• Steel and Composite Structures
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• v.42 no.2
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• pp.257-264
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• 2022

The analysis of the progressive collapse resistance of structures is a well-known issue among structural engineers. Large-span reticulated dome structures are commonly utilized in large public buildings, necessitating research into their progressive collapse resistance to assure user safety. The most significant part of improving the structural resilience of reticulated domes is to evaluate their key elements. Based on a stiffness-based evaluation approach, this work offers a calculating procedure for element importance coefficient. For both original and damaged structures, evaluations are carried out using the global stiffness matrix and the determinant. The Kiewitt, Schwedler, and Sunflower reticulated domes are investigated to explore the distribution characteristic of element importance coefficients in the single-layer dome structures. Moreover, the influences of the load levels, load distributions, geometric parameters and topological features are also discussed. The results can be regarded as the initial concept design reference for single-layer reticulated domes.

• Smart Structures and Systems
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• v.10 no.4_5
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• pp.471-483
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• 2012

In this paper, the structural health monitoring (SHM) benchmark problem of the Canton tower is studied. Based on the field monitoring data from the 20 accelerometers deployed on the tower, some modal frequencies and mode shapes at measured degrees of freedom of the tower are identified. Then, these identified incomplete modal data are used to update the reduced finite element (FE) model of the tower by a novel algorithm. The proposed algorithm avoids the problem of subjective selection of updated parameters and directly updates model stiffness matrix without model reduction or modal expansion approach. Only the eigenvalues and eigenvectors of the normal finite element models corresponding to the measured modes are needed in the computation procedures. The updated model not only possesses the measured modal frequencies and mode shapes but also preserves the modal frequencies and modes shapes in their normal values for the unobserved modes. Updating results including the natural frequencies and mode shapes are compared with the experimental ones to evaluate the proposed algorithm. Also, dynamic responses estimated from the updated FE model using remote senor locations are compared with the measurement ones to validate the convergence of the updated model.

• Steel and Composite Structures
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• v.45 no.3
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• pp.331-348
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• 2022

The main goal of this article is to develop the finite element formulation based on the nonlocal strain gradient and the refined higher-order deformation theory employing a new function f(z) to investigate the static bending and free vibration of functionally graded porous (FGP) nanobeams. The proposed model considers the simultaneous effects of two parameters: nonlocal and strain gradient coefficients. The nanobeam is made by FGP material that exists in un-even and logarithmic-uneven distribution. The governing equation of the nanobeam is established based on Hamilton's principle. The authors use a 2-node beam element, each node with 8 degrees of freedom (DOFs) approximated by the C¹ and C² continuous Hermit functions to obtain the elemental stiffness matrix and mass matrix. The accuracy of the proposed model is tested by comparison with the results of reputable published works. From here, the influences of the parameters: nonlocal elasticity, strain gradient, porosity, and boundary conditions are studied.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.437-449
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• 1998

In order that the steel girder and the concrete slab act as a composite structure, the connectors must have adequate strength and stiffness. If there are no horizontal or vertical separations at the interface, the connectors are described as rigid, and complete interaction can be said to exist under these idealized circumstances. However, all connectors are flexible to some extent, and therefore incomplete interaction always exists. This paper presents a practical structural analysis of composite girders with incomplete interaction by three methods. One is the stiffness matrix method derived from the general solutions of differential equation, another is the finite element analysis that alternate method of solution treats the structure as a frame and defines the spring as an additional member, and the other is the finite element analysis using principle of virtual work. The deflection characteristic of composite girder is investigated using these three methods. Also, this paper propose a simplified procedure of estimating a degree of imperfection for a composite girder with incomplete interaction using the sectional properties of girder and spring constants of shear connectors.

• Structural Engineering and Mechanics
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• v.14 no.6
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• pp.699-712
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• 2002

In this paper, a new quadrilateral 5-node non-conforming membrane element with drilling degrees of freedom is presented. The main advantage of these elements is the relatively small number of integration points to evaluate a stiffness matrix comparing to the existing transition membrane elements (CLM elements). Moreover, the presented elements pass the patch test by virtue of the Direct Modification Method incorporated into the element formulation. The presented 5-node elements are proved to be very efficient when used in the local mesh refinement for the in-plane structures which have stress concentrations. And some numerical studies also show the good performance of the new element developed in this study.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.17-27
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• 1995

For the post-buckling and elasto-plastic analysis of shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors in the iteration process and evaluating the total Green-Lagrange stain corresponding U total displacements. In the calculation of the stiffness matrix, the element formulation takes into account the effect of finite rotation increments by retaining second order rotation terms in the incremental displacement field. The selective or reduced integration scheme using the heterosis element is applied in order to overcome both shear locking phenomena and the zero energy mode. The load/displacement incremental scheme is adopted for geometric non-linear F .E. analysis. Based on such methodology, the computer program is developed and numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references's results.

• Structural Engineering and Mechanics
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• v.21 no.5
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• pp.519-537
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• 2005

A new generalized Bernoulli/Timoshenko beam-column element on a two-parameter elastic foundation is presented herein. This element is based on the exact solution of the differential equation which describes the deflection of the axially loaded beam resting on a two-parameter elastic foundation, and can take into account shear deformations, semi - rigid connections, and rigid offsets. The equations of equilibrium are formulated for the deformed configuration, so as to account for axial force effects. Apart from the stiffness matrix, load vectors for uniform load and non-uniform temperature variation are also formulated. The efficiency and usefulness of the new element in reinforced concrete or steel structures analysis is demonstrated by two examples.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1672-1677
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• 2003

In this paper, the spectral element model is derived for the vibration and stability analyses of an axially moving viscoelastic beam subjected to axial tension. The viscoelastic material is represented by using a one-dimensional constitutive equation of hereditary integral type. The accuracy of the present spectral element model is first verified by comparing the eigenvalues obtained by the present spectral element model-based SEM with those obtained by the exact theory and the conventional FEM. The effects of viscoelasticity on the vibration and stability of an example moving viscoelastic beam are numerically investigated.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.10
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• pp.379-383
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• 1985

A method employing infinite elements is described for the magnetic field computations of the magnetic circuits with permanent magnet. The system stiffness matrix is derived by a variational approach, while the interfacial boundary conditions between the finite element regions and the infinite element regions are dealt with using collocation method. The proposed method is applied to a simple linear problems, and the numerical results are compared with those of the standard finite element method and the analytic solutions. It is observed that the proposed method gives more accurate results than those of the standard finite element method under the same computing efforts.

• Journal of Advanced Marine Engineering and Technology
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• v.2 no.1
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• pp.3-14
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• 1978

The authors have developed a calculating method of propeller shaft alignment by the finite element method. The propeller shaft is divided into finite elements which can be treated as uniform section bars. For each element, the nodal point equation is derived from the stiffness matrix, the external force vector and the section force vector. Then the overall nodal point equation is derived from the element nodal point equation. The deflection, offset, bending moment and shearing force of each nodal point are calculated from the overall nodal point equation by the digital computer. Reactions and deflections of supporting points of straight shaft are calculated and also the reaction influence number is derived. With the reaction influence number the optimum alignment condition that satisfies all conditions is calculated by the simplex method of linear programming. All results of calculation are compared with those of Det norske Veritas, which has developed a computor program based on the three-moment theorem of the strength of materials. The authors finite element method has shown good results and will be used effectively to design the propeller shaft alignment.