Effect of Blast Loading on Seismically Detailed RC Columns and Buildings

Explosions caused by standoff charges near buildings have drastic effects on the internal and external structural elements which can cause loss of life and fatal injuries in case of failure or collapse of the structural element. Providing structural elements with blast resistance is therefore gaining increasing importance. This paper presents numerical investigation of RC columns with different reinforcement detailing subjected to near-field explosions. Detailed finite element models are made using LS-DYNA software package for several columns having seismic and conventional reinforcement detailing which were previously tested under blast loads. The numerical results show agreement with the published experimental results regarding displacements and damage pattern. Seismic detailing of columns enhances the failure shape of the column and decrease the displacement values compared to columns with conventional reinforcement detailing. Further, the effect of several modeling parameters are studied such as mesh sensitivity analysis, inclusion of air medium and erosion values on the displacements and damage pattern. The results show that decreasing the mesh size, increasing erosion value and inclusion of air region provide results that are very close to experimental results. Additionally, application is made on a slab-column multistory building provided with protective walls having different connection details subjected to blast loads. The results of this study are presented and discussed. Use of a top and bottom floor slab connection of protective RC walls are better than using the full connection at the four sides to the adjacent columns and slabs. This leads to minimizing the distortion and failure of column, and therefore it increases the chance of saving the building from collapse and saving human lives. Doi: 10.28991/cej-2021-03091733 Full Text: PD

NUMERICAL INVESTIGATION OF THE PERFORMANCE OF INSULATED FRP-STRENGTHENED REINFORCED CONCRETE BEAMS IN FIRE

Fiber reinforced polymers (FRP) have been widely used in retrofitting and strengthening of deteriorated or deficient reinforced concrete (RC) elements. A major concern about those systems is their performance under elevated temperature which limits the application of FRP for strengthening requirements. Fire protection of the strengthening FRP system can be made by applying an external coating layer of a thermal resisting material. In order to predict the fire performance of such insulated FRP-strengthened members and their efficiency, experimental investigations are required to be carried out for such elements under realistic fire conditions, which requires time and cost. This paper presents numerical modelling of RC beams strengthened with externally bonded FRP and insulated by a fire protection layer under elevated temperature specified by standard fire tests. The nonlinear time domain transient thermal-stress finite element analysis is performed using the general purpose software ANSYS 12.1 in order to study the heat transfer mechanism and deformation within the beam for fire conditions initiating at the bottom side of the beam. The finite element model accounts for the variation in thermal and mechanical parameters of the constituent materials such as concrete, steel reinforcement bars, FRP and insulation material with temperature. Application is made on an FRP-strengthened and insulated RC T-beam which has been experimentally tested in the published literature in order to verify the adopted modelling procedure. The obtained numerical results are in good agreement with the experimental results regarding the temperature distribution across the beam and mid-span deflection. The presented procedure thus provides an economical and effective tool to investigate the effectiveness of fire insulation layers when subjected to high temperatures and to design thermal protection layers for FRP strengthening systems that satisfy fire resistance requirements specified in building codes and standards

Methylene tetrahydrofolate reductase, transforming growth factor-β1 and lymphotoxin-α genes polymorphisms and susceptibility to rheumatoid arthritis

AbstractBackgroundRheumatoid arthritis is a widely prevalent autoimmune disorder with suggested genetic predisposition.ObjectivesThe aim of this study is to detect the pattern of genetic polymorphism of methylene tetrahydrofolate reductase (MTHFR C677 T and A1298 C), transforming growth factor-β1 (TGF-β1 T869 C) and lymphotoxin-α (LT-α A252G) in patients having rheumatoid arthritis and correlate these patterns to disease activity and serum levels of tumor necrosis factor-alpha (TNF-α), B-Cell Activating Factor (BAFF), and osteopontin.MethodsA total of 194 subjects, 90 controls and 104 patients with rheumatoid arthritis were genotyped for MTHFR C677 T and A1298 C, TGF-β1 T869 C and LT-α A252G polymorphisms using a methodology based on PCR-RFLP. Also serum levels of TNF-α, osteopontin and BAFF were measured by ELISA kits.ResultsThe CT genotype and T allele of MTHFR C677 T and GG genotype and G allele of LT-α A252G are associated with the risk of RA and with higher levels of the pro-inflammatory cytokine, TNF-α in patients with rheumatoid arthritis.ConclusionOur findings suggest that there is association between MTHFR C677 T and LT-α A252G genes polymorphisms and increased risk of RA in this sample of Egyptian population

