Person: LİVAOĞLU, RAMAZAN
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LİVAOĞLU
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RAMAZAN
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Publication The effect of the ratio of ?-shaped shear connectors on the flexural behavior of a reinforced concrete frame(Sage Publications, 2020-05-27) Quy Thue Nguyen; Livaoğlu, Ramazan; Quy Thue Nguyen; LİVAOĞLU, RAMAZAN; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-3436-8551; 0000-0001-8484-6027; IUQ-1185-2023; M-6474-2014; AAW-6878-2021Failure in a structural system can appear because of different types of pathologies and can cause a large number of problems during seismic action. Among these pathologies are design and execution flaws, underestimation of the required capacity of cross-section or seismic demand, and use of low quality of materials. The jacketing technique for a frame element is the most common use strengthening method in the practice to remove such disadvantages in a structural system. Then, the shear stress transferability at the concrete-to-concrete interface surface is the main objective. Shear connectors application is a solution for that consideration, but the investigation in the literature focusing this point is not adequate. The effect of the ratio of steel shear connectors on the interfaces of a reinforced concrete frame constructed using reinforced concrete formworks on its flexural behavior is numerically evaluated. Initially, the same ratio of pi-shaped and ?-shaped shear connectors, 0.312%, is applied to determine the more effective shape. It should be clear that the ratio of shear connectors on any separate surface is calculated as the fraction of the total area of the cross-section of shear connectors placed perpendicularly (pi-shaped) at the surface and the area of that surface. The same ratio is understood as after evaluating the pi-shaped shear links, each of them is replaced by a ?-shaped link at the same location. As a result, compared to the bending capacity of the frame whose surfaces are smooth, ?-shaped connectors enhance the bending capacity of the frame up to 9.67% while the amount of improvement brought by pi-shaped ones is modest, about 2.172%. After that, a wide variety of the ratio of ?-shaped connectors, 9 values, are placed on concrete-to-concrete interfaces. Tremendously, due to clamping stress brought by ?-shaped shear connectors at the concrete substrates, the nonlinear behavior is improved and the amount of enhancement rises as the number of applied connectors is augmented but not linearly. The most important observation is that the amount of improvement is insignificant after the ratio of shear connectors reaches the percentage of between 0.3% and 0.4%. On the other hand, compared with the frame whose interfaces are smooth, the displacement ductility factor of the frame strengthened using 0.4% decreases an amount of about 30%.Publication Damage detection of high-rise buildings using an eigenvalue problem-based inverse solution(Elsevier, 2021-10-08) Nguyen, Quy Thue; Livaoğlu, Ramazan; Nguyen, Quy Thue; LİVAOĞLU, RAMAZAN; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-3436-8551; 0000-0001-8484-6027; AAW-6878-2021; IUQ-1185-2023; M-6474-2014Structural health monitoring (SHM) has been applied in the regular control of high-rise buildings' health that has deteriorated having being subjected to a sudden loading. Storey-level damage detection has been a subject of focus, due to the complexity of high-rise buildings. In this study, that of two-dimensional (2D) high-rise buildings is the objective of this study. The eigenvalue problem-based inverse solution is a promising method to identify the changes in the mechanical matrices of a building, once the issues related to the huge number of degrees of freedom (DOFs) can be dealt with. The Guyan static condensation procedure is applied to reduce the full matrices based on the limited size of eigenvectors measured in field. The modal data is obtained from a simple sensor network in which requires only one uniaxial accelerometer per floor. Two techniques, particularly damage detection and mass recognition, are developed, based on the inverse solution. The proposed approach is validated numerically on 20-storey and 30-storey buildings. Reliable storey-level detection is achieved as long as the modal data is noise-free or low-level noise-contaminated. Furthermore, the mass recognition procedure is successfully verified using an experimental test on a 3-storey frame.Publication Investigation of wall flexibility effects on seismic behavior of cylindrical silos(Techno, 2015-01-10) Livaoğlu, Ramazan; Durmuş, Ayşegül; LİVAOĞLU, RAMAZAN; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0001-8484-6027; M-6474-2014; S-4676-2019This paper is concerned with effects of the wall flexibility on the seismic behavior of ground-supported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literature to determine the dynamic pressure stemming from the bulk material assume silo structure as rigid. However, it is expected that