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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Steel Construction
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Journal DOI :
Korean Society of Steel Construction
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Volume & Issues
Volume 11, Issue 6 - Dec 1999
Volume 11, Issue 5 - Oct 1999
Volume 11, Issue 4 - Aug 1999
Volume 11, Issue 3 - Jun 1999
Volume 11, Issue 2 - Apr 1999
Volume 11, Issue 1 - Feb 1999
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An Image Processing Algorithm for a Visual Weld Defects Detection on Weld Joint in Steel Structure
Seo, Won Chan ; Lee, Dong Uk ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 1~11
The aim of this study is to construct a machine vision monitoring system for an automatic visual inspection of weld joint in steel structure. An image processing algorithm for a visual weld defects detection on weld bead is developed using the intensity image. An optic system for getting four intensity images was set as a fixed camera position and four different illumination directions. The input images were thresholded and segmented after a suitable preprocessing and the features of each region were defined and calculated. The features were used in the detection and the classification of the visual weld defects. It is confirmed that the developed algorithm can detect weld defects that could not be detected by previously developed techniques. The recognized results were evaluated and compared to expert inspectors' results.
A Program for Distortional Analysis of Steel Box Girder Bridges
Lee, Hee Up ; Yang, Chang Hyun ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 13~22
The objective of this paper is to develop a program for distortional analysis of steel box girder bridges. This program is formulated by using MSDM(modified slope deflection method). Two examples are carried out to verify the validity of the developed technique and its computation procedures. The analyzed results are compared with the previously proposed methods, BEF(beam on elastic foundation) and EBEF(equivalent beam on elastic foundation). The BEF method is limited only to prismatic straight box girders. In the EBEF method, stiffness of the intermediate diaphragms is infinitely considered. On the other hand, stiffness of the intermediate diaphragms is idealized as spring contant in this study. And then, nonprismatic straight box girders can be analyzed using the same procedure. Therefore, the comparison shows that the MSDM algorithm proposed in this paper is more efficient and reliable. Also parametric studies are perfomed using the proposed algorithm.
Accuracy Evaluation of Alternative Concept Joint Models
Lee, Kwang Ju ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 23~31
The concept models are used for the analysis of joints because they are simple to use and accurate. The modeling parameters of concept models are estimated using the results of experiments performed on the joints. The concept joint models accurately describe the behavior of joints under the loads which are used in the experiments for the estimation of parameters. However, they may not be accurate under the loads which are not used in the experiments. The accuracy can be dependent on the loads which are used in the evaluation of accuracy. In this study, antioptimization is presented to find the worst possible loads, under which the accuracy of concept joint models can be evaluated. The procedure was applied to the accuracy evaluation of concept joint models in an isolated 3-D joint and 2-D joints of a vehicle structure.
Behavior of the Crack Initiation, Transition and Fatigue Crack Growth of Rail Steel
Lee, Jong Sun ; Kang, Ki Weon ; Choi, Rin ; Kim, Jung Kyu ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 33~42
In the present study, crack initiation criteria, static failure and tensile mode fatigue behavior for a rail steel are evaluated to assure the railway vehicle's safety. The transverse fissure, which is the most critical damage in the rail, is initiated by the maximum shear stress and its location is subsurface. In addition, the possibility of transition from the shear mode to the mixed mode increases with increasing the length of subsurface crack. Because of the brittleness by the welding, the fracture toughness of the welded part is lower than of the base metal. For low
, the stage II fatigue crack growth rates of the welded part is slower than of the base metal but, for high
, this different behavior for fatigue crack growth rate is nearly diminished. These trends are more remarkable for low stress ratio, R=0.1. It is believed that this behavior is caused by the change of the microstructure which that of the welded part is coarser than of base metal.
