Strength analysis of massive reinforced-concrete structures using the method of equivalent shells

Analysis of the strength of reinforced-concrete structures by the finite-element method is currently in extremely widespread use. Existing computer software packages make it possible to determine with high accuracy internal forces in thin-wall slab and beam components. These values are subsequently used to calculate the reinforcement required in conformity with regulatory documents. The design of reinforced-concrete structures possesses a number of characteristic features associated primarily with their massiveness. Massiveness is usually understood to be the ratio of the length of the component under consideration to the size of its cross section, which is equal to three and lower. In modeling these structures, use of shell or beam finite-elements may result in considerable errors. Use of threedimensional elements makes it possible to create a computational scheme that approximates the actual structure as closely as possible. The problem of this method is that values of the nodal stresses are given as results of program analysis, whereas existing procedures used to calculate the reinforcement needed require use of normal forces and bending moments. In Manual [1], it is recommended to determine the design reinforcement in short cantilevers based on values of the principal tensile stresses: