Yazar "Yuksel, S. Bahadir" seçeneğine göre listele

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    Assessment of non-prismatic beams having symmetrical parabolic haunches with constant haunch length ratio of 0.5
    (TECHNO-PRESS, 2012) Yuksel, S. Bahadir
    Single span historic bridges often contain non-prismatic members identified with a varying depth along their span lengths. Commonly, the symmetric parabolic height variations having the constant haunch length ratio of 0.5 have been selected to lower the stresses at the high bending moment points and to maintain the deflections within the acceptable limits. Due to their non-prismatic geometrical configuration, their assessment, particularly the computation of fixed-end horizontal forces (FEFs) and fixed-end moments (FEMs) becomes a complex problem. Therefore, this study aimed to investigate the behavior of non-prismatic beams with symmetrical parabolic haunches (NBSPH) having the constant haunch length ratio of 0.5 using finite element analyses (FEA). FEFs and FEMs due to vertical loadings as well as the stiffness coefficients and the carry-over factors were computed through a comprehensive parametric study using FEA. It was demonstrated that the conventional methods using frame elements can lead to significant errors, and the deviations can reach to unacceptable levels for these types of structures. Despite the robustness of FEA, the generation of FEFs and FEMs using the nodal outputs of the detailed finite element mesh still remains an intricate task. Therefore, this study advances to propose effective formulas and dimensionless estimation coefficients to predict the FEFs, FEMs, stiffness coefficients and carry-over factors with reasonable accuracy for the analysis and re-evaluation of the NBSPH. Using the proposed approach, the fixed-end reactions due to vertical loads, and also the stiffness coefficients and the carry-over factors of the NBSPH can be determined without necessitating the detailed FEA.
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    Behavior of symmetrically haunched non-prismatic members subjected to temperature changes
    (TECHNO-PRESS, 2009) Yuksel, S. Bahadir
    When the temperature Of a Structure varies, there is a tendency to produce changes in the shape of the structure. The resulting actions may be of considerable Importance in the analysis of the structures having non-prismatic members. Therefore, this Study aimed to Investigate the modeling, analysis and behavior of the non-prismatic members subjected to temperature changes with the aid of finite element modeling. The fixed-end moments and fixed-end forces Of Such members due to temperature changes were computed through a comprehensive parametric Study. It was demonstrated that the conventional methods using, frame elements can lead to significant errors, and the deviations can reach to unacceptable levels for these types of structures. The design formulas and the dimension less design coefficients were proposed based on a comprehensive parametric structural stress, two-dimensional plane-finite element models. The fixed-end actions of the non-prismatic members having parabolic and straight]launches due to temperature changes can be determined using the proposed approach Without necessitating a detailed finite element model Solution. Additionally, the robust results of the finite element analyses allowed examining the Sources and magnitudes of the errors in the conventional analysis.
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    Behavior of tunnel form buildings under quasi-static cyclic lateral loading
    (TECHNO-PRESS, 2007) Yuksel, S. Bahadir; Kalkan, Erol
    In this paper, experimental investigations on the inelastic seismic behavior of tunnel forrn buildings (i.e., box-type or panel systems) are presented. Two four-story scaled building specimens were tested under quasi-static cyclic lateral loading in longitudinal and transverse directions. The experimental results and supplemental finite element simulations collectively indicate that lightly reinforced structural walls of tunnel form buildings may exhibit brittle flexural failure under seismic action. The global tension/compression couple triggers this failure mechanism by creating pure axial tension in outermost shearwalls. This type of failure takes place due to rupturing of longitudinal reinforcement without crushing of concrete, therefore is of particular interest in emphasizing the mode of failure that is not routinely considered during seismic design of shear-wall dominant structural systems.
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    Design Formulas for the Groups of Six Cylindrical Silos Due to Interstice Loadings
    (SAGE PUBLICATIONS INC, 2011) Yuksel, S. Bahadir
    Different and huge amounts of granular materials can be stored in and between the cells of the grouped reinforced concrete cylindrical silos. The determination of design forces acting on these grouped silos requires significant computational effort due to structural continuity and the force transfer between the adjacent silos. In this conjunction, the present study carried out a series of two-dimensional linear elastic analyses for various groups of six cylindrical silos to examine their behaviors against interstice loadings. A detailed parametric study was performed by varying the silo-wall thickness, intersection wall thickness and the intersection wall lengths of the groups of six cylindrical silos in order to confirm their effectiveness on the resultant design forces. Bending moments, hoop forces and shear forces occurring at the interstice walls due to interstice loadings were computed with finite element analyses. Based on the results of the present numerical analyses, the design formulas were introduced and the design coefficients were proposed to compute the design forces without necessitating any finite element analyses.
