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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Civil Engineers
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Journal DOI :
Korean Society of Civil Engeneers
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Volume & Issues
Volume 16, Issue 3_6 - Nov 1996
Volume 16, Issue 2_6 - Nov 1996
Volume 16, Issue 1_6 - Nov 1996
Volume 16, Issue 3_5 - Sep 1996
Volume 16, Issue 2_5 - Sep 1996
Volume 16, Issue 1_5 - Sep 1996
Volume 16, Issue 3_4 - Jul 1996
Volume 16, Issue 2_4 - Jul 1996
Volume 16, Issue 1_4 - Jul 1996
Volume 16, Issue 3_3 - May 1996
Volume 16, Issue 2_3 - May 1996
Volume 16, Issue 1_3 - May 1996
Volume 16, Issue 3_2 - Mar 1996
Volume 16, Issue 2_2 - Mar 1996
Volume 16, Issue 1_2 - Mar 1996
Volume 16, Issue 3_1 - Jan 1996
Volume 16, Issue 2_1 - Jan 1996
Volume 16, Issue 1_1 - Jan 1996
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Use of Nonlinear Transfer Functions in Interpretation of Dynamic Response of a TLP
Paik, In-Yeol ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 645~645
Nonlinear transfer functions are useful tools in determining the nature and importance of various nonlinear effects on the dynamic response of flexible offshore structures such as tension leg platforms(TLP). In this study it is shown that when a TLP is analyzed in its displaced position, the surge motion exhibits significant amount of response components at frequencies which are outside of the range of the excitation frequencies but which correspond to the natural frequencies of the TLP. By applying nonlinear system modeling in the frequency domain, the linear and nonlinear transfer functions are computed from these results and the total response are decomposed into linear and nonlinear contributions separately. The coherency spectrum shows the degrees of nonlinearity clearly over the frequency range and shows the validity of the system model.
Multilevel Shape Optimum Design of Truss Structures Considering the Sectional Properties of H Shape Steel Products
Jung, Young-Chae ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 655~655
This study is aimed to optimize the section areas and the shapes of the steel truss structures which are constructed with the H shape steel products made in the factories. The multilevel shape optimizing problems of truss structures are formulated with the objective function and with the constraints which take the section areas of the fixed shape truss structure as the design variables in the first level and the objective function which fixes the section areas of truss structure optimized in the first level and takes the coordinates of one as design variables in the second level through the allowable iteration number. The objective function is formulated as the total weight of the truss structure. The constraints are derived by using the criteria with respect to the tensile working stresses or the compressive ones considering the buckling according to the kinds of steel member based on the part of steel bridge in the Korean design standard of highway bridges, the deflection of truss structure and the upper and lower limit design variables. The sectional properties of H shapes are derived by using the correlation ship equitions obtained from regression analysis for the section modulli and the section areas, and the section inertia moments of seventy H shape steel products. In the first level, the SUMT method using the modified Newton Raphson direction method is introduced to solve the nonlinear optimizing programming problems formulated in this study, and In the second level, the steepest descent method is used to find the optimum coordinates of truss structure which minimize the objective function of optimizing problem. This optimizing algorithm developed for the optimum section area and the shape of truss structure is tested out and examined through some numerical examples, and the numerical results of them are compared with the ones of the other papers and analyzed to examine the possibility of optimization. the applicability and the convergency of this algorithm.
Development of Stochastic Finite Element Model for Underground Structure with Uncertainties in the Physical Properties in Discontinuous Rock Mass
Chung, Young-Soo ; Choi, Kyu-Sup ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 669~669
A stochastic finite element model is proposed for the structural analysis of underground caverns considering uncertainties of physical properties in discontinuous rock mass. Here, the Monte carlo simulation technique, which has been widely used in probability analyses in many engineering fields, is applied for the analysis of underground structures. To consider the effect of discontinuities. the joint finite element model, which is known to be excellent in explaining faults. cleavage. things of that nature, has been used in this study. To reflect the uncertainty of material properties, various random variables are assumed as the elastic the modulus, the poisson's ratio. the joint shear stiffness, and the joint normal stiffness, all of which could be simulated in terms of normal distribution. A Computer program has been newly coded, of which validity has been confirmed through verification examples. And, the applicability of the program has been tested by performing the structural analysis of a circular cavern in discontinuous rock mass.
