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Öğe A case study comparing seismic retrofitting techniques for a historically significant masonry building's minaret(Pergamon-Elsevier Science Ltd, 2024) Kiral, Adnan; Ergun, Mustafa; Tonyali, Zeliha; Artar, Musa; Senturk, IdrisHistorical masonry structures are extremely susceptible to earthquakes due to their characteristic features. Seismic performance and corresponding damage patterns vary between these buildings. Even though the main structure was undamaged, many minarets suffered damage or collapsed due to the transmission of large forces from the main mass to the minaret and the abrupt changes in cross-section due to the geometry of the minaret. This study uses an ancient masonry mosque as a case study, whose minaret and main building are constructed as a single structure. The mosque's minaret under seismic excitation is the focus of this study. The adopted model is called Alaeddin Bey Mosque in Mus,, T & uuml;rkiye. The seismic performance assessment of the minaret, considering various retrofitting options, is mainly based on four critical parameters: base shear, acceleration, displacement, and maximum tensile forces in all three dimensions. The analyzed retrofitting methods include base isolation located in the basement of the mosque, viscous dampers placed only in the upper part of the minaret, Carbon Fiber-Reinforced Polymer fabric fitted to only the minaret, and steel plates applied to only the minaret. Representative structural models of the mosque have been modelled with SAP2000 software. The main novelty of this study is the use of viscous dampers in the minaret. It is the first time a design methodology has been introduced for viscous damper applications in minarets. This methodology aims to prevent local damage to the minaret due to the forces generated by the dampers, while also considering the constraints of limited internal space within the minaret. The finding of this study shows that viscous damper application yields significantly better results compared to the application of Carbon Fiber-Reinforced Polymer fabric and steel plates. However, although base isolation reduces the tensile stress values throughout the entire mosque to levels well below the material's strength, viscous damper application in the minaret significantly reduces tensile stresses only in the minaret. As a result, viscous dampers are recommended for damage reduction in the minaret only. Otherwise, base isolation should be considered for reducing stress values throughout the entire mosque including the minaret. This study contributes towards the development of new seismic retrofitting methods for historic masonry buildings 'minaret.Öğe Dynamic analyses of experimentally-updated FE model of historical masonry clock towers using site-specific seismic characteristics and scaling parameters according to the 2018 Turkey building earthquake code(Pergamon-Elsevier Science Ltd, 2019) Genc, Ali Fuat; Ergun, Mustafa; Gunaydin, Murat; Altunisik, Ahmet Can; Ates, Sevket; Okur, Fatih Yesevi; Mosallam, Ayman S.This paper presents a dynamic analysis considering site-specific seismic characteristics for a masonry clock tower located at the city of corum, Turkey according to the new Turkish earthquake code. Finite element model of the tower was modeled using ANSYS software in order to determine numerical dynamic characteristics of the structure such as natural frequencies and mode shapes. Non-destructive experimental measurements were performed to extract the experimental dynamic characteristics. Experimental results were used as a reference parameter for finite element model updating to reflect the current structural behavior of clock tower. Model updating procedure was carried out by changing of initial material properties of structural stone elements, and maximum differences were reduced from 23.44% to 4.90%. Numerical results indicated that displacements have an increasing trend with the height of the clock tower. Furthermore, the maximum displacements occurred at the top point between the values of 18.88 mm to 42.5 mm. Numerical results also showed that both the maximum and minimum principal stresses occurred at the upper body (clock zone) walls and transition segment between the values of 1.08 MPa/2.86 MPa and - 0.87 MPa/ - 3.00 MPa, respectively. The maximum and minimum principal strains occurred at the upper body (clock zone) walls between the values of 0.65E-3/1.56E-3 and - 0.78E-3/ -1.50E-3, respectively. It is also concluded that non-destructive experimental measurement is very useful method to evaluate in-situ structural identification, validate and update the initial finite element model for further analyses.Öğe Evaluation of Dynamic and Fatigue Behavior of Damaged Steel Beams Strengthened with Different Types of Techniques and a New Strengthening Method Proposal(Springer Heidelberg, 2024) Ergun, Mustafa; Ates, SevketIn recent years, the use of carbon fiber-reinforced polymers to strengthen fatigue-damaged steel beams has increased significantly as an alternative to traditional methods due to their easy application to the damaged area, lightweight, durability, and sustainability. In addition to all these positive contributions, there are some disadvantages, such as debonding damage under loading. These disadvantages encourage researchers to produce new materials or apply materials used for other purposes in other fields for fatigue damage. In this paper, an alternative new strengthening technique is mentioned to improve the dynamic and fatigue