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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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Seismic Response of Structures with Buckling-Restrained Braces
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 197~207
Energy dissipation capacity and earthquake responses of steel structures installed with unbonded braces(UB) were investigated. Parametric studies were performed for a single-degree-of-freedom structure under harmonic loads, and optimum yield strength of unbonded braces were derived. Nonlinear dynamic time history analyses were carried out to investigate the seismic response of multi-story model structures with UB having various size and strength. Various techniques were applied to determine proper story-wise distribution of UB in multi-story structures. The analysis results show that the maximum displacements of structures generally decrease as the stiffness of UB increases. However for some natural frequencies and seismic loads the maximum displacement and accumulated damage increases as the stiffness of UB increases.
Modal Analysis of the Vector Triggering Random Decrement Function
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 209~218
The Vector Random Decrement technique has been developed as an efficient method for transforming ambient responses into free decays of linear structures. It is shown that the VRD functions nay contain as much information about the modes as the really measured free decay responses. In this paper, the theory of the VRD technique is extended by applying the concept of the mode shape ratio into the Ibrahim Time Domain modal parameter identification algorithm. The VRD function is not shifted in the correction procedures for constant time shifts of the proposed VRD technique. Thus, a number of points equal to the largest of the time shifts used in the vector triggering condition are not deleted. In the VRD functions, any influence of the input to the system is averaged out. The proposed technique is compared with the traditional VRD technique by assessment of the modal parameters. The applicability of the VRD technique has been justified through a simulation study and a study of the response of a laboratory beam model subject to ambient loads.
Structural Response of Underground LNG Storage Tank (Parameter Study for Design Conditions)
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 219~235
This paper deals with parametric studies of the structural response of underground LNG storage tanks according to change in design conditions. In the design of underground LNG storage tank, it is requited to determine the optimal tank shape and dimension to represent a more improved structural behavior under many loading conditions and load combinations. Consequently, main factors which affect to the structural response of LNG storage tanks from planning and design up to maintenance, are investigated, and the differences in structural behavior due to those factors are analyzed. On the basis of the obtained results item parametric studies, a guideline for a more reasonable design is introduced.
Efficient Analysis of Shear Walls with Openings
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 237~249
The wall system that is composed only of reinforced concrete walls and slabs is adopted on many high-rise apartment buildings recently constructed. In the apartment buildings, a shear wall may have one or mote openings for functional reasons. Many researches on the analysis of shear wall with openings were performed. But, some restrictions prevent those research results being applied to practical analysis and design procedure. It is necessary to use subdivided finite elements lot accurate analysis of the wall system with openings. But it would cost tremendous amount of analysis time and computer memory if the entire building structure is subdivided into a finer mesh. An efficient analysis method which can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super element, matrix condensation technique and fictitious beam technique. Analyses of example structures having various types of openings were performed to verify the efficiency of proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.
Control of Prestressing Forces in a Splicing Method using the Partial Post-tensioning and Releasing Procedure
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 251~259
A new splicing technique by the secondary moment which is intentionally induced by the tensioning effect of continuous tendons and the releasing effect of temporary beam tendons was developed. The tensioning and releasing works are essential and the decisions of the magnitude and order about them may be important engineering problems in this technique. In this paper, it was studied lot the practically optimum procedure of the tensioning and releasing works. As the result, it is concluded that the gradual progress through the three stages is reasonable for the procedure and the tensioning work have to precede the releasing work. Additionally, the magnitude of preceding tensioning force should be obtained by the sensitivity analysis and the minimum limit is more critical than the minimum limit.
System for Preliminary Structural Design using Multi-Level Neural Networks
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 261~270
The use of ANN is appropriate to computerize the information and knowledge used in the preliminary design stage where it lacks of formality of representation of designers' experience and intuition. Considering that there exists very little design information in preliminary design stage to start with, the ANN model for this stage must be designed to have input much less than output. However, this situation usually causes various problems such as in teaming time, convergence and reliability of solutions. To address this problem, this paper proposes multi-level neural networks lot progressive structural design considering that all the design information can not be obtained at a time but we growing gradually. The use of multi-level networks developed in this paper has been proved its validity by applying it to the preliminary design of cable-stayed bridges.
