Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Conference Object A Boundary Element Method for Axisymmetric Elastodynamic Analysis(John Wiley and Sons Inc., 1996) Özkan, Gonca; Mengi, YalçınA new numerical method is proposed for the boundary element analysis of axisymmetric bodies. The method is based on complex Fourier series expansion of boundary quantities in circumferential direction, which reduced the boundary element equation to an integral equation in (r-z) plane involving the Fourier coefficients of boundary quantities, where r and z are the coordinates of the r theta z cylindrical coordinate system. The kernels appearing in these integral equations can be computed effectively by discrete Fourier transform formulas together with the fast Fourier transform (FFT) algorithm, and the integral equations (r-z) plane can be solved by Gaussian quadrature, which establishes the Fourier coefficients associated with boundary quantities. The Fourier transform solution can then be inverted into r theta z space by using again discrete Fourier transform formulas together with FFT algorithm. In this paper, we present the formulation of the proposed method which is outlined above. A comparison is given between the existent methods in literature and our method, which shows that the use of FFT algorithm for the integrations in circumferential direction provides considerable saving in computer time.Conference Object Upscaling Surface Flow Equations Depending Upon Data Availability at Different Scales(Springer Verlag, 2003) Tayfur, GökmenSt. Venant equations, which are used to model sheet flows, are point-scale, depth-averaged equations, requiring data on model parameters at a very fine scale. When data are available at the scale of a hillslope transect, the point equations need to be upscaled to conserve the mass and momentum at that scale, Hillslope-scale upscaled model must be developed if data are available at that scale. The performance of the three models applied to simulate flows from non-rilled surfaces revealed that the hillslope-scale upscaled model performs as good as the point-scale model though it uses far less data. The transectionally-upscaled model slightly underestimates the observed data.Conference Object Citation - WoS: 1Effect of Water Source on Human Health: a Case Study From Biga Peninsula, Turkey(2009) Baba, Alper; Gündüz, OrhanThe concentrations of certain elements including arsenic (As), fluoride (F) and aluminum (AI) were measured in groundwater in the different part of Biga Peninsula which is located in the western parts of Turkey. The concentration values of As and AI in groundwater ranged between 10-40 ppb, 0.5-0.8 ppm and 1-11.5 ppm, respectively, in this region. Al values exceed the Turkish drinking water standard value of 0.2 ppm. Furthermore, As concentration in water from alteration zones exceed the drinking water standard value of 10 ppb. Based on this background, this study was intended to investigate the source of these heavy metals and its neurotoxin effects on human health as many people living in this region have undergone medical treatment, which are believed to be related to the quality of water resources originating from densely altered volcanic rocks.Conference Object Citation - Scopus: 1Strength Requirements of Permanent Metal Deck Forms Used for Lateral Bracing of Steel Bridge Girders(2006) Eğilmez, Oğuz Özgür; Helwig, T.A.; Herman, R.S.Permanent metal deck forms (PMDF) are often used in steel bridges to support the weight of the wet concrete during deck construction. Although the PMDF also has the potential to provide bracing to steel bridge girders during construction, the stiffness of the PMDF system as a lateral brace is drastically reduced by the eccentric support angle connection detail used to attach the forms to the girders. Laboratory tests have shown that a simple modification to the connection detail can substantially increase the stiffness of these PMDF systems and allow utilization of the PMDF for girder bracing. This paper presents results from a parametrical study conducted to determine stability and strength requirements for PMDF used to provide lateral bracing to steel bridge girders. Detailed FEA models were used to determine the stability bracing strength requirements for the fasteners that are used to connect the PMDF along the sidelaps of the sheets and to the girders. Design expressions are presented as well as an example demonstrating the use of the design equations.Conference Object Roc Curves for Evaluating Sensor Performance as Low Energy Impacts Damage a Composite Wing(DEStech Publications Inc., 2009) Aktaş, Engin; Seaver, M.Eight fiber Bragg gratings and 3 ICP accelerometers attached to the upper surface of a foam core composite wing (1320 mm X 152.4 mm X 13.4 mm) were used to record the wing's response to broad band (0 - 1500 Hz) Gaussian excitation following a series of low energy (-6.5 J) impacts to the surface of the wing. For each damage level, at least 15 measurements were made over a period of three days to enable a statistical evaluation of each sensor's performance. Damage detection relied on measuring nonlinearity in the response data using a second order correlation metric called the Bicoherence. The amplitudes of any peaks seen in the Bicoherence were compared with thresholds determined from the variance in the off diagonal terms in the Bicoherence measurement. This approach allows the evaluation of both the probability of detection (POD) and the probability of false alarms (PFA) for each measurement without the need for a healthy baseline. The results show that all eight FBGs out perform the accelerometers and that one FBG in particular is more sensitive to nonlinearity than the others. The measurement sensitivity of the Bicoherence is also compared with static tip deflection measurements.