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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 17, Issue 3_6 - Nov 1997
Volume 17, Issue 2_6 - Nov 1997
Volume 17, Issue 1_6 - Nov 1997
Volume 17, Issue 3_5 - Sep 1997
Volume 17, Issue 2_5 - Sep 1997
Volume 17, Issue 1_5 - Sep 1997
Volume 17, Issue 3_4 - Jul 1997
Volume 17, Issue 2_4 - Jul 1997
Volume 17, Issue 1_4 - Jul 1997
Volume 17, Issue 3_3 - May 1997
Volume 17, Issue 2_3 - May 1997
Volume 17, Issue 1_3 - May 1997
Volume 17, Issue 3_2 - Mar 1997
Volume 17, Issue 2_2 - Mar 1997
Volume 17, Issue 1_2 - Mar 1997
Volume 17, Issue 3_1 - Jan 1997
Volume 17, Issue 2_1 - Jan 1997
Volume 17, Issue 1_1 - Jan 1997
Selecting the target year
Evaluation of Sectionnal Forces of Pier by Mode Spectral Analysis Methods
Lee, Gye-Ho ; Yoo, Young-Hwa ; Shin, Hyun-Mock ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 683~683
As an importance of seismic design have been increasing, it is necessary to establish an adequate guidelines of which designers can make use for the effective design according to the types of bridges. When applying the codes, seismic design forces are determined by single mode spectral analysis method for the general bridges whose geometric shape is relatively simple, where seismic design forces are obtained only using the fundamental frequency. On the contrary, when the geometeric irregularities such as span length and pier hight are significant, one may expect a substantial errors which may be taken into account in multi-mode spectral analysis. For the determination and comparison of the design forces respectively by mode spectral analysis, the program based on design codes which performs a 3-dimensional dynamic analysis is developed and applied to several example bridges. It can be noted from the results that for the bridges whose natural periods are below 4 seconds, seismic forces by the single mode spectral analysis method are a little higher than that by the multi-mode spectral analysis method, while for the bridges whose natural periods are above 4 seconds it is re-commanded to apply multi-mode spectral analysis method.
Solution of Eigenvalue Problems for Nonclassically Damped Systems
Kim, Man-Cheol ; Jung, Hyung-Jo ; Oh, Ju-Won ; Lee, In-Won ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 695~695
A solution method is presented to solve the eigenvalue problem arising in the dynamic analysis of nonclassically damped structural systems. The proposed method is obtained by applying the modified Newton-Raphson technique and the orthonormal condition of the eigenvectors to the linear eigenproblem through matrix augmentation of the quadratic eigenvalue problem. In the iteration methods, such as the inverse iteration method and the subspace iteration method, singularity may be occurred during the factorizing process when the shift value is close to an eigenvalus of the system. However, even through the shift value is an eigenvalue of the system, the proposed method provides nonsingularity, if the desired eigenvalue is not multiple, and that is analytically proved. Since the modified Newton-Raphson technique is adopted to the proposed method, initial values are need. The initial values of the proposed method can be obtained by the intermediate results of iteration methods or results of approximate methods. Because the Lanczos method effectively produces better initial values than other methods, the results of the Lanczos method are taken as the initial values of the proposed method. Two numerical examples are presented to demonstrate the effectiveness of the proposed method and the results are compared with those of the well-known subspace iteration method and the Lanczos method.
Nonlinear Finite Element Analysis of RC Flexural Members using Equivalent Strain
Kim, Young-Jin ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 705~705
It is the purpose of this investigation to develop the material models and computational procedure for predicting the structural response of reinforced concrete flexural members over the entire loading range up to failure. To develop a nonlinear material model, concrete is treated as an orthotropic nonlinear material and steel is modeled as an elasto-plastic material. For cracked concrete, smeared cracking model, shear retention factor, and strength reduction effect are employed. The finite element computer program is developed using incremental iterative algorithm and finite element formulations. The predictions of the models and algorithm are compared with the available experimental data and analytically predicted data. The comparisons are judged good and it can be seen that the developed models and analytical algorithm could be applied to predict the behaviors of RC flexural members.
