Analysis of Reinforced Concrete and Composite Columns With and Without Steel Fibers

Analysis of eccentrically loaded plain and steel fiber high strength reinforced concrete and concrete-encased composite columns is presented. In the analysis procedure, the experimental nonlinear stress−strain relations are used for plain and steel fiber concrete material. The concrete compression zone of the section is divided into segmental subdivisions parallel to the neutral axis. The compression stress resultants of the concrete material and structural steel have been calculated in the centre of each segment. In the presented study, a computer program has been developed based on the proposed procedure for the prediction of ultimate strength analysis of eccentrically loaded steel fiber high strength reinforced concrete and composite columns. The main parameters of this study are the concrete compressive strength, load eccentricity, steel yield stress, slenderness effect and steel fiber content. The results show that adding steel fibers into high strength concrete significantly improves the ductility and deformability of reinforced concrete and composite columns under biaxial bending and axial load

Load-Deflection Curves of Reinforced Concrete Columns Subjected to Biaxial Bending and Axial Load

WOS: 000276283900003In the presented study, a theoretical method is proposed for the determination of the load deflection curves of reinforced concrete columns subjected to biaxial bending and axial load. The proposed method can be applicable to the polygonal sections consisted of various reinforcing steel configurations. In the proposed procedure the nonlinear behaviour of the materials are considered. Therefore, the concrete compression zone is divided into segments for the computation of concrete stresses. The proposed procedure has been compared with the results of square and L-shaped reinforced concrete columns tested under biaxial bending and axial load. The theoretical load deflection curves computed using test parameters of concrete compression strength, yield strength of steel, cross section properties and eccentricities of column specimens have been compared with the experimental curves and the results are found to be in good agreement

Investigation of the behavior of carbon fiber reinforced polymer confined standard cylinder concrete specimens under axial load

WOS: 000443171200006The use of fiber reinforced polymer composites for strengthening in concrete structures has become quite prevalent in recent years. Especially, to provide ductile behavior from the structural elements that produced by using the high strength concrete under the load effects, the externally wrapping of these elements with using the fiber reinforced polymer materials comes into prominence as an alternative method for strengthening. These materials with high tensile strength can often be preferred due to their lightweight and easy to apply. In this study, cylinder-shaped concrete specimens with compressive strengths range between 53.13 similar to 74.87 MPa, are wrapped one or two layer with using bi-directional carbon fiber reinforced fabric (CFRP). These wrapped specimens were tested under the axial comprehensive loads and the effects of the CFRP wrapping on concrete strength and ductility was investigated. In addition, stress-strain relations obtained from the tested specimens were compared with the results of existing models for strengthened cylindrical specimen with CFRP in literature. As a result a significant increase was obtained in the compressive strength and deformation capacity of CFRP wrapped specimens. Especially, it was observed that the stress-strain values obtained from the two layers CFRP wrapped specimens show good agreement with the values obtained from the models

An evaluation of fine grained sedimentary materials in terms of geotechnical parameters which define and control excavation performance of EPB TBM's

Studies have been conducted on Istanbul-Buyukcekmece Waste Water Tunnel route in order to determine the influence of plastic behavior and adhesion potential of fine grained clayey sedimentary soils as well as the lump form effect on the EPB-TBM's excavation performance. This research was designed to develop data modelling methodology for a risk assessment of excavating in form of lumps, the adhesion problem on the metal surfaces, and clogging

The effect of silymarin on hepatic regeneration after partial hepatectomy: Is silymarin effective in hepatic regeneration?

Aim: Silymarin from Silybum marianum was found to reduce liver injury. The aim of the present study was to investigate the effects of silymarin on hepatic regeneration in partially hepatectomized rats. Methods: Thirty Wistar-Albino rats were divided into 3 groups of 10 animals as sham, control and experimental groups. In the sham group (n=10) abdominal incision was closed after laparotomy. In the control group (n=10), the rats underwent 70% hepatectomy after laparotomy. In the experimental group (n=10) after partial 70% hepatectomy, silymarin (200 mg/kg/d) were given to rats for 10 days. Rats in three groups were sacrificed on 10 days. Aspartate (AST) and alanine transaminase (ALT), gamma glutamyl transferase (GGT), ALP, LDH and total bilirubin levels were measured using intracardiac blood samples. Tissue malondialdehyde (MDA) and tissue glutathion (GSH) and Superoxide dismutase (SOD) levels were measured. To reveal the increase in the mass of the remnant liver tissue in the control and experimental groups relative weight of the liver was calculated. Histopathological analysis of the liver was performed using a semi-quantitative scoring system. Results: A statistically significant difference among three groups was not shown for AST and ALT levels. A statistically significant difference was found between the groups as for total bilirubin and gamma glutamyl transferase levels. Increases in relative liver weights were seen with time in Groups 2 and 3. A statistically significant difference was not found for tissue malondialdehyde, Glutathion and Superoxide dismutase levels between hepatectomy and hepatectomy + silymarin groups. On liver tissue sections of the rats in the hepatectomy + silymarin group, increased regeneration and lipid peroxidation were observed accompanied by decreased antioxidant response. Conclusion: It has been observed that silymarin with many established functions such as antiproliferative, anti-inflammatory and energy antioxidant effects, does not contributed to proliferative regeneration of the liver-which has very important metabolic functions-after partial hepatectomy; instead it will decrease serum levels of transaminases. © 2015, Int J Clin Exp Med.All rights reserved