Polimorfismos dos genes metilenotetrahidrofolato redutase, fator de crescimento transformador β1 e linfotoxina‐α e susceptibilidade à artrite reumatoide

ResumoAntecedentesA artrite reumatoide é uma doença autoimune amplamente prevalente com sugerida predisposição genética.ObjetivosDetectar o padrão de polimorfismo dos genes metilenotetrahidrofolato redutase (MTHFR C677T e A1298C), fator de crescimento transformador β1 (TGF‐β1 T869C) e linfotoxina‐α (LT‐α A252G) em pacientes com artrite reumatoide e correlacionar esses padrões com a atividade da doença e os níveis séricos de fator de necrose tumoral alfa (TNF‐α), fator ativador de linfócitos B (BAFF) e osteopontina.MétodosForam genotipados 194 indivíduos – 90 controles e 104 com artrite reumatoide – à procura de polimorfismos dos genes MTHFR C677T e A1298C, TGF‐β1 T869C e LT‐α A252G com uma metodologia baseada na PCR‐RFLP. Mensuraram‐se também os níveis séricos de TNF‐α, osteopontina e BAFF com kits de Elisa.ResultadosO genótipo CT e o alelo T do MTHFR C677T e o genótipo GG e alelo G do LT‐α A252G estão associados ao risco de AR e a níveis mais elevados da citocina pró‐inflamatória TNF‐α em pacientes com artrite reumatoide.ConclusãoOs achados do presente estudo sugerem que há associação entre os polimorfismos dos genes MTHFR C677T e LT‐α A252G e um risco aumentado de AR nessa amostra da população egípcia.AbstractBackgroundRheumatoid arthritis is a widely prevalent autoimmune disorder with suggested genetic predisposition.ObjectivesThe aim of this study is to detect the pattern of genetic polymorphism of methylene tetrahydrofolate reductase (MTHFR C677T and A1298C), transforming growth factor‐β1 (TGF‐β1 T869C) and lymphotoxin‐α (LT‐α A252G) in patients having rheumatoid arthritis and correlate these patterns to disease activity and serum levels of tumor necrosis factor‐alpha (TNF‐α), B‐Cell Activating Factor (BAFF), and osteopontin.MethodsA total of 194 subjects, 90 controls and 104 patients with rheumatoid arthritis were genotyped for MTHFR C677T and A1298C, TGF‐β1 T869C and LT‐α A252G polymorphisms using a methodology based on PCR‐RFLP. Also serum levels of TNF‐α, osteopontin and BAFF were measured by ELISA kits.ResultsThe CT genotype and T allele of MTHFR C677T and GG genotype and G allele of LT‐α A252G are associated with the risk of RA and with higher levels of the pro‐inflammatory cytokine, TNF‐α in patients with rheumatoid arthritis.ConclusionOur findings suggest that there is association between MTHFR C677T and LT‐α A252G genes polymorphisms and increased risk of RA in this sample of Egyptian population

NUMERICAL INVESTIGATION OF FRP-STRENGTHENED REINFORCED CONCRETE BEAMS AT HIGH TEMPERATURES

Fiber reinforced polymers (FRP) strengthening systems are mainly used to retrofit existing and deficient structural members. The performance of such strengthened structures at elevated temperatures is a critical issue that threatens the safety of the structure. Published research includes experimental testing of reinforced concrete (R.C) beams strengthened using FRP and subjected to fire tests. However, there is a need for numerical tools that simulate the performance of these FRP-strengthened elements in case of fire. This research work presents numerical modelling and nonlinear analysis conducted to assess the performance of reinforced concrete beams strengthened with externally bonded carbon FRP sheets when subjected to standard fire conditions. Finite element model using the general purpose software ANSYS 12.1 is developed and validated with experimental results published in the literature by other researchers.The developed finite element model achieved good correlation with the experimental results. Further, application of the validated finite element model is extended into a parametric study to explore the influence of different variables on the performance of the FRP system when subjected to fire. Different aggregate types, moisture contents, concrete cover thickness, insulation material types and insulation material thickness are included in the study. The developed finite element model is thus regarded a valid and economical alternative to experiments for prediction of the performance of FRP strengthened and insulated R.C beams under fire conditions. Additionally, it can be used for estimation of the fire rating of such structures as well as for design of adequate fire protection layers

