This paper aims to quantify the evolution of damage in masonry walls under induced seismicity. A damage index equation, which is a function of the evolution of shear slippage and opening of the mortar joints, as well as of the drift ratio of masonry walls, was proposed herein. Initially, a dataset of experimental tests from in-plane quasi-static and cyclic tests on masonry walls was considered. The experimentally obtained crack patterns were investigated and their correlation with damage propagation was studied. Using a software based on the Distinct Element Method, a numerical model was developed and validated against full-scale experimental tests obtained from the literature. Wall panels representing common typologies of house façades of unreinforced masonry buildings in Northern Europe i.e. near the Groningen gas field in the Netherlands, were numerically investigated. The accumulated damage within the seismic response of the masonry walls was investigated by means of representative harmonic load excitations and an incremental dynamic analysis based on induced seismicity records from Groningen region. The ability of this index to capture different damage situations is demonstrated. The proposed methodology could also be applied to quantify damage and accumulation in masonry during strong earthquakes and aftershocks too.
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The majority of houses in the Groningen gas field region, the largest in Europe, consist of unreinforced masonry material. Because of their particular characteristics (cavity walls of different material, large openings, limited bearing walls in one direction, etc.) these houses are exceptionally vulnerable to shallow induced earthquakes, frequently occurring in the region during the last decade. Raised by the damage incurred in the Groningen buildings due to induced earthquakes, the question whether the small and sometimes invisible plastic deformations prior to a major earthquake affect the overall final response becomes of high importance as its answer is associated with legal liability and consequences due to the damage-claim procedures employed in the region. This paper presents, for the first time, evidence of cumulative damage from available experimental and numerical data reported in the literature. Furthermore, the available modelling tools are scrutinized in terms of their pros and cons in modelling cumulative damage in masonry. Results of full-scale shake-table tests, cyclic wall tests, complex 3D nonlinear time-history analyses, single degree of freedom (SDOF) analyses and finally wall element analyses under periodic dynamic loading have been used for better explaining the phenomenon. It was concluded that a user intervention is needed for most of the SDOF modelling tools if cumulative damage is to be modelled. Furthermore, the results of the cumulative damage in SDOF models are sensitive to the degradation parameters, which require calibration against experimental data. The overall results of numerical models, such as SDOF residual displacement or floor lateral displacements, may be misleading in understanding the damage accumulation. On the other hand, detailed discrete-element modelling is found to be computationally expensive but more consistent in terms of providing insights in real damage accumulation.
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Background: The shift in healthcare to extramural leads to more patients with complex health problems receiving nursing care at home. However, the interest of baccalaureate nursing students for community nursing is moderate, which contributes to widespread labour-market shortages. This study investigates the effect of a more ‘communitycare-oriented’ curriculum on nursing students’ perceptions of community care. Methods: A quasi-experimental quantitative survey study with a historic control group (n = 477; study cohorts graduating in 2015, 2016, and 2017; response rate 90%) and an intervention group (n = 170; graduating in 2018; response rate 93%) was performed in nursing students of a University of Applied Sciences in a large city in the Netherlands. The intervention group underwent a new curriculum containing extended elements of community care. The primary outcome was assessed with the Scale on Community Care Perceptions (SCOPE). The control and intervention group were compared on demographics, placement preferences and perceptions with a chi-square or T-test. Multiple regression was used to investigate the effect of the curriculum-redesign on nursing students’ perceptions of community care.Results: The comparison between the control and intervention group on students’ perceptions of community care shows no significant differences (mean 6.18 vs 6.21 [range 1–10], respectively), nor does the curriculum-redesign have a positive effect on students’ perceptions F (1,635) = .021, p = .884, R2 = < .001. The comparison on placement preferences also shows no significant differences and confirms the hospital’s popularity (72.7% vs 76.5%, respectively) while community care is less often preferred (9.2% vs 8.2%, respectively). The demographics ‘working in community care’ and ‘belonging to a church/religious group’ appear to be significant predictors of more positive perceptions of community care. Conclusions: Graduating students who experienced a more ‘community-care-oriented’ curriculum did not more often prefer community care placement, nor did their perceptions of community care change. Apparently, four years of education and placement experiences have only little impact and students’ perceptions are relatively static. It would be worth a try to conduct a large-scale approach in combination with a carefully thought out strategy, based on and tying in with the language and culture of younger people. Keywords: Community care, Nurse education, Curriculum design, Perceptions, Career choice
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