Dynamic calculation of a steel-concrete cylindrical shell by FEM

Abstract

This paper proposes a method for calculating the natural frequencies of a two-layer cylindrical shell placed in a soil medium. The first method is based on the use of analytical expression obtained using the semi-integral theory of cylindrical shells. The second is based on the method of finite elements (FEM) with the construction of the computational model in the environment Lira Sapr. The modeling of composite shell layers in the software package was carried out by plates connected with each other by means of absolutely rigid bodies. The soil accounting was realized in two ways: 1) by creating an array of volumetric bodies; 2) by setting the pastel coefficient for the outer layer of the composite shell. It is noted that the second method of ground accounting allows to reduce the time of data input in 5-6 times with the same results. The discrepancy between the results of the determination of the frequencies of natural vibrations according to the analytical method and the finite element method does not exceed 10%. The use of the analytical expression allows to calculate the results 10 times faster and does not require special software, therefore it is more advantageous when determining the frequencies for a 2-layer cylindrical shell.