Strength And Stability Analysis Of Bimetallic LNG Storage Tank Dome Structure

The dome of the bimetallic LNG storage tank is a combined structure of a rib-ring type grid frame and a tank roof,with a large span,complex structure and light mass.The dome structure is sensitive to external compressive loads and is prone to buckling failure.The method of combining beam-shell elements is used to establish a finite element model of the dome structure,and the top steel structure platform pressure and ceiling tension are applied to the model.The deformation and stress of the dome structure are mainly concentrated on the tank roof,the maximum deformation and stress under the working pressure reach 4.4mm and 65 MPa,respectively,and the maximum deformation and stress under the test pressure are the largest among the three conditions,reaching6.9mm and 103 MPa respectively which are less than the maximum allowable value given by the specification.Based on the connection structure of the pump well pipe opening from the dome and hoisting to the dome,a model of the pump well pipe passing through the dome is established.By applying the weight load of the submersible pump and accessories to the model,the strength of the connection between the pump well and the dome is calculated and analyzed,it was found that the maximum deformation and stress of 2.2 mm and54.5 MPa appeared in the tank roof at the connection between the pump well pipe and the dome,which were both smaller than the maximum deformation and stress under the working pressure.Finally,the stability analysis of the dome structure is carried out.First,the eigenvalue buckling analysis is performed to extract the initial geometric defects,and then the geometric nonlinear buckling analysis is carried out with the initial defects imposed.The complete NR method is used to iteratively solve,and the arc length method is used to help control the convergence of the iterations.The calculated stable allowable bearing capacity of the dome structure is 4.5k Pa,which is greater than the external pressure load of 4.3k Pa,and stability check meets specification requirements...