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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 30, Issue 6D - Dec 2010
Volume 30, Issue 6C - Dec 2010
Volume 30, Issue 6B - Dec 2010
Volume 30, Issue 6A - Dec 2010
Volume 30, Issue 5D - Oct 2010
Volume 30, Issue 5C - Oct 2010
Volume 30, Issue 5B - Oct 2010
Volume 30, Issue 5A - Oct 2010
Volume 30, Issue 4D - Aug 2010
Volume 30, Issue 4C - Aug 2010
Volume 30, Issue 4B - Aug 2010
Volume 30, Issue 4A - Aug 2010
Volume 30, Issue 3D - Jun 2010
Volume 30, Issue 3C - Jun 2010
Volume 30, Issue 3B - Jun 2010
Volume 30, Issue 3A - Jun 2010
Volume 30, Issue 2D - Apr 2010
Volume 30, Issue 2C - Apr 2010
Volume 30, Issue 2B - Apr 2010
Volume 30, Issue 2A - Apr 2010
Volume 30, Issue 1D - Feb 2010
Volume 30, Issue 1C - Feb 2010
Volume 30, Issue 1B - Feb 2010
Volume 30, Issue 1A - Feb 2010
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Nonlinear Analysis of Concrete Girders Strengthened with Unboded Prestressed CFRP Plates
Choi, Kyu-Chon ; Lee, Jae Seok ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 495~502
A study for the nonlinear analysis method of flexural behavior of concrete girders strengthened with unbonded prestressed CFRP plates is presented. The concrete girders strengthened with unbonded prestressed CFRP plates exhibit more complex nonlinear behavior due to the slip between the concrete girder and the CFRP plates than the case of bonded CFRP plates. The unbonded CFRP plate is modeled as an assemblage of the curved elements both ends of which are rigidly linked to the nodes of fibered frame elements. The slip effect of the unbonded CFRP plate is taken into account using the force equilibrium relationship at each node. To evaluate the validity and the capability of the proposed analysis method, the ultimate analysis results of the concrete beams strengthened with unbonded prestressed CFRP plate are compared with the experimental results obtained from other investigators. The proposed analysis method is found to predict ultimate behaviors of these beams fairly well. Additionally the time-dependent deformations of the concrete beam seems to have little influence on the ultimate behaviors of concrete beams strengthened with unbonded prestressed CFRP plate, and the cracks of the concrete beam which occurred before strengthening it with CFRP plate are found to have almost no influence on the ultimate capacity of the beam.
A Study on Compact Section Requirements for Plate Girder Web Panels with Longitudinal Stiffeners
Lee, Myung Soo ; Lee, Doo Sung ; Lee, Sung Chul ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 503~512
In AASHTO LRFD (2007), a compact section is defined as a section in which no premature failure caused by local buckling of web and flange plate or later buckling occurs before the section reaches the plastic moment, Mp. The current AASHTO LRFD (2007) provides the compact section requirement by limiting the web slenderness only for webs without longitudinal stiffeners. The role of longitudinal stiffener is to increase the web buckling strength caused flexure. Although a web does not satisfy the compactness requirement without longitudinal stiffeners, the web buckling can be prevented by use of valid longitudinal stiffeners. Therefore, the web may be able to reach the plastic moment. However, the reason why a longitudinal stiffener may not be used to satisfy compactness requirement is not cleary explained in AASHTO LRFD (2007). In this study, the buckling and ultimate strength behaviors of stiffened webs subjected to bending are investigated through the linear buckling and nonlinear finite element analysis. It is found that steel plate girders having webs that do not satisfy the compactness requirement are able to reach the plastic moment if the longitudinal stiffeners have sufficient rigidities and are properly located. From a nonlinear regression analysis of the results, a new compactness requirement is suggested for webs stiffened with one longitudinal stiffener.