Stability and Post-buckling Analysis of Stiffening Truss Girders
Kim, Moon-Young ; Lee, Byoung-Ju ; Ahn, Sung-Won ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 683~683
Geometrically non-linear finite element formulation based on the truss element and the shear deformable frame element is presented in order to evaluate stability and post-buckling behaviors of plane truss girders. The tangent stiffness for the truss element and the shear flexible frame element are calculated by using Hermitian polynomials considering shear effects as shape functions. In determining static deflections and buckling loads and tracing post-buckling of truss type structures, results analyzed by the equivalent beam element show good agreement with results by the truss, the frame. and the combined element. As a result, it is judged that this procedure by the equivalent beam element is effective for analyzing stability behaviors of the stiffening truss girders.
Buckling Strength of Open Section Short Columns Composed of Orthotropic Plate Elements
Yoon, Soon-Jong ; Chae, Soo-Ha ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 693~693
The fiber reinforced thermosetting plastic composites are new materials for civil engineering structures. Due to their attractive mechanical and physical properties. this material could play a major role in the construction field in He near future. For the mass production of the material, the pultrusion process is adopted to produce uniform cross section having various configurations with unlimited length. Tn general, thin-walled open cross sections composed of orthotropic plate elements in which the fibers are placed parallel to the longitudinal axis of the member are produced and utilized in various structures such as chemical plants, paper mills, and waste water treatment systems. However, the structural behavior under various loading conditions are not fully understood and design procedures are not well established. In this study the elastic local buckling analysis is performed based on the classical orthotropic plate theory and equations for finding the buckling stress of thin-walled open short columns composed of orthotropic plate elements are presented. Elastic buckling analyses of orthotropic plates having different boundary conditions are performed and ensuing results are utilized to formulate the characteristic equation for the local buckling strength of channel and zee sections. In structural shapes such as a channel and/or a zee section, two plate elements are connected rigidly at the common junction of the member and therefore the restraining effect at the common junction of the plate components must be taken into account. The graphical form of results is presented for a design aid in which the data was generated by the numerical analysis technique In the calculation, material properties and section dimensions are selected from the manufacturer's design manual. The applicability of derived equations was confirmed by comparison with the equation developed for the isotropic counter parts such as steel and aluminum structural shapes.
The Share Optimization of Truss Structures with Multi-Objective Using Fuzzy Theory
Lee, Gyu-Won ; Yang, Chang-Yong ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 705~705
This research presents a shape optimization algorithm of truss structures with fuzziness design constraints and multi-objective using fuzzy theory. The algorithm developed utilized the two-level technique which consists of the first level and second level. The optimization formulation in the first level which is solved by the Multi-objective Fuzzy Optimization technique design takes the cross-sectional areas of truss structures as design variables, volume as the first objective function and displacement conflicting with the first objective function as the second objective function. The optimization for mutation in the second level utilizing unidirectional search of the Powell method which makes it possible to minimize only objective function. which treats the volume as the first objective function and displacement as the second objective function. Overall truss configuration or geometric layout is set to the design variable. The algorithm in this research is numerically tested for truss structure having two and thirteen members. The proposed technique has been tested using two different truss structures to yield optimim designs with efficient convergence rate regardless of constraint types and configuration of truss structures.
Active Structural Vibration Control Considering Time Delay Effects and Design Constraints
Koh, Hyun-Moo ; Park, Kwan-Soon ; Park, Won-Suk ; Lee, Heui-Hwang ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 715~715
Time delay effect can cause instability and performance degradation of vibration control system for civil structures. This paper solves the problems by using discrete time LQR with output feedback considering time delay effect. Design constraints are satisfied using relative weighting parameter and energy normalization method. Numerical simulations are illustrated through the control of a 3-DOF model with active and hybrid mass damper. Responses to E1 Centre earthquake (1940, NS) show that the proposed controller stabilizes the system and satisfies design constraints when there is a time delay. Free vibration control experiment of a 1-DOF cable-stayed bridge model is performed. Experimental results verify the effectiveness of the control algorithm considering time-delay.
