Abstract
Steel storage tanks and other structures of such kind of buildings have been extensively designed following the requirements of continuous cyclic operations. Because of many economically based reasons any engineering inspections of a huge volume are very expensive, so numerical investigations of the local defects are practically important. Natural inspection of tank dents (volumes of tanks were from 1 000 to 50 000 m3, diameter of dents from 0,40 to 4,50 m, a depth up to 120 mm) has shown that analytical approach of their investigation by using existing design standards is rather complicated. The main objectives of the presented investigations are: to determine an appropriate size of the finite element for geometrical defect modelling on thin wall of the steel cylindrical tank; to identify stress/strain state by using finite element method in the place of the defect; to define the appropriate results of the proposed analytical solutions and requirements of the codes with FEM results. The results, derived from the proposed formulas, are compared to those of natural inspection of real tanks and also with the results obtained by numerical modelling using the finite element method.
Highlights
Rapid development in the world of huge industrial complexes in 1960–1970 became possible due to exact and effective analytical methods of calculations and analysis
Analysing further the calculations results we can see that location of the points with maximum stresses (Fig 6) does not agree with that one of the points with maximum displacements (Fig 7) in case of the same defect
From the above results it follows that in case of small defect radius β = 1, points having maximum stresses agree with those maximum displacements with all kinds of the calculations
Summary
Rapid development in the world of huge industrial complexes in 1960–1970 became possible due to exact and effective analytical methods of calculations and analysis. Codes of designing and operating tanks exist in the USA, Russia and Germany (Table 1) This parameter f is a depth of the dent. In the Eurocode [12] the maximum deviation from a perfect form of the structure was proposed It amounts to 1,6 % of the dent diameter. The accumulation of the „soft“ defects and the increase of the available ones requires a regular evaluation of the tank fitness for further use This question is very important for structures with a finishing operation period. The developments of accurate analytical models are essential for the state investigation of the structures to be applied To date such solutions are of special concern for practising engineers
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