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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 28, Issue 6D - Nov 2008
Volume 28, Issue 6C - Nov 2008
Volume 28, Issue 6B - Nov 2008
Volume 28, Issue 6A - Nov 2008
Volume 28, Issue 5D - Sep 2008
Volume 28, Issue 5C - Sep 2008
Volume 28, Issue 5B - Sep 2008
Volume 28, Issue 5A - Sep 2008
Volume 28, Issue 4D - Jul 2008
Volume 28, Issue 4C - Jul 2008
Volume 28, Issue 4B - Jul 2008
Volume 28, Issue 4A - Jul 2008
Volume 28, Issue 3D - May 2008
Volume 28, Issue 3C - May 2008
Volume 28, Issue 3B - May 2008
Volume 28, Issue 3A - May 2008
Volume 28, Issue 2D - Mar 2008
Volume 28, Issue 2C - Mar 2008
Volume 28, Issue 2B - Mar 2008
Volume 28, Issue 2A - Mar 2008
Volume 28, Issue 1A - Jan 2008
Volume 28, Issue 1D - Jan 2008
Volume 28, Issue 1C - Jan 2008
Volume 28, Issue 1B - Jan 2008
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Experimental Study on Tensile Fatigue Strength of the High Strength Bolts
Han, Jong Wook ; Park, Young Suk ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 165~170
New high strength bolts are required due to the development of the high strength steel, the ultra-thick steel plates, and the long-span bridge, though high strength bolts with tensile strength of 1,000 MPa are mainly used in construction site of every country. The high strength bolts are often subjected to a repeated tension-type of loading in which the fatigue failure is a major mode of failure. However, the theoretical and experimental study for the fatigue failure of tension bolt has not been well established in Korea. In this study, we performed a tensile fatigue test of F8T, F10T and F13T, F13T-N high strength bolts under tension. We proposed three fatigue strength specifications by performing 95% survival probability analysis for F8T, F10T, F13T, and F13T-N bolt under the
cycles of repeated loading. And the fatigue strength for the advanced screw thread shape bolt developed in this study are compared with the previous KS screw thread shape bolt.
Nonlinear Dynamic Behavior of Temporary Rail Considering the Effect of Vibration
Lim, Hyung Joon ; Ryu, Dong Hyeon ; Won, Jong Hwa ; Kim, Moon Kyum ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 171~178
The object of this study is to propose a rate of vibration increase in the analysis of temporary rail non-fixed in the vertical direction and characterize the nonlinear dynamic behavior of temporary rail while considering longitudinal and latitudinal load, vibration and lifting. The rate of vibration increase is proposed through measurement of an actual structure that is largely affected by loading and vibration of the superstructure. Dynamic behavior was additionally characterized by the dynamic response resulting from nonlinear dynamic finite element analysis with vehicle loading, including the rate of vibration increase. As a result, the rate of vibration increase by the vibration of an Auto Bar Machine is determined as 7% and the maximum stress in the analysis of the nonlinear rail is increased 14.5% over that of linear rail, and temporary rail is shown to be very sensitive to the velocity of the superstructure.
Evaluation on the Edge Stiffening Affect of Composite Girder Bridge
Sung, Ki Tae ; Park, Young Hoon ; Lee, Seung Yong ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 179~186
To analyzing the validity for using the stiffness ratio in evaluating edge stiffness effect of the composite girder bridges, modification factors are analyzed with changing girder spacing. The relation between stiffness ratio, loading type, girder spacing and modification factors is analyzed. From the results of comparing modification factors analyzed from the field loading test and the established design method with the modification factor analyzed from this study, it was concluded that evaluating the edge stiffness effect using stiffness ratio is possible.