Evaluation of Flexural Ductility of Negative Moment Region of I-Girder with High Strength Steel
Joo, Hyunsung ; Moon, Jiho ; Choi, Byung-Ho ; Lee, Hak-Eun ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 513~523
For continuous I-girder bridges, a large negative bending moment is generated near pier region so that plastic hinge is first formed at this point. Then, the bending moment is redistributed when the I-girder has enough flexural ductility (or rotational capacity). However, for I-girder with high strength steel, it is known that the flexural ductility is considerably decreased by increasing the yield strength of material. Thus, it is necessary to conduct a study for guaranteeing proper flexural ductility of I-girder with high-strength steel. In this study, the evaluation of flexural ductility of negative moment region of I-girder with high strength steel where yield stress of steel is 680 MPa is presented based on the results of finite element analysis and experiment. From the results, it is found that the flexural ductility of the I-girder is significantly reduced due to the increase of elastic deformation and the decrease of plastic deformation ability of the material when the yield strength increases. In this study, the method to improve the flexural ductility of I-girder with high strength steel is proposed by an unequal installation of cross beam and an optimal position of cross beam is also suggested. Finally, the effects of the unequal installation of cross beam on the flexural ductility are discussed based on the experimental results.
Performance Evaluation for All-In-One Construction Method of Curbstone and Gutter Using Formwork Rail and Jig
Choi, Jae-Jin ; Ko, Man-Gi ; Kim, Kyoung-Ju ; Choi, Khyung-Dong ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 525~534
A road curbstone is a structure installed at the boundary of the sidewalk and the street with the objectives of road drainage, drawing attention and such. The current general construction method of curbstones places foundation concrete for the curbstones first, waits until the concrete reaches the strength to support the curbstones, places the curbstones on top, and then places the gutter and rear filling concrete. Such method has the issues of poor compaction and weakened bond strength of concrete due to split placing of concrete, and causes the curbstones to easily separate due to vehicle impact or earth pressure, in turn creating maintenance costs and spoiling the aesthetics. To improve such conventional construction methods, an all-in-one method was developed using formwork rail and jig where both the curbstones and gutter can be worked at the same time, and to evaluate the structural performance, static tests of lateral loading test, pullout test, and bending test were executed, and dynamic tests such as pendulum test and actual vehicle impact test were executed. In all tests, the all-in-one construction method using formwork rail and jig was shown to be superior to the conventional construction method by the increase of construction quality and bond strength of concrete.
Comparison of Measured Natural Frequencies of a Railway Bridge Specimen Between Different Excitation Methods
Kim, Sung-Il ; Lee, Jungwhee ; Lee, Pil-Goo ; Kim, Choong-Eon ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 535~542
Precise estimation of a structure's dynamic characteristics is indispensable for ensuring stable dynamic responses during lifetime especially for the structures which can experience resonance such as railway bridges. In this paper, the results of forced vibration tests of different excitation methods (vibration exciter and impact hammer) are compared to examine the differences and the cause of differences of extracted natural frequencies. Consequently a natural frequency modification method is suggested to eliminate effects of non-structural disturbance factors. Also, sequential forced vibration tests are performed before and after track construction according to the construction stage of a railway bridge, and the variation of natural frequencies are examined. Effect of added mass of vibration exciter and variation of support condition due to the level of excitation force are concluded as the major cause of natural frequency differences. Thus eliminating these effects can enhance the reliability of the extracted natural frequencies. Construction of track affects not only the mass of structure but also the stiffness of the structure. Also, the amount of increase in stiffness varies according to the level of structural deflection. Therefore, reasonable estimation of the level of structural response during operation is important for precise natural frequency calculation at design phase.
