A Proposed Equation for the Evaluation of the Nominal Ultimate Bending Moment Capacity of Rectangular Singly Reinforced RPC Sections

Based on compressive stress – compressive strain curves of Reactive Powder Concrete (RPC) which have been established recently in a Ph.D thesis(1), an equivalent bi-linear compressive stress block for RPC sections under pure bending moment is proposed and used to derive an equation for calculating the nominal ultimate bending moment capacity (Mn) of rectangular singly reinforced RPC sections. The accuracy of the derived equation of Mn is examined by comparison with the results of existing experimental tests

Membrane Action in Orthotropically R.C. Rectangular Slabs Supported on Three Edges Only with Variable Axial Restraints

In this paper, large deformation analysis is carried out on uniformly loaded orthotropically reinforced concrete rectangular slabs that have one free edge and different restraints on the other edges. For the purpose of such analysis, the slabs are assumed to behave in a rigid-perfectly plastic manner and to yield under the combined effect of bending and membrane action. Two cases are analysed; the case of a slab having two adjacent edges fixed- one edge simply supported and one edge free, and the case of a slab having two adjacent edges simply supported- one edge fixed and one edge free. Results of the analysis indicate considerable enhancements in the load carrying capacity of such slabs above those predicted by Johanson's simple yield line theory(1).The amount of the load enhancement in a particular slab is found to depend on many parameters such as the steel ratio rx + , orthotropy ratio g, compressive strength of concrete fʹc , yield stress of steel fy , and the slab aspect ratio Ly/Lx, such that a higher enhancement in load is achieved for a slab having a higher value of fʹc but lower values of Ly/Lx , rx + , g and fy

Mechanical Properties of Reactive Powder Concrete (RPC) with Various Steel Fiber and Silica Fume Contents

An experimental work was carried out to investigate some mechanical properties of Reactive Powder Concrete (RPC) which are particularly required as input data for structural design. These properties include compressive strength, tensile strength (direct, splitting and flexural), flexural toughness, load-deflection capacity and static modulus of elasticity. The effects of three variable parameters on these properties were carefully studied which are, the silica fume content SF (0%, 10%, 15%, 20%, 25%, and 30%) as a partial replacement by weight of cement, hooked macro steel fibers volume fraction Vf (0%, 1%, 2% and 3%) and superplasticizertype(Sikament®-163N and PC200).The diameter of the steel fiber is 0.5mm and its length is 30mm with aspect ratio 60.The experimental results showed that as the silica fume content (SF) increases from 0% to 30% the compressive strength significantly increases, while the increase in tensile strength is relatively lower. The inclusion of steel fibers leads to a considerable increase intensile strength, while the addition of steel fibers causes a slight increase in compressive strength of RPC as fiber volume fraction increases from 0% to 3%.The increase in the steel fibers volume fraction and silica fume content improved the loaddeflection behavior and consequently gave higher ductility and fracture toughness of RPC

Experimental Investigation of Composite Steel-Concrete Arches

This research is concerned with behavior of composite steel-concrete arches under static load. For this purpose, eight models of composite steel-concrete arches are fabricated as test specimens.According to their supporting systems, the eight fabricated specimens are equally divided into Hinge-Roller and Hinge-Hinge supported arches in which varied numbers of shear connectors are used to investigate the effects of support conditions and degree of shear connection on the behavior of the composite arches. The specimens are tested under monotonically increasing point load applied on their crowns (on the top of concrete slabs). The mechanical properties of the used materials are determined by laboratory tests. Push-out tests on three specimens, fabricated for this purpose, are also carried out to determine the properties of the stud shear connectors. It is concluded that increasing the number of connectors tends to increase the ultimate load capacity and decrease both displacement and slip in the composite arches. This trend is considerably satisfied when the horizontal movements of supports are constrained (Hinge-Hinge supported arches)

Delaying surgery for patients with a previous SARS-CoV-2 infection

Not availabl

Preoperative nasopharyngeal swab testing and postoperative pulmonary complications in patients undergoing elective surgery during the SARS-CoV-2 pandemic.