Punching Shear Strength of RC Slabs by Simple Truss Model
Lee, Yongwoo ; Hwang, Hoonhee ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 187~196
The punching shear strength of RC slabs is estimated analytically by the simple truss model. To avoid intrinsic difficulties in punching shear analysis of reinforced concrete slabs, the slabs were divided into three sub-structures as the punching cone and the remaining parts. The strength of the punching cone was evaluated by the stiffness of inclined strut. The stiffness of springs which control lateral displacement of the roller supports consists of the steel reinforcement which passed through the punching cone. Initial angle of struts was determined by curve fitting method of the experimental data with variable reinforcement ratio in order to compensate for uncertainties in the slab's punching shear, the simplification errors and the stiffness of the remaining sub-structures. The validity of computed punching shear strength by simple truss model was shown by comparing with experimental results. The punching shear strength, which was determined by snap-through critical load of shallow truss, can be used effectively to examine punching shear strength of RC slabs.
Statistical Estimation of Wind Speed in the Gwangyang-Myodo Region
Bae, Yong Gwi ; Han, Gwan Mun ; Lee, Seong Lo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 197~205
In order to estimate mean wind speed in the Gwangyang-Myodo Region, the probability distribution model of extreme values has been used in the statistical analysis of joint distribution probability of daily maximum wind speed and corresponding direction in this paper. For this purpose frequency of daily maximum records at respective stations is inquired into and sample of largest yearly wind speed of sixteen compass direction and non-direction is extracted from daily data of maximum wind speed and appropriate direction of the meteorological observing stations nearby the bridge construction site. These extreme speed records are applied to Gumbel and Weibull distribution model and parameters are estimated through method of moment and method of least squares etc. And also, distribution and parameters are inquired into whether it is fitted through the probability plot correlation coefficient examination. From fitted parameters the largest yearly wind speed of sixteen compass direction and non-direction is extrapolated taking into account factors regarding sample size of data and distance from the bridge construction site according to the appropriate stations.
Developments of Advanced Connection Type for Improvements of Mixed Structures (II)
Yun, Ik Jung ; Lho, Byeong Cheol ; Kim, Moon Kyum ; Cho, Sung Young ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 207~214
This study presents a way to validate the quality level of the proposed connection type and verify the experimental test, and performs a 3D nonlinear analysis corresponding to the experimental test. Two mixed-structure beams were cast and tested under a four-point static loading. Force-displacement relation, force-strain relation, force-opening width, and failure mode were observed from comparing the numerical results of the adopted FE model. Nonlinear analysis of mixed structures was carried out by utilizing the contact elements of a general purpose structural analysis computer program (ABAQUS). The results of numerical and experimental simulation show that the proposed L-shaped connection has greater stiffness under flexural loading and better structural performance with regard to the connection.
Estimating Tensile Force of Hangers in Suspension Bridges Using Frequency Based SI Technique : III. Experimental Verification
Jang, Han Teak ; Kim, Byeong Hwa ; Park, Taehyo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 215~222
This paper introduces an experimental verification of a tension estimation method based on system identification approach for a double hanger system on a suspension bridge. A laboratory model of such double hanger system has been made for this study. Total nine cases of the vibration tests have been conducted with respect to three levels of applied tension and three cases of the location of clamp. For a set of the collected acceleration response data, modal analysis has been followed in order to extract the natural frequencies and mode shapes of the selected cable systems. For the extracted modal parameters, the existing tension estimation methods based on the string theory and axially loaded beam theory have been firstly applied to estimate the tensile force on the double hanger cable system. Next, the tensile force on cables has been estimated by the system identification approach. It is seen that the errors in the tension estimation using the frequency-based system identification technique are about 3% for all cases while the estimation error using the existing method is up to 53.1%.
Maintenance Planning for Deteriorating Bridge using Preference-based Optimization Method
Lee, Sun-Young ; Koh, Hyun-Moo ; Park, Wonsuk ; Kim, Hyun-Joong ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 223~231
This research presents a new maintenance planning method for deteriorating bridges considering simultaneously the minimization of the maintenance cost and maximization of the bridge performance. Optimal maintenance planning is formulated as a multi-objective optimization problem that treats the maintenance cost as well as the bridge performance such as the condition grade of the bridge deck, girder and pier. To effectively address the multi-objective optimization problem and decision making process for the obtained solution set, we apply a genetic algorithm as a numerical searching technique and adopt a preference-based optimization method. A numerical example for a typical 5-span prestressed concrete girder bridge shows that the maintenance cost and the performance of the bridge can be balanced reasonably without severe trade-offs between each objectives.
