Influence of boundary conditions on the out-of-plane response of brick masonry walls in buildings with RC slabs

In modern unreinforced masonry buildings with stiff RC slabs, walls of the top floor are most susceptible to out-of-plane failure. The out-of-plane response depends not only on the acceleration demand and wall geom-etry but also on the static and kinematic boundary conditions of the walls. This paper discusses the influence of these boundary conditions on the out-of-plane response through evaluation of shake table test results and numerical modelling. As a novum, it shows that the in-plane response of flanking elements, which are or-thogonal to the wall whose out-of-plane response is studied, has a significant influence on the vertical re-straint at the top of the walls. The most critical configuration exists if the flanking elements are unreinforced masonry walls that rock. In this case, the floor slabs can uplift, and the out-of-plane load-bearing walls loose the vertical restraint at the top. Numerical modelling confirms this experimentally observed behaviour and shows that slab uplift and the difference in base and top excitation have a strong influence on the out-of-plane response of the walls analysed

Rütteltischversuche an einem Gebäude mit Mauerwerks- und Stahlbetonwänden (Shake table tests on a building with masonry and reinforced concrete walls)

Im Rahmen eines europäischen Forschungsprojektes unter Federführung der École Polytechnique Fédérale de Lausanne (EPFL) wurde ein vierstöckiges Gebäude mit Mauerwerks-und Stahlbetonwänden auf dem Rütteltisch des TREES-Labors am EUCENTRE in Pavia (Italien) getestet. Der Test wurde im Maßstab 1:2 durchgeführt und ist Teil einer größeren Forschungsinitiative an der EPFL zu gemischten Stahlbeton-Mauerwerks-Tragsystemen. Das Hauptaugenmerk während des Rütteltischversuches lag darin, einen besseren Einblick in das dynamische, nicht-lineare Verhalten solcher gemischten Strukturen zu erhalten sowie Daten für die Validierung numerischer Modelle zu gewinnen. Dieser Beitrag stellt den Versuchskörper, die Instrumentierung und die Bodenbewegung, mit welcher der Rütteltisch angeregt wurde, dar und diskutiert erste Ergebnisse des Versuchs

Environmental and lifestyle risk factors for early-onset dementia: a systematic review

The term early-onset dementia (EOD) encompasses several forms of neurodegenerative diseases characterized by symptom onset before 65 years and leading to severe impact on subjects already in working activities, as well as on their family and caregivers. Despite the increasing incidence, the etiology is still unknown, with possible association of environmental factors, although the evidence is still scarce. In this review, we aimed to assess how several environmental and lifestyle factors may be associated with the onset of this disease

Shake-table test on a four-storey structure with reinforced concrete and unreinforced masonry walls

With the introduction of higher seismic design forces in the Swiss loading standard of 2003 most unreinforced masonry (URM) buildings failed to satisfy the seismic design check. For this reason, in new construction projects, a number of URM walls are nowadays replaced by reinforced concrete (RC) walls. The lateral bracing system of the resulting structure consists therefore of URM walls and some RC walls which are coupled by RC slabs and masonry spandrels. Within the scope of a FP7-Series project a four-storey RC-URM wall structure is tested on the shake-table at the TREES laboratory of the EUCENTRE in Pavia (Italy). The test is conducted at half-scale and is part of a larger research initiative on mixed RC-URM wall systems initiated at EPFL. The key objective of the test is to gain insights into the dynamic behaviour of RC-URM wall structures and to provide input for the definition of a performance-based design approach of such mixed structural system. This paper presents details on the structural system, the instrumentation and the selected ground motion and discusses preliminary results of the shake-table test

A masonry catalogue for the Groningen region

Human induced seismicity has become an uprising problem in the Groningen region of The Netherlands, in which the vast majority of buildings are non-seismically engineered unreinforced masonry houses. In order to accurately assess the seismic vulnerability of these buildings, a characterization of the constitutive masonry is required. In 2015, as a part of a larger project, a campaign on the material characterization of existing buildings was performed, including laboratory and in-situ testing of the masonry walls. The campaign constitutes the germ for the creation of a regional material properties database. 16 buildings were tested in total, comprising residential structures and schools, dating from the early ‘20s to 2005. The constitutive walls included both clay and calcium silicate brick masonry of various qualities and conditions. The in-situ testing included non-destructive tests such as rebound hammer and sonic tests, and semidestructive test, i.e. flat jack and shove test. Samples were carefully taken to the laboratory, where the destructive campaign took place, including compressive, flexural, shear and bond wrench tests. Despite of the limited number of sampled buildings, the campaign provided a better insight of the researched material. The available data suggests that the use of sub-typologies (e.g. depending of the masonry quality or condition) could reduce the dispersion on the results. A first attempt of correlation between in-situ and laboratory tests is proposed, which could benefit from further calibration. In this paper, the material characterization campaign is described, and the main outcomes are discussed

Dynamic testing of a four-storey building with reinforced concrete and unreinforced masonry walls: Prediction, test results and data set