behavior of fatigue-damaged steel beams. This technique is a strengthening application made using epoxy-based filler and carbon fiber-reinforced polymer fabric. Numerical and experimental studies are carried out on fatigue-damaged steel beams by applying this new technique and using different carbon fiber-reinforced polymers, such as a single and double layer of fabric and a single plate layer. The most significant improvement in dynamic behavior occurred on the specimen, strengthened with this newly proposed technique. In contrast, the lowest increase occurs on the sample strengthened with a single layer of fabric. While the lowest increase arises on the sample strengthened with a single layer of fabric in terms of fatigue life, the most significant progress in fatigue behavior makes on the sample strengthened with a single plate layer. As a result of comparing the results, it is concluded that this new strengthening technique could be an essential alternative to the currently used strengthening methods.Öğe Evaluation of the seismic performance pre- and post-restoration of a masonry clock tower's FE model updated via experimental and optimization methods(Pergamon-Elsevier Science Ltd, 2024) Ergun, Mustafa; Tayfur, BilalThis article presents comprehensive numerical and partial experimental studies to determine the seismic performance of the recently restored masonry clock tower in Bayburt before and after restoration. The numerical dynamic characteristics of the structure are obtained by free vibration analysis conducted on the preliminary finite element model, while the experimental ones are determined through ambient vibration testing. The ultimate finite element models reflecting the actual state of the structure pre- and post-restoration are created through a model updating process based on the principle of minimizing the differences between numerical and experimental dynamic properties via the Tabu Search Algorithm. Dynamic analyses of the models are carried out by the mode superposition method in the time domain, using eleven earthquake ground motion records selected considering the tectonic structure of the region and scaled to the design spectrum explicitly established to the site. Seismic responses are evaluated based on displacement, maximum-minimum principal stress, and maximum-minimum principal strain. The maximum principal stress value, the most critical parameter jeopardizing the safety of masonry structures, is 2.069 MPa before the restoration reaches 2.489 MPa, with an increase of approximately 20.3 % after the restoration. Since this value is less than the tensile strength of the masonry material, 3.120 MPa, it is not at a level that poses any risk to the structure. Other structural reactions also remain below the limit values. Therefore, according to today's seismic hazard analysis criteria, it can be said that the clock tower is safe. However, the North Anatolian Fault Zone, with high tectonic activity passing just south of the city, has the potential to produce severe earthquakes that may affect the region in the future. Therefore, it is necessary to periodically monitor the seismic behaviors of the historical masonry structures in Bayburt and take essential precautions based on the results.Öğe Investigation of temperature effect on the optimal weight design of steel truss bridges using Cuckoo Search Algorithm(Elsevier Science Inc, 2024) Keles, Meryem; Artar, Musa; Ergun, MustafaIn this article, the optimum weight design of steel truss bridges is carried out by considering the effect of temperature. One of the most significant issues such structures may encounter throughout their service life is the extreme temperature changes that can occur for various reasons. If a steel bridge is designed without considering this unfavorable scenario that might arise in the future, significant damage could happen in terms of the usability limit state, and it might even collapse by exceeding its carrying capacity before reaching its service life. Therefore, this study aims to conduct weight optimizations of steel truss bridges, considering the effect of temperature. Thus, it has been revealed how high-temperature variations alter material properties and affect the overall optimum weight of the structure. For this purpose, the minimum-weight designs of three planar steel truss bridges previously analyzed by other researchers have been re-evaluated using the Cuckoo Search Algorithm. The main program containing the flow steps of the algorithm based on the finite element method is coded in MATLAB. Stress and displacement limit values are used as constraints in solving the problems. The optimum weight results for each structure in the case of temperature effect not being considered are relatively similar. Thus, it has been demonstrated that the Cuckoo Search Algorithm can optimize such problems by comparing its results with similar studies in the literature. Then, the analyses are renewed by incorporating the temperature effect using this proven method. When the findings of both cases are examined, it is observed that the optimum weight values for all structures under the influence of temperature increase. This is due to the decrease in the material's modulus of elasticity because of the high-temperature change. In this case, the cross-section is insufficient owing to the loss of rigidity, and larger profiles are needed. The structure's weight tends to increase depending on the severity of the temperature. Also, numerical simulations of the structures under the same conditions are carried out with SAP2000 software to supplement the design optimization analyses detailed above and enrich the research content.