STUDY OF BASE COMPONENTS OF SHELL-BOTTOM JUNCTION STRESS-STRAIN STATE DEPENDENCE ON BOTTOM-FOUNDATION INTERACTION MODEL

Steel storage tanks (SST) are relating to a mass-volume construction category, widely used in petroleum industry for crude oil and petroleum products storage. Such constructions are of category of critical objects, therefore SST performance must be deeply studied and calculation methodology must be improved. Shell-bottom junction is one of the important critical components of such constructions. This junction calculation methods are well developed and approved for steel tanks of standard series. Though all above mentioned methods are based on the physical model with bidirectional bottom-foundation connection. In fact tank bottom has a unilateral connection with foundation (foundation doesn't impede bottom upward displacement). Therefore real performance mode of shell-bottom junction differs from calculation model with bidirectional bottom-foundation connection. This fact might have influence on the computational accuracy. Purpose. In this article base components of shell-bottom junction stress-strain state due to unilateral bottom-foundation interaction model is being analyzed. Also the difference in tank calculation results using unilateral and bidirectional bottom-foundation connection model is studied. Conclusion. Under certain relation of geometric parameters, modulus of foundation and loading level of steel tank, essential differences (from 5 to 20%) in bending moment values take place in shell-bottom junction while using unilateral and bidirectional bottom-foundation interaction models. Under internal excessive pressure absence, a bending moment value in shell-bottom junction with unilateral bottom-foundation interaction was found to be smaller than in case of bidirectional bottom-foundation connection. This case can be explained by occurrence of undetected (inner) bottom uplift. This fact accounting makes it possible to reduce metal consumption and to obtain a certain saving rate.