• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.149-156
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• 2011

In this paper, a methodology is proposed to improve the stress prediction of plates via Saint Venant's principle. According to Saint Venant's principle, the stress resultants can be used to describe linear elastic problems. Many engineering problems have been analyzed by Euler-Bernoulli beam(E-B) and/or Kirchhoff-Love(K-L) plate models. These models are asymptotically correct, and therefore, their accuracy is mathematically guaranteed for thin plates or slender beams. By post-processing their solutions, one can improve the stresses and displacements via Saint Venant's principle. The improved in-plane and out-of-plane displacements are obtained by adding the perturbed deflection and integrating the transverse shear strains. The perturbed deflection is calculated by applying the equivalence of stress resultants before and after post-processing(or Saint Venant's principle). Accuracy and efficiency of the proposed methodology is verified by comparing the solutions obtained with the elasticity solutions for orthotropic beams.

• Bulletin of the Society of Naval Architects of Korea
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• v.13 no.1
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• pp.1-9
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• 1976

Using the computer programs for calculation of natural vibrations of ship's hull developed by the authors et al., an investigation into influences of various parameters on the accuracy of calculation was done through example calculations of a 30,000 DWT petroleum products carrier M/S Sweet Brier built by Korea Shipbuilding and Engineering Corporation. The methodical principles employed for the computer program development are as follows; (a) the ship system is reduced to an equivalent discrete elements system conforming to Myklestad-Prohl model, (b) the problem formulation is of transfer matrix method, and (c) to obtain solutions an extended $G\ddot{u}mbel's$ initial value method is introduced. The scope of the investigation is influences of number of discrete elements, choice of significant system parameters such as rotary inertia, bending stiffness and shear stiffness, and simplification of distributions of added mass and stiffness as trapezoidal ones referred to those of midship section on the calculation accuracy. From the investigation the followings are found out; (1) To obtain good results for the modes up to the seven-noded thirty or more divisions of the hull is desirable. For fundamental mode fifteen divisions may give fairly good results. (2) The influence of rotary inertia is negligibly small at least for the modes up to the 5- or 6- noded. (3) In the case of assuming either bending modes or shear modes the calculation results in considerably higher frequencies as compared with those based on Timoshenko beam theory. However, the calculation base on the slender beam theory surprisingly gives frequencies within 10% error for fundamental modes. (4) It is proved that to simplify distributions of added mass and stiffness as trapezoidal ones referred to those of midship section is a promising approach for the prediction of natural frequencies at preliminary design stage; provided good accumulation of data from similar type ships, we may expect to obtain natural frequencies within 5% error.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.572-582
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• 1989

Elastic deformations of an infinitely long strip and a beam loaded by uniform pressure upon their upper surfaces, with the fixed-free end dondition, are considered within the range of small strains. All local governing equations are satisfied up to first order in strains, and to take into account the higher order terms neglected in the local governing equations, the overall equilibrium is imposed exactly up to the leading order. The success of the approach relies upon the semi-inverse method and the decomposition of deformations in which the classical linear theory guides the solution. The solution bridges the gap between the two extremes-the classical solutions valid only for infinitesimal deformations and the solutions form the technical theories for deformations with large rotations. The solutions may be used to confirm the technical theories and to verify numerical solutions obtained from finite element analysis.

• Journal of Industrial Technology
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• v.4
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• pp.29-35
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• 1984

Buckling is a significant behavior to be considered whenever we design steel structures. In the case of H-shape beams, the lateral buckling occured by bending moment must be considered. Because of the lateral buckling of H-shape beams, the bending strength of the beams are determined by the lateral buckling stress instead of the allowable bending stress. Lateral buckling stress equation, consisting of two terms, i. e. ${\sigma}_{cr}({\nu},{\omega})={\sqrt{[{\sigma}_{cr}({\nu})]^2+[{\sigma}_{cr}({\omega})]^2}}$ has been using, but for the practical purpose of use the following equations are using two, i. e. ${\sigma}_{cr}({\nu})={\frac{0.65E}{{\ell}_h/A_f}}$, ${\sigma}_{cr}({\omega})={\frac{{\pi}^2E}{({\ell}_b/i_b)^2}}$. When we use the above equations, the results are different according to the shape of beam section, and they a re rather complex. In this study lateral buckling stress equation is derived, and the proposed formula$({\sigma}_{cr}(t))$ is compared with above mentioned two basic and practical equations. To verify the proposed formula experimentaly, 16H-shape beams which have different slender ratios arc tested by applying pure bending momet. Through the experiments the buckling behavior of H-shape beams is clarified, and the results shows that the proposed formula$({\sigma}_{cr}(t))$ is accurate enough for practical purpose.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.609-614
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• 2001

