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RISS 인기검색어
- 검색키워드
- 저자 : Ramazan Livaoğlu (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Investigation of wall flexibility effects on seismic behavior of cylindrical silos
Ramazan Livaoğlu,Ayşegül Durmuş 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.1
This paper is concerned with effects of the wall flexibility on the seismic behavior of groundsupported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literatureto 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.
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Combination of an inverse solution and an ANN for damage identification on high-rise buildings
Quy T. Nguyen,Ramazan Livaoğlu 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.3
Structural health monitoring (SHM) is currently applied to control regularly the health of high-rise buildings which have deteriorated after being subjected to a sudden loading. Damage detection at element levels of a structure consisting of an enormous number of elements becomes the main objective. In this study, the complicated problem is simplified by a two-step solution. Damaged storeys are preliminarily detected before a full damage scenario at an element level is achieved. In Step 1, to overcome the issues related to the huge number of degrees of freedom (DOFs), the full building is simplified to a beam-like system using the Guyan condensation technique. As the natural characteristics of the two lowest modes at the intact and a damaged stage are obtained, the eigenvalue problem based inverse solution is applied to approximately detect damaged storeys. Furthermore, an updating procedure that is proposed in this study effectively enhances the first prediction. In Step 2, an artificial neural network (ANN) model is designed to indicate damaged members on detected storeys using only the first three modal modes. Compared to other approaches applied to detect damages on high-rise buildings, the robustness of the proposed method is that the required number of lowest modal modes is two and three in Step 1 and Step 2 respectively. Furthermore, regardless of the extension of the building in the horizontal direction, only one lateral displacement of each storey is measured to detect damaged storeys in Step 1 and generally detect damaged elements in Step 2. For light and asymmetrical damage scenarios, two more vertical displacements should be considered to obtain accurate element-level detection. However, for all cases, the required number of DOFs is significantly lower than the full system.
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Modal strain energy-based updating procedure for damage detection: a numerical investigation
Quy Thue Nguyen,Ramazan Livaoğlu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4
Structural health monitoring is used to control the health of regularly deteriorating special structures or those subjected to sudden loading. Damage localization and severity estimation are important goals of researchers. In this study, an existing modal strain energybased approach is enhanced by a proposed updating procedure to detect damage and estimate severity. Numerical validation is conducted on a cantilever beam and a portal frame. The updated results obtained using the suggested technique are better compared with those of the existing method. On the basis of only the fundamental mode shape, the updating technique can successfully localize damaged elements regardless of the complexity of damage scenarios, and it can estimate severity with acceptable accuracy levels as long as the modal data are free of noise or submerged in noise at low levels.
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