Merter, Onur
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Merter, O.
Onur Merter
Merter O
Merter, Onur.
O. Merter
Onur Merter
Merter O
Merter, Onur.
O. Merter
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onur.merter@ieu.edu.tr
merteronur@gmail.com
merteronur@gmail.com
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05.03. Civil Engineering
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Current Staff
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Sustainable Development Goals
5
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0
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9
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13
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8
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14
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17
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1
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2
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4
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11
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5
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16
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3
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2
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6
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12
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10
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15
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7
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Documents
23
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109
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8
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22
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93
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13
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9
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14/603
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25
Scopus Citation Count
28
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3
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3
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1.92
Scopus Citations per Publication
2.15
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4
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0
| Journal | Count |
|---|---|
| Lecture Notes in Civil Engineering | 3 |
| Civil Engineering Journal-Stavebni Obzor | 1 |
| COMPDYN Proceedings | 1 |
| Earthquake and Structures | 1 |
| Earthquakes And Structures | 1 |
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13 results
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Now showing 1 - 10 of 13
Article Inelastic Input Energy Spectra of Far-Fault Ground Motions: Influence of Hysteresis Model(Yildiz Technical Univ, 2022) Merter, Onur; Ucar, TanerThe main purpose of the present study is to compute the input energy spectra of selected far-fault ground motions (GMs) for linear elastic systems, and inelastic systems having a constant ductility ratio. Elastic-perfectly plastic (EPP) and Modified Takeda hysteresis models have been adopted in nonlinear modeling of single-degree-of-freedom (SDOF) systems. Accelerograms of far-fault GMs have been compiled from the Pacific Earthquake Research Center (PEER) database. Linear and nonlinear time history analyses have been performed using the selected GMs records for SDOF systems having a damping ratio of 5%. Input energy spectral ordinates have been computed in terms of energy equivalent velocity. The results have shown that there is no significant difference be tween elastic and inelastic input energy spectral values at intermediate and long periods. However, for short period systems, input energy demand imposed on inelastic systems is generally greater than that of imposed on elastic systems. For short period systems, it can be inferred from the computations of the study that the input energy spectral values obtained using Modified Takeda hysteresis model are greater than those of other models that have been employed. However, input energy spectra for inelastic systems have no significant dependency on hysteresis models, especially for intermediate and long period systems.Conference Object Citation - Scopus: 1Effect of Kinematic Hardening and Ductility Ratio on Inelastic Input Energy Spectra of Near-Fault Ground Motions(Springer Science and Business Media Deutschland GmbH, 2021) Ucar T.; Merter O.In energy-based seismic design of structures, ground motion effect is considered as an energy input to the systems. Consistent development of input energy spectra is of great importance for the energy-based seismic design since the total energy input to structural systems can be practically obtained by means of these graphs. The main purpose of the present study is to investigate the influence of post-yield stiffness ratio and ductility demand on inelastic input energy spectra of near-fault ground motions. A wide range of nonlinear single-degreed-of-freedom (SDOF) systems characterized by their natural periods ranging from 0.02 to 3.0 s and normalized lateral strength are considered. Bilinear elastoplastic (BEP) hysteresis models with six different post-yield stiffness ratios are used to generate the results for constant ductility ratios ranging from 2 to 5. Mean ± one standard deviation input energy equivalent velocity spectra of a set of 21 near-fault accelerograms exhibiting pulse-like characteristics are computed based on nonlinear time history analyses of SDOF systems with 5% damping. The analytical results have shown that the influence of post-yield stiffness ratio on inelastic input energy spectra of near-fault ground motions can be neglected practically, whereas the influence of ductility ratio is more obvious. Moreover, a transition period of approximately 0.7 s between the increasing and decreasing input energy equivalent velocity spectra based on ductility ratio is identified. