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RISS 인기검색어
- 검색키워드
- 저자 : Gharaei-Moghaddam, Nima (검색결과 4 건)
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Frame Nonlinear Analysis by Force Method
M. Rezaiee-Pajand,N. Gharaei-Moghaddam 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2
The focus of this paper is on the force-based finite element for analysis of planar frames. Both material and geometrical nonlinear behavior are considered in this study. The formulations are based on the two-field Hellinger-Reissner functional. Nonlinear effects of the internal forces interactions are considered by using 2D tangent material stiffness and fiber discretization technique. Due to presence of the rigid body modes in the global coordinates, the element is formulated in a basic coordinate system. Corotational approach transforms responses of the basic coordinate system to the global one and makes the element applicable for structures with arbitrarily large rigid body displacements and rotations. Moreover, shear-locking problem is removed in this formulation. Two iterative and non-iterative algorithms for the element state determinations are proposed. Finally, the new element accuracy and also efficiency are verified by some numerical examples.
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Two new triangular finite elements containing stable open cracks
Mohammad Rezaiee-Pajand,Nima Gharaei-Moghaddam 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.1
The focus of this paper is on the elements with stable open cracks. To analyze plane problems, two triangular elements with three and six nodes are formulated using force method. Flexibility matrices of the elements are derived by combining the non-cracked flexibility and the additional one due to crack, which is computed by utilizing the local flexibility method. In order to compute the flexibility matrix of the intact element, a basic coordinate system without rigid body motions is required. In this paper, the basic system origin is located at the crack center and one of its axis coincides with the crack surfaces. This selection makes it possible to formulate elements with inclined cracks. It is obvious that the ability of the suggested elements in calculating accurate natural frequencies for cracked structures, make them applicable for vibration-based crack detection.
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Two new triangular finite elements containing stable open cracks
Rezaiee-Pajand, Mohammad,Gharaei-Moghaddam, Nima Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.1
The focus of this paper is on the elements with stable open cracks. To analyze plane problems, two triangular elements with three and six nodes are formulated using force method. Flexibility matrices of the elements are derived by combining the non-cracked flexibility and the additional one due to crack, which is computed by utilizing the local flexibility method. In order to compute the flexibility matrix of the intact element, a basic coordinate system without rigid body motions is required. In this paper, the basic system origin is located at the crack center and one of its axis coincides with the crack surfaces. This selection makes it possible to formulate elements with inclined cracks. It is obvious that the ability of the suggested elements in calculating accurate natural frequencies for cracked structures, make them applicable for vibration-based crack detection.
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Vahid Mohsenian,Nima Gharaei-Moghaddam,Alireza Arabshahi 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4
In most cases, the normal or log-normal distributions are assumed for the recorded statistical data in the process of fragility curve construction. This study aims to evaluate the validity of these assumptions and their infl uence on the accuracy of the results. For this purpose, considering the intensity corresponding to diff erent damage levels as the statistical data, the analytical method is used for the development of fragility curves, taking advantage of incremental dynamic analysis for six multistory moment-resisting steel frame structures with 3, 5, 7, 10, 12 and 15 stories. Comparison of the fragility curves attained by the assumptions of normal and log-normal distribution shows close agreement between the results, such that the maximum diff erence for diff erent performance levels in the frame structures is determined to be about 13%. According to the outcomes of numerical tests such as Shapiro–Wilk and Kolmogorov–Smirnov and the graphical and descriptive tests performed on the attained statistical results, the assumption of the normal distribution is not incorrect for all of the performance levels. However, the assumption of the log-normal distribution is a more reliable hypothesis. Accordingly, it is proposed to utilize this assumption for the development of fragility curves in the reliability evaluation of structures subjected to seismic loading.
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