Öğe Investigation of vibration performance of pure active single and multi-feedback controls for a tall RC building(Elsevier Science Inc, 2023) Uyar, Mehmet; Ergun, MustafaStructural control methods are applied to eliminate the structural damages caused by the vibrations in the buildings and to improve their dynamic behavior of them under dynamic lateral loads. In this paper, the pure active control performance of a tall building under the influence of earthquake records, in which the effective time duration is determined by considering the ARIAS energy distribution, is presented. The building's pure active control performance in the period when the earthquake records have the maximum effect on the structure is examined. Eleven earthquake records are selected to better evaluate the effect of vibration control perfor-mance. A genetic algorithm is used to determine the parameters of single and multi-feedback controllers, and its effect on the vibration eliminations at the top and all floors is studied. Also, the effect of displacement and velocity feedback on seismic vibration control is evaluated. To carry out the vibration control studies of the building, the mathematical model is extracted from the finite element model created in ANSYS and verified with finite element analysis. It is observed that the displacement value at a reference location on the building is reduced from 0.735 m to 0.019 m, 0.004 m, and 0.002 m, respectively, by the Proportional-Integral-Derivative, Direct Velocity Feedback, and Optimal controllers. The results show that the multi-feedback control is more effective than the single-feedback control application in reducing the vibration amplitudes at all floors in the pure active control system.Öğe Modal identification and fatigue behavior of Eynel steel arch highway bridge with calibrated models(Springer Heidelberg, 2021) Sunca, Fezayil; Ergun, Mustafa; Altunisik, Ahmet Can; Gunaydin, Murat; Okur, Fatih YeseviIn this paper, modal parameters of the Eynel steel arch highway bridge are identified and the fatigue behavior of the bridge is investigated. Modal parameters were extracted from three ambient vibration tests carried out over the period since the bridge came into service. The bridge became operational in 2009, and experimental measurements were taken in 2010, 2019, and 2021. The Enhanced Frequency Domain Decomposition (EFDD) method in the frequency domain and the Stochastic Subspace Identification (SSI) method in the time domain were used. Modal parameters were compared and any differences found over time in the measurement test results were investigated. Comparison of the results shows that changes in the natural frequencies were very limited and there was no change between the mode shapes. When experimental natural frequencies were compared, the maximum difference between the first and second measurements was calculated as 2.827%. Similarly, the maximum difference between the first and third measurements was 5.587% for the second mode, and around 3% for the other modes. This result is as expected because: (i) the bridge is not subject to heavy vehicle traffic and only connects village roads; (ii) no significant earthquake occurred during this period in the region which might have caused structural damage; (iii) no corrosion was found in the structural system elements as there was no contact with the reservoir water; (iv) no settlement or sliding occurred in the ground and boundary conditions remained unchanged. Moreover, the fatigue behavior of the bridge was investigated using the stress life method and AASHTO LRFD Bridge Design Specifications. To rationalize the results against the fatigue effects, the verified finite element model was used. From the fatigue analyses, it was concluded that the fatigue life of the bridge was within safe limits.Öğe THE MOST APPROPRIATE EARTHQUAKE RECORD GROUPS FOR DYNAMIC ANALYSIS OF A BUILDING(Yildiz Technical Univ, 2018) Atmaca, Barbaros; Ergun, Mustafa; Ates, SevketIn this paper, seven real earthquake records are scaled according to Eurocode 8 design acceleration spectrum by using SESCAP (Selection and Scaling Program). SESCAP is a scaling program based on time domain scaling method and developed by using MATLAB, GUI software. Real and scaled earthquake records are used for linear time history analyses of a six-storied reinforced concrete building modeled as spatial by SAP2000. Eurocode 8 allows the use of real earthquake records for linear and nonlinear time history analyses of structures. In the case of using three earthquake records in linear and nonlinear time history analyses, maximum results of structural responses are used for design of structures. If at least seven time history analyses are performed, the mean responses of the structures are taken into account rather than the maximum results. For the selection of maximum results of structural response from thirty five groups are created by calculating combination of threes of seven real and scaled earthquake records, and another group including all of the seven real and scaled earthquake records are created for selection of mean. Relative floor displacements along X axis of the building are preferred as structural response of the building in this study. It is seen that differences between mean value and maximum value of the relative floor displacements along X axis of the building induced by seven and three scaled earthquake records respectively are less than ones obtained from real earthquake records.