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- MakaleYalnız künye2018Scopus SJRQ3Automated Model Updating Effect on the Linear and Nonlinear Dynamic Responses of Historical Masonry Structures
Altunişik, A.C.; Okur, F.Y.; Genç, A.F.; Günaydin, M.; Karahasan, O.
Finite element models supply the simulation of the problems to obtain the structural behaviors under different loading conditions. The updating processes based on changing the uncertain parameters such as material properties, boundary conditions, meshing size etc. are made to create actual finite element models in order to represent the real conditions of the problems. This procedure can be made using two methods, namely manual model updating and global/local automatic model updating. The global/local automatic model updating procedures are very popular owing to the applicability to all kind of engineering structures, minimizing the differences nearly to zero, availability of damage localization and structural health monitoring. In this paper a historical masonry armory building selected as an application and its finite element analyses, experimental measurements and automated model updating processes are carried out. The finite element model of the structures was developed with ANSYS software and first three natural frequencies are attained. The experimental dynamic characteristics such as natural frequencies, damping ratios and mode shapes are obtained using ambient vibration method. The differences between experimental and numerical frequencies are minimized up to the range of 0–1%, by using local updating procedure. The linear and nonlinear seismic analyses of the building are conducted on initial and updated models. At the end of the analyses, maximum displacements, principal stresses and strains are given with detail. In addition, crack distributions diagrams are attained to validate the stresses accumulation points. It can be seen that there is an increasing trend in the displacement, stress and strain values after finite element model updating both linear and nonlinear analysis. In addition, linear and nonlinear analysis results are compared with each other to evaluate the nonlinear analysis effect. It is concluded that the displacement and strain values are increased after nonlinear analysis. But, there is not any agreement in stress values.
AtıfScopus17WoS15OpenAlex15
İncele - MakaleYalnız künye2017Scopus SJRQ2Finite Modeling Updating Effects on the Dynamic Response of Building Models
Günaydin, M.; Adanur, S.; Altunisik, A. C.; Sevim, B.; Bayraktar, A.
An improved finite element model was used to obtain more accurate modeling of engineering structures. The main goal of this paper was to determine how this improved modeling procedure affects the dynamic response of buildings based on experimental modal parameters such as natural frequencies, mode shapes and damping ratios. For experimental assessment, three small, one-story, two-bay, reinforced concrete buildings with raft foundation were constructed under laboratory conditions. The initial three-dimensional finite element models, built with the ANSYS software, were used to analytically identify modal parameters, including natural frequencies and mode shapes. Following the analytical study, the ambient vibration tests were performed to obtain modal parameters, experimentally. The enhanced frequency domain decomposition method and the stochastic subspace identification method were used to identify the modal parameter. The analytical and experimental modal parameters were compared and then initial finite element models were updated to minimize the differences by changing of some uncertain parameters such as materials properties. With model updating, the maximum difference between the measured and initially obtained frequency was reduced from 28.47 to 4.88%. To show the model updating effect on dynamic response of building models, dynamic analysis with the experimental computed damping ratios and 5% damping ratio were carried out using 1992 Erzincan earthquake ground motion record. For the experimental damping ratios, the maximum differences in the displacements and stresses between the initial and updated models were obtained as 23 and 32%, respectively. These differences were calculated as 43 and 15 % for the 5 % damping ratio. Comparisons of dynamic analyses results for the initial and updated model show that the finite element model updating affects the dynamic response of the buildings considerably.
AtıfWoS12OpenAlex11İncele - MakaleYalnız künye2011Scopus SJRQ1Finite element model updating effects on nonlinear seismic response of arch dam-reservoir-foundation systems
Bayraktar, Alemdar; Sevim, Baris; Altunisik, Ahmet Can
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 an onlinear 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. (C) 2010 Elsevier B.V. All rights reserved.
AtıfWoS50OpenAlex62İncele - MakaleYalnız künye2011Scopus SJRQ2Vibration-based operational modal analysis of the mikron historic arch bridge after restoration
Altunişika, Ahmet Can; Bayraktar, Alemdar; Sevima, Bariş; Birincia, Fatma
This research presents finite element modelling, vibration-based operational modal analysis, and finite element model updating of a restored historic arch bridge. Mikron historic bridge, constructed on Fi{dotless}rti{dotless}na River in Rize, Turkey, is the subject of this case study. The General Directorate for Highways of Turkey repaired the bridge's main structural elements, arches, sidewalls, and filler material in 1998. To construct a 3D finite element model of the bridge, ANSYS finite element software estimated the analytical dynamic characteristics. Induced ambient vibrations such as human walking and wind excited the model bridge to allow measurement of the bridge's responses. Enhanced frequency domain decomposition in frequency domain and stochastic subspace identification in time domain methodologies extracted experimental dynamic characteristics. A comparison of the analytical and experimental results showed significant agreement between mode shapes, but some differences in natural frequencies appeared. Consequently, updating the finite element model of the bridge by changing boundary conditions minimised the differences between analytical and experimental natural frequencies. After the finite element model updating process, the differences between natural frequencies declined from 7% to 2%.
AtıfScopus20WoS20OpenAlex21İncele