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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Computational Structural Engineering Institute of Korea
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Journal DOI :
The Computational Structural Engineering Institute
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Volume & Issues
Volume 15, Issue 4 - Dec 2002
Volume 15, Issue 3 - Sep 2002
Volume 15, Issue 2 - Jun 2002
Volume 15, Issue 1 - Mar 2002
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The Impact Analysis for Water-Entry of Cylindrical Body
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 1~8
When a body enters waters, its original kinetic energy or momentum is distributed among the body and surrounding water in the form of added mass. Due to the transfer of the energy or momentum, the bode is subjected to the hydrodynamic impact forces and acceleration. This impact behavior can be an important criterion of submersible vehicle launched to the air. In this paper, based on Life-boat model, an approximate method is proposed for the evaluation of the forces and responses of cylindrical rigid bode by water entry impact. The impact forces are calculated by yon Karman's momentum theory and motion responses the body, especially acceleration, are calculated by a numerical integration of the motion equations derived by hydrodynamic force equilibrium. The proposed method is expected to be a simple but efficient tool lot the preliminary design or motion analysis of a body subjected to water entry impact.
The Finite Element Analysis of Foundation Layer by Introducing Interface Element
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 9~20
The purpose of this research is to develop computational procedures for studying nonlinear soil-structure interaction Problems. In orders to study soil-structure interaction behavior, the finite element analysis for the strip footing subjected to both vortical and lateral loads, and foundation layer reinforced with sheet pile are considered, interface elements are used between the footing and the soil to model the interaction behavior The main analyzed results are as follows; 1. For the prediction of settlement and lateral displacement, the result due to interface element was evaluated larger then without interface element. 2. For the determination of ultimate bearing capacity, the value using interface element appeared smaller by 12%, which was safe. 3. The horizontal and vertical displacement of strip footing affected by the presence of interface element.
Application of Response Spectrum Method for Analysis of a Floor System Subjected to Dynamic Loads on Multiple Locations
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 21~32
In general, the response spectrum analysis method (R.S.A) is widely used for seismic analysis of building structure. But, it is not common to apply R.S.A for the analysis of structural vibration caused by dynamic loads of equipments, machines and moving leads, etc. The time history analysis method(T.H.A) for the vibration analysis, compared with R.S.A, is very complex, difficult and time consuming. So the application of R.S.A, that is convenient to calculate maximum responses for structural vibration, is proposed in this study. At first, the procedure for the application of the R.S.A to calculate of the maximum vibration response induced by dynamic load applied on the single point is described. And then, the process, which can save the time and the memory for calculation of the maximum vibration response induced by dynamic loads on the multi-point is proposed, and the maximum structural response caused by moving loads are obtained. Lastly, the accuracy of the proposed method is verified by comparing the results of R.S.A to T.H.A for some example models.
3D Tunnel Modeling by Parametric Representation of Geometry
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 33~42
A method of automatic 3D tunnel modeling is proposed. The proposed method used the parametric representation of geometry and a hierarchical and relational data structure. These two bases provide the generalization and extension for 3D tunnel modeling. Especially, these two fundamentals ion the basis iota representing the characteristics of the tunnel structure for analysis. The constant-curvature characteristic is exploited to generate 3D mesh on the tunnel surface. This is attributed to the advantage that any 2D automatic mesh generation algorithm can be applied to 3D mesh modeling.
Nondestructive Damage Detection in PSC Beams : Frequency-Based Method Versus Mode-Shape-Based Method
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 43~58
A methodology to nondestructively locate and estimate size of damage in beam-type structures using a few natural frequencies or a few mode shapes is presented. A damage-localization algorithm to locate damage from changes in natural frequencies and a damage-sizing algorithm to estimate crack-size from natural frequency perturbation are outlined. A damage index algorithm to localize and estimate severity of damage from monitoring changes in mode shapes is outlined. The frequency-based method and the mode-shape-based method are evaluated for several damage scenarios by locating and sizing damage in PS concrete beams lot which a few natural frequencies and mode shapes are generated from finite element models. The result of the analyses indicates that the two methods correctly localize and closely estimate the size of the crack simulated in the test beam.
Random Vibration and Harmonic Response Analyses of Upper Guide Structure Assembly to Flow Induced Loads
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 59~68
The cylindrical Upper Guide Structure assembly of the reactor intervals wish the Core Support Barrel and the Inner Barrel Assembly is subjected to flow induced loads horizontally which include random pressure fluctuation due to turbulent flow and pump pulsation pressures. The purpose of this papers is to perform random vibration and harmonic response analyses fort flow induced loads. The dynamic response characteristics due to random turbulence and pump pulsation loads were evaluated using the lumped mass beam model. Especially the model considered the annulus effects due to water gaps existing between cylindrical structures such as the Upper Guide Structure Barrel, the Core Support Barrel, and the Inner Barrel Assembly. The effect of the Inner Barrel Assembly inside the Upper Guide Structure assembly was studied. The peak dynamic responses lot each loading condition due to the addition of IBA were affected by the natural frequencies of the structures. Therefore the peak dynamic responses of the structures should be conservatively obtained from evaluation of dynamic analysis for various loading conditions.