An Experimental Study on the Prediction of Yield Load Using Ring Analysis Method in Circular Tubular X-Type Cross Sections
Park, Il Min ; Na, Seon Hong ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 43~54
The divergence connection between steel circular tubes is widely used in such structures as factory facilities, steel circular hollow section truss, and off-shore tower. Steel circular hollow section (SCHS) have close section, and it makes their per-unit production expense higher than open sectioned products like L-shape, H-shape steels, but the sectional resistance of SCHS against vertical compression and torsion is very high. Despite the structural merits of SCHS, however, many engineers dislike to use them in their design because of uncertainty regarding the stress distribution and deformation behavior at their connections. Therefore, this thesis dealt with X-type connections, the most common forms of connection, and studied their load-deformation relationship. It observed how to show the load-deformation relationship at steel circular tube connections according to the diameter-thickness ratio (D/T) of the chord and diameter of branch-diameter of chord ratio (d/D) and suggested prediction yield load using by ring analysis method.
Bending, Free Vibration and Buckling Analysis of Anisotropic Composite Laminated Plate and Shell Structures
Yoon, Seok Ho ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 55~67
The ratios of elastic to shear modulus of the structures as laminated composite plates and shells, are very large. They are much susceptible to effect of shear deformation. In order to obtain the accurate solutions of laminated composite plate and shells, the effects of shear strain should be considered for the analysis and design of them. Especially, the more exact solution can be obtained in applying to higher-order shear deformation theory. Therefore, in this paper, the third-order shear deformation theory is used to present the distributions of bending, the characteristics of natural frequencies and the buckling load according to the effects of ply orientation, number of layers for the laminated composite plates and shells with simply supported boundary conditions.
Evaluation of the Lateral Ultimate Strength of Steel Moment Resisting Frames under Axial and lateral Forces
Kim, Jong Sung ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 69~78
When the lateral forces are applied to a frame, columns in the frame are usually accompanied with sidesway. If this sidesway is large, the frame is subjected to buckling and an early yielding of members which reduces the overall frame stiffness. In this study, numerical analysis of frames were conducted to evaluate the ultimate lateral strength of steel moment resisting frames permitted to sidesway under axial and lateral forces, and develope the procedure for determining the limits of column slenderness ratios. In the numerical analysis, the effects of the relative stiffness ratio between beam and column, deterioration of overall frame stiffness, slenderness ratio and loading conditions were considered. The elasto-plastic analysis method in which the
effect is implemented, presented by the author previously, was adopted in the analysis. Incremental lateral forces were applied to the frame under constant axial loads and the generalized inverse is employed for the post-ultimate behavior.
Damage Assessment of Steel Box-girder Bridge using Neural Networks
Lee, In Won ; Oh, Ju Won ; Park, Sun Kyu ; Kim, Ju Tae ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 79~88
Damages of a steel box girder bridge are detected using neural networks. Damage detection using neural networks has increasing momentum in structural engineering. It is a new effort to overcome the limitations of the conventional analytical approaches and applied to the damage detection of a steel box-girder bridge. Data sets for training neural networks are obtained from the acceleration response of the bridge under moving load. Finite element model is first defined and damages of 5, 10, 15 and 20% are assumed in the model. Not only the trained damages but untrained damages are detected in the assessment stage. The untrained damages can be detected with acceptable errors. Because the number of damaged locations are limited to a few parts, more researches are needed to put this technique into practice.
Strength of Concrete-Filled Rectangular Steel Tubular Columns
Yoo, Yeong Chan ; Moon, Tae Sup ;
Journal of Korean Society of Steel Construction, volume 11, issue 1, 1999, Pages 89~98
The objective of this paper is to investigate the structural behavior of concrete filled steel tubular columns subjected to eccentric load. With experiment and analytical study, the buckling behavior of columns is investigated and compared with each other to the view of main parameters. Appling foreign standards in the experimental results, we suggested new strength formula of concrete-filled steel tubular columns. The parameters are slenderness, eccentric ratio, and concrete filled or not. The experiment are carried out by simple loading.