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.Article Citation - WoS: 3Citation - Scopus: 3Derivation of Yield Force Coefficient for Rc Frames Considering Energy Balance and P-Delta Effects(Techno-Press, 2021) Ucar, Taner; Merter, OnurCurrently, prominent energy balance concept can efficiently be used to calculate the yield base shear force of structures. Energy balance equation is an additional constraint for the balance of seismic input energy by the energy absorption of the structure. This equation can be defined as the sum of elastic and plastic energies of structural systems using elastic and plastic load-deformation characteristics and the total energy dissipation capacity can finally be equated to the seismic energy demand. The objective of this paper is to present a procedure for the determination of energy-based yield force coefficient of reinforced concrete (RC) frame structures considering P-delta effects. The total of elastic and plastic energies are computed by means of elastic spectral velocity and energy modification factor, which is originally derived for structural systems with geometric nonlinearity. Total inelastic energy of single-degree-of-freedom (SDOF) system is transformed into the total inelastic energy of the multi-degree-of-freedom (MDOF) system using the conversion based on structural dynamics. Plastic energy of MDOF system is formulated after total seismic energy demand is obtained. It is accordingly equated to the total work done by inelastic MDOF structure with P-delta effects and consequently, a dimensionless yield force coefficient is derived. Nonlinear static analyses are performed for selected multi-story RC frames and yield force coefficients are compared with the results of the energy-based formulation. The results show that the proposed formulation taking P-delta effects into account can be effectively used to estimate the yield force coefficient of RC frame structures.Article Numerical Evaluation of the Performance of Uhpc Beams Under Bending and Shear Loads Using Different Material Models(2024) Akin-Adamu, Ayodele; Yalçinkaya, Çağlar; Merter, OnurThe Microplane and Menetrey-Willam concrete models are formulated on the research work of Bazant and Gambarova and Menetrey-Willam in the nineties respectively. They are used in this thesis to predict how reinforced Ultra-High-Performance Concrete (UHPC) beams will behave when subjected to flexural and shear dominant loadings. The numerical models are available in ANSYS, and they can simulate UHPC's extraordinary mechanical properties, such as high compression and tension strength, strain hardening, and softening behavior in compression and tension. In this research, four UHPC beams with dimensions of 180 wide by 270 deep by 4000 mm long with tensile reinforcements were studied using the two cementitious composite models mentioned above with the ANSYS software. The beams were investigated under flexural four-point loading and shear three-point loading with the ANSYS program. A quarter-geometric section model of the full beam was considered for the four-point loading to take advantage of symmetry in the longitudinal and transverse directions of the beam. For the three-point loading, the full geometry model of the beam was considered only because of the lack of symmetry. The results from the ANSYS finite element software were validated with an experimental study conducted by different researchers to show its capacity to predict the bending and shear behavior of reinforced UHPC beams. The comparisons of the results of both material models show that they can simulate the behavior of UHPC beams by using experimental load-deflection plots of the beam specimens and force strain plots of the longitudinal tensile reinforcements in the sample beams.Article Correlation Between the Plastic Energy Associated With the Equivalent Monotonic Response and the Maximum Hysteretic Energy Using the Gauss-Newton Algorithm(Taylor and Francis Ltd., 2025) Merter, O.This study aims to improve seismic energy dissipation assessment by estimating the energy factor (Formula presented.), defined as the ratio of plastic energy from an equivalent monotonic response to maximum hysteretic energy. The transformation to an equivalent monotonic form provides a simplified representation of complex cyclic behavior, enabling reliable comparison and practical application in seismic design. Nonlinear time history analyses are conducted on single-degree-of-freedom (SDOF) systems using 56 pulse-like and non-pulse-like ground motions from the 2023 Kahramanmaraş, Pazarcık earthquake. Results show strong agreement between (Formula presented.) -spectra and regression models, validating the effectiveness of the Gauss-Newton algorithm across structural periods and inelastic behavior. © 2025 Elsevier B.V., All rights reserved.Conference Object Hysteretic Energy to Input Energy Ratio Spectra of the 2023 Kahramanmaras Earthquake(Springer international Publishing Ag, 2025) Merter, Onur; Ucar, TanerHysteretic energy, closely related to seismic hazard as it quantifies the energy a structure can dissipate through inelastic deformation under earthquake forces, has been chosen as a key parameter in energy-based design approaches due to its direct measurement of energy dissipation during cyclic loadings. A total of 56 distinct pulse-like and non-pulse-like ground motion records from the 2023 Kahramanmaras earthquake are selected. Time history analyses are performed on the selected inelastic single-degree-of-freedom (SDOF) systems, followed by the computation of hysteretic energy spectra for 5% damping. The bilinear hysteretic model is employed to represent the nonlinear cyclic behavior of the structural systems and different ductility ratios are considered. Simultaneously, inelastic input energy spectra are computed for all selected ground motion records. Then, the hysteretic energy to input energy ratio spectra are graphically computed for