Cracking Analysis of RC Tension Members Using Polynomial Strain Distribution Function
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 69~84
In this papers, an analytical model which can simulate the post-cracking behavior and tension stiffening effect in a reinforced concrete(RC) tension member is proposed. Unlike the classical approaches using the bond stress-slip relationship or the assumed bond stress distribution, the tension stiffening effect at post-cracking stage is quantified on the basis of polynomial strain distribution functions of steel and concrete, and its contribution is implemented into the reinforcing steel. The introduced model can be effectively used in constructing the stress-strain curve of concrete at post-cracking stage, and the loads carried by concrete and reinforcing steel along the member axis can be directly evaluated on the basis of the introduced model. In advance, the prediction of cracking loads and elongations of reinforced steel using the introduced model shows good agreement with results from the previous analytical studies and experimental data.
An Adaptive Analysis in the Element-free Galerkin Method Using Bubble Meshing Technique
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 85~94
In this study an adaptive node generation procedure in the Element-free Galerkin (EFG) method using bubble-meshing technique is Proposed. Since we construct the initial configuration of nodes by subdivision of background cell, abrupt changes of inter-nodal distance between higher and lower error regions are unavoidable. This unpreferable nodal spacing induces additional errors. To obtain the smooth nodal configuration the nodal configurations are regenerated by bubble-meshing technique. This bubble meshing technique was originally developed to generate a set of well-shaped triangles and tetrahedra. In odder to evaluate the effect of abrupt changes of nodal spacing, one-dimensional problems with various nodal configurations mere investigated. To demonstrate the performance of proposed scheme, the sequences of making optimal nodal configuration with bubble meshing technique are investigated for several problems.
Nonlinear Moment-Curvature Relations and Numerical Structural Analysis of High-Strength PSC Flexural Members
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 95~104
A methods to calculate non-linear moment-curvature relations of high-strength PSC flexural members for numerical analysis has been proposed. The moment-curvature relations were calculated with assumptions of design codes and by the layer method. The results of the proposed procedures for moment-curvature relations and numerical analysis were compared with those of pre-existing tests. The absorption energy rate of the design codes was about 30% larger than that of the layer method. The ultimate load and the external work of the layer method were 90% and 85% of those of tests, respectively The ultimate load of the strength design method was 97% of that of tests, but the external work was over-estimated with 122%. The ultimate load and external work by the proposed equation of the CEB-FIP Model Code were 113% and 173% of those of tests, respectively. It show that the use of ultimate strain of 0.0035 should be over-estimated for high-strength concrete. The procedure of non-linear numerical analysis of this research could be stably simulated the behavior of concrete flexural members until the ultimate state, and calculate results of the load-deflection relation and cracking pattern were very similar with those of tests.
Ultimate Resisting Capacity of RC Columns Considering P-
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 105~116
In this paper, an analytical model to predict the resisting capacity of slender RC columns is introduced. Material and geometric nonlinearities are taken into account, and the layer approach is adopted to simulate the different material properties across the sectional depth. On the basis of the obtained numerical analysis results, an improved design equation as a function of concrete strength, slenderness ratio, steel ratio and eccentricity for slender RC columns, which can be used effectively in the preliminary design stage, is introduced. Finally, P-M interaction diagrams constructed by the introduced equation are compared with the ACI method with the objective of establishing the relative efficiencies of the introduced equation.
3-D Frame Design Using Second-Order Plastic-Hinge Analysis Accounting for Lateral Torsional Buckling
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 117~126
In this paper, 3-D fame design using second-orders plastic-hinge analysis accounting for lateral torsional buckling is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional second-order plastic-hinge analyses, which do not consider the degradation of the flexural strength caused by lateral torsional buckling, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, second-order effect, and geometric imperfections are presented. In this study, a model consisting of the unbraced length and cross-section shape is used to account for lateral torsional buckling. The proposed analysis is verified by the comparison of the LRFD results. A case studs shows that lateral torsional buckling is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient reliable tool ready to be implemented into design practice.
Improved Damage Assessment Algorithm Using Limited Mode Shapes
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 127~136
This papers presents a practical damage detection algorithm based on damage index method that accurately assesses both the location and severity of the localized detriment in a bridge structure using only limited mode shapes. In the algorithm, the ratio of the modal vector sensitivity of an undamaged structure to that of a damaged structure is used as an indicator of damage. However, a difficulty arises when the damaged element is located at a node of mode where the amplitude of medal vector is close to zero, leading the singularity of the ratio (i.e., division-by-zero). This singularity problem is overcome by introducing a parameter denoted a sensitivity filter, a function of mode shape of the structure, in modal vector sensitivity. Using this concept, an improvement can be considerably achieved in the estimation of both degree of severity and location of damage. To verify the proposed algorithm, its numerical implementations are conducted for a simply supported beam and a 2-span continuous beam.