NONLINEAR FINITE ELEMENT ANALYSIS OF INSULATED FRP STRENGTHENED REINFORCED CONCRETE COLUMNS SUBJECTED TO FIRE

In recent decades, Fiber Reinforced Polymers (FRP) have shown tremendous potential for retrofitting or repairing existing deficient or damaged concrete structural elements due to their superior properties such as high strength, corrosion resistance and ease of application. However, concern arises about the vulnerability of FRP material to combustion under fire condition, since they are usually applied to the exterior surface of structural members. Damage of the FRP strengthening layer due to high temperature is likely to decrease the load carrying capacity of the columns and threaten the safety of the structure. This paper presents numerical investigation of the behaviour of reinforced concrete (RC) columns strengthened with FRP sheets and insulated by a thermal resisting coating under service load and fire conditions. The finite element numerical modelling and nonlinear analysis are made using the nonlinear finite element analysis software ANSYS 12.1 [1]. The numerical model is verified for several FRP confined and insulated RC columns that have been experimentally tested under service load and standard fire tests in the published literature. The obtained numerical results are in good agreement with the experimental ones regarding the temperature distribution and axial deformation response. Consequently, the presented modelling gives an economic tool to investigate the behaviour of loaded FRP strengthened RC columns under high temperatures occurring in case of fire, if the modelling is verified against experimental works. Furthermore, the model can be used to design thermal protection layers for FRP strengthened RC columns to fulfill fire resistance requirements specified in building codes and standards

Value of mitral annular plane systolic excursion in the assessment of contractile reserve in patients with ischemic cardiomyopathy before cardiac revascularization

Background: Mitral annular plane systolic excursion (MAPSE) is an M-mode derived echocardiographic marker of left ventricular longitudinal function, the aim of this study is to evaluate the value of MAPSE in assessment of contractile reserve in patients with ischemic cardiomyopathy before cardiac revascularization. Methods: The study included 50 patients with ischemic cardiomyopathy with ejection fraction (EF) ≤35%, the patients presented to echocardiography laboratory for dobutamine stress echocardiography (DSE) to assess viability and contractile reserve before revascularization, patients with primary valvular disease, and those with significant mitral annular calcifications were excluded from the study. A low dose DSE was done to all patients using standardized incremental infusions of 5, 10, and 20 μg/kg/min and the following parameters were measured at both baseline and peak dose, (EF, wall motion score index(WMSI) and MAPSE). Contractile reserve was measured as the difference between the low dose and baseline values of the EF and WMSI. Results: The study included 50 patients aged 55.08 ± 7.15 years, 94% were males, the DSE protocol was complete in all patients without serious side effects. A total of eight hundred segments were analyzed, at baseline 65% were dysfunctional including 31.2% hypokinetic, 28.8% were akinetic, and 5% were dyskinetic. At low dose study 70% of the dysfunctional myocardium showed viability, EF increased significantly from 30.84 ± 4.56 to 42.24 ± 8.15%, p 10% (AUC = 0.6, sensitivity 67.86, specificity 59.09), and Δ MAPSE ≥1.8 mm can predict contractile reserve at ΔWMSI ≤0.20 (AUC = 0.61, sensitivity 65.5, specificity 75.6). Conclusions: MAPSE is a rapid simple quantitative echocardiographic method that can asses contractile reserve in patients with ischemic cardiomyopathy before cardiac revascularization. Keywords: Mitral annulus systolic excursion, Contractile reserve, Ischemic cardiomyopath

Efficiency of coating layers used for thermal protection of FRP strengthened beams

