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Alemdar Bayraktar - One of the best experts on this subject based on the ideXlab platform.
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Finite Element Model calibration of precast structures using ambient vibrations
Construction and Building Materials, 2015Co-Authors: Gokhan Osmancikli, Alemdar Bayraktar, Temel Turker, şenay Ucak, Ayman MosallamAbstract:Abstract In this paper, the Finite Element Model calibration of precast structures was investigated by considering ambient vibration test results. Two precast structures, an overpass and a precast production facility, were selected for investigation. The initial Finite Element Models of these structures were developed by using SAP2000 software and the initial dynamic characteristics were determined. The experimental measurements were carried out by Operational Modal Analysis method under ambient vibrations, such as wind and traffic loads, and the exact dynamic characteristics were identified experimentally. During the ambient vibration tests, structural responses were measured on different points of these precast structures. Measurement time, frequency span and effective mode number were determined by the pretest investigations. The modal parameters were extracted from the collected signals by Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques. At the end of the study, the analytical and experimental dynamic characteristics were compared with each other and the initial Finite Element Models of these structures were updated by changing the stiffness coefficients of the connection joints.
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structural safety assessment of bowstring type rc arch bridges using ambient vibration testing and Finite Element Model calibration
Measurement, 2014Co-Authors: Temel Turker, Alemdar BayraktarAbstract:Abstract The structural safety evaluation of a bowstring type reinforced concrete (RC) arch bridge was investigated by ambient vibration testing and Finite Element Model calibration in this study. The bridge named as Ali Cetinkaya Bridge in Samsun, Turkey, was selected for this investigation. The bridge constructed in 1937 consists of the seven discrete arches and its total length is approximately 250 m. The bridge damaged by environmental effects and it was closed to the traffic loads. The presented study consists of four main parts: ambient vibration test, initial Finite Element Modeling, Finite Element Model calibration and structural analysis of the calibrated Finite Element Model. The ambient vibration tests were performed using Operational Modal Analysis Method under the wind, human and water flow loads to identify the actual natural dynamic parameters, such as the natural frequencies and mode shapes, modal damping ratios. Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods were used to extract the experimental dynamic characteristics. The initial Finite Element Model was developed by including the soil effects in SAP2000 program to obtain the analytical dynamic characteristics. In the initial Finite Element Model, the beam, plane and solid Elements were used. After that, the initial Finite Element Model was calibrated according to the ambient vibration test results considering the material properties and boundary sections as variable parameters. The calibrated Model assumed to reflect the current state of the bowstring bridge was analyzed under dead, moving, traffic, water and earthquake loads. The maximum displacements, tensile stress, compressive stress and shear stress were attained each case and compared with each other.
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Finite Element Model updating effects on nonlinear seismic response of arch dam reservoir foundation systems
Finite Elements in Analysis and Design, 2011Co-Authors: Alemdar Bayraktar, Baris Sevim, Ahmet Can AltunisikAbstract:This paper investigates the effects of Finite Element Model updating on nonlinear seismic response of arch dam-reservoir-foundation systems. The highest arch dam in Turkey named Berke is selected for the numerical and experimental applications. Firstly, 3D Finite Element Model of Berke Dam was constituted using an ANSYS software. In the analytical Modeling, arch dam-reservoir-foundation interaction is represented by Lagrangian approach. Then ambient vibration tests were conducted to dam for four days, and experimental dynamic characteristics were estimated using an Enhanced Frequency Domain Decomposition technique. Experimental characteristics are compared with those of analytical obtained by the linear Finite Element analysis of the coupled system. Good agreement between mode shapes is observed during this comparison, though natural frequencies disagree by 15-20%. The linear Finite Element Model of Berke Dam was updated by adjusting the material properties of the dam and foundation. By introducing the Drucker-Prager damage criterion, the updated linear Finite Element Model was extended into a nonlinear Model. Nonlinear seismic behavior of Berke Dam was determined considering the acceleration record of Adana-Ceyhan, Turkey, earthquake in 1998 that occurred near the arch dam region. It is highlighted that the Finite Element Model updating provides a significant influence on the nonlinear seismic response of arch dams.
