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

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

Designing strategies for topological interlocking assemblies in architecture. Flat vaults

The modular interlocked blocks in flat structures are known in ancient buildings with pure-compression constructions. Over the last two decades, this structural bond has become relevant, studied by mechanical engineers, and material scientists due to the properties and design freedom that modular structures have. The structural hierarchy existing in topologically interlocked structures enhance the performance, allowing to design and fabricate custom block elements. The main reason to consider this system is that, from the architectural perspective, it is composed by identical modular elements, and it discretizes flat or curved surfaces into elements that work only by contact and compression. This article presents preliminary studies for its application and different approaches for designing discrete interlocked assemblies with a focus on the application for architectural structures: studying the structuralperformance of contact analysis and introducing the combination of topological interlocking with different structural principles

Real and apparent direction of inertia in the ultimate limit state in doubly symmetrical reinforced concrete sections

The principal direction of inertia in the ultimate limit state under axial load and biaxial bending of a doubly symmetrical reinforced concrete section is not the same as the direction of the principal axis of symmetry. If a hyperbolic stress&-strain relationship is used to describe the behavior of concrete in compression, then, to some extent, the maximum capacity direction deviates from the apparent main axis of inertia (the main axis of symmetry). This study explores the real maximum capacity direction of bending of two reinforced concrete sections with a variable amount of steel using two different axial compression loads and two different stress-strain relationships for concrete (parabolic- rectangular and hyperbolic). The results are presented in a collection of interaction diagrams