Öğe Nondestructive Experimental Measurement, Model Updating, and Fatigue Life Assessment of carsamba Suspension Bridge(Asce-Amer Soc Civil Engineers, 2022) Gunaydin, Murat; Sunca, Fezayil; Altunisik, Ahmet Can; Ergun, Mustafa; Okur, Fatih YeseviThis paper includes the structural condition assessment of a 164-m suspension bridge in accordance with numerical and experimental methods. A finite-element model was developed using SAP2000 software so that the assessment of the bridge could be calculated numerically. The operational modal analysis method was also used to obtain experimental dynamic characteristics. In this context: (i) numerical dynamic characteristics of the bridge were obtained and compared with the experimental dynamic characteristics, (ii) a model updating procedure was carried out to minimize the differences between the numerical and experimental natural frequencies, (iii) static and dynamic analyses of the bridge were carried out by using the initial and updated finite-element models, (iv) fatigue life assessment of the bridge was investigated, and (v) the utility of the bridge for pedestrians and vehicles was checked according to various regulations. The results showed that updating the finite-element model had a significant role to play in the static and dynamic behavior of the bridge. The results also demonstrated that the bridge was designed to be extremely safe against static, dynamic, and fatigue loads. Finally, it was concluded that the bridge investigated behaves as a girder bridge rather than a suspension bridge.Öğe Optimum weight design of steel truss roof systems considering corrosion effect(Elsevier Science Inc, 2023) Aydogdu, Afranur Yaren; Artar, Musa; Ergun, MustafaIn this paper, the ideal weight for steel truss roof systems is determined while corrosion is considered. Because one of the most crucial problems that steel truss roof systems may experience during their service life is the effect of corrosion. If a corroded structure is designed without considering this effect during the design phase, sig-nificant damages and even collapses may occur before it reaches its service life. For this reason, the aim of this study is to make weight optimizations by considering the corrosion effect of steel truss roof systems. Thus, it has been revealed how corrosion that may develop on the truss members' surfaces affects the structure's overall optimum weight. Swarm intelligence-based algorithm approaches, Ant Colony Optimization (ACO), and But-terfly Optimization Algorithm (BOA) are used for this purpose to determine the optimal weight design of five different steel truss roof systems that were previously researched. The main program, which includes structural analysis (FEA) and optimization algorithms, is coded in the MATLAB programming language. The compression and tension bars selected as the limiting functions of the optimization problems are obtained from the stress, displacement, and slenderness conditions specified in the American Institute of Steel Construction-Allowable Strength Design (AISC-ASD, 1989) standard. It is seen that the optimum weight results obtained from all opti-mization methods for each structure in the non-corrosive condition are relatively similar. This result proves the correctness of the algorithms proposed in this paper. Then, under the influence of corrosion, the optimal weight designs of the structures are carried out. When the findings for the two cases are examined, it can be seen that the optimum weight values for all structures have slightly increased. This is because larger profiles are required due to overcapacity brought on by section loss. The weight of the structure increases in lockstep with the severity of corrosion. All the results like this are presented in detail with the help of tables and graphs in the relevant sections.Öğe Seismic behavior assessment of historical Alaeddin Bey Mosque and strengthening suggestions by CFRP fabric and steel plate(Pergamon-Elsevier Science Ltd, 2022) Senturk, Idris; Ergun, Mustafa; Artar, MusaIn this study, the effects of different strengthening methods that can be applied for earthquake-damaged historical masonry structures on structural performance were investigated. For this purpose, the Historical Alaeddin Bey Mosque in the central district of Mus was modeled in three dimensions according to the macromodeling technique using the finite element method in the SAP2000 program. The earthquake performance of the structure was determined by considering the earthquake-acceleration records of Erzincan, Kocaeli, and Van, respectively. The maximum tensile and compressive stresses in all three directions on the structural elements were taken into account as the earthquake behavior parameters of the structure. According to the earthquake analysis made in the time domain, it was determined that the polygonal pulpit of the minaret was at risk of being damaged under the effect of the Erzincan earthquake, and it has been concluded that this region should be strengthened. The damaged area of the minaret was strengthened by the application of CFRP fabric and steel plate materials (together or separately) in five different ways, from inside and outside and at different distance intervals. The conclusions obtained as a result of the earthquake analyses on the reinforced models were examined, and it was explained in detail with the help of tables and graphics that method would be more effective in strengthening such damages.