IBS Beam Element for Nonlinear Seismic Analysis of Steel Moment Frames
Kim, Dal Sung ; Kim, Dong Seong ; Kim, Kee Dong ; Ko, Man Gi ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 233~242
This study presents a non-prismatic beam element for modeling the elastic and inelastic behavior of steel beams, which have the post-Northridge(cover plate) connections in steel moment frames that are subjected to earthquake ground motions. The elastic stiffness matrix for non-prismatric members with increased beam section (IBS) connection is in the closed-form. The plasticity model is of a discrete type and is composed of a series of nonlinear hinges connected by rigid links. The hardening rules can model the inelastic behavior for monotonic and random cyclic loading, and the effects of local buckling. Moreover the determination of yield surfaces, stiffness parameters, and hardening (or softening) rule parameters for IBS beam element were described. Analytical results of the IBS beam element show good correlation with test data and FEM results.
Time-dependent Analysis of Cracked Reinforced Concrete Sections with Biaxial Bending
Yang, Joo Kyoung ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 243~247
An analytical approach to calculate time-dependent stresses and strains in initially cracked reinforced concrete section with biaxial bending was proposed. The method utilized the aging coefficient approach of Bazant and the linear creep theory. The position of neutral axis and strain and stress distributions of cracked section after creep and shrinkage were determined from the requirements of strain compatibility and equilibrium of a section. With this proposed algorithm, examples were given for rectangular section and a comparative analysis for stress and strain was also made.
Correlation Between Flexural Toughness and Cracking Characteristics of Micro-fiber Reinforced Mortar According to Fiber Contents
Shin, Kyung-Joon ; Jang, Kyu-Hyou ; Kim, Eui Sung ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 249~257
Various methods have been used to reinforce the cementitious material such as mortar and concrete that have weak tensile strength. Major reinforcing method is to mix matrix with fibers which have strong tensile strength. Recently, micro-fiber reinforced mortar has been studied which removes coarse aggregate and uses micro-fiber with small diameter in order to homogenize the matrix properties and maximize the performance of fiber. Performance of micro-fiber reinforced mortar showing multiple cracking behavior is hardly represented only by the flexural toughness. Therefore, This paper reports the cracking behavior as well as mechanical behavior for various mixtures which have different fiber type and mixture proportions to find the proper parameter representing the cracking characteristic. Correlations between flexural toughness and various cracking characteristics such as cracking area, width and number are explored. As a result, it is found that flexural toughness, volume of fiber and number of cracks are suitable for representing the characteristics of micro-fiber reinforced mortar.
Load Distribution Ratios of Indeterminate Strut-Tie Models for Simply Supported RC Deep Beams - (I) Proposal of Load Distribution Ratios
Kim, Byung Hun ; Yun, Young Mook ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 259~267
The ultimate strengths of reinforced concrete deep beams are governed by the capacity of the shear resistance mechanism composed of concrete and shear reinforcing bars, and the structural behaviors of the beams are mainly controlled by the mechanical relationships according to the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strengths and complicated structural behaviors is presented for the design of simply supported reinforced concrete deep beams. In addition, a load distribution ratio, defined as a magnitude of load transferred by a vertical truss mechanism, is proposed to help structural designers perform the design of simply supported reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of a load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the prime design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete influencing the ultimate strength and behavior are reflected upon based on various and numerous numerical analysis results. In the companion paper, the validity of presented model and load distribution ratio was examined by employing them to the evaluation of the ultimate strengths of various simply supported reinforced concrete deep beams tested to failure.
