a b s t r a c tThis article presents results from the experimental testing of two half-scale RC U-shaped walls under quasi-static cyclic bi-directional loading along the diagonal direction of the U-shaped section, which were recently completed at EPFL. The main objective of the article is to emphasise particularities in the behaviour of U-shaped walls under diagonal loading and to point out related design and analysis issues. Several phenomena specific to diagonal loading are discussed: (1) strain gradient across the wall width promotes out-of-plane buckling of the boundary elements in the flange ends; (2) plane section analysis does not yield reliable moment capacity estimates for the diagonal loading direction and (3) under diagonal loading the compression depth in the flange end boundary elements is larger than for the other loading directions, exposing unconfined concrete to large compressive strains. These phenomena lead to a reconsideration of the following design and analysis issues for U-shaped walls: (a) the distribution of the vertical reinforcement layout; (b) the use of plane section analysis for estimating the strength capacity of the wall; (c) the confinement length of the boundary elements of the flanges; and (d) the assessment of the out-of-plane stability of flange ends.

SUMMARYMid-rise to high-rise buildings in seismic areas are often braced by slender reinforced concrete (RC) walls, which are interconnected by RC floor diaphragms. In design, it is typically assumed that the lateral forces are distributed in proportion to the wall's elastic stiffness. Pushover analyses of systems comprising walls of different lengths have, however, shown that large compatibility forces can develop between them, which should be considered in design, but the analyses have also shown that the magnitude of the computed forces is very sensitive to the modelling assumptions. Using the results of a complex shell element model as benchmark, different simple hand-calculation methods and inelastic beam element models are assessed and improved to yield reliable estimates of the base shear distribution among the individual walls comprising the interconnected wall system.

The definition of COVID-19 as occupational disease follows the investigation of any other occupational disease caused by an infectious agent. The risk is not equal for all occupations and the occupational physician has to assess the working conditions to conclude a diagnosis of occupational COVID-19. In the pandemic context, employees face also other occupational hazards. The high level of work load and the scarce resources lead to stress, physical and mental exhaustion and irregular sleep. The protection measures, of undisputable benefit, increase the risk for contact dermatitis. There is a high probability for medium and possible long term effects of COVID-19, such as the post-traumatic stress disorder or the respiratory sequelae. These consequences need to be acknowledged and properly manged by the medical team taking care of the patient. This review presents the main characteristics of the occupational related disorders during and after the current pandemia.