http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Zafer Sakka,R. Ian Gilbert 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.3
A numerical investigation of the impact of steel ductility on the strength and ductility of two-way corner and edge-supported concrete slabs containing low ductility welded wire fabric is presented. A finite element model was developed for the investigation and the results of a series of concurrent laboratory experiments were used to validate the numerical solution. A parametric investigation was conducted using the numerical model to investigate the various factors that influence the structural behavior at the strength limit state. Different values of steel uniform elongation and ultimate to yield strength ratios were considered. The results are presented and evaluated, with emphasis on the strength, ductility, and failure mode of the slabs. It was found that the ductility of the flexural reinforcement has a significant impact on the ultimate load behavior of two-way corner-supported slabs, particularly when the reinforcement was in the form of cold drawn welded wire fabric. However, the impact of the low ductility WWF has showed to be less prominent in structural slabs with higher levels of structural indeterminacy. The load-deflection curves of corner-supported slabs containing low ductility WWF are brittle, and the slabs have little ability to undergo plastic deformation at peak load.
Zafer Çıplak,Bengü Getiren,Ceren Gökalp,Ceren Atila Dinçer,Atila Yıldız,Nuray Yıldız 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12
Metal/metal oxide nanostructures based reduced graphene oxide (LrGO-Ag, LrGO-Cu2O, LrGO-Ag-Cu2O) nanocomposites were obtained via green method using Cetraria islandica (L.) Ach. lichen extract. Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscope energy-dispersive X-ray spectroscopy (SEM–EDX), ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed to analyze the prepared nanostructures. The results indicated that the nanocomposites were synthesized effectively and Ag-Cu2O nanoparticles with the mean diameter of 27nm were well dispersed on the LrGO. The conversion of methylene blue (MB) to Leuco Methylene Blue (LMB) and 4-Nitrophenol (4- NP) to 4-Aminophenol (4-AP) was performed by biosynthesized catalysts in the presence of NaBH4. The reaction rate of LrGO-Ag-Cu2O nanocomposite during 4-NP and MB reduction was found as 0.0026 s1 and 0.0497 s1, respectively. The LrGO-Ag-Cu2O nanocomposite showed superior catalytic performance for the reduction of both textile dyes.
Relationship of Non-Dipper and Reverse-Dipper Pattern with Sleep Quality in Normotensive Patients
Zafer Yalım,Sümeyra Alan Yalım 대한수면연구학회 2020 Journal of sleep medicine Vol.17 No.1
Objectives: It has been observed in many different populations that circadian blood pressure (BP) patterns have a significant impact on cardiovascular (CV) results. Important predictors of CV morbidity and mortality are known as non-dipper (ND) and reverse-dipper (RD) BP pattern. RD and ND patterns are frequently encountered in many normotensive patients in daily practice. Methods: The purpose of this study is to evaluate the frequency and quality of sleep, especially in normotensive young individuals, by using sleep questionnaires and to evaluate their relationship with poor BP patterns. A total of 195 normotensive patients (68 dippers, 63 ND, and 65 RD) were enrolled into this cross-sectional study. The insomnia severity index (ISI), Epworth sleepiness scale (ESS), and Pittsburgh sleep quality index (PSQI) approved questionnaires were applied to evaluate the presence and severity of sleep disorders and to determine the patient’s sleep quality. Results: When dipper and ND groups were compared, significant differences were observed in ISI, ESS, and PSQI (p<0.001). Then, the study patients were re-evaluated as dipper, ND, and RD groups and seen this significant difference continued (p<0.001). Also, the sleep time was significantly different between all groups of dipper (7.23±0.11 hours), ND (6.72±0.15 hours), and RD (5.79±0.11 hours) (p<0.001). In the correlation analysis, a significant inverse relationship was observed between sleep time and all survey results (p<0.05). Conclusions: RD and ND patterns are associated with sleep quality in healthy individuals. It is necessary to evaluate patients with RD and ND BP patterns in normotensive individuals in terms of sleep disorders in detail.
Edge-clamped two-way slabs containing low-ductility steel
Zafer Sakka,R. Ian Gilbert 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.6
This paper describes a series of full range load tests on two-way, edge-clamped reinforced concrete slab panels containing either Class L WWF or Class N deformed bars. Five rectangular slab panels were tested each with two adjacent fully restrained edges and two free edges. A point support was included under the corner of each panel at the intersection of the two free edges. Each slab specimen was loaded by four transverse loads applied symmetrically in the mid-panel region by a deformation-controlled actuator in a stiff testing frame. The continuous edge supports were provided by clamping two adjacent edges in a carefully designed and constructed testing frame. The slabs were instrumented with load cells to measure applied forces and reactions, strain gauges to measure strain in the steel reinforcement and on the concrete surfaces, linear variable displacement transducers and lasers to measure deflections at all stages of loading. The results of the tests are presented and evaluated, with particular emphasis on the strength, ductility and failure mode of the slabs.
Reliability-based assessment of damaged concrete buildings
Zafer I. Sakka,Ibrahim A. Assakkaf,Jamal S. Qazweeni 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6
Damages in concrete structures due to aging and other factors could be a serious and immense matter. Making the best selection of the most viable and practical repairing and strengthening techniques are relatively difficult tasks using traditional methods of structural analyses. This is due to the fact that the traditional methods used for assessing aging structure are not fully capable when considering the randomness in strength, loads and cost. This paper presents a reliability-based methodology for assessing reinforced concrete members. The methodology of this study is based on probabilistic analysis, using statistics of the random variables in the performance function equations. Principles of reliability updating are used in the assessment process, as new information is taken into account and combined with prior probabilistic models. The methodology can result in a reliability index β that can be used to assess the structural component by comparing its value with a standard value. In addition, these methods result in partial safety factor values that can be used for the purpose of strengthening the R/C elements of the existing structure. Calculations and computations of the reliability indices and the partial safety factors values are conducted using the First-order Reliability Method and Monte Carlo simulation.
The effect of in-plane deformations on the nonlinear dynamic response of laminated plates
Zafer Kazanci,Halit S. Turkmen 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.4
In this study, the effect of in-plane deformations on the dynamic behavior of laminated plates is investigated. For this purpose, the displacement-time and strain-time histories obtained from the large deflection analysis of laminated plates are compared for the cases with and without including in-plane deformations. For the first one, in-plane stiffness and inertia effects are considered when formulating the dynamic response of the laminated composite plate subjected to the blast loading. Then, the problem is solved without considering the in-plane deformations. The geometric nonlinearity effects are taken into account by using the von Kármán large deflection theory of thin plates and transverse shear stresses are ignored for both cases. The equations of motion for the plate are derived by the use of the virtual work principle. Approximate solution functions are assumed for the space domain and substituted into the equations of motion. Then, the Galerkin method is used to obtain the nonlinear algebraic differential equations in the time domain. The effects of the magnitude of the blast load, the thickness of the plate and boundary conditions on the in-plane deformations are investigated.