• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.445-452
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• 2005

This paper presents a design method to minimize Life Cycle Cost (LCC) of steel box girders. The LCC considered in this paper includes initial cost, expected life-cycle maintenance cost and repair cost. A load carrying capacity curve is derived from a condition grade curve of steel girders and load tarrying capacity that is measured in safety diagnostic test. And then, optimal design of steel box girders is performed on the basis of load carrying capacity curve. In this paper time and number of times for repair of steel girders are determined based on the calculated load carrying capacity curve. Also, annual costs considering real discount rate are compared and analyzed in various cases. It is concluded that the optimal design of steel box gilders considering LCC by the presented method will lead to more economical and safer girders than conventional design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1327-1336
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• 2013

In this study, the effects of corrugated webs on the ultimate behavior of horizontally curved I-shaped girders are investigated. Because of the geometric characteristics of corrugated plates, corrugated webs can be used for enhancing torsional and warping stiffness of plate girders. Many researches have been conducted to study the effects of corrugated webs on the ultimate behavior of straight girders. But, the studies of the ultimate behavior of horizontally curved girders with corrugated webs, which generally show out-of plane behavior manly, have been rarely performed so far. By performing inelastic-nonlinear analysis, the ultimate behavior of curved girders with corrugated webs is studied in this paper. Laterally unsupported length and subtended angle of girders, and length of height of corrugation of webs are considered as the geometric parameters which would be expected to affect the ultimate behavior. By this analytical study with considering the geometric parameters, the changes of ultimate behavior and load carrying capacity of curved girders with corrugated webs are investigated. Also, the effects of corrugated webs on the increase of load carrying capacity for curved girders are studied with comparing to the capacity of general curved girders with flat webs. According to the analytical results, corrugated webs can be used to increase the ultimate load carrying capacity of curved girders, because of their high torsional and warping stiffness. But, it is also indicated that they may decrease the load carrying capacity of curved girders which have relatively small subtended angle or initial curvature, because of an accordion effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6385-6390
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• 2015

With bending moment, torsional moment due to geometric properties as "Initial curvature" acts in horizontally curved I-girder. These behavior causes the secondary effect of bending in minor-axis because of interaction between bending and torsion. The bending and torsion interaction cause a loss of load bearing capacity by induced the early inelastic or plasticity condition in curved girder. Also eccentric load by movements of traffic can increase torsion. However, Equation of interaction between bending and torsion for straight girder, not deal with characteristics of curved girder behavior in previous studies, can be overestimated for ultimate strength in horizontally curved I-girder acting vertical force. Therefore, using more rational, obvious suggestion is required when design curved girder. In this study, we identified the bending-torsional moment interaction for the horizontally curved I-girder of the eccentric load acting by FEM analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.169-179
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• 2005

An improved method for evaluating effective buckling lengths of beam-column members in plane frames is newly proposed based on system inelastic buckling analysis. To this end, the tangent stiffness matrix of be am-column elements is first calculated using stability functions and then the inelastic buckling analysis method is presented. The scheme for determining effective length of individual members is also addressed. Design examples and numerical results ?uc presented to show the validity of the proposed method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.159-170
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• 2005

The grid structure is parallel main girders intersected with crossgirder. It distribute the loads to adjoining main girder through the crossgirder when a girder is subjected to a load. grillage girder bridge has high load-carrying capacity, it can save materials and become more economical type of bridge. In this paper, the grillage girder bridge analysis program developed by using the transfer matrix method deals with following problems: the comparision with Leonhardt, Szabo, FEM yang and jung in the analysis of grillage girder bridges, quality of straight and curved bridges with skew angle, forces of straight and curved bridges according to skew angle and bending stiffness/torsional stiffness ratio.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.95-105
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• 2014

Reinforced concrete (RC) shield tunnel lining must be designed for fireproof performance because the lining is sometimes exposed to very high temperature due to traffic accidents. Both experimental and numerical studies are carried out to evaluate fire resistance performance of precast RC tunnel lining systems. In the experimental studies, six full-scale precast RC tunnel segments are exposed to fire in order to examine the influence of various parameters on the fire resistance performance of precast RC tunnel lining. We used the temperature curve of the RABT criteria, which are severe conditions of fire temperatures. The fire test showed that the explosive spalling was not observed by substituting concrete to PP fiber reinforced concrete. A transient heat flow analysis was carried out in consideration of the material properties that change with temperature, and the results showed good agreement with the test results.

• Journal of Korean Society of Steel Construction
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• v.9 no.1 s.30
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• pp.51-63
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• 1997

Highly curved steel-box bridges are usually constructed as ramp structures for the highway interchange and metropolitan elevated highway junction, but a number of these bridges are deteriorated and damaged to a significant degree due to heavy traffic. The main objective of the study is to develop a practical reliability-based assessment of safety and residual load carrying-capacity of existing curved steel-box ramp bridges. In the paper, for the realistic assessment of safety and residual load carrying-capacity of deteriorated and/or damaged curved steel-box bridges, an interactive non-linear limit state model is formulated based on the von Mises's combined stress yield criterion. It is demonstrated that the proposed model is effective for the assessment of reliability-based safety and the evaluation of residual load carrying-capacity of curved steel-box bridges. In addition, this study comparatively shows the applicability of various reliability analysis methods, and suggests a practical and effective one to be used in practice.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.477-483
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• 2007

In this study, the numerical fire analysis for temperature distribution and spalling behavior of underground concrete box structures that contained lifelines, such as power cables and communication cables. The temperature field of inner space was assumed based on the fire curve with the thermal gradient obtained from CFD analysis. It was assumed that the spalling behaviors of concrete are occurred when the concrete temperature reached the threshold, as dehydration degree. In this case, the elements correspond to spalling parts were removed and the analysis model were updated. Three fire scenarios were analyzed and the results were showed adequate spalling behavior. The bearing capacities of the box structures would be estimated in the companion paper.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.194-200
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• 2010

Recently, a longitudinal tunnel construction has increased because of subway construction extension, geomorphological effect and the development of construction Technologies etc. When the fire occurs in a tunnel and an underground structure, the many damage of human life and the economic losses are caused. In Korea, fire resistance character study of a tunnel and an underground structure is proceeding. However, when a concrete is exposed to high temperature, study of load carrying capacity reduction and stability evaluation for spalling of a concrete is not enough. Therefore in this study, fire resistance character of a concrete evaluated according to time heating temperature curve(RABT and RWS) and a result compared on virtual fire accident in order to apply fire scenario. Also this study performed thermo-mechanical coupled analysis of a FEM-based numerical technique and estimated fire-induced damage of a tunnel and an underground structure.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.237-240
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• 2008

Today, some bridges or highways are becoming superannuated in Korea. Also, in this section, rehabilitation, replacement and expansion are necessary to increasing traffic volumes these days. Bridge reconstruction is major problem because it has relation to civil application, economical loss and loss of vehicles made a detour while this work. Many precast components and methods of construction are developed for this issue. Many research of various precast components and new materials are being performed owing to apply to prefabrication bridges. The present paper represents experimental studies on the performance of precast CFFT pier model. Also, stay-in-place RC pier and stay-in-place CFFT pier are made an experiment on due to comparing test results. Hysteretic responses of all columns are obtained through the test. Compared with the displacement ductility factors, conclusions of seismic performances can be made.