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seismic response of a historical masonry minaret using a Finite Element Model updated with operational modal testing
Journal of Vibration and Control, 2011Co-Authors: Alemdar Bayraktar, Baris Sevim, Ahmet Can Altunisik, Temel TurkerAbstract:This paper presents the earthquake response of a historical masonry minaret after a Finite Element Model updating was undertaken using the information from full scale ambient vibration testing. The Iskenderpasa historical masonry minaret dating back to the 16th century with a height of 21m located in the city center of Trabzon, Turkey is selected as an application. Analytical modal analysis is performed on the 3D Finite Element Model of the minaret considering field survey and engineering judgments to obtain the analytical frequencies and mode shapes. The field ambient vibration tests on the minaret under natural excitations such as wind loading and human movement are conducted. The Peak Picking and the Stochastic Subspace Identification techniques are used to extract the modal parameters from the ambient vibration test. A good correlation was found among the modal parameters identified from the two techniques. The Finite Element Model of the minaret is updated to minimize the differences between analytically and experimentally estimated modal properties by changing some uncertain Modeling parameters such as material properties and boundary conditions. The analytical Model of the minaret after Finite Element Model updating is analyzed using the 1992 Erzincan earthquake record, which occurred near the area, to determine the earthquake behavior of the minaret. At the end of the study, maximum differences in the natural frequencies are reduced on average from 27% to 5% and a good agreement is found between analytical and experimental natural frequencies and mode shapes by Model updating. Also, it is seen from the earthquake analysis that the displacements increase along the height of the minaret and the maximum and minimum principal stresses occur at the region of the transition segment and the cylindrical body.
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modal testing Finite Element Model updating and dynamic analysis of an arch type steel footbridge
Journal of Performance of Constructed Facilities, 2009Co-Authors: Alemdar Bayraktar, Baris Sevim, Ahmet Can Altunisik, Temel TurkerAbstract:This paper describes an arch type steel footbridge, its analytical Modeling, modal testing, Finite-Element Model updating, and dynamic analysis. A modern steel footbridge which has an arch type structural system and is located on the Karadeniz coast road in Trabzon, Turkey is selected as an application. An analytical modal analysis is performed on the developed three-dimensional Finite-Element Model of footbridge to provide analytical frequencies and mode shapes. Field ambient vibration tests on the footbridge deck under natural excitation such as human walking and traffic loads are conducted. The output-only modal parameter identification is carried out by using peak picking of the average normalized power spectral densities in the frequency domain and stochastic subspace identification in the time domain, and dynamic characteristics such as natural frequencies, mode shapes, and damping ratios are determined. The Finite-Element Model of the footbridge is updated to minimize the differences between analyt...
W G Jiang - One of the best experts on this subject based on the ideXlab platform.
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a concise Finite Element Model for pure bending analysis of simple wire strand
International Journal of Mechanical Sciences, 2012Co-Authors: W G JiangAbstract:A concise Finite Element Model for simple wire strand under pure bending is presented in this paper. Accurate bending symmetric boundary condition has been developed and applied to the periodic artificial cross-sectional end boundaries of the wire strand Finite Element Model. To achieve better analysis accuracy, full three-dimensional solid Elements were used for structural discretization. For the global behaviour of the wire strand, i.e. bending moment vs. bending curvature, the Finite Element results showed good agreement with the analytical elastic strand Model of Costello (Theory of wire rope, 2nd ed. New York: Springer-Verlag; 1997) in elastic loading regime. Furthermore, the Finite Element Model can predict the detailed progressive nonlinear plastic behaviour of the wire strand.
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a concise Finite Element Model for simple straight wire rope strand
International Journal of Mechanical Sciences, 1999Co-Authors: W G Jiang, M S Yao, J M WaltonAbstract:Abstract Due to its complex geometry, a wire in a rope is subjected to the combined effects of tension, shear, bending, torsion, contact, friction and possible local plastic yielding when loaded. In this paper an accurate and general strand Model using the Finite Element method (FEM) is presented. The Model is capable of taking into account all the above effects and has been successfully used to predict the global behaviour of simple straight wire rope strand as well as the stress distribution within the wires under axial loads (tensile and torsional). In simplifying the Finite Element Model, precise boundary conditions were developed. The Finite Element analysis results showed excellent agreement with the analytical theory of Costello and the experimental results of Utting and Jones. By using the Model developed in this paper, localised highly non-linear phenomena such as contact stress, residual stress, friction and plastic deformation can be studied effectively.
