• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.33-43
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• 2005

The girder wheel load distribution factors stated in the Korean Bridge Specification and AASHTO Standard Specifications do not account for the effect of skewness of plate girders, and very little research has been conducted on girder wheel load distribution factors. The purpose of the study is to propose load distribution factor formulas for skew plate girder bridges which comprise various parameters through structural analysis. To confirm the validity of finite element models used in this study analytic values are compared with the field test results. From the results it should be noted that span length is not such a dominant parameter compared with others. In view of better load distribution of interior girders, skew arranged cross beams or bracing are preferable, furthemore bracing system is more effective than cross beam system. By means of regression analysis on the basis of analytic results wheel load distribution factor formulas are proposed and compared with current codes.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.175-188
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• 2012

A parametric study for varying the radii of curvature is performed with a curved tub girder bridge having three continuous spans. The bracing forces of top lateral bracings from the results of numerical equations are compared to those of 3-dimensional finite element analyses. New modifying factors applicable in computing the nominal member forces of top lateral bracings were suggested. The numerical equations were derived based on one girder system, and it is shown that the numerical equations exhibit some errors compared with 3D FEA results. The main reason for this phenomenon lies on the number of girders. The twin girder system has an external cross-beam between inner and outer girder. It also has larger lateral stiffness than the single girder system. Finally, the distributions by the torsion, bending, distortion, and lateral loading of the top lateral bracing forces were presented in this paper.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.66-69
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• 2008

This study presents deflection analysis of long span structures for pedestrian bridge on crossroads. For long span structures, the size of structural members should be determined considering the esthetic view and vehicle below the structures. As a result, the slenderness ratio of members is increased and the structure may be suffered from significant deflection. The under-tensioned system on lower part of the structure, is applied in order to reduce the deflection and the size of members. In this regard, the under-tensioned system enables the load of upper parts to carη to the end of beam by means of tensional force in cable. In addition, effectiveness of under-tensioned system can be different depending on the size of cable, the number and spacing of posts. This study is performed with conforming the effect by analytical various parameters (size of cable, number and spacing of post). Dead and live loads is supposed to apply in the slab, and the analytical result by MIDAS program are presented addressing the effect of the under-tensioned system.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.23-29
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• 2002

Many of the bridge systems, including the girders and cross-beams, and concrete decks behave as the special orthotropic plates. Such systems with boundary conditions other than Navier or Levy solution types, or with irregular cross sections, analytical solution is very difficult to obtain. Numerical method for eigenvalue problems are also very much involved in seeking such a solution. A method of calculating the natural frequency corresponding to the first mode of vibration of beam and tower structures with irregular cross-sections was developed and reported by Kim in 1974. Recently, this method was extended to two dimensional problems including composite laminates, and has been applied to composite plates with shear deformation effects. In this paper, application of this method to the specially orthotropic laminated plates with various boundary condition is accomplished and the result of analysis is presented.

• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.243-251
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• 2016

Longitudinally structural cracks are sometimes observed in the pavement on steel plate deck bridges because traffic truck loadings can cause large local deformations of the thin deck plate stiffened by longitudinal and transverse beams. In this study, an improved finite strip method using flat-shell strip, prism, and link elements is presented to investigate local deformations of steel decks with pavements in which flexural and torsional stiffness effects of thin floor beams are rigorously taken into account. A simplified deck model extracted from steel plate-girder bridges is analyzed using the developed FSM and the commercial FE program, ABAQUS and also, their numerical results are compared and discussed.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.179-187
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• 2017

The design provisions for the maximum steel ratio in reinforced concrete flexural members is normally provided to ensure sufficient ductility and economy by steel yielding at member failure. In the Concrete Structural Design Code (2012), the maximum steel ratio is expressed in terms of a net strain in tensile steel, and leading to very high steel ratio in the case of using high strength materials. Thereby, this may result in difficulty to satisfy a required workability at concrete placing. On the contrary, in the Korean Highway Bridge Design Code (Limit State Design) the maximum steel ratio is given in terms of the maximum neutral axis depth ratio that is 0.4. From these results, a rational model for the maximum steel ratio is suggested so as to satisfy a ductility as well as a workability.

