Earthquake-resistance Reliability Analysis And Seismic Disaster Prediction Of Large Scale Storage Tank

With the rapid development of economy, the dependence on the import of petroleum become more and more, and considering the national oil security, our nation is rapidly constructing the national strategic oil reserve bases. As the most popular application of the oil reserve bases, single tank volume gradually becomes bigger and bigger. Owing to the failed majority of storage tanks are filled with inflammable and explosive media, which once are failed by earthquake, not only directly life-threatening in the near but also may bring about fatal secondary disaster. Especially to large scale storage tanks, if large quantities of oil flow out and are on fire, which will cause heavy loss to production and national economy. The earthquake-resistance design of storage tank must be done due to the seriousness after seismic disaster, but the mechanism of dynamic response of storage tank, particularly especially to large scale storage tank, is rather complicated, which cause difficulty to earthquake-resistance design. Presently, the seismic dynamic response of storage tank is quite simplified in the codes and standards of earthquake-resistance design and appraiser of large scale storage tank. It is necessary to deeply analyze the seismic dynamic response of large scale storage tank, improve the reliability of earthquake-resistance design, establish relatively complete seismic disaster prediction method in order to escape from the seismic disaster of storage tanks as far as possible, or accurately predict seismic disaster and adopt timely and effective emergency measures near the happening of seismic disaster.In the basis of the fundamental principle of fluid-solid coupling dynamics, this paper adopt the potential fluid unit of the general finite analytic software Adina8.5 to numerically simulate the fluid-solid coupling of the 1000000 cubic meters anchored tank and its corresponding dynamic response of the storage tanks which are in different seismic intensity and stock solution height. The simulation result shows that the seismic intensity and stock solution height has an large influence on the dynamic response of the storage tank which becomes more remarkable when the seismic intensity is more heavy and stock solution height is higher. According to the simulation result, Reducing the height of stock solution in the seismic active phase and multi-phase can improve the earthquake-resistance reliability of storage tank structure.By means of simplifying calculation of Housner model and Haroun-Housner model, summarizing the analytical solutions of seismic dynamic response, combining the current code for storage tank design and standard for earthquake-resistant evaluation, a series of earthquake-resistant calculations have been done. The calculation results also show that seismic intensity, storage tank volume and the height of stock solution have a large influence on seismic dynamic response, especially when the height of stock solution is equal or greater than 2 /3H 0 and seismic intensity is 8-degree or 9-degree, the response becomes more intense. The seismic dynamic response is different from the“thin and high”small scale storage tank to the“short and thick”large scale storage tank. The effect of the ratio between the height and the radius of storage tank and the ratio between the thickness of tank shell and the radius is comprehensively considered and a deformation parameter K is defined,.The design theories of the building structure reliability are drew into the earthquake-resistance design of large scale storage tank, the random variables of large scale storage tank are summarized, the main failure modes are fixed and the its corresponding limit state equations are get. By use of the JC method of reliability computation which combines the self-programming computer programs in MATLAB optimization toolbox, the main failure modes in different height of stock solution and seismic intensity are calculated. The conclusion shows that the reliability lowers due to the augment of height of stock solution and seismic intensity, and that the height is above 2/3 that of the whole stock solution is inappropriate, which claims that the numerical simulation coincides in earthquake-resistance calculation.Based on the current situation that the necessity and urgency of seismic disaster prediction of large scale storage tank conflict with the incomplete prediction methods for earthquake damage, and the analysis of seismic dynamic response and the calculation of earthquake-resistance reliability of the large scale vertical storage tank, refer to seismic disaster prediction methods in“the technical code for earthquake disaster prediction and information management system”(GB/T 19428-2003), seismic disaster prediction models that are clear in concept, thinking and are easy to be used and realized on a computer, which is proven by examples, in the basis of theory of probability is constructed.