This paper presents the results of a series of shake-table tests on a half-scale, four-storey building with reinforced concrete (RC) and unreinforced masonry (URM) walls. Due to the lack of reference tests, the seismic behaviour of such mixed structures is poorly understood. The test unit was subjected to several runs of increasing intensity yielding performance states between minor damage and near collapse. Before the test, the expected peak table accelerations leading to different limit states were estimated using the capacity spectrum method, and the predicted values corresponded rather well to actual sustained accelerations. Next to these analyses, the paper describes the test unit, instrumentation and input motion, and comments on the response of the mixed structure in terms of damage evolution and global response quantities, such as force-displacement response and drift and acceleration profiles. The raw and post-processed data sets are made publically available, and all relevant information with regard to data organisation is described in an appendix to this paper. The test serves therefore as a benchmark for the validation of numerical models of such mixed structures. The project aims at providing a foundation for the development of seismic design and assessment methods of mixed structures, which are currently not covered by structural codes, including Eurocode 8

Air Quality and Environmental Effects Due to COVID-19 in Tehran, Iran: Lessons for Sustainability

The 2019 coronavirus disease (COVID-19) global pandemic spread can be considered a disastrous crisis that, in a given geographical area, significantly affects the increase in mortality rate with direct and indirect impacts on different scales and social, economic, political, and ecological factors. The effects of this crisis can be more intense in urban areas with high population density. Due to the more significant presence of vulnerable groups, the risk of death increases significantly. This research describes the environmental impacts of the COVID-19 pandemic in the city of Tehran, the 37th most populated city in the world. The concentration of six air pollutants (carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), particulate matter with a diameter of 10 microns (PM10), sulfur dioxide (SO2), particulate matter with a diameter of fewer than 2.5 microns (PM2.5) and the Air Quality Index (AQI) were measured in 22 urban regions of Tehran before (20 March) and from (21 March to 10 February) the lockdown, in air pollution evaluation stations. In order to conduct this research, first, the values of the air pollutant indices of the 22 districts of Tehran in the two previous periods (before 20 March) and during quarantine (21 March to 10 February) were obtained from the air pollution measurement stations of the 22 districts of Tehran, together with the results. After the operationalization and quantification of the indicators according to the research objectives, they were entered into the ArcGIS environment, and the spatial analysis of each pollutant was performed, before and during the quarantine. Finally, it was found that the AQI was reduced from 74.95 to 54.15

Selenoprotein P concentrations and risk of progression from mild cognitive impairment to dementia

: There is a growing literature investigating the effects of selenium on the central nervous system and cognitive function. However, little is known about the role of selenoprotein P, the main selenium transporter, which can also have adverse biological effects. We conducted a prospective cohort study of individuals aged 42-81 years who received a clinical diagnosis of mild cognitive impairment. Using sandwich ELISA methods, we measured full-length selenoprotein P concentrations in serum and cerebrospinal fluid to assess the relation with dementia incidence during a median follow-up of 47.3 months. We used Cox proportional hazards regression and restricted cubic splines to model such relation. Of the 54 participants, 35 developed dementia during follow-up (including 26 cases of Alzheimer's dementia). Selenoprotein P concentrations in serum and cerebrospinal fluid were highly correlated, and in spline regression analyses they each showed a positive non-linear association with dementia risk, particularly after excluding dementia cases diagnosed within 24 months of follow-up. We also observed differences in association according to the dementia subtypes considered. Risk ratios of dementia peaked at 2-6 at the highest levels of selenoprotein P, when compared to its median level, also depending on matrix, analytical methodology and dementia subtype. Findings of this study, the first to assess selenoprotein P levels in the central nervous system in vivo and the first to use a prospective study design to evaluate associations with dementia, suggest that higher circulating concentrations of selenoprotein P, both in serum and cerebrospinal fluid, predict progression of MCI to dementia. However, further confirmation of these findings is required, given the limited statistical precision of the associations and the potential for residual confounding

Selenoprotein P Concentrations in the Cerebrospinal Fluid and Serum of Individuals Affected by Amyotrophic Lateral Sclerosis, Mild Cognitive Impairment and Alzheimer’s Dementia

Selenoprotein P, a selenium-transporter protein, has been hypothesized to play a role in the etiology of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's dementia (AD). However, data in humans are scarce and largely confined to autoptic samples. In this case-control study, we determined selenoprotein P concentrations in both the cerebrospinal fluid (CSF) and the serum of 50 individuals diagnosed with ALS, 30 with AD, 54 with mild cognitive impairment (MCI) and of 30 controls, using sandwich enzyme-linked immunosorbent assay (ELISA) methods. We found a positive and generally linear association between CSF and serum selenoprotein P concentrations in all groups. CSF selenoprotein P and biomarkers of neurodegeneration were positively associated in AD, while for MCI, we found an inverted-U-shaped relation. CSF selenoprotein P concentrations were higher in AD and MCI than in ALS and controls, while in serum, the highest concentrations were found in MCI and ALS. Logistic and cubic spline regression analyses showed an inverse association between CSF selenoprotein P levels and ALS risk, and a positive association for AD risk, while an inverted-U-shaped relation with MCI risk emerged. Conversely, serum selenoprotein P concentrations were positively associated with risk of all conditions but only in their lower range. Overall, these findings indicate some abnormalities of selenoprotein P concentrations in both the central nervous system and blood associated with ALS and neurocognitive disorders, though in different directions. These alterations may reflect either phenomena of etiologic relevance or disease-induced alterations of nutritional and metabolic status