This paper is to explain reasonable shear behavior that can apply usually to reinforced concrete beams on the basic concepts of existent analysis and experimental research information. This study is succession $paper^{2) 3) 4) 5)}$ of treatise announced in existing and main control variable of reinforced concrete beams with stirrups used internal force state factor($\alpha$). Shear failure of reinforced concrete beams with stirrups is Influenced greatly because of the actual geometrical shape(a/d) of the concrete and flexural reinforcement steel ratio, stirrup reinforcement ratio and concrete compression strength, size effect etc. Therefore, shear behavior of reinforced concrete beams with stirrups that flexural crack is happened can be explained easily through proper extent proposal of internal force state factor($\alpha$) that express internal force state flowing. Use existent variable truss model by analysis model to explain arch action. Also, wish to compose each failure factors and correlation with internal force state factor by function, and when diagonal cracks happens, internal force state factor($\alpha$) study whether shear stress and some effect are.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.38-44
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• 2007

The structural response characteristics of Tension leg platforms(TLPs) in waves are examined for presenting the basic data for structural design of TLPs. The numerical approach is based on a combination of the three dimensional source distribution method and the structural response analysis method, in which the superstructure of TLP is assumed to be flexible instead of rigid. Hydrodynamic and hydrostatic forces on the submerged surface of a TLP have been accurately calculated by excluding the assumption of the slender body theory. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in structural analysis. The mooring forces are estimated as the sum of pretension of tendons and variational tension due to longitudinal displacements. Stiffness matrices of elastic beam elements connecting nodes are formulated by ordinary method of three dimensional frame analysis. The equation of motion about the whole structure is obtained by the sum of forces and moments acting on each nodes.

• Structural Engineering and Mechanics
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• v.26 no.4
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• pp.441-457
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• 2007

A new numerical model based on the spline finite strip method is presented here for the analysis of buckling of built-up columns with and without end stay plates. The channels are modelled with spline finite strips while the connecting elements are represented by a 3D beam finite element, for which the stiffness matrix is modified in order to ensure complete compatibility with the strips. This numerical model has the advantage to give all possible failure modes of built-up columns for different boundary conditions. The end stay plates are also taken into account in this method. To validate the model a comparative study was carried out. First, a general procedure was chosen and adopted. For each numerical analysis, the lowest buckling loads and modes were calculated. The basic or "pure" buckling modes were identified and their critical loads were compared with solutions obtained using analytical methods and/or other numerical methods. The results showed that the proposed numerical model can be used in practice to study the elastic buckling of built-up columns. This model is considered accurate and efficient for the local buckling of short columns and global buckling for slender columns.

• International Journal of High-Rise Buildings
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• v.3 no.3
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• pp.215-221
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• 2014

Ultra-high strength concrete and high tensile steel are becoming very attractive materials for high-rise buildings because of the need to reduce member size and structural self-weight. However, limited test data and design guidelines are available to support the applications of high strength materials for building constructions. This paper presents significant findings from comprehensive experimental investigations on the behaviour of tubular columns in-filled with ultra-high strength concrete at ambient and elevated temperatures. A series of tests was conducted to investigate the basic mechanical properties of the high strength materials, and structural behaviour of stub columns under concentric compression, beams under moment and slender beam-columns under concentric and eccentric compression. High tensile steel with yield strength up to 780 MPa and ultra-high strength concrete with compressive cylinder strength up to 180 MPa were used to construct the test specimens. The test results were compared with the predictions using a modified Eurocode 4 approach. In addition, more than 2000 test data samples collected from literature on concrete filled steel tubes with normal and high strength materials were also analysed to formulate the design guide for implementation in practice.

• Steel and Composite Structures
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• v.8 no.2
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• pp.159-178
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• 2008

An analytical procedure is presented for the determination of the buckling load and the buckling temperature of a straight, slender, geometrically perfect, axially loaded, translationally and rotationally restrained steel column exposed to fire. The exact kinematical equations of the column are considered, but the shear strain is neglected. The linearized stability theory is employed in the buckling analysis. Behaviour of steel at the elevated temperature is assumed in accordance with the European standard EC 3. Theoretical findings are applied in the parametric analysis of restrained columns. It is found that the buckling length factor decreases with temperature and depends both on the material model and stiffnesses of rotational and translational restraints. This is in disagreement with the buckling length for intermediate storeys of braced frames proposed by EC 3, where it is assumed to be temperature independent. The present analysis indicates that this is a reasonable approximation only for rather stiff rotational springs.

• Structural Engineering and Mechanics
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• v.15 no.5
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• pp.495-511
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• 2003

New material applications and transparency are desired by contemporary architects. Its superb transparency and high strength make glass a very suitable building material -in spite of its brittleness- even for primary load bearing structures. Currently we will focus on load bearing glass beams, subjected to different loading types. Since glass beams have a very slender, rectangular cross section, they are sensitive to lateral torsional buckling. Glass beams fail under a critical buckling load at stresses that lie far below the theoretical simple bending strength, due to the complex combination of torsion and out-of-plane bending, which characterises the instability phenomenon. The critical load can be increased considerably by preventing the upper rim from moving out of the beam's plane. Different boundary conditions are examined for different loading types. The load carrying capacity of glass beams can be increased three times and more using relatively simple, cheap lateral restraints.