Vertical Free Vibration of Suspension Bridges Considering Shear Deformation and Rotary Inertia (I) Analytic Method
Kim, Moon-Young ; Rho, Bum-Jun ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 715~715
The energy formulation extended from Abdel-Ghaffar's theory is presented in order to investigate dynamic characteristics of suspension bridges considering the effects of the shear deformation and the rotary inertia. The equations of motion are obtained from Hamilton's principle and analytic solutions for natural frequences corresponding to the symmetric and antisymmetric mode shapes are derived. Numeric results are presented for the selected problems which demonstrate that the present analytic solutions are reliable and accurate for the free vibration analysis of 3 span hinged suspension bridges. In the companion paper, two finite element formulations are presented. In the first formulation, the entire suspension bridge is analyzed by suspension bridge elements and in the second formulation, main cables and stiffening girders are discritized by the truss element and the equivalent beam element, respectively. Through numerical examples, the natural frequences obtained from two modeling analysis are compared with analytic solutions.
Vertical Free Vibration of Suspension Bridges Considering Shear Deformation and Rotary Inertia (II) Numerical Method
Kim, Moon-Young ; Lee, Byoung-Ju ; Rho, Bum-Jun ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 727~727
In the companion paper, vertical equation of motions considering the effects of the shear deformation and the rotary inertia had been presented based on Abdel-Ghaffar's vertical vibration theory and natural frequences and mode shapes of 3 span hinged suspension bridges are analytically derived. In this paper, two finite element formulations considering the effects of the shear deformation and the rotary inertia are presented in order to investigate dynamic characteristics of suspension bridges. At first, the shear-flexible bridge element considering combined effects of the main cable and the stiffening girder is developed based on Abdel-Ghaffar's vertical vibration theory. Secondly, both main cables and hangers of the suspension bridge by the truss element, and the truss stiffening girders by the truss element or the equivalent beam element are modeled and vertical free vibration analysis is performed. Through numerical examples, the natural frequences obtained from two modeling analysis are compared with analytic solutions. Resultantly, the validity and accuracy of the present vibration analysis taking into account combined effects of main cables and shear-flexible stiffening girders are demonstrated.
Reliability-Based Assessment of Structural Safety of Segmental PC Box Girder Bridges Erected by the FCM during Construction
Cho, Hyo-Nam ; Choi, Young-Min ; Yoon, Jung-Hyun ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 739~739
In this study the safety assessment models for PC box-girder bridges erected by the FCM(Free Cantilever Method) that prompts more precise but economical construction are proposed for the assurance of structural safety to prevent the bridge collapse during construction. The structural reliability approach that reasonably considers the uncertainties associated with the loads and resistance is used for the rational and practical safety assessment of PC box-girder bridges during construction. This study focuses on the assessment of statistical uncertainties of resistance and loads as well as the development of limit state models for temporary pier and PC box section. The application of the models and the AFOSM reliability method to actual existing bridges proves the practical applicability of the proposed models. And also the critical factors for the safety control during construction stage are identified based on the sensitivity analysis of the major random variates.
Dynamic Response of Beams and Plates on Elastic Foundation to Moving Loads
Kim, Seong-Min ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 749~749
This paper presents the dynamic displacement responses of a beam of infinite length on the elastic foundation and a plate of infinite area on the elastic foundation subjected to moving constant and harmonic loads with a constant advance velocity. Formulations were developed in the transformed field domains of time, space and moving space, and the solutions were obtained numerically using the Fast Fourier Transforms (FFT). The effects of velocity, frequency and damping on the deflected shapes and on the maximum displacements were investigated. The two systems showed very similar characteristics. The critical (resonant) frequencies and velocities could be obtained from the analyses and formulae to find them were suggested.
Two Dimensional Wave Propagation Analysis on the Buried Explosives
Kim, Suk-Ki ; Lee, Sang-Ho ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 757~757
Two dimensional axisymmetrical explosion phenomena from the buried explosives are numerically simulated by using finite difference algorithm. The detonation process is implemented by releasing the explosive chemical energy stored in the finite difference mesh at the time of detonation. The constitutive law for the medium through which explosive wave propagate is the Von-Mises. Governing equations of this study are conservation equations of momentum, mass, and energy in Lagrangian coordinate system which is fixed to the material. Due to the shock front which violates the continuity assumptions inherent in the differential equations numerical artificial viscosity is used to spread the shock front over several computational zones. These governing equations are solved by finite difference method with discretized time and space coordinates. The associated normality flow rule as a plastic theory is implemented to find the plastic strains.