Lateral Drift Control and Resizing Technique for Tall Buildings using Lateral-Stiffness Influence Matrix
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 271~279
This study develops the module to find the lateral stiffness influence matrix of each story and performs the displacement sensitivity analysis by virtual load method for the efficiency of optimal design using lateral stiffness influence matrix. Also, resizing technique based on the estimated lateral stiffness increment factors is developed to apply directly the results of optimal design. To this end, resizing technique is divided into the continuous and discrete section design methods. And then the relationships between section properties and section size are established. Specifically, an initial design under strength constraints is first performed, and then the lateral load resistant system is designed to control lateral displacements yet exceeding the drift criteria. Two types of 45-story three dimensional structures we presented to illustrate the features of the lateral drift control and resizing technique for tall buildings proposed in this study.
Development of DCOC Algorithm Considering the Variation of Effective Depth in the Optimum Design of PRC Continuous Beam
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 281~291
This paper describes the minimum cost design of prestressed reinforced concrete (PRC) hem with rectangular section. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non prestressing steel, and formwork is minimized. The design constraints include limits on the minimum deflection, flexural and shear strengths, in addition to ductility requirements, and upper-Lower bounds on design variables as stipulated by the specification. The optimization is carried out using the methods based on discretized continuum-type optimality criteria(DCOC). Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables - effective depth, eccentricity of prestressing steel and non prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. In this paper the effective depth is considered to be freely-varying and one uniform for the entire multispan beam respectively. Also the maximum eccentricity of prestressing force is considered in every span. In order to show the applicability and efficiency of the derived algorithm, several numerical examples of PRC continuous beams are solved.
Efficient Vibration Analysis of Stadium Stands
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 293~303
Recently, the use of the high strength materials and development of construction techniques have resulted in more flexible and longer spanning in the stadium systems. So the natural frequency of stadium structures are became low. Stadium stand could be led to significant dynamic response as like resonance due to spectator rhythmical activities. The accurate analysis of dynamic behavior of stadium systems and the precise investigation of the dynamic loads on stadium structures are demanded for effective design. It is desirable to apply measured dynamic loads created by spectator activities because these dynamic loads are not easy to express numerical formula. As the floor mesh of stadium stand is refined, the number of divided elements increases in numerical analysis. the rise of the number of elements makes the numbers of nodal points increased and numerous computer memory required. So it is difficult to analysis refine full model of stadium structures by using the commercial programs. In this study, the various dynamic loads induced by spectator movements are measured and analyzed. And a new modeling method that reduce the nodal points are introduced. Vibration analysis of stadium stands is executed to inspect accuracy and efficiency of proposed method in this paper.
A Study on Improvement of Genetic Algorithm Operation Using the Restarting Strategy
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 305~313
The genetic algorithm(GA), an optimization technique based on the theory of natural selection, has proven to be relatively robust means to search for global optimum. It is converged near to the global optimum point without auxiliary information such as differentiation of function. When studying some optimization problems with continuous variables, it was found that premature saturation was reached that is no further improvement in the object function could be found over a set of iterations. Also, the general GA oscillates in the region of the new global optimum point so that the speed of convergence is decreased. This paper is to propose the concept of restarting and elitist preserving strategy as a measure to overcome this difficulty. Some benchmark examples are studied involving 3-bar truss and cantilever beam with plane stress elements. The modifications to GA improve the speed of convergence.