Evaluation of Local Effect Prediction Formulas for RC Slabs Subjected to Impact Loading
Chung, Chul-Hun ; Choi, Hyun ; Lee, Jung Whee ; Choi, Kang Ryong ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 543~560
Safety-related concrete structures in a nuclear power plant must be protected against the impact of flying objects, referred to in the profession as missiles. In practice, the structural verification is usually carried out by means of empirical formulas, which relate the velocity of the impinging missile to the wall thickness needed to prevent scabbing or perforation. The purpose of this study is to reevaluate the predictability of the local effect prediction formulas for the penetration and scabbing depths and perforation thickness. Therefore, available formulas for predicting the penetration depth, scabbing thickness, and perforation thickness of concrete structures impacted by solid missiles are summarized, reviewed, and compared. A series of impact analyses is performed to predict the local effects of the projectile at impact velocities varing from 95 to 215 m/s. The results obtained from the numerical simulations have been compared with tests that were carried out at Kojima to validate numerical modelling. The simulation results show reasonable agreement with the Kojima test results for the overall impact response of the RC slabs. From these results, it seems that the Degen equation give a very good estimate of perforation thickness against a tornado projectile for test data. Finally, the results obtained from the impact analysis have been compared with Degen formula to determine the perforation thickness of the RC slab.
Application of Performance Based Mixture Design (PBMD) for High Strength Concrete
Kim, Jang-Ho Jay ; Oh, Il Sun ; Phan, Duc Hung ; Lee, Keun Sung ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 561~572
This paper is a study about application of recently proposed Performance Based Mixture Design (PBMD) for design of high strength concrete (HSC) to obtain HSC mix proportion that satisfies required performances. The PBMD method which uses Satisfaction curve based on a Bayesian method is a performance oriented concrete mix proportion design procedure easily applicable to any condition and environment for a possible replacement to the current prescriptive design standards. Based on extensive experimental results obtained for various materials and performance parameters of HSC, the application feasibility of the developed PBMD procedure for HSC has been verified. Also, the proposed PBMD procedure has been used to perform application examples to obtain desired target performances of HSC with optimum concrete mixture proportions using locally available materials, local environmental conditions, and available concrete production technologies. The validity and precision of HSC mix proportion design obtained using the PBMD method is verified with the experimental and ACI presented results to check the feasibility for actual design usage.
The Quality Properties of Self Consolidating Concrete Using Lightweight Aggregate
Kim, Yong Jic ; Choi, Yun Wang ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 573~580
This paper presents the development of self-consolidating concrete (SCC) using lightweight aggregates. SCC using Lightweight aggregate properties have been evaluated in terms of flowability, segregation resistance and filling capacity of fresh concrete as per the standards of the Japanese Society of Civil Engineering (JSCE). The measurement of the mechanical properties of hardened SCC using lightweight aggregate, including compressive strength, splitting tensile strength, elastic moduli and density, as well as its dry shrinkage and carbonation properties were also carried out. The characteristics of SCC using lightweight aggregate at the fresh state showed that as the use of the lightweight aggregate, the flowability improves without exception of Mix No. 9 but the segregation resistance tends to decrease without exception of Mix No. 3, 4 and 5. The 28 days compressive strength of the SCC using lightweight aggregate was found to be 30 MPa or higher. The relationship between the compressive strength and the splitting tensile strength was found to be similar to the expression presented by CEB-FIP, and the relationship between the compressive strength and the elastic moduli was found to be similar to the expression suggested by ACI 318-08 which takes into consideration the density of concrete. The density of the SCC using lightweight aggregate decreased by up to 26% compared to that of the control SCC. Also, The dry shrinkage and carbonation depth of the SCC using lightweight aggregate increased compared to that of the control SCC.
Layered Section Analysis for PSC Girder with Variable Cross Section Using SI Technique
Kim, Byeong Hwa ; Park, Taehyo ; Jeon, Hye-Kwan ;
Journal of The Korean Society of Civil Engineers, volume 30, issue 6A, 2010, Pages 581~590
This study introduces a layered sectional analysis for a PSC girder with a vaiable cross section and curved tendons. To consider the shear equilibrium at a concrete layer with curved tendons, the shear stress distribution has been computed at each section. In addition, to improve the convergence to the solution, a system identification technique is newly adopted in the solution process for strain computation. To examine the feasibility of the proposed approach, a static load test has been conducted for a full scale PSC girder with variable cross section. The prediction shows a good agreement with experiment. It is seen that a uniform cross section has the same moment capacity with a variable cross section while the variable cross section has more shear capacity than the uniform cross section. It is also noted that the maximum displacement of a variable cross section is a little smaller than a uniform cross section.