Temel Turker - One of the best experts on this subject based on the ideXlab platform.
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Finite Element Model calibration of precast structures using ambient vibrations
Construction and Building Materials, 2015Co-Authors: Gokhan Osmancikli, Alemdar Bayraktar, Temel Turker, şenay Ucak, Ayman MosallamAbstract:Abstract In this paper, the Finite Element Model calibration of precast structures was investigated by considering ambient vibration test results. Two precast structures, an overpass and a precast production facility, were selected for investigation. The initial Finite Element Models of these structures were developed by using SAP2000 software and the initial dynamic characteristics were determined. The experimental measurements were carried out by Operational Modal Analysis method under ambient vibrations, such as wind and traffic loads, and the exact dynamic characteristics were identified experimentally. During the ambient vibration tests, structural responses were measured on different points of these precast structures. Measurement time, frequency span and effective mode number were determined by the pretest investigations. The modal parameters were extracted from the collected signals by Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques. At the end of the study, the analytical and experimental dynamic characteristics were compared with each other and the initial Finite Element Models of these structures were updated by changing the stiffness coefficients of the connection joints.
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structural safety assessment of bowstring type rc arch bridges using ambient vibration testing and Finite Element Model calibration
Measurement, 2014Co-Authors: Temel Turker, Alemdar BayraktarAbstract:Abstract The structural safety evaluation of a bowstring type reinforced concrete (RC) arch bridge was investigated by ambient vibration testing and Finite Element Model calibration in this study. The bridge named as Ali Cetinkaya Bridge in Samsun, Turkey, was selected for this investigation. The bridge constructed in 1937 consists of the seven discrete arches and its total length is approximately 250 m. The bridge damaged by environmental effects and it was closed to the traffic loads. The presented study consists of four main parts: ambient vibration test, initial Finite Element Modeling, Finite Element Model calibration and structural analysis of the calibrated Finite Element Model. The ambient vibration tests were performed using Operational Modal Analysis Method under the wind, human and water flow loads to identify the actual natural dynamic parameters, such as the natural frequencies and mode shapes, modal damping ratios. Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods were used to extract the experimental dynamic characteristics. The initial Finite Element Model was developed by including the soil effects in SAP2000 program to obtain the analytical dynamic characteristics. In the initial Finite Element Model, the beam, plane and solid Elements were used. After that, the initial Finite Element Model was calibrated according to the ambient vibration test results considering the material properties and boundary sections as variable parameters. The calibrated Model assumed to reflect the current state of the bowstring bridge was analyzed under dead, moving, traffic, water and earthquake loads. The maximum displacements, tensile stress, compressive stress and shear stress were attained each case and compared with each other.
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seismic response of a historical masonry minaret using a Finite Element Model updated with operational modal testing
Journal of Vibration and Control, 2011Co-Authors: Alemdar Bayraktar, Baris Sevim, Ahmet Can Altunisik, Temel TurkerAbstract:This paper presents the earthquake response of a historical masonry minaret after a Finite Element Model updating was undertaken using the information from full scale ambient vibration testing. The Iskenderpasa historical masonry minaret dating back to the 16th century with a height of 21m located in the city center of Trabzon, Turkey is selected as an application. Analytical modal analysis is performed on the 3D Finite Element Model of the minaret considering field survey and engineering judgments to obtain the analytical frequencies and mode shapes. The field ambient vibration tests on the minaret under natural excitations such as wind loading and human movement are conducted. The Peak Picking and the Stochastic Subspace Identification techniques are used to extract the modal parameters from the ambient vibration test. A good correlation was found among the modal parameters identified from the two techniques. The Finite Element Model of the minaret is updated to minimize the differences between analytically and experimentally estimated modal properties by changing some uncertain Modeling parameters such as material properties and boundary conditions. The analytical Model of the minaret after Finite Element Model updating is analyzed using the 1992 Erzincan earthquake record, which occurred near the area, to determine the earthquake behavior of the minaret. At the end of the study, maximum differences in the natural frequencies are reduced on average from 27% to 5% and a good agreement is found between analytical and experimental natural frequencies and mode shapes by Model updating. Also, it is seen from the earthquake analysis that the displacements increase along the height of the minaret and the maximum and minimum principal stresses occur at the region of the transition segment and the cylindrical body.
