Methodological contribution of K. W. Johansen to structural analysis of long cylindrical roof shells: beam method

Abstract

Evaluating the state of stress of a cylindrical shell based on elastic analysis originally involved a series of hypotheses concerning the conditions around it and the structural material used. All these hypotheses involved either idealising a reality that was impossible to ascertain a priori, or referring to an ideal, homogeneous and isotopic material, when reinforced concrete does not have any of those properties. However, it was impossible to guarantee that the state of stress obtained in the shell represented the indisputable "real state" of the structure. Thanks to the progress made in the study of plastic methods, a key figure in this context is the Danish engineer Knud Winstrup Johansen; in 1944, he published a pioneering article which set out the origin of the application of limit analysis to the structural calculation of long cylindrical roof shells based on a plastic approach to equilibrium, enabling simple and accurate calculation of these types of structure, as will be discussed below.