Prediction of the Loading Characteristics by Neural Networks Using Structural Analysis of Composite Cylindrical Shells
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 137~146
The predictions of the loading characteristics was performed by the neural networks which use the results through structural analysis. The momentum backperpagtion which can be modified the teaming rate and momentum coefficient, was developed. Input patterns of the neural networks are the 9 strains which positioned at the side of the shell and output layers is the loading characteristics. Hidden layers were increased from 1 layers to 3 layers. Developed program which were trained by 9 strains predict the loading characteristics under 0.5%. Inverse engineering can be applicable to the composite laminated cylindrical shells with developed neural networks.
Dynamic Suppression Effects of Liquid Container to the Baffle Number and Hole Diameter
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 147~154
The dynamic load caused by sloshing of internal fluid severely affects the structural and control stabilities of cylindrical liquid containers accelerating vertically. If the sloshing frequency of fluid is near the frequency of control system or the tank structure, large dynamic force and moment act on launching vehicles. For the suppression of such dynamic effects, generally flexible ring-type baffles are employed. In this paper, we perform the numerical analysis to evaluate the dynamic suppression effects of baffle. The parametric analysis is performed with respect to the baffle inner-hole diameter and two different baffle spacing types : equal spacing with respect to the tank and one with respect to the fluid height. The ALE (arbitrary Lagrangin-Eulerian) numerical method is adopted for the accurate and effective simulation of the hydrodynamic interaction between fluid and elastic structure.
Optimum Design of Journal Bearings considering the Wear Rate
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 155~164
The journal bearings use in machine parts which move relative to each other and those reduce friction and wear of journals. The journal bearings are designed to operate in the hydyodynamic lubrication regime, but elastohydrodynamic lubrication nay occur if the pressures are too high or the running speeds are too low at machine elements. It is the phenomenon that the lubricant film is broken and some parts of surfaces are in rolling contact, so that wear will increase in mixed lubrication regime. The purpose of this study is to minimize the wear rate of journal bearings for extending machine life. The wear mate in mixed lubricated regime is selected as objective function because most of wear of the journal bearings develops in elastohydrodynamic lubrication. The journal bearings we represented by a bearing radius, shaft radius, and bearing width, but the bearing radius only is selected as design variables due to a bearing radius has an influence on friction loss, stability limit velocity, and film parameter, which are used as constraints. For numerical calculation, PLBA, that is a class of the RQP algorithm, is used.
Influence of Column Base Rigidity on Behavior of Steel Buildings
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 165~172
Generally, the steel rigid frame has been analyzed using finite element analysis tools. While many efforts have been poured into the understanding and accurate prediction for the nonlinear behavior of the columns and beam-columns connections, the base of the columns are modeled as simply hinged or fixed. However, the base of the steel columns practically is neither fixed not hinged. It behaves as semi-rigid. In this paper, the supports of the columns we modeled as semi-rigid and the importance of such approach in moment-resisting columns is evaluated. Two typical buildings designed by the US specification are modeled and analyzed by the finite element based on stiffness method and flexibility method. The column bases of three-story buildings are modeled as rotational springs with a varying degree of stiffness and strength that simulates the semi-rigidity of the base. Depending on the degree of stiffness and strength, the semi-rigidity varies from the hinged to the fixed. Buildings with semi-rigid column bases behaves similarly to the building with fixed bases. It has been numerically observed through the pushover and nonlinear time history analyses that the decrease of the stiffness of the column base induces the rotational demand on the int air beams. an increase of rotation demands on the first store connections and lead to a soft-story mechanists Due often to the construction and environmental effects, undesired reduction of column base stiffness may cause an increase of rotation demands on the first store connections and lead to a soft-story mechanism. support, steel moment resisting frame, frame analysis
Modeling of Walking Loads for Floor Vibration Analysis
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 173~188
In General, the measured loads and load-time function suggested by Bachmann iota walking are used for vibration analysis of structures subjected to footstep loads. It is not easy to measure walking loads because they we influenced by various parameters. Therefore, it is needed to model the walking loads that can be applied to structure analysis. Parameter study is used for the walking loads having various walking frequency for vibration analysis of structures under walking loads. In this study, walking loads were measured directly by using a force plate within two load cells, and the parameters of the walking loads were analyzed. The measured walking loads are decomposed into harmonic loads by using the Fouler series. Functional relationship between the walking frequency and the Fourier coefficients can be derived from the coefficients of harmonic loads obtained by the decomposition process, and the walking loads were formulated. It is possible to apply the venerated walking loads easily or conveniently by the proposed equation to the analysis of a structure subjected to walking loads.
Free Vibration of Horizontally Curved Beams with Clothoid Transient Curve
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 1, 2002, Pages 189~195
This paper deals with the free vibration of horizontally curved beams with transition currie. Based on the dynamic equilibrium equations of a curved beam element subjected to the stress resultants and inertia forces, the governing differential equations are derived for the out-of-plane vibration of curved beam with variable curvature. These equations are applied to the beam having transition curve in which the clothiod curve is chosen in this study. The differential equations are solved by the numerical methods lot calculating the natural frequencies and mode shapes. For verifying theories developed herein, the frequency parameters obtained from this studs and ADINA are compared with each other. As the numerical results, the various parametric studies effecting on natural frequencies are investigated and those results are presented in tables and figures.