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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 19, Issue 3_6 - Nov 1999
Volume 19, Issue 2_6 - Nov 1999
Volume 19, Issue 1_6 - Nov 1999
Volume 19, Issue 3_5 - Sep 1999
Volume 19, Issue 2_5 - Sep 1999
Volume 19, Issue 1_5 - Sep 1999
Volume 19, Issue 3_4 - Jul 1999
Volume 19, Issue 2_4 - Jul 1999
Volume 19, Issue 1_4 - Jul 1999
Volume 19, Issue 3_3 - May 1999
Volume 19, Issue 2_3 - May 1999
Volume 19, Issue 1_3 - May 1999
Volume 19, Issue 3_2 - Mar 1999
Volume 19, Issue 2_2 - Mar 1999
Volume 19, Issue 1_2 - Mar 1999
Volume 19, Issue 3_1 - Jan 1999
Volume 19, Issue 2_1 - Jan 1999
Volume 19, Issue 1_1 - Jan 1999
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Estimation of Torsional Crack Width in Unbonded Axial Prestressed Concrete Members
Ko, Won-Jun ; Park, Sun-Kyu ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 837~837
Abreast with the development in computational power and the introduction of modem design concepts, 3-dimensional structural design and highly complex problems related to torsion, become manageable tasks. The very characteristics of the prestressed concrete structures which require high-strengthened prestressing reinforcement, corrosional tendency of prestressed concrete member is especially high. As the reinforcement and concrete getting more strengthened and in line with that designers tend to favor more slenderer members thesedays, torsional crack surfaces as a serious problem. Thus more efficient estimation method on acceptable crack width is than the one applied to the reinforced concrete members is in dire need. However, major design codes do not agree on torsional crack criteria and generally leave this matter of setting maximum tolerable torsional crack width to designer's discretion and the actual installation conditions. In summary, an endeavor have been made to put forth a rather accurate and practical scheme of estimating maximum torsional crack width. It is hoped that the scheme presented would contribute in design improvement, especially in the area of serviceability. This session presents an effective formula for crack width prediction in unbonded axial prestressed concrete members subjected to the action of pure torsion. The scheme presented utilizes the crack theory, which takes fully the strain relationship between the reinforcement and concrete into consideration, put forth in CEBFIP Model Code 1990. Parameters related to flexure and
crack theory on torsion are applied in modified forms. Formula derived from this study through theory-based systematic approach allows the maximum torsional crack width be calculated directly. Compared with current methods in which the maximum torsional crack width is estimated via, the proposed formula not only facilitates the computation but also outputs more accurate results.
A Reformed Rating Method for Highway Bridges Based on Statistical Analysis of Existing Data
Kim, Dong-Yong ; Kyung, Kab-Soo ; Jeon, Jun-Chang ; Lee, Hee-Hyun ; Chang, Dong-Il ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 847~847
This study is performed to suggest a way to get the reasonable stress correction factor used in estimating the load carrying capacity of the bridge structures and to evaluate the effect of additional forces(creep, shrinkage and thermal force) on the capacity of the steel-concrete composite bridges. Based on the statistical analyses of the stress correction factor, it is known that the response ratio and the impact factor obtained from the loaded point or near should be used in calculating the factor. And, since the load carrying capacity is decreased with taking into account the additional forces, they have to be considered for realistic and conservative evaluation of the bridge structures.
Efficient Mode Superposition Method for Non-Classically Damped Systems
Cho, Sang-Won ; Jung, Hyung-Jo ; Kim, Dong-Ok ; Lee, In-Won ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 858~858
The improved mode superposition methods for non-classically damped systems are presented in this paper. Generally, the mode superposition method uses a relatively small subset of the normal modes of structures. The mode acceleration method and the modal truncation augmentation method improve the results of the mode superposition method by considering effects of truncated high modes. For using these methods to analyze non-classically damped systems, the systems are approximated to the classically damped systems and thereby the errors are induced. In this paper, the mode acceleration method and the modal truncation augmentation method are expanded to analyze the non-classically damped systems. The applicability of the expanded methods is verified by closed form solutions and numerical examples. The expanded modal truncation augmentation method is conditionally stable depending on the pattern of the external loading in the non-classically damped systems whereas the expanded mode acceleration method is stable for the all cases of loading. In the stable case, the results are the same with those of the expanded mode acceleration method.
Discrete Optimization of Plane Frames Using Standard Sections
Kim, Bong-Ick ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 869~869
This paper presents the applications of Genetic Algorithms(GAs) and Simulated Annealing(SA) for the design of framed structures with discrete design variables. GAs and SA are heuristic search techniques. GAs are imitating the process of natural selection and SA perturbs the current design to produce candidates. In this paper, the structures used are reinforced concrete building plane frames and steel plane frames with W-sections. Search techniques are used that is linked with a design given by GAs and SA. The effectiveness of this search techniques are demonstrated through several examples.
Passive Control of Bridge Flutter by Changing Airflow Around the Deck Section
Kwon, Soon-Duck ; Jung, Sung-Moon ; Chang, Sung-Pil ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 879~879
In this study, a new passive aerodynamic control method is proposed. Control plate which is oscillated by TMD-like mechanism stabilizes bridge flutter. Effectiveness of proposed model is verified by experimental and analytical study. In addition, various parameters of the proposed system are investigated. Applicability to long span bridge is also examined. According to the research results, proposed model is very effective in suppressing flutter, and it also shows remarkable robustness.
