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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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Korean Society of Civil Engeneers
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Volume & Issues
Volume 29, Issue 6D - Nov 2009
Volume 29, Issue 6C - Nov 2009
Volume 29, Issue 6B - Nov 2009
Volume 29, Issue 6A - Nov 2009
Volume 29, Issue 5D - Sep 2009
Volume 29, Issue 5C - Sep 2009
Volume 29, Issue 5B - Sep 2009
Volume 29, Issue 5A - Sep 2009
Volume 29, Issue 4D - Jul 2009
Volume 29, Issue 4B - Jul 2009
Volume 29, Issue 4A - Jul 2009
Volume 29, Issue 4C - May 2009
Volume 29, Issue 3D - May 2009
Volume 29, Issue 3C - May 2009
Volume 29, Issue 3B - May 2009
Volume 29, Issue 3A - May 2009
Volume 29, Issue 2D - Mar 2009
Volume 29, Issue 2C - Mar 2009
Volume 29, Issue 2B - Mar 2009
Volume 29, Issue 2A - Mar 2009
Volume 29, Issue 1D - Jan 2009
Volume 29, Issue 1C - Jan 2009
Volume 29, Issue 1B - Jan 2009
Volume 29, Issue 1A - Jan 2009
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Shear Force Variation of Stiffening Girder caused by Vibration of Stay Cable
Kim, Hyeon Kyeom ; Hwang, Jae Woong ; Lee, Myeong Jae ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 1~8
Stay cable is easily exposed to vibration induced rainy wind effects. There are some problems for not only unexpected vibration but also well-known vibration. An outbreak of displacement by the said effects brings damages such as over-tension of cables and barriers, fatigue of anchorages and dampers, and additional shear force variation of stiffening girders. This study suggests analytic methodology for dynamic tension variation of cables and shear force variation of stiffening girders. Additionally this study announces with dynamic problems for cable stayed bridge briefly. To realize this subject, we divide restoring force into chord component and normal component and then make up the differential equations which can satisfy physical phenomenon for each component. Finally we apply adequate functions such as sinusoidal and parabola in order to reduce these differential equations. Therefore we can meet with good results through a series of above process. As a remarkable result, CIP recommendations (2002) give inadequate solution with over 10% error. However it gives very good solution if parts of our study are reflected at the said recommendations. The fact means that CIP recommendations (2002) well-known as international standard of stay cables are not even concern about this subject yet. For verification of this study, F.E. analysis using E.C.C. with external forces was fulfilled, and the accuracy and conciseness of this study were shown.
Tensile Force Estimation of Externally Prestressed Tendon Using SI technique Based on Differential Evolutionary Algorithm
Noh, Myung-Hyun ; Jang, Han-Taek ; Lee, Sang-Youl ; Park, Taehyo ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 9~18
This paper introduces the application of DE (Differential Evolutionary) method for the estimation of tensile force of the externally prestressed tendon. The proposed technique, a SI (System Identification) method using the DE algorithm, can make global solution search possible as opposed to classical gradient-based optimization techniques. The numerical tests show that the proposed technique employing DE algorithm is a useful method which can detect the effective nominal diameters as well as estimate the exact tensile forces of the externally prestressed tendon with an estimation error less than 1% although there is no a priori information about the identification variables. In addition, the validity of the proposed technique is experimentally proved using a scale-down model test considering the serviceability state condition without and with the loss of the prestressed force. The test results prove that the technique is a feasible and effective method that can not only estimate the exact tensile forces and detect the effective nominal diameters but also inspect the damping properties of test model irrespective of the loss of the prestressed force. The 2% error of the estimated effective nominal diameter is due to the difference between the real tendon diameter with a wired section and the FE model diameter with a full-section. Finally, The accuracy and superiority of the proposed technique using the DE algorithm are verified through the comparative study with the existing theories.
Flexural Stiffness and Characteristics of Vibration in CFT Truss Girder
Chung, Chul-Hun ; Song, Na-Young ; Kim, In-Gyu ; Jin, Byeong-Moo ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 19~30
The primary objective of the present study was to attempt to quantify the effect of the existing codes for CFT composite section on initial section flexural stiffness, based on the measured vibration frequency of CFT truss girders. The formulae for the initial flexural stiffness of the composite sections in the different codes are compared with the free vibration test results. The results of the free vibration test on the CFT truss girders are in good agreement with the analysis results when used in ACI formulae. The free vibration analysis of CFT truss girders for different f/L ratios was conducted to determine how the natural frequency of the CFT truss girder is affected by different f/L ratios. The presence of the f/L ratios in CFT truss girders alters its frequencies of vibration because of the global stiffness of the CFT girders. The frequency in horizontal modes decreases as the f/L ratio increases. However, the frequency in vertical modes increases as the f/L ratio increases.