This paper investigates the efficiency of coating layers used for thermal protection of Fiber-Reinforced Polymer (FRP) strengthened Reinforced Concrete (RC) beams. An experimental program was carried out on 36 RC beams protected by using different coating layers of Perlite, Vermiculite, Portland Cement (PC) mortar, clay and ceramic fiber. The tested beams were exposed to 100, 200, 300, 400, 500, and 600 °C for 2 h, left to cool gradually, then tested to failure. The obtained results demonstrated that exposure to elevated temperature without protection reduces the residual flexural strength of RC beams by 20–66%, depending on the degree of temperature. Protecting RC beams by a 30 mm-thick layer of the tested materials was demonstrated to be efficient in reducing heat transfer through 2-h exposure to 600 °C, and thus provide higher fire rating. Protection layers of cement mortar, Aswan clay, Vermiculite, Perlite and ceramic fiber blanket, showed residual flexural capacity equal to 61%, 68%, 72%, 73% and 74% that of the control beam, respectively. Moreover, using double coating layers of ceramic fiber followed by Perlite plaster, Vermiculite plaster, PC plaster or Aswan clay, with overall total thickness of 50 mm was demonstrated to give better protection, and maintain residual flexural capacity only 5% less than the flexural capacity of control beams

Pulmonary

Background: Diabetes mellitus is a chronic and debilitating disease. Its complications give rise to micro and macrovascular diseases which affect eyes, kidneys, heart, blood vessels, nerves and also lungs. There may be a relationship between diabetes and reduced lung function, so this study was designed to evaluate the impairment of lung function on spirometry among diabetic patients. Objectives: To study the effect of diabetes mellitus on the evolution of respiratory function parameters. Patients and methods: Hundred subjects were enrolled in the study, 30 patients with type I, another 30 patients with type II and 40 subjects were controls. Mean age was 42.78 ± 3.14 years, 45 were males and 55 were females. Mean HbA1C was 8.9 ± 1.1%. 22 patients with diabetes duration from 5 to 10 years, 38 patients with a duration of more than 10 years. Spirometric tests were done for all groups by computerized Spirometry with six parameters {Forced vital capacity (FVC), Forced expiratory volume in first second (FEV1), Peak expiratory flow rate (PEFR), Forced expiratory volume in first second to forced vital capacity (FEV1/FVC), Peak expiratory flow rate (FEFR 25–75) and Diffusing capacity for carbon monoxide (DLCO)}. Result: There was a predominant reduction in all the Spirometric parameters of diabetic patients toward the restrictive pattern as there was significant deterioration in DLCO in comparison with healthy controls. FVC (p < 0.01), and FEV1/FVC% (p < 0.001) were significantly lower in type1 diabetic patients in comparison to those of type II. Impairment of lung functions was obvious with a longer duration of diabetes. Conclusion: Diabetes is associated with a significant impaired pulmonary function in a restrictive pattern as compared to non diabetics. The pulmonary function impairment was found to be more marked with diabetic duration especially after 10 years. Subjects with type I diabetes had lower FVC and FEV1/FVC% than predicted; it could be related to poor glycemic control

Pulmonary function changes in diabetic lung

AbstractBackgroundDiabetes mellitus is a chronic and debilitating disease. Its complications give rise to micro and macrovascular diseases which affect eyes, kidneys, heart, blood vessels, nerves and also lungs. There may be a relationship between diabetes and reduced lung function, so this study was designed to evaluate the impairment of lung function on spirometry among diabetic patients.ObjectivesTo study the effect of diabetes mellitus on the evolution of respiratory function parameters.Patients and methodsHundred subjects were enrolled in the study, 30 patients with type I, another 30 patients with type II and 40 subjects were controls. Mean age was 42.78±3.14years, 45 were males and 55 were females. Mean HbA1C was 8.9±1.1%. 22 patients with diabetes duration from 5 to 10years, 38 patients with a duration of more than 10years. Spirometric tests were done for all groups by computerized Spirometry with six parameters {Forced vital capacity (FVC), Forced expiratory volume in first second (FEV1), Peak expiratory flow rate (PEFR), Forced expiratory volume in first second to forced vital capacity (FEV1/FVC), Peak expiratory flow rate (FEFR 25–75) and Diffusing capacity for carbon monoxide (DLCO)}.ResultThere was a predominant reduction in all the Spirometric parameters of diabetic patients toward the restrictive pattern as there was significant deterioration in DLCO in comparison with healthy controls. FVC (p<0.01), and FEV1/FVC% (p<0.001) were significantly lower in type1 diabetic patients in comparison to those of type II. Impairment of lung functions was obvious with a longer duration of diabetes.ConclusionDiabetes is associated with a significant impaired pulmonary function in a restrictive pattern as compared to non diabetics. The pulmonary function impairment was found to be more marked with diabetic duration especially after 10years. Subjects with type I diabetes had lower FVC and FEV1/FVC% than predicted; it could be related to poor glycemic control