Discrete Optimum Design of Steel Framed Structures Subjected to Deformed of Panel Zone
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 315~327
The main objective of this study is to develop an discrete optimization algorithm of plane steel frames with rigid using second-order-elastic-plastic hinge analysis which is considering panel zone. Conventional analyses of steel frame are usually tarried out without considering the effect of panel zone deformation on frame behavior The validity of this model is established by comparison without panel zone on joint models is analyzed numerically to demonstrate the importance of using realistic models in steel frame analysis. The objective function is taken as Weight of steel frames and the constraints we formulated based on AISC-LRFD(1994). The validity of the developed algorithm we demonstrate by comparing the result with those of SAP2000. The result of the study indicates that the optimal design algorithm considering of panel zone behavior more economic design than simple steel frame design methods.
Design of Viscoelastic Dampers to Meet Performance Objectives
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 329~339
This research presents a systematic design procedure for supplemental viscoelastic dampers required to satisfy the given performance objectives using capacity spectrum method. To obtain required damper size, the amount of supplemental damping was computed from effective damping minus equivalent damping and inherent damping of structure. In the case of viscoelastic damper, iterative procedure is required because of the inherent stiffness of the damper. To verify the design method proposed in this study, parametric studies were performed for single degree of freedom systems with design variables. The method was also applied to a 10-story steel framed structure and the earthquake responses were obtained. According to time history analysis result the controlled displacements turned out to be close to the target displacement regardless of the design parameters.
Application of Modeling of Electromagnetic Wave Propagation for Thickness Determination Using Finite Difference-Time Domain
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 341~349
The radar method is becoming one of the major nondestructive testing(NDT) techniques lot concrete structures. Numerical modeling of electromagnetic wane is needed to analyze radar measurement results. Finite difference-time domain(FD-TD) method can be used to simulate electromagnetic wave propagation through concrete specimens. Five concrete specimens with different thickness are modeled in 3-dimension. Radar modeling results compare measurement results to find backface of the concrete specimens and measure thickness of the concrete specimens.
Efficient Three Dimensional Analysis of High-Rise Shear Wall Building with Openings
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 351~365
The box system that is composed only of reinforced concrete walls and slabs we adopted on many high-rise apartment buildings recently constructed in Korea. And the framed structure with shear wall core that can effectively resist horizontal forces is frequently adopted for the structural system for high-rise building structures. In these structures, a shear wall may have one or more openings for functional reasons. It is necessary to use subdivided finite elements for accurate analysis of the shear wall with openings. But it would take significant amount of computational time and memory if the entire building structure is subdivided into a finer mesh. An efficient analysis method that can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super element, substructure, matrix condensation technique and fictitious beam technique. Three-dimensional analyses of the box system and the framed structure with shear wall core having various types of openings were performed to verify the efficiency of the proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.
Lowest Symmetrical and Antisymmetrical Natural Frequencies of Shallow Arches on Two-Parameter Elastic Foundations
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 367~377
This paper deals with the free vibrations of shallow arches resting on elastic foundations. Foundations we assumed to follow the hypothesis proposed by Pasternak. The governing differential equation is derived for the in-plane free vibration of linearly elastic arches of uniform stiffness and constant mass per unit length. Two arch shapes with hinged-hinged and clamped-clamped end constraints we considered in analysis. The frequency equations (lowest symmetrical and antisymmetrical frequency equations) we obtained by Galerkin's method. The effects of arch rise, Winkler foundation parameter and shear foundation parameter on the lowest two natural frequencies are investigated. The effect of initial arch shapes on frequencies is also studied.
Nonlinear Hysteretic Behavior of Hybrid Steel Beams with Reinforced Concrete Ends
Journal of the Computational Structural Engineering Institute of Korea, volume 15, issue 2, 2002, Pages 379~387
This paper presents an analytical model on nonlinear hysteretic behavior of hybrid steel beam with reinforced concrete ends. The modeling method and appropriate coefficients with IDARC2D were proposed from the comparison with previous test results. Since the polygonal model of IDARC2D nay overestimate, new analytical model with the initial stiffness reduction coefficient was proposed. The hysteretic coefficients for the analysis of the hybrid steel beam with reinforced concrete ends were also presented. The analytical results were compared with previous experiments. The initial stiffness and the strength were predicted with less than 5% error and 10% error, respectively.