An Experimental Study of the Shear Key Shapes in Segmental PC Bridges
Yoo, Seung-Woon ; Oh, Byung-Hwan ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 725~725
In recent decades, the precast prestressed concrete segmental method of bridge construction has been increasingly popular. Increased speed of erection, improved aesthetics, and mitigation of traffic disturbances are among the factors which have made precast segmental construction chosen in many recent bridge projects. Shear behavior and strength of shear key joints are critical problem in the design of precast prestressed concrete segment bridges. An experimental program was conducted to study the shear behavior and strength of joints in precast PC bridges. The parameters considered in the test included joint type (monolithic, flat, or keyed), joint surface preparation (dry or epoxy joint), confining pressure
, key shape (protrusion ratio or inclination angle). From the results of this test, the optimum shape of a shear key was proposed and the optimum type of jointing reviewed to provide the guideline of design and analysis of the joints in precast PC bridges.
Correlation Analysis by Substructure Method for Forced Vibration Test of Hualien Large-Scale Seismic Test Structure
Park, Hyung-Ghee ; Joe, Yang-Hee ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 735~735
A multi-national long-term research project is now in progress to clarify the uncertainties in the existing soil-structure interaction analysis procedures based on the forced vibration test and actual earthquake response records of large-scale seismic test structure constructed in Hualien, Taiwan. In this study, the material properties of the soil-structure system obtained by geophysical survey or laboratory test are re-evaluated by correlation studies between the forced vibration test and the analysis results in frequency domain. Based on this study results, a modified lumped-parameter soil-structure interaction model using the revised properties of soil and structure are suggested to be compatible with the test results. The results indicates that the mechanical properties of the soil and structure determined in original survey/test were overestimated.
The Analysis of Track Structures with Non-linear Track Modulus Based on Field Measurements
Kang, Kee-Dong ; Kim, In-Jae ; Park, Dae-Geun ; Bae, Sang-Hwan ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_6, 1996, Pages 743~743
The theory of "Beam on elastic Foundation" is generally used for the analysis of track structures in which the rail is supported by a series of continuous linear spring on an elastic foundation. Each individual element of the rail seat is modelled by a spring. The most important aspect of the track analysis is to calculate the loads that are transmitted to the track elements i.e. rails, sleepers, fasteners, ballast etc. It is for that reason that the track modulus should be defined as accurate as possible. Since the track modulus is calculated considering the combined influence of all track elements it is relatively difficult to define by a simple equation The track modulus can be easily changed to account for variation in the sub - ballast condition and using term of the element. The ballast has a large impact on the track modulus that result from variations in the specific gravity, rigidity and hardness of the ballast material. The track modulus can also be influenced by changing weather conditions, for example by repeated freezing and thawing of the ballast and ground. Until now in spite of this approximation of the track modulus it was acceptable to perform the track analysis with an assumed linear track modulus under the applied load. Linear superposition of the individual track components can not predict the actual track reaction for the ballastless track which is generally adopted for subways and for high speed railway track with their increased train speed. This is specially important for subway structures where the track modulus is governed by the rubber boot and the pad on which the concrete sleeper is supported. In order to perform an exact track analysis it is important to consider the non-linear behavior of the various track components. Results of a non-linear track analysis indicate that the bending moment in the rail is smaller and the rail compression is larger than those determined by linear track analysis. These results may have a direct impact on the concrete sleeper design. This paper includes verification of the track reactions determined by non-linear track analysis with those determined by tests on ballastless subway track on the Seoul Metro and those track reactions defermined on the Korean National Railway Kyongbu line which were performed as part of research for the Korean High Speed Rail Project. A comparison of on linear and nonlinear analysis results is also provided.