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modal testing Finite Element Model updating and dynamic analysis of an arch type steel footbridge
Journal of Performance of Constructed Facilities, 2009Co-Authors: Alemdar Bayraktar, Baris Sevim, Ahmet Can Altunisik, Temel TurkerAbstract:This paper describes an arch type steel footbridge, its analytical Modeling, modal testing, Finite-Element Model updating, and dynamic analysis. A modern steel footbridge which has an arch type structural system and is located on the Karadeniz coast road in Trabzon, Turkey is selected as an application. An analytical modal analysis is performed on the developed three-dimensional Finite-Element Model of footbridge to provide analytical frequencies and mode shapes. Field ambient vibration tests on the footbridge deck under natural excitation such as human walking and traffic loads are conducted. The output-only modal parameter identification is carried out by using peak picking of the average normalized power spectral densities in the frequency domain and stochastic subspace identification in the time domain, and dynamic characteristics such as natural frequencies, mode shapes, and damping ratios are determined. The Finite-Element Model of the footbridge is updated to minimize the differences between analyt...
Biswa Nath Datta - One of the best experts on this subject based on the ideXlab platform.
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Finite Element Model updating eigenstructure assignment and eigenvalue embedding techniques for vibrating systems
Mechanical Systems and Signal Processing, 2002Co-Authors: Biswa Nath DattaAbstract:Abstract This paper presents a brief overview of the existing direct methods for the Finite-Element Model (FEM) updating problem and reviews the recently developed ‘direct and partial modal’ approach for the partial eigenstructure assignment problem and the ‘eigenvalue embedding’ techniques for vibrating systems, in the context of the solution of this problem.
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Finite Element Model updating eigenstructure assignment and eigenvalue embedding techniques for vibrating systems
Mechanical Systems and Signal Processing, 2002Co-Authors: Biswa Nath DattaAbstract:Abstract This paper presents a brief overview of the existing direct methods for the Finite-Element Model (FEM) updating problem and reviews the recently developed ‘direct and partial modal’ approach for the partial eigenstructure assignment problem and the ‘eigenvalue embedding’ techniques for vibrating systems, in the context of the solution of this problem.
Costas Papadimitriou - One of the best experts on this subject based on the ideXlab platform.
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implementation of an adaptive meta Model for bayesian Finite Element Model updating in time domain
Reliability Engineering & System Safety, 2017Co-Authors: Hector A Jensen, C Esse, V Araya, Costas PapadimitriouAbstract:Abstract This work explores the feasibility of integrating an adaptive meta-Model into a Finite Element Model updating formulation using dynamic response data. A Bayesian Model updating approach based on a stochastic simulation method is considered in the present formulation. Such approach is combined with a surrogate technique and an efficient Model reduction technique. In particular, an adaptive surrogate Model based on kriging interpolants and a Model reduction technique based on substructure coupling are implemented. The integration of these techniques into the updating process reduces the computational effort to manageable levels allowing the solution of complex problems. The effectiveness of the proposed strategy is demonstrated with three Finite Element Model updating applications.
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Model reduction techniques for bayesian Finite Element Model updating using dynamic response data
Computer Methods in Applied Mechanics and Engineering, 2014Co-Authors: Hector A Jensen, E Millas, Danilo S Kusanovic, Costas PapadimitriouAbstract:Abstract This work presents a strategy for integrating a class of Model reduction techniques into a Finite Element Model updating formulation. In particular a Bayesian Model updating approach based on a stochastic simulation method is considered in the present formulation. Stochastic simulation techniques require a large number of Finite Element Model re-analyses to be performed over the space of Model parameters during the updating process. Substructure coupling techniques for dynamic analysis are proposed to reduce the computational cost involved in the dynamic re-analyses. The effectiveness of the proposed strategy is demonstrated with identification and Model updating applications for Finite Element building Models using simulated seismic response data.