• Journal of Korean Society of Steel Construction
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• v.19 no.3
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• pp.281-290
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• 2007

In this paper, the dynamic behavior of a 12m plate girder railway bridge is analyzed using the commercial FEM program. A time history load is applied to a standard train load via the shape function ofthe beam element. In addition, lateral behavior characteristics were simulated using the Klingel sine movement. A feasibility study of the FEM program and an analysis were performed by comparing the displacement and the acceleration, from the experimental data and the results of the FEM analysis. the time history of the lateral and vertical displacements are reflected in the experimental results. Six kinds of reinforcements were studied from the effects of the displacement and the acceleration. The RF-1 model that was applied to the upper lateral bracing system, and the RF-3 model that reinforced the plate, turned out to be the most effective reinforcement methods with respect to weight limits and construction simplification.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.5
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• pp.68-79
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• 1998

In the years, the concern about high-strength concrete which is new material has been heightened as a result of active research and development. Recently, as the building structure has been being bigger, higher, longer and more specialized, the demand of material with high-strength concrete for building has been increasing. The demand of high -strength concrete is expected to increase with expansion of usage about the complex concrete structures such as bridge structure as well as nuclear plants, underground structures, hydraulic structures and arctic area sturctures. In this research, silica-fume was used as an admixture in order to get a high-strength concrete. Water/binder ration was limited no more than 18 percent and the amount of unit cement was increased. In this study, a number of trial in concrete mix was carried out to get optimal mix design, and the target slump with $10{\pm}2cm$ was set for in-situ construction. High-strength concrete with cylinder strength of 1,200kgf/$cm^2$ in the 28-days was produced and tested. The static test was carried out to measure the ultimate load, the initial load of flexural and diagonal cracking, crack patterns, fracture modes. The load versus strain and load versus deflection relations were obtained form the static test. The test results were compared with the shear strengths predicted by the equations of ACI code 318-89 and orther researchers. Based on the test results, shear strength equation of reinforced concrete beam using high strength concrete was proposed. Form an evaluation of the results of this experimental investigation, it was concluded that shear strength after diagonal tention cracking diminished with the increase in compressive strength for beams.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.293-303
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• 2005

The girder wheel load distribution factors stated in the Korean Bridge Specification and AASHTO Standard Specifications do not account for the effect of skewness of plate girders, and very little research has been conducted on girder wheel load distribution factors. The purpose of the study is to propose load distribution factor formulas for skew plate girder bridges which comprise various parameters through structural analysis. To comprise the validity of finite element models used in this study analytic values are compared with the field test results. From the results it should be noted that span length is not such a dominant parameter compared with others. In view of better load distribution of interior girders, skew arranged cross beams or bracing are preferable, furthemore bracing system is more effective than cross beam system. By means of regression analysis on the basis of analytic results wheel load distribution factor formulas are proposed and compared with current codes.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.201-204
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• 2008

The Sectional Design Model(AASHTO LRFD) is appropriate for the design of typical bridge girders, slabs, and other regions of components where the assumptions of traditional engineering beam theory are valid. The shear resistance of a concrete member may be separated into a component, $V_c$, that relies on tensile stresses in the concrete, $V_s$, that relies on tensile stresses in the transverse reinforcement. The expressions for $V_c$ and $V_s$ apply to both prestressed and nonprestressed section, with the terms ${\beta}$ and ${\theta}$ depending on the applied loading(M, V, N, and T) and the properties of the section. With ${\beta}$ taken as 2.0 and ${\theta}$ as 45$^{\circ}$, the expressions for shear strength become essentially identical to those traditionally used for evaluating shear resistance. Recent large-scale experiments, however, have demonstrated that these traditional expression can be seriously unconservative for large members not containing transverse reinforcement. And This paper can present only a brief introduction to shear design of AASHTO LRFD and is to review of the technical difficulty.