An Experimental Study on Flexural Behavior of SRC (Steel Reinforced Concrete) Beams
Jo, Byung-Wan ; Park, Seung-Kook ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 889~889
The steel reinforced concrete (SRC) beam, which has widely been used in the large-scaled concrete structure, was studied to investigate the cause of unexpected cracks and to verify the composite actions between two materials. Vertical stiffners between flanges, studs and dowel bars, stirrups, and design strength of concrete were chosen as experimental variables in the four-points loading test. The results showed that the vertical stiffner prevented not only the local buckling of web, but also bond failures between steel and concrete. It increased the flexural resistancy (fracture loads) due to the composite action of two materials, compared to those of any experimental variables. However, the composite behavior of SRC beam was not affected seriously by additional studs, dowel bars, the design strength of concrete and amounts of stirrups.
Shaking Table Tests and Simplified Analysis for Bridge with Base Isolators Consisting of PTFE Plates and Rubber Rings
Kim, Young-Suk ; Im, Jong-Seoung ; Yun, Chung-Bang ; Kim, Doo-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 899~899
Shaking table tests are carried out for a 1/4 scale bridge model base-isolated with sliding type bearings consisting of PTFE plates and rubber rings. Then a simplified 2-degrees of freedom (DOF's) model is developed for the earthquake response analysis of the base-isolated bridge. The sliding friction of the bearing is represented as a function of the sliding velocity for the analysis. Comparison with the shaking table test results indicates that the simplified model with 2-DOF's yields very resonable results for earthquake responses.
A Study on Distortional Analysis of Steel Box Girders
Lee, Hee-Up ; Yang, Chang-Hyun ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 907~907
In this study, two approaches are presented for distortional analysis of steel box girders. One is the stiffness matrix which is derived from the exact solution of the differential equation for distortion. This stiffness matrix can be readily used in the conventional direct stiffness method. The other is the development of approximate formulas obtained by applying Ritz method. Several illustrating analyses are carried out to verify the validity of the developed technique and its computational procedures. From the analyzed results, the proposed methods are shown to be in good agreement with the exact solutions and FEM. It is also found that the developed algorithm can be applied to analyze curved steel box girders as well as straight steel box girders with intermediate diaphragms. Therefore, the proposed equations and program can be used efficiently for distortional analysis of steel box girders.
Longitudinal Prestress Losses of Precast Concrete Bridge Deck
Chang, Sung-Pil ; Shim, Chang-Su ; Choi, Kyu-Yong ; Chung, Chul-Hun ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 917~917
For estimating the loss of longitudinal prestress to prevent cracks in transverse Joints between precast concrete decks, analytical and experimental studies were performed. Initial losses and time-dependent losses of prestress were measured through the experiments of composite beams and a composite bridge with two-girder. Analytical studies to investigate the time-dependent behavior of composite bridge wit Precast decks, based on AAEM (Age-Adjusted Effective Modulus) method, were employed, and the results were compared with those of experiments. The effects of creep and shrinkage on the prestress loss were estimated by the analytical studies. Based on the present study results, a design recommendation is proposed.
Torsional Analysis of Symmetrically Laminated Composite Open-Section Beams by Vlasov-Type Thin-Walled Beam Theory
Shin, Dong-Ku ; Park, Young-Suk ; Kim, Jeong-Kook ; Kim, Man-Ho ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 929~929
The torsional behavior of laminated composite thin-walled beams with open section is investigated by applying the Vlasov-type anisotropic thin-walled beam theory. Singly-symmetric I- and channel sections are considered and constituent thin-walled elements of cross section are assumed to be symmetrically laminated with respect to its mid-plane. The stresses in the contour direction of laminated thin-walled elements are assumed to be zero. Explicit expressions for various sectional properties of the singly-symmetric cross section including the elastic centroid, torsion center, and bending, torsional and warping stiffnesses are presented. The coupled differential equations governing the linear behavior of anisotropic thin-walled beams under torsional load are solved in an analytical method. To validate the present procedure, analytical solutions are compared with the finite element solutions obtained by using three dimensional model. Several numerical examples using various boundary conditions and lamination schemes are considered to understand the torsional behavior of laminated thin-walled open section beams.
Stochastic Finite Element Analysis of Underground Structure by the Adaptive Importance Sampling Method
Ra, Kyeong-Woong ; Kim, Sang-Hyo ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 943~943
The structural responses of underground structures are examined in probability by using the elasto-plastic stochastic finite element method, in which the spatial distributions of material properties are assumed to be stochastic fields. In addition, the adaptive importance sampling method using the response surface technique is used to improve simulation efficiency. The method is found to provide appropriate information although the nonlinear limit state involves a large number of basic random variables and the failure probability is small. The probability of plastic local failures around an excavated area is effectively evaluated and the reliability for the limit displacement of the ground is investigated. It is demonstrated that the adaptive importance sampling method can be very efficiently used to evaluate the reliability of a large scale stochastic finite element model, such as the underground structures located in the multi-layered ground.
A Study for Reduction Strategy and Case Study of Contract Change Orders in Large Construction Project
Koo, Jai-Dong ; Woo, Jong-Tae ; Yang, Tae-Seon ;
Journal of The Korean Society of Civil Engineers, volume 19, issue 1_6, 1999, Pages 951~951
Contract change orders are occurred by various causes and problems because of conditions project work conditions for executing construction project. This paper deals with reduction strategy in order to minimizing contract change orders of construction project by case study for reduction of contract change orders in large construction project. Especially, we have studied and taken a model of focus on subway construction project. Also this paper deals with contract change orders of main causes and problems occurs undertaking subway construction project, for examples, short of survey durations and design durations in construction project, low price tender contracts of design fees, unsatisfied review design products. Thus, this paper were suggested, introduction and sellection to minimize contract change orders undertaking construction project, to garrantee of sufficient design fees and design durations in construction project, to meet needs clear definition of design scope and liability scope, in order to taking a qualified with design products and construction project. Also, this paper was insisted upon planning stage, survey stage, design stage in construction project stages.