NDE of Fracture in an Ultra Light-Weight Concrete Composite
Heo, Gwang-Hee ; Youn, Il-Ro ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 771~771
The paper reports a study of fracture in an ultra lightweight cement composite being developed for applications in the mining industry. The material (density=1.2 gm./cc. or 75 pcf) consists of high-volume fly-ash (65%) and high air content (40% by volume). Brittleness caused by the porous microstructure is countered by the incorporation of synthetic (nylon) fibers. Notched beam specimens were tested to determine the fracture properties. During these tests slow crack growth was monitored using the electronic speckle-pattern interferometry (ESPI) technique. An Environmental Scanning Electron Microscope (ESEM) was used to inspect the microstructure and mechanisms contributing to the fracture characteristics. Conventional uniaxial compression, split tensile and modulus of rupture tests were also conducted to determine material properties, and for comparison with normal weight concrete.
Suppression of Wind Induced Vibration of three Dimensional Bridge using Actively Controlled Edge Surfaces
Kwon, Soon-Duck ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 779~779
This study is intended to investigate the effects of active aerodynamic control in three dimensional bridge. The aeroelastic equation of motion including structural and aerodynamic interaction between deck and control surface is derived. The derived equation combined with modem control theory is adopted for suppressing wind induced vibration. The proposed method can sustain the stability until design wind velocity, and reduce gust response as well. Minimum energy control scheme would be applied for flutter problem. Multi-controller which would be operated under malfunction of some controllers is proper to enhance the robustness of active control system.
Mode Interactive Buckling Analysis of Cold-Formed Members
Kim, Hyeong-Yeol ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 789~789
A solution algorithm is developed and presented for mode interactive instability analysis of cold-formed structural members. The finite element based formulation takes into account the interaction between the local and overall buckling modes, and considers postbuckling behavior of structures having arbitrary boundary conditions and cross-sectional shapes, with geometrical imperfections. The solution of mode interaction problem is obtained by two integrated numerical procedures, which combine the nonlinear postbuckling analysis procedure and simplified method of mode interaction analysis. In order to validate the problem formulation, several examples are solved and compared with the experimental data as well as the solutions of analytical methods. The results of this study have confirmed that, in certain circumstances, ignoring the mode interaction may lead to an overestimation of buckling loads of thin-walled members.
Development of Wheel Load Distribution Formulas and Member Force Functions of Continuous Composite Girder Bridges
Oh, Ji-Taek ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 801~801
This study proposes formulas for wheel load distribution on the girders of composite girder bridges, the functions for maximum member forces that may happen under the live and dead load in continuous bridges. Wheel load distribution formulas are developed based on a modeling technique for composite girder bridges. In this modeling technique, the deck slab and the girder of a bridge are transformed into a continuous beam and an elastic support, respectively. To confirm the validity of the proposed formulas, its results are compared with those of other researches. The proposed formulas give wheel load distribution factors which are generally much lower than the current AASHTO values, and higher than the OHBDC values in interior girders. The functions of member forces are derived from symbolic manipulations, which are relatively simpler than other methods and provide a basis for a parametric study. The proposed formulas for wheel load distribution factors and member forces may be useful for the design of composite girder bridges because of their simplicity and rationality.
Parameter Estimation for Structural Evaluation of High Speed Railway Tunnel
Lee, Seong-Won ; Yang, Sin-Chu ;
Journal of The Korean Society of Civil Engineers, volume 17, issue 1_5, 1997, Pages 813~813
It is important to predict exact values of material properties in order to structural evaluation of Seoul-Busan high speed railway tunnel. The object of this study lies in the development of a efficient procedure for parameter estimation of the properties. To develope this procedure on the base of the standard design section, first, the elastic modulus and lateral pressure coefficient of rock materials are selected the most influence factor of displacement behavior of tunnel. Second, initial modulus prediction is developed by the regression analysis. Final prediction is acomplished by the optimization technique. The proposed procedure is verified through various numerical model tests and field data.