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    Discussion of paper "Seismic behavior and modeling of steel reinforced concrete (SRC) walls' by Xiaodong Ji, Ya Sun, Jiaru Qian and Xinzheng Lu, Earthquake Engineering and Structural Dynamics 2015; 44(6):955-972
    (WILEY-BLACKWELL, 2015) Yuksel, S. Bahadir
    The paper under discussion presents a series of quasi-static tests used to examine the behavior of steel reinforced concrete (SRC) walls subjected to high axial force and lateral cyclic loading. A total of six wall specimens were designed, including five SRC walls and one reinforced concrete (RC) wall. In the Summary' section of the discussed paper, the authors state that: The use of SRC walls has gained popularity in the construction of high-rise buildings because of their superior performance over conventional RC walls'. The authors also proposed that, the SRC wall specimens showed increased flexural strength and deformation capacity relative to their RC wall counterpart. The discussion is prompted to rectify some statements and conclusions of the paper under discussion. Copyright (c) 2015 John Wiley & Sons, Ltd.
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    Neuro-fuzzy and artificial neural networks modeling of uniform temperature effects of symmetric parabolic haunched beams
    (TECHNO-PRESS, 2015) Yuksel, S. Bahadir; Yarar, Alpaslan
    When the temperature of a structure varies, there is a tendency to produce changes in the shape of the structure. The resulting actions may be of considerable importance in the analysis of the structures having non-prismatic members. The computation of design forces for the non-prismatic beams having symmetrical parabolic haunches (NBSPH) is fairly difficult because of the parabolic change of the cross section. Due to their non-prismatic geometrical configuration, their assessment, particularly the computation of fixed-end horizontal forces and fixed-end moments becomes a complex problem. In this study, the efficiency of the Artificial Neural Networks (ANN) and Adaptive Neuro Fuzzy Inference Systems (ANFIS) in predicting the design forces and the design moments of the NBSPH due to temperature changes was investigated. Previously obtained finite element analyses results in the literature were used to train and test the ANN and ANFIS models. The performances of the different models were evaluated by comparing the corresponding values of mean squared errors (MSE) and decisive coefficients (R-2). In addition to this, the comparison of ANN and ANFIS with traditional methods was made by setting up Linear-regression (LR) model.
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    A NEW SET OF DESIGN AIDS FOR GROUPS OF FOUR CYLINDRICAL SILOS DUE TO INTERSTICE AND INTERNAL LOADINGS
    (JOHN WILEY & SONS LTD, 2009) Yuksel, S. Bahadir; Arikan, Serkan
    The computation of design Forces For reinforced concrete groups of four cylindrical silos requires significant Computational effort due to Continuity in the walls between adjacent silos. This paper presents a simple but accurate procedure for lite Computation of design forces acting oil groups of four cylindrical silos due to stored materials. In this conjunction, finite element analyses were performed by using eight-node Solid elements for various groups of four cylindrical silos under interstice and internal loadings. The design forces at the prescribed sections of interstice and external walls were computed. The silo wall thicknesses, intersection wall thicknesses and intersection wall lengths of these grouped silos were varied with an extensive parametric Study to demonstrate their influence., Oil resultant design forces. Design formulas Were proposed and dimension less design coefficients were derived from the comprehensive series of finite element analyses considering the effect of continuity in the walls. The results were expressed in simplified form, so that the prediction of bending moments, axial forces and shear forces became straightforward for design purposes. In addition, the rigidity Of the interstice Walls Was varied by changing the modulus of elasticity and the redistribution of design forces was investigated. Copyright (C) 2007 John Wiley & Sons, Ltd.
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    Slit-connected coupling beams for tunnel-form building structures
    (JOHN WILEY & SONS LTD, 2008) Yuksel, S. Bahadir
    Openings to provide functional use in shear walls of tunnel-form building,.; result in coupled shear walls and coupling beams. These beams are deep compared to their clear span above the door openings: however, then thickness is less than 250 mm. Moreover. the are subjected to high shear forces Under lateral loads. Dimensional constraints make their desian against high shear forces difficult When code-specified reinforcement configurations are applied. In this paper, slits at each end of coupling beams are proposed to decrease the shear stiffness and shear forces of these deep Coupling beams. The structural behavior of coupled shear walls with slit-connected coupling beams (SCCBs) is investigated by performing two-dimensional static and dynamic analyses. Stiffness terms of SCCBs are obtained as a result of extensive finite element Simulations. Based on the parametric study conducted. an equivalent prismatic beam model representing SCCBs is proposed. Thereby, coupled shear walls having SCCBs can be analyzed by the equivalent frame method using the equivalent prismatic beam model. Copyright (c) 2007 John Wiley & Sons, Ltd.