the horizontal dynamic material pressures can be modified due to varying horizontal extensional stiffness of the bulk material which depends on the wall stiffness. In this study, finite element analyses were performed for six different slenderness ratios according to both rigid and flexible wall approximations. A three dimensional numerical model, taking into account bulk material-silo wall interaction, constituted by ANSYS commercial program was used. The findings obtained from the numerical analyses were discussed comparatively for rigid and flexible wall approximations in terms of the dynamic material pressure, equivalent base shear and bending moment. The numerical results clearly show that the wall flexibility may significantly affects the characteristics behavior of the reinforced concrete (RC) cylindrical silos and magnitudes of the responses under strong ground motions.Publication Dynamic characteristics of minarets of hoca tabip mosque(Ediciones Univ Oviedo, 2015-01-01) Livaoğlu, Ramazan; Baştürk, Mehmet Hudai; Serhatoğlu, Cavit; Doğangün, Adem; Aenlle, ML; Pelayo, F; Canas, FJC; Prieto, MG; Hermanns, L; Rey, MJL; FraileDeLerma, A; Canteli, AF; LİVAOĞLU, RAMAZAN; SERHATOĞLU, CAVİT; DOĞANGÜN, ADEM; Uludağ Üniversitesi; Aenlle, ML; Pelayo, F; Canas, FJC; Prieto, MG; Hermanns, L; Rey, MJL; FraileDeLerma, A; Canteli, AF; 0000-0001-8484-6027; 0000-0002-1867-7103; AAH-4411-2021; AAR-6126-2020; M-6474-2014; S-4676-2019With its thousands of years of history and traces from the past, Bursa is an open-air living history museum. Unfortunately Bursa is located in the earthquake zone and many catastrophic earthquakes occurred in the past. From inscriptions, it is learned that great majority of historical buildings like mosques, madrasahs, inns were damaged by the latest earthquake occurred in 1855. Because of their slender form, minarets were influenced much more than the other structures.Because one of the most important component of liabilities of our society is to preserve and transfer this historical heritage to our posterity, another problematic issue arise on this subject is the lack of literature about minarets. This is because that minarets were built in only Islamic regions. Furthermore, literature review shows that there are only a few scientific studies about seismic behavior of this type of structures. For the mentioned reasons, in this study, dynamic characteristics of Hoca Tabip Mosque which was built in 15th century, were evaluated. One of the in situ tests, modal analysis technique was carried out and the dynamic characteristics of the minaret were captured. At the same time the construction techniques were investigated. These results were compared with those obtained from the numerical model of minaret which was constituted using in situ size measuring. Finally, it was seen that the results from two approaches correspond to each other. In conclusion, it is shown that the numerical model which was carried out in this study represent actual structure with high accuracy.Publication Effect of infill walls and plaster for a four storey r/c building(Ediciones Univ Oviedo, 2015-01-01) Kaplan, Onur; Güney, Yücel; Doğangün, Adem; Livaoğlu, Ramazan; Aenlle, ML; Pelayo, F; Canas, FJC; Prieto, MG; Hermanns, L; Rey, MJL; FraileDeLerma, A; Canteli, AF; DOĞANGÜN, ADEM; LİVAOĞLU, RAMAZAN; Uludağ Üniversitesi; Aenlle, ML; Pelayo, F; Canas, FJC; Prieto, MG; Hermanns, L; Rey, MJL; FraileDeLerma, A; Canteli, AF; 0000-0002-1867-7103; 0000-0001-8484-6027; AAR-6126-2020; S-4676-2019; M-6474-2014Infill walls are non-structural elements, which are mainly used for architectural purposes. Besides contribution of infill walls is ignored during the structural analysis, the effect of the infill walls are usually taken into account through the application of additional loads and masses appropriately distributed along the interfaces between the surrounding frame and the infill walls. In doing so, the stiffness and strength contribution of the latter elements as well as their interaction with the members of the Reinforced Concrete (RC) frame are also ignored. Practically some of the earthquake design codes like Turkish code neglect the effects of the non-structural infill walls. However the presence of infill walls significantly increases the stiffness and the strength of a frame. The reasons of this increment are high in-plane stiffness of infill and the composite action of the infill and the frame. On the other hand, plastering significantly affects the behaviour of infill walls. Thus, the dynamic characteristics of a building also affected by the mu 11 walls of building having plaster or not.The objective of this study is selected to compare the behaviour of mull walls with and without plaster by focusing on dynamic characteristics of a 4-storey residential R/C building in Eskisehir, Turkey. Natural periods, mode shapes and damping ratios of the building were determined for two different construction stages by using ambient vibration test. To obtain experimental dynamic characteristics, Enhanced Frequency Domain Decomposition (EFDD) technique was used. These 4-storey residential R/C building is located in Eskisehir, Turkey. The investigated building in which seismic loads are jointly resisted by frames and structural walls. There are only one shear wall along x-direction and four shear walls along y-direction. The floor area of the building is 400 m(2) and story heights are 2.83 m. Total area of infill walls for one storey are 5.44 m(2) and 10.75 m(2) at x-direction y-direction, respectively.As a result of this study, vibration measurements are established that, plaster significantly changed the dynamic characteristics of building. Decrease in the periods both x and y directions and also torsional period showed that the plaster increases the lateral stiffness of the infill walls and thereby it increased the lateral stiffness of the building.Publication Dynamic identification of monumental and historical minaret of the sehadet(Ediciones Univ Oviedo, 2015-01-01) Serhatoğlu, Cavit; Livaoğlu, Ramazan; Bağbancı, Bilal; Aenlle, ML; Pelayo, F; Canas, FJC; Prieto, MG; Hermanns, L; Rey, MJL; FraileDeLerma, A; Canteli, AF; SERHATOĞLU, CAVİT; LİVAOĞLU, RAMAZAN; Uludağ Üniversitesi; Aenlle, ML; Pelayo, F; Canas, FJC; Prieto, MG; Hermanns, L; Rey, MJL; FraileDeLerma, A; Canteli, AF; 0000-0001-8484-6027; AAH-4411-2021; S-4676-2019; M-6474-2014Modal analysis has been used in three decades in the civil engineering disciplines in order to solve complex structural dynamic problems. In this study, dynamic parameter such as fundamental frequency, mode shapes and damping ratios of minaret of Sehadet mosque, historical masonry minaret, was investigated using operational modal analysis method. However; dynamic character identification of historical masonry minarets are considerably difficult for Structural Health Monitoring. The historical masonry minarets have complicated stiffness, heterogenic element material and direct indeterminable boundary conditions. Thus, scope of this study, ambient vibration test which is measure in-situ tests were carried out for determination of dynamic characteristics with the aid of accelerometers and appropriate analysis programs. In order to achieve the modal analysis- frequency domain, Peak-picking method was employed in derivation of modal data from frequency response function data. In addition ultrasound test was performed to the material taken from minaret elements, which is coarse (kufeki) stone and laboratory test was made to the stone sample for the characteristic properties of material. Thereby, only few criteria such as boundary conditions and mesh control calibration was made for the correct model of the minaret. Three dimensional finite element model was designed for the minaret using finite elements analysis program, ABAQUS. The results obtained from a finite element analyses of the minaret were compared with results of experimental approach. Finally, it can be easily stated that the proposed finite element models themselves are the meritorious approximations to the real problem, and this makes the model appealing for use in comprehensive investigations.Publication Dynamic response of traditional and buttressed reinforced concrete minarets(Pergamon-Elsevier Science, 2015-03-01) Türkeli, Erdem; Livaoğlu, Ramazan; Doğangün, Adem; LİVAOĞLU, RAMAZAN; DOĞANGÜN, ADEM; Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0001-8484-6027; 0000-0002-1867-7103; M-6474-2014; S-4676-2019; AAR-6126-2020The destructive 17 August 1999 M-w 7.4 Kocaeli and 12 November 1999 M-w 7.2 Duzce Earthquake caused significant damage on reinforced concrete (RC) minarets and many of them severely damaged or collapsed causing the loss of lives. Damages or collapses of these RC minarets after the miserable actions of nature compel us to revise our knowledge about the dynamic response. The experiences from the catastrophic strong ground motions also dictate to the practitioners that alternative structural load carrying systems should be used and/or the seismic resistance of widely used systems should be improved. In this study, the dynamic behaviors of traditional and proposed buttressed RC minarets were compared with each other. Findings of this study show that using buttressed structural load carrying systems in the earthquake prone regions is beneficial and these supporting system behaved well when compared to traditional RC systems. (C) 2014 Elsevier Ltd. All rights reserved.Publication Investigation of the infill wall effect on the dynamic behaviour of RC frames(Ediciones Univ Oviedo, 2015-01-01) Timurağaoğlu, M. Ömer; Livaoğlu, Ramazan; Doğangün, Adem; Aenlle, M. L.; Pelayo, F.; Canas, F. J. C.; Prieto, M. G.; Hermanns, L.; Rey, M. J. L.; FraileDeLerma, A.; Canteli, A. F.; TİMURAĞAOĞLU, MEHMET ÖMER; LİVAOĞLU, RAMAZAN; DOĞANGÜN, ADEM; Uludağ Üniversitesi/Fen Bilimleri Enstitüsü.; Aenlle, M. L.; Pelayo, F.; Canas, F. J. C.; Prieto, M. G.; Hermanns, L.; Rey, M. J. L.; FraileDeLerma, A.; Canteli, A. F.; 0000-0002-6329-905X; 0000-0001-8484-6027; 0000-0002-1867-7103; AAR-6126-2020; S-4676-2019; M-6474-2014; ABF-2355-2020The simplicity of construction and