Load Distribution Ratios of Indeterminate Strut-Tie Models for Simply Supported RC Deep Beams - (II) Validity Evaluation
Kim, Byung Hun ; Jeung, Chan Haek ; Yun, Young Mook ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 269~279
In this study, the ultimate strengths of 229 simply supported reinforced concrete deep beams tested to shear failure were evaluated by the ACI 318-05's strut-tie model approach implemented with the presented indeterminate strut-tie model and its load distribution ratio. The ultimate strengths of the deep beams were also estimated by the experimental shear equations, design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the present strut-tie model and its load distribution ratio was examined through the comparison of the strength analysis results classified according to the prime design variables of the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete.
A Development of Torsional Analysis Model and Parametric Study for PSC Box Girder Bridge with Corrugated Steel Web
Lee, Han-Koo ; Kim, Kwang-Soo ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 281~288
The Prestressed Concrete (hereinafter PSC) box girder bridges with corrugated steel webs have been drawing an attention as a new structure type of PSC bridge fully utilizing the feature of concrete and steel. However, the previous study focused on the shear buckling of the corrugated steel web and development of connection between concrete flange and steel web. Therefore, it needs to perform a study on the torsional behavior and develop the rational torsional analysis model for PSC box girder with corrugated steel web. In this study, torsional analysis model is developed using Rausch's equation based on space truss model, equilibrium equation considering softening effect of reinforced concrete element and compatibility equation. Validation studies are performed on developed model through the comparison with the experimental results of loading test for PSC box girder with corrugated steel webs. Parametric studies are also performed to investigate the effect of prestressing force and concrete strength in torsional behavior of PSC box girder with corrugated steel web. The modified correction factor is also derived for the torsional coefficient of PSC box girder with corrugated steel web through the parametric study using the proposed anlaytical model.
Failure and Flexural Behavior of Reinforced Concrete Beams Strengthened with CFRP Strips
Lim, Dong Hwan ; Park, Sung Hwan ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 289~295
The purpose of this study was to examine the flexural behavior of reinforced concrete beams strengthened with CFRP strips. A total of 12 rectangular beams were tested. Test variables in this study were the shapes, bonded length and the number of longitudinal layers of CFRP strips. From the experimental study, flexural capacity of the beams strengthened with CFRP strips significantly increased compared to the reinforced concrete beam without a CFRP strip. Maximum increase of ultimate strength was found about 120% more than the control beam. In this test, most of the strengthened beams failed suddenly due to the debonding of CFRP strips. It is also observed that the debonding of the strip was initiated in the flexural zone of the beam and propagated rapidly to the end of the beam. The ultimate tensile strains of CFRP strips in this test were occurred at the level of 36% of rupture tensile strength of the CFRP strip, and an analytical approach to compute the flexural strength of reinforced beams strengthened with CFRP strips based on the effective stresses was conducted.
Self-Healing Property of Hardened Cement Paste
Kim, Jae Young ; Byun, Seung Ho ;
Journal of The Korean Society of Civil Engineers, volume 28, issue 2A, 2008, Pages 297~304
It is well known that cracks in concrete decrease permeability and durability of concrete because cracks enhance the penetration of water or corrosive chemicals like as chlorides, carbon dioxides, sulfates and some others. But some of cracks in hardened cements may be sealed in case of contacting water. This phenomenon is called "self healing" and it has a close relation to hydration products newly formed on surfaces of cracks. Many studies on self healing in concretes commonly showed that CSH gel has been observed on crack surfaces. And some studies have reported that calcium hydroxides and ettringite were observed as well as CSH gel on crack surfaces. This study was carried out to investigate hydration products formed by self healing process and also examine the influence of waterproof admixture for concretes on self healing of cement. As a result of XRD, DSC, SEM and EDX analysis of crack surfaces, it was found that self healing of cement was related to CSH gel, calcium hydroxides and ettringite. And waterproof admixture increased fibrous (needle-like) hydration products which were in network form. It is estimated that such fibrous products are effective for self healing process of cement system.