different ductility ratios, and the mean values are presented along with their standard deviations. It is observed that the hysteretic energy to input energy ratio spectra tend to remain nearly constant beyond a certain period value. In the study, the hysteretic energy to input energy ratio spectra are also generated separately for the selected pulse-like and non-pulse-like ground motions, allowing for the identification of the impact of pulse behavior.Conference Object Citation - Scopus: 3A Study on Elastic Input Energy Spectra for Actual Earthquake Ground Motions at Stiff Soil Sites(National Technical University of Athens, 2019) Merter O.In energy-based seismic design approach, effect of ground motions on structures is considered as an energy input to structures. The earthquake input energy spectra are created combining the maximum input energies of single-degree-of-freedom (SDOF) systems having a certain damping ratio for different natural vibration periods. The determination of input energy spectra is of great importance for the energy-based seismic design since the total energy input to structural systems can be practically obtained via these graphs. This study presents the investigation of elastic input energy spectra for selected actual earthquake ground motions at stiff soil sites. Accelerogram set is selected from Pacific Earthquake Engineering Research (PEER) database for the specific range of average shear wave velocities in the top thirty meters of soils. Time history analyses are conducted for linear elastic SDOF systems having viscous damping ratio of 5% and energy-time histories are computed. Then the elastic input energy spectra for selected actual earthquake ground motions are obtained. The mean of energy spectra is investigated together with the mean plus one and two standard deviations of the energy spectra. The aim of the present study is to evaluate the earthquake input energy demand spectra of SDOF systems for stiff soil site classes. The results show that the elastic design input energy spectrum can be proposed for selected ground motions at stiff soil sites. © 2019 The authors.Article Citation - WoS: 3Citation - Scopus: 3An Energy-Based Approach To Determine the Yield Force Coefficient of Rc Frame Structures(Techno-Press, 2021) Merter, Onur; Ucar, TanerThis paper proposes an energy-based approach for estimating the yield force coefficient of reinforced concrete (RC) frame structures. The procedure is mainly based on the energy balance concept and it considers the nonlinear behavior of structures. First, an energy modification factor is defined to consistently obtain the total energy of the equivalent elastic-plastic single-degree-of-freedom (SDOF) system. Then, plastic energy is formulated as functions of the several structural parameters such as the natural frequency, the strength reduction factor and the yield displacement. Consequently, the plastic energy formulation is derived for multi-degree-of-freedom (MDOF) systems and the yield force coefficient is determined by equating the plastic energy relation to the work needed to push the structure from the yield displacement up to the maximum displacement monotonically. The validity of the energy-based approach is assessed on several RC frame structures by means of nonlinear static pushover analysis considering both material and geometrical nonlinearity. A modification factor is proposed for the yield force coefficient to consider the strain-hardening effects in lateral forces. Moreover, the modified energy-based yield force coefficients are correlated to practical design by using the ductility ratios imposed by Turky Building Earthquake Code and a quite good agreement is observed.Article Citation - WoS: 7Citation - Scopus: 8Predictive Model for Constant-Ductility Energy Factor Spectra of Near- and Far-Fault Ground Motions Based on Gauss-Newton Algorithm(Taylor & Francis Ltd, 2022) Ucar, Taner; Merter, OnurGauss-Newton algorithm is originally applied for estimating constant-ductility energy factor spectra of near- and far-fault ground motions. First, constant-ductility energy factors are clarified, a three-parameter exponential equation relating energy factor to period is proposed and estimation of parameters of the proposed equation by means of Gauss-Newton algorithm is fully demonstrated. A set of 100 both pulse-like and non-pulse like near-fault ground motion records and 112 ordinary far-fault ground motion records is assembled as seismic input. Mean energy factor spectra of the utilized ground motions are preliminarily computed from nonlinear time history analyses for five constant ductility ratios ranging from 2 to 6, and then the same spectra are estimated by Gauss-Newton method. Very strong correlation between the computed and the estimated energy constant-ductility energy factor spectra is observed after few iteration steps.Article Citation - WoS: 1Citation - Scopus: 1Input Energy Spectrum Damping Modification Factors(Techno-Press, 2024) Merter, O.; Ucar, T.This study examines damping modification factors (DMFs) of elastic input energy spectra corresponding to a set of 116 earthquake ground motions. Mean input energy per mass spectra and mean DMFs are presented for both considered ground motion components. Damping ratios of 3%, 5%, 10%, 20%, and 30% are used and the 5% damping ratio is considered the benchmark for DMF computations. The geometric mean DMFs of the two horizontal components of each ground motion are computed and coefficients of variation are presented graphically. The results show that the input energy spectra-based DMFs exhibit a dependence on the damping ratio at very short periods and they tend to be nearly constant for larger periods. In addition, mean DMF variation is obtained graphically for also the damping ratio, and mathematical functions are fitted as a result of statistical analyses. A strong correlation between the computed DMFs and the ones from predicted equations is observed. © 2024 Techno-Press, Ltd.
