• Structural Engineering and Mechanics
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• 제7권3호
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• pp.259-276
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• 1999

An analytical solution for the shape functions of a beam segment supported on a generalized two-parameter elastic foundation is derived. The solution is general, and is not restricted to a particular range of magnitudes of the foundation parameters. The exact shape functions can be utilized to derive exact analytic expressions for the coefficients of the element stiffness matrix, work equivalent nodal forces for arbitrary transverse loads and coefficients of the consistent mass and geometrical stiffness matrices. As illustration, each distinct coefficient of the element stiffness matrix is compared with its conventional counterpart for a beam segment supported by no foundation at all for the entire range of foundation parameters.

• Steel and Composite Structures
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• 제18권4호
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• pp.947-970
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• 2015

An equivalent friction element is proposed to simulate the friction in cable-strut joints. Equivalent stiffness matrixes and load vectors of the friction element are derived and are unified into patterns for FEM by defining a virtual node specially to store internal forces. Three approaches are described to verify the rationality of the new equivalent friction element: applying the new element in a cable-roller model, and numerical solutions match well with experimental results; applying the element in a continuous sliding cable model, and theoretical values, numerical and experimental results are compared; and the last is applying it in truss string structures, whose results indicate that there would be a great error if the cable of cable supported structures is simulated with discontinuous cable model which is usually adopted in traditional finite element analysis, and that the prestress loss resulted from the friction in cable-strut joints would have adverse effect on the mechanical performance of cable supported structures.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.323-330
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• 2004

The purpose of this paper is to experimentally identify the finite element (FE) model of a building structure with magnetorheological (MR) fluid damper. Using FE model based system identification (FEBSI) technique, The model of MR damper having nonlinear characteristics is expressed with equivalent linear properties such as mass, stiffness, and damping. Bingham model is used for MR damper modeling. The equivalent stiffness and damping matrices of MR damper are predicted by applying an equivalent linearization technique, and those values are compared with the experimentally obtained ones.

• 한국공간구조학회논문집
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• 제17권3호
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• pp.65-73
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• 2017

Recently, the trend is emerging a variety of irregular tall buildings. It is important to design the building for lateral load according to this trend. Fluid Structure Interaction(FSI) simulation can be performed to understand the vibrations of the structure against dynamic wind loads. In order to make the physical characteristics of the actual structure and the analytical model the same, we studied core inserting equivalent stiffness modeling method. As a result of this analysis, the stiffness of the structure can be set similar to that of the two axes of the structure, and turbulence can be reproduced through the acceleration tendency.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.130-133
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• 2005

Efficient finite element method has been introduced for metallic sandwich plates subject to 3-point bending. A full model 3-point bending FE-analysis shows that plastic behavior of inner structures appears only at the load point. So, Unit structures of sandwich plates are defined to numerically calculate the bending stiffness with recurrent boundary condition of pure bending. And then equivalent models with same bending stiffness and strength of full models are designed analytically. It is demonstrated that results of both models are almost same and FE analysis method with equivalent models can reduce analysis time effectively.

• Structural Engineering and Mechanics
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• 제82권3호
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• pp.369-383
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• 2022

In this study, an equivalent boundary conditions (BCs) determination method is developed numerically for a panel reinforced concrete (RC) slab to realistically analyze the deformation and fatigue behaviors of a bridge RC slab. For this purpose, a finite element analysis of a bridge RC slab is carried out beforehand to calculate the stiffness of the bridge RC slab, and then the equivalent BCs for the panel RC slab are determined to achieve the same stiffness at the BCs to the obtained stiffness of the bridge RC slab at the corresponding locations of the bridge RC slab. Moreover, for the simulation of fatigue behaviors, fatigue analysis of the panel RC slab is carried out employing a finite element method based on a numerical model that considers the bridging stress degradation. Both the determined equivalent BCs and the BCs that have been typically applied in past studies are employed. The analysis results confirm that, in contrast to the panel RC slab with typically used BCs, the panel RC slab with equivalent BCs simulate the same bending moment distribution and deformation behaviors of the bridge RC slab. Furthermore, the equivalent BCs reproduce the extensive grid crack pattern in the panel RC slab, which is alike the pattern normally witnessed in a bridge RC slab. Conclusively, the panel RC slab with equivalent BCs behaves identical to the bridge RC slab, and, as a result, it shows more realistic fatigue behaviors observed in the bridge RC slab.

• Structural Engineering and Mechanics
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• 제87권2호
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• pp.173-189
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• 2023

For a given structural geometry, the stiffness and damping parameters of the soil and the dynamic response of the structure may change in the face of an equivalent linear soil behavior caused by a strong earthquake. Therefore, the influence of equivalent linear soil behavior on the impedance functions form and the seismic response of the soil-structure system has been investigated. Through the substructure method, the seismic response of the selected structure was obtained by an analytical formulation based on the dynamic equilibrium of the soil-structure system modeled by an analog model with three degrees of freedom. Also, the dynamic response of the soil-structure system for a nonlinear soil behavior and for the two types of impedance function forms was also analyzed by 2D finite element modeling using ABAQUS software. The numerical results were compared with those of the analytical solution. After the investigation, the effect of soil nonlinearity clearly showed the critical role of soil stiffness loss under strong shaking, which is more complex than the linear elastic soil behavior, where the energy dissipation depends on the seismic motion amplitude and its frequency, the impedance function types, the shear modulus reduction and the damping increase. Excellent agreement between finite element analysis and analytical results has been obtained due to the reasonable representation of the model.

• 한국기계가공학회지
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• 제19권3호
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• pp.77-85
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• 2020

In this study, we proposed a method to replace the solid finite element model of the boiler membrane wall for coal-fired power plants using an equivalent shell model. The application of a bending load to the membrane wall creates greater displacement at both ends of the central portion when compared with the middle when an isotropic elastic constant is used in the shell model. This is inconsistent with the results of the solid model where the central portion is uniformly deformed. Here, we presented a method to determine the orthotropic elastic constants of the shell model in terms of bending stiffness and vibration characteristics to solve this problem. Our analysis of the orthotropic shell model showed that the error ratio was 0.9% for the maximum displacement due to the bending load, 0.3% for the first natural frequency, and 2.5% for the second natural frequency when compared with the solid model. In conclusion, a complicated boiler membrane wall composed of a large number of pipes and fins can be replaced with a simple shell model that shows equivalent bending stiffness and vibration characteristics using our proposed method.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.296-303
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• 2004

In this study, equivalent linear damping and stiffness of a single-degree-of-freedom (SDOF) structure with a rotational friction damper are estimated using the result of experiments and compared with those obtained from non-linear time history analyses. First, the transfer function of the test model is constructed and then the equivalent stiffness and damping are calculated, using the half-power bandwidth (HPB) method. For comparative study, those properties are estimated based on stochastic theory in the time domain. Both equivalent linear systems identified from experiments and numerical analyses correspond well. Further, it is observed that there exists an optimal clamping force on the rotational friction damper from estimated equivalent damping.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.262-265
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• 2007

Metallic sandwich plates constructed of two face sheets and low relative density cores have lightweight characteristics and various static and dynamic load bearing functions. To predict the formability and performance of these structured materials, a computationally efficient FE-analysis method incorporating virtual equivalent projected model has been newly introduced for analysis of metallic sandwich plates. Two dimensional models using the projected shapes of 3D structures have the same equivalent elastic-plastic properties with original geometries including anisotropic stiffness, yield strength and linear hardening function. The projected shapes and virtual properties of the virtual equivalent projected model have been estimated analytically with the same equivalent properties and face buckling strength of 3D pyramidal truss core.