Vehicle-Bridge Interaction Analysis of Railway Bridges by Using Conventional Trains
Cho, Eun Sang ; Kim, Hee Ju ; Hwang, Won Sup ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 31~43
In this study, the numerical method is presented, which can consider the various train types and can solve the equations of motion for a vehicle-bridge interaction analysis by non-iteration procedure through formulating the coupled equations of motion. The coupled equations of motion for the vehicle-bridge interaction are solved by the Newmark
of a direct integration method, and by composing the effective stiffness matrix and the effective force vector according to a analysis step, those can be solved with the same manner of the solving procedure of equilibrium equations in static analysis. Also, the effective stiffness matrix is reconstructed by the Skyline method for increasing the analysis effectiveness. The Cholesky's matrix decomposition scheme is applied to the analysis procedure for minimizing the numerical errors that can be generated in directly calculating the inverse matrix. The equations of motion for the conventional trains are derived, and the numerical models of the conventional trains are idealized by a set of linear springs and dashpots with 16 degrees of freedom. The bridge models are simplified by the 3 dimensional space frame element which is based on the Euler-Bernoulli theory. The rail irregularities of vertical and lateral directions are generated by the PSD functions of the Federal Railroad Administration (FRA). The results of the vehicle-bridge interaction analysis are verified by the experimental results for the railway plate girder bridges of a span length with 12 m, 18 m, and the experimental and analytical data are applied to the low pass filtering scheme, and the basis frequency of the filtering is a 2 times of the 1st fundamental frequency of a bridge bending.
An Improved Reliability-Based Design Optimization using Moving Least Squares Approximation
Kang, Soo-Chang ; Koh, Hyun-Moo ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 45~52
In conventional structural design, deterministic optimization which satisfies codified constraints is performed to ensure safety and maximize economical efficiency. However, uncertainties are inevitable due to the stochastic nature of structural materials and applied loads. Thus, deterministic optimization without considering these uncertainties could lead to unreliable design. Recently, there has been much research in reliability-based design optimization (RBDO) taking into consideration both the reliability and optimization. RBDO involves the evaluation of probabilistic constraint that can be estimated using the RIA (Reliability Index Approach) and the PMA(Performance Measure Approach). It is generally known that PMA is more stable and efficient than RIA. Despite the significant advancement in PMA, RBDO still requires large computation time for large-scale applications. In this paper, A new reliability-based design optimization (RBDO) method is presented to achieve the more stable and efficient algorithm. The idea of the new method is to integrate a response surface method (RSM) with PMA. For the approximation of a limit state equation, the moving least squares (MLS) method is used. Through a mathematical example and ten-bar truss problem, the proposed method shows better convergence and efficiency than other approaches.
Geometrical Nonlinear Analyses of Post-buckled Columns with Variable Cross-section
Lee, Byoung Koo ; Kim, Suk Ki ; Lee, Tae Eun ; Kim, Gwon Sik ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 53~60
This paper deals with the geometrical nonlinear analyses of post-buckled columns with variable cross-section. The objective columns having variable cross-section of the width, depth and square tapers are supported by both hinged ends. By using the Bernoulli-Euler beam theory, differential equations governing the elastica of post-buckled column and their boundary conditions are derived. The solution methods of these differential equations which have two unknown parameters are developed. As the numerical results, equilibrium paths, elasticas and stress resultants of the post-buckled columns are presented. Laboratory scaled experiments were conducted for validating the theories developed in this study.
Hybrid Structural Health Monitoring of Steel Plate-Girder Bridges using Acceleration-Impedance Features
Hong, Dong-Soo ; Do, Han-Sung ; Na, Won-Bae ; Kim, Jeong-Tae ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 61~73
In this paper, hybrid health monitoring techniques using acceleration-impedance features are newly proposed to detect two damage-type in steel plate-girder bridges, which are girder's stiffness-loss and support perturbation. The hybrid techniques mainly consists of three sequential phases: 1) to alarm the occurrence of damage in global manner, 2) to classify the alarmed damage into subsystems of the structure, and 3) to estimate the classified damage in detail using methods suitable for the subsystems. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the alarmed damage is classified into subsystems by recognizing patterns of impedance features. In the final phase, the location and the extent of damage are estimated by using modal strain energy-based damage index method and root mean square deviation (RMSD) method. The feasibility of the proposed hybrid technique is evaluated on a laboratory-scaled steel plate-girder bridge model for which hybrid acceleration-impedance signatures were measured for several damage scenarios. Also, the effect of temperature on the accuracy of the impedance-based damage monitoring results are experimentally examined from combined scenarios of support damage cases and temperature changes.
