compared to the natural period, the impulse becomes the dominant factor. A dynamic analysis of the impact of a 100 kg TNT charge on the horizontal shell structure with account for the first natural frequency showed that at distances less than 52.6 m, the blast loading can be considered short and substituted with an instantaneous impulse.  At larger distances, however, both the impulse action and the overpressure must be taken into account. REFERENCES 1. Dong X., Lian J., Wang H., Yu T., Zhao Y. Structural vibration monitoring and operational modal analysis of offshore wind turbine structure. Ocean Engineering. 2018. V. 150. Pp. 280-297.https://doi.org/10.1016/j.oceaneng.2017.12.052 2. Balageas D., Fritzen C.-P., Güemes A. Structural Health Monitoring. John Wiley & Sons. 2010. 496 pp. 3. Jana K., Pal S., Haldar S. Modal analysis of power law functionally graded material plates with rectangular cutouts. 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