BACKGROUND: Surgical services are preparing to scale up in areas affected by COVID-19. This study aimed to evaluate the association between preoperative SARS-CoV-2 testing and postoperative pulmonary complications in patients undergoing elective cancer surgery. METHODS: This international cohort study included adult patients undergoing elective surgery for cancer in areas affected by SARS-CoV-2 up to 19 April 2020. Patients suspected of SARS-CoV-2 infection before operation were excluded. The primary outcome measure was postoperative pulmonary complications at 30 days after surgery. Preoperative testing strategies were adjusted for confounding using mixed-effects models. RESULTS: Of 8784 patients (432 hospitals, 53 countries), 2303 patients (26.2 per cent) underwent preoperative testing: 1458 (16.6 per cent) had a swab test, 521 (5.9 per cent) CT only, and 324 (3.7 per cent) swab and CT. Pulmonary complications occurred in 3.9 per cent, whereas SARS-CoV-2 infection was confirmed in 2.6 per cent. After risk adjustment, having at least one negative preoperative nasopharyngeal swab test (adjusted odds ratio 0.68, 95 per cent confidence interval 0.68 to 0.98; P = 0.040) was associated with a lower rate of pulmonary complications. Swab testing was beneficial before major surgery and in areas with a high 14-day SARS-CoV-2 case notification rate, but not before minor surgery or in low-risk areas. To prevent one pulmonary complication, the number needed to swab test before major or minor surgery was 18 and 48 respectively in high-risk areas, and 73 and 387 in low-risk areas. CONCLUSION: Preoperative nasopharyngeal swab testing was beneficial before major surgery and in high SARS-CoV-2 risk areas. There was no proven benefit of swab testing before minor surgery in low-risk areas

Age–sex differences in the global burden of lower respiratory infections and risk factors, 1990–2019: results from the Global Burden of Disease Study 2019

Summary Background The global burden of lower respiratory infections (LRIs) and corresponding risk factors in children older than 5 years and adults has not been studied as comprehensively as it has been in children younger than 5 years. We assessed the burden and trends of LRIs and risk factors across all age groups by sex, for 204 countries and territories. Methods In this analysis of data for the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we used clinician-diagnosed pneumonia or bronchiolitis as our case definition for LRIs. We included International Classification of Diseases 9th edition codes 079.6, 466–469, 470.0, 480–482.8, 483.0–483.9, 484.1–484.2, 484.6–484.7, and 487–489 and International Classification of Diseases 10th edition codes A48.1, A70, B97.4–B97.6, J09–J15.8, J16–J16.9, J20–J21.9, J91.0, P23.0–P23.4, and U04–U04.9. We used the Cause of Death Ensemble modelling strategy to analyse 23 109 site-years of vital registration data, 825 site-years of sample vital registration data, 1766 site-years of verbal autopsy data, and 681 site-years of mortality surveillance data. We used DisMod-MR 2.1, a Bayesian meta-regression tool, to analyse age–sex-specific incidence and prevalence data identified via systematic reviews of the literature, population-based survey data, and claims and inpatient data. Additionally, we estimated age–sex-specific LRI mortality that is attributable to the independent effects of 14 risk factors. Findings Globally, in 2019, we estimated that there were 257 million (95% uncertainty interval [UI] 240–275) LRI incident episodes in males and 232 million (217–248) in females. In the same year, LRIs accounted for 1·30 million (95% UI 1·18–1·42) male deaths and 1·20 million (1·07–1·33) female deaths. Age-standardised incidence and mortality rates were 1·17 times (95% UI 1·16–1·18) and 1·31 times (95% UI 1·23–1·41) greater in males than in females in 2019. Between 1990 and 2019, LRI incidence and mortality rates declined at different rates across age groups and an increase in LRI episodes and deaths was estimated among all adult age groups, with males aged 70 years and older having the highest increase in LRI episodes (126·0% [95% UI 121·4–131·1]) and deaths (100·0% [83·4–115·9]). During the same period, LRI episodes and deaths in children younger than 15 years were estimated to have decreased, and the greatest decline was observed for LRI deaths in males younger than 5 years (–70·7% [–77·2 to –61·8]). The leading risk factors for LRI mortality varied across age groups and sex. More than half of global LRI deaths in children younger than 5 years were attributable to child wasting (population attributable fraction [PAF] 53·0% [95% UI 37·7–61·8] in males and 56·4% [40·7–65·1] in females), and more than a quarter of LRI deaths among those aged 5–14 years were attributable to household air pollution (PAF 26·0% [95% UI 16·6–35·5] for males and PAF 25·8% [16·3–35·4] for females). PAFs of male LRI deaths attributed to smoking were 20·4% (95% UI 15·4–25·2) in those aged 15–49 years, 30·5% (24·1–36·9) in those aged 50–69 years, and 21·9% (16·8–27·3) in those aged 70 years and older. PAFs of female LRI deaths attributed to household air pollution were 21·1% (95% UI 14·5–27·9) in those aged 15–49 years and 18·2% (12·5–24·5) in those aged 50–69 years. For females aged 70 years and older, the leading risk factor, ambient particulate matter, was responsible for 11·7% (95% UI 8·2–15·8) of LRI deaths. Interpretation The patterns and progress in reducing the burden of LRIs and key risk factors for mortality varied across age groups and sexes. The progress seen in children younger than 5 years was clearly a result of targeted interventions, such as vaccination and reduction of exposure to risk factors. Similar interventions for other age groups could contribute to the achievement of multiple Sustainable Development Goals targets, including promoting wellbeing at all ages and reducing health inequalities. Interventions, including addressing risk factors such as child wasting, smoking, ambient particulate matter pollution, and household air pollution, would prevent deaths and reduce health disparities