Chloride Threshold Value for Steel Corrosion considering Chemical Properties of Concrete
Song, Ha-Won ; Jung, Min-Sun ; Ann, Ki Yong ; Lee, Chang-Hong ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 75~84
The present study assesses the chloride threshold level for corrosion of steel in concrete by examining the properties of four different binders used for blended concrete in terms of chloride binding, buffering of cement matrix to a pH fall and the corrosion behaviour. As binders, ordinary Portland cement (OPC), 30% pulverised fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF) were used in a concrete mix. Testing for chloride binding was carried out using the water extraction method, the buffering of cement matrix was assessed by measuring the resistance to an artificial acidification of nitric acid, and the corrosion rate of steel in mortar with chlorides in cast was measured at 28 days using an anodic polarisation technique. Results show that the chloride binding capacity was much affected by
content and physical adsorption, and its order was 60% GGBS>30% PFA>OPC>10% SF. The buffering of cement matrix to a pH fall was varied with binder type and given values of the pH. From the result of corrosion test, it was found that the chloride threshold ranged 1.03, 0.65, 0.45 and 0.98% by weight of cement for OPC, 30% PFA, 60% GGBS and 10% SF respectively, assuming that corrosion starts at the corrosion rate of
. The mole ratio of [
], as a new presentation of the chloride threshold, indicated the value of 0.008-0.009, irrespective of binder, which would be indicative of the inhibitive characteristic of binder.
A Rheological Approach on Prediction of Concrete Creep
Kwon, Ki-yeon ; Min, Kyung-hwan ; Kim, Youl-hee ; Yoon, Young-soo ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 85~93
The primary objective of this study is to construct more simple and reasonable rheological model and propose a methodology for predicting a phenomenon of concrete creep. Deformations of concrete under sustained stress can be expressed by the sum of immediately elastic deformation, time-dependent and time-independent short-term creep, and long-term creep according to the mechanism and time-dependency. To simulate these deformations, a rheological model having six parameters was constructed. In the composing of each parameter, the microprestress-solidification theory and design model code were incorporated together with the numerical approach for the components which can not be theoretically approached. Finally, actual test data were applied in the verification of the proposed model, and suitability of the model was confirmed by comparisons with existing predicting models and design codes.
Mix Proportions of Early-Strength Pavement Concrete Using Calcium Nitrate
Won, Jong Pil ; Lee, Si Won ; Lee, Sang Woo ; Park, Hae Geun ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 95~100
This study proposed mix proportions of early strength pavement concrete for large size area using calcium nitrate. Therefore, we used type III cement with calcium nitrate. Laboratory tests conducted to air content, slump loss test, setting time test, compressive strength test and flexural strength test. Our early strength pavement concrete mixture proportion proposed in this study for large size area attained the required compressive strength of 21 MPa and a flexural strength of 3.8 MPa, which allowed it to be opened to traffic within 8 hours. Based on test results, we suggested optimum mix proportions of early strength pavement concrete for large size area using calcium nitrate.
Cracking and Durability Characteristics of High-early-strength Pavement Concrete for Large Areas using Calcium Nitrate
Won, Jong Pil ; Lee, Si Won ; Lee, Sang Woo ; Park, Hae Geun ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1A, 2009, Pages 101~108
The performance of high-early strength pavement concrete for large areas is influenced by the physical and chemical environment during service life. Generally, penetration, diffusion, and absorption of harmful materials that exist outside the concrete cause damage to its structure. Thus, we have to use a mixture for durability to keep the required quality for the planned service life. Moreover, in using high-early-strength cement and accelerators, a high heat of hydration to create the initial strength can cause cracks. Based on evaluations from optimal mix proportions of high-early-strength pavement concrete for large areas, we conducted water permeability, abrasion resistance, freeze-thaw, plastic, drying, and autogenous shrinkage tests. Test result showed that a mix of accelerator and PVA fibers showed excellent performance.