دانلود رایگان مقاله انگلیسی عملکرد لرزه ای مخزن های ذخیره مایع کره ای: یک حالت مطالعاتی - اشپرینگر 2018

Abstract

Spherical storage tanks are widely used for various types of liquids, including hazardous contents, thus requiring suitable and careful design for seismic actions. On this topic, a signifcant case study is described in this paper, dealing with the dynamic analysis of a spherical storage tank containing butane. The analyses are based on a detailed fnite element (FE) model; moreover, a simplifed single-degree-of-freedom idealization is also set up and used for verifcation of the FE results. Particular attention is paid to the infuence of sloshing efects and of the soil–structure interaction for which no special provisions are contained in technical codes for this reference case. Sloshing efects are investigated according to the current literature state of the art. An efcient methodology based on an “impulsive–convective” decomposition of the container-fuid motion is adopted for the calculation of the seismic force. With regard to the second point, considering that the tank is founded on piles, soil–structure interaction is taken into account by computing the dynamic impedances. Comparison between seismic action efects, obtained with and without consideration of sloshing and soil–structure interaction, shows a rather important infuence of these parameters on the fnal results. Sloshing efects and soil–structure interaction can produce, for the case at hand, benefcial efects. For soil–structure interaction, this depends on the increase of the fundamental period and of the efective damping of the overall system, which leads to reduced design spectral values.

Conclusions

In this study, the seismic behavior of a spherical pressure vessel containing butane was analyzed, accounting for the infuence of sloshing efects and of the soil–structure interaction. Both a detailed FE model of the spherical tank and a simplifed SDOF-inverted pendulum model were implemented. It was shown which are the most unfavorable conditions to be considered under sloshing and soil–structure interaction efects: (1) liquid in the sphere up to the “block level”; (2) structure perfectly constrained at the basis. Structural robustness was also checked: plastic mechanisms in the X-braces or malfunctioning of the base constraints were independently modeled, thus showing structural performance in case of unexpected high (i.e., higher than code design earthquakes) seismic event or malfunctioning of constraints.

In conclusion, a signifcant case study concerning the seismic behavior of a spherical tank containing butane was presented in this paper. In spite of the limitations due to the uniqueness of the real case object of study, some specifc issues dealing with spherical tanks were simultaneously addressed (sloshing, soil–structure interaction, FE modeling), so providing a rational framework for the analysis of such special structures, particularly useful for practical purposes. Whereas the detailed observations may be dependent on the analyzed case study, the broad conclusions, such as the considerations about simplifed modeling, sloshing or soil–structure interaction, should apply to many practical cases.