Best Practice Recommendations for Geriatric Dysphagia Management with 5 Ws and 1H

Background: Dysphagia is a geriatric syndrome. Changes in the whole body that occur with aging also affect swallowing functions and cause presbyphagia. This condition may progress to oropharyngeal and/or esophageal dysphagia in the presence of secondary causes that increase in incidence with aging. However, no study has been published that provides recommendations for use in clinical practice that addresses in detail all aspects of the management of dysphagia in geriatric individuals. This study aimed to answer almost all potential questions and problems in the management of geriatric dysphagia in clinical practice. Methods: A multidisciplinary team created this recommendation guide using the seven-step and three-round modified Delphi method via e-mail. The study included 39 experts from 29 centers in 14 cities. Results: Based on the 5W and 1H method, we developed 216 detailed recommendations for older adults from the perspective of different disciplines dealing with older people. Conclusion: This consensus-based recommendation is a useful guide to address practical clinical questions in the diagnosis, rehabilitation, and follow-up for the management of geriatric dysphagia and also contains detailed commentary on these issues

Mortality analysis of COVID-19 infection in chronic kidney disease, haemodialysis and renal transplant patients compared with patients without kidney disease: A nationwide analysis from Turkey

© The Author(s) 2020.Background. Chronic kidney disease (CKD) and immunosuppression, such as in renal transplantation (RT), stand as one of the established potential risk factors for severe coronavirus disease 2019 (COVID-19). Case morbidity and mortality rates for any type of infection have always been much higher in CKD, haemodialysis (HD) and RT patients than in the general population. A large study comparing COVID-19 outcome in moderate to advanced CKD (Stages 3-5), HD and RT patients with a control group of patients is still lacking. Methods. We conducted a multicentre, retrospective, observational study, involving hospitalized adult patients with COVID-19 from 47 centres in Turkey. Patients with CKD Stages 3-5, chronic HD and RT were compared with patients who had COVID-19 but no kidney disease. Demographics, comorbidities, medications, laboratory tests, COVID-19 treatments and outcome [in-hospital mortality and combined in-hospital outcome mortality or admission to the intensive care unit (ICU)] were compared. Results. A total of 1210 patients were included [median age, 61 (quartile 1-quartile 3 48-71) years, female 551 (45.5%)] composed of four groups: Control (n = 450), HD (n = 390), RT (n = 81) and CKD (n = 289). The ICU admission rate was 266/ 1210 (22.0%). A total of 172/1210 (14.2%) patients died. The ICU admission and in-hospital mortality rates in the CKD group [114/289 (39.4%); 95% confidence interval (CI) 33.9-45.2; and 82/289 (28.4%); 95% CI 23.9-34.5)] were significantly higher than the other groups: HD = 99/390 (25.4%; 95% CI 21.3-29.9; P<0.001) and 63/390 (16.2%; 95% CI 13.0-20.4; P<0.001); RT = 17/81 (21.0%; 95% CI 13.2-30.8; P = 0.002) and 9/81 (11.1%; 95% CI 5.7-19.5; P = 0.001); and control = 36/450 (8.0%; 95% CI 5.8-10.8; P<0.001) and 18/450 (4%; 95% CI 2.5-6.2; P<0.001). Adjusted mortality and adjusted combined outcomes in CKD group and HD groups were significantly higher than the control group [hazard ratio (HR) (95% CI) CKD: 2.88 (1.52- 5.44); P = 0.001; 2.44 (1.35-4.40); P = 0.003; HD: 2.32 (1.21- 4.46); P = 0.011; 2.25 (1.23-4.12); P = 0.008), respectively], but these were not significantly different in the RT from in the control group [HR (95% CI) 1.89 (0.76-4.72); P = 0.169; 1.87 (0.81-4.28); P = 0.138, respectively]. Conclusions. Hospitalized COVID-19 patients with CKDs, including Stages 3-5 CKD, HD and RT, have significantly higher mortality than patients without kidney disease. Stages 3-5 CKD patients have an in-hospital mortality rate as much as HD patients, which may be in part because of similar age and comorbidity burden. We were unable to assess if RT patients were or were not at increased risk for in-hospital mortality because of the relatively small sample size of the RT patients in this study