economic reasons have made the infilled frame one of the most preferred structural form for reinforced concrete (RC) frame buildings around the world. For these reasons, the usage of infill walls with reinforced concrete frames increased rapidly over the past decades. On the other hand, although the reinforced concrete frame-infill systems are commonly used throughout the world, the infill is rarely included in the numerical analysis of the structures. For this reason the main goal of this study is to investigate, obtain and compare the dynamic characteristics such as natural frequencies, mode shapes and damping ratios of RC frames with and without infill wall by using classic vibration test results within elastic limit. In addition, the contribution of infill wall to the RC frame behavior for the small strain level is also the target of this paper. For this purpose, full scaled, one bay and one storey RC frames with and without infill wall are constructed and tested.Enhanced Frequency Domain Decomposition technique is used in order to attain the experimental dynamic characteristics of the frames. The results from tests showed that the forced vibration test measurements are sufficient and satisfying to identify the dynamic properties of the RC frames for both with and without infill walls. Furthermore, addition of infill wall to the bare frame does not have an important effect on the dynamic characteristics of the system for small strain level. On the other hand, it is shown that the application of plaster to the infill wall changes the dynamic behavior of the system significantly even for such a so small forces used in this study.Publication Structural damage identification of high-rise buildings: An artificial neural network based hybrid procedure(Pergamon-elsevier Science Ltd, 2023-06-06) Nguyen, Quy Thue; Livaoğlu, Ramazan; LİVAOĞLU, RAMAZAN; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0001-8484-6027; M-6474-2014Structural damage detection of high-rise buildings is by far not reached because of their complexity. In this study, an artificial neural network (ANN) method-based two-step approach is suggested to detect damage at element levels of a 3D 30-storey 90 m high RC building containing 2880 degrees of freedom (DOFs). One biaxial accelerometer per floor is erected, making the number of measured DOFs equal to about 2% of the full system. Only the first three bending modes in the orthogonal axes are accounted for. A network is constructed in Step 1 to detect damaged storeys based on the similarities between tall buildings and beam-like systems. All components' stiffness parameters of each storey are assigned to one variable. In Step 2, another network is built focusing only on the detected storeys to localize ruined elements. Furthermore, aiming at detecting damage considering modal data generated under ambient conditions, inevitable measurement noise effects are also considered to challenge the proposed ANN technique. As a result, the light and robust networks lead to precise storey- and element-level detection promptly as long as the desired vibration-based properties are free of noise as well as noise-corrupted.Publication Damage detection at storey and element levels of high-rise buildings: A hybrid method(Springer London Ltd, 2022-03-22) Quy Thue Nguyen; Livaoğlu, Ramazan; LİVAOĞLU, RAMAZAN; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-3436-8551; 0000-0001-8484-6027; IUQ-1185-2023; AAW-6878-2021; M-6474-2014Storey-level detection of high-rise buildings has become a subject of focus but still inadequate, whereas element-level detection is by far not reached because of the complexity of tall buildings, especially in a three-dimensional (3D) problem. In this study, element-level detection of two 3D 30-storey 90-m-high RC buildings (symmetrical and asymmetrical) composed of 2880 degrees of freedom (DOFs) is aimed. Only one biaxial accelerometer per floor is required to measure lateral displacements, making the number of measured DOFs equal to about 2% of the full system. To circumvent the complicated problem, a two-step procedure is proposed to detect damage at storey and then element levels. The backbone idea lies in the similarities in terms of bending behaviour at low modes between tall buildings and beam-like systems. Particularly, in Step 1, in each direction, a full 3D building is approximately simplified to a beam-like system using the Guyan static condensation procedure based on the measured DOFs. Thereafter, an eigenvalue problem-based inverse solution is implemented directly on the simplified system to detect damaged storeys using only the first two bending modes. In Step 2, an artificial neural network model is designed to indicate ruined shear walls and columns focusing only on the preliminarily identified storeys, effectively reducing the number of desired variables. Only modal data at the lowest three swaying modes are accounted for. As a result, storey- and element-level detection is accurately achieved as long as the identified modal data are noise-free or low-level noise polluted.