• Steel and Composite Structures
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• v.37 no.2
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• pp.117-136
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• 2020

Curved steel-concrete composite box girder has been widely adopted in urban overpasses and ramp bridges. In order to investigate its mechanical behavior under complicated and combined bending, shear and torsion load, two large-curvature composite box girders with interior angles of 25° and 45° were tested under static hogging moment. Based on the strain and deflection measurement on critical cross-sections during the static loading test, the failure mode, cracking behavior, load-displacement relationship, and strain distribution in the steel plate and rebar were investigated in detail. The test result showed the large-curvature composite box girders exhibited notable shear lag in the concrete slab and steel girder. Also, the constraint torsion and distortion effect caused the stress measured at the inner side of the composite beam to be notably higher than that of the outer side. The strain distribution in the steel web was approximately linear; therefore, the assumption that the plane section remains plane was approximately validated based on strain measurement at steel web. Furthermore, the full-process non-linear elaborate finite element (FE) models of the two specimens were developed based on commercial FE software MSC.MARC. The modeling scheme and constitutive model were illustrated in detail. Based on the comparison between the FE model and test results, the FE model effectively simulated the failure mode, the load-displacement curve, and the strain development of longitudinal rebar and steel girder with sufficient accuracy. The comparison between the FE model and the test result validated the accuracy of the developed FE model.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.527-537
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• 2007

The main girders and cross-beams of an H-beam bridge consisted of factory-made H-beams, providing better conditions for quality control. Also, on-site fabrication works can be minimized and most of the stiffeners can be omitted, enabling simple and economic construction. In this study, the effect of the Multi-Stepwise TPSM (M-TPSM) on improving the maximum span length and section efficiency is analyzed. Compared to a 30-m-long, five-girder conventional plate girder bridge, structural analysis results showed that 50.7~55.1% of the girder height and 24.1~26.2% of the self-weight may be reduced by the application of M-TPSM to a five-girder H-beam bridge constructed with H-$900{\times}300$beams. In case of conventional H-beam bridges without M-TPSM, it was found that seven girders are required for a similar level of load-carrying capacity. Therefore, it is concluded that by the application of the M-TPSM, the H-beam bridge would become one of most cost-competitive options for short- and medium-span bridges.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.179-185
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• 2009

In recent, the investigations related to the FRP(Fiber Reinforced Polymers) have been increased due to their superior material and mechanical properties such as environmental resistance, high specific strength and stiffness. Considering these advantages, the FRP tube may be proper for strut on the PSC box girder bridge that can maximize the efficiency of cross section and are effective on economics and aesthetics of bridges. In this research, the specimen tests of the FRP tube and compression tests of the concrete member enclosed with the FRP were performed in order to evaluate the suitability of the FRP tubes, which are applied to the PSC box girder bridge with strut. The specific strength of concrete and the energy absorbing capacity as well as ductility were increased according to the experimental results, and it was found that FRP tubes have sufficient safety as strut member.

• Steel and Composite Structures
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• v.52 no.1
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• pp.77-87
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• 2024

Analytical methods for assessment of the out-of-plane buckling of unbraced top chords of truss bridges may look obsolete while comparing them to finite element analysis. However they are, usually, superior when rapid assessment is necessary. Analytical methods consider the top chord as a bar on elastic supports provided by bracing (Holt, Timoshenko). Correct assessment of the support elasticity (stiffness) is crucial. In the case of truss bridge spans of traditional structural layout (cross-beams at the truss chord nodes only), the elasticity may be set based on the analysis of the, so called, U-frame stiffness. Here the analyses consider the U-frame itself (a pair of verticals and a cross-beam) or the U-frame with adjacent diagonals or the pair of diagonals (in the absence of verticals) and the members of the bottom chord in the adjacent panels. For all the cases, the stability analysis of the chord as a bar in compression is necessary. Unfortunately, the method cannot be applied to contemporary truss bridges without verticals, that usually have independent cross-beam decks (the cross-beams attached to truss chords at their nodes and between them). This is the motivation for the analysis resulting in the method of setting the stiffness of the equivalent U-frame for the aforementioned truss bridges. Truss girders of both, gussetless and gusseted, joints are taken into account.

• Journal of the Korean Society of Safety
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• v.23 no.2
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• pp.87-97
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• 2008

The Ilsun Bridge is the world's longest box girder bridge(801m) with corrugated steel webs and has the widest width($21.2{\sim}30.9m$: tri-cellular cross section) among these kinds of composite girder bridges. It has fourteen spans(50m, 10 at 60m, 50m, 2 at 50.5m) where twelve spans are erected by the incremental launching method and two spans by full staging method. Special topics related to the structural safety of prestressed concrete box girder bridge with corrugated steel web in construction stage and service were reviewed. Investigations focus on the span-to-depth ratio, shear stress of corrugated steel webs and optimization of tile length of steel launching nose. The span-to-depth ratio of Ilsun bridge has been found to be well-planned while the corrugated steel web has been designed highly conservative and it has been observed that the conventional nose-deck interaction equation do not fit well with corrugated steel web bridges. As a result, detailed construction stage analysis was performed to check the stress levels and the safety of preceding design conditions. Finally, from the design review of Ilsun bridge, this study suggests optimal design issues which should be of interest in designing a prestressed concrete box girder bridge with corrugated steel webs.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.659-672
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• 1997

Thermal response induced from nonlinear temperature distribution in composite box gilder bridges depends on several variables(environmental conditions, physical and material properties, location and orientation of bridge, and cross-section geometry). In this paper, parametric study are conducted in order to find the effects of variations of seasons, location and orientation of bridge, sectional geometry and some material properties on the axial deformation, curvature and stresses in composite box girder bridge. A two-dimensional transient finite element model to conduct this parametric studies is briefly presented. Firstly, the effects of the parameters on the diurnal variation of curvature are considered, and for the time of maximum curvature, on the distribution of temperature and stresses of composite box girder sectional are considered. Finally, some considerations about the influence of the parameters on the daily maximum values of axial deformation, curvature and stresses are carried out. The influence of thermal effect on structures is important as much as the influence of live or dead load in some cases. In the design of steel composite bridges, the thermal stresses calculated on the supposition that the temperature difference between the concrete slab and steel girder is $10^{\circ}C$ and the temperature distributions are uniform in concrete slab and steel girder can be underestimated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5A
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• pp.887-899
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• 2006

The aim of this study is to investigate a correlation between fundamental data on aerodynamic characteristics of bridge girder cross-sections, such as aerodynamic force coefficients and flutter derivatives, and their aerodynamic behaviour. The section model tests were carried out in three stages. In the first stage, seven deck configurations were studied, namely; Six 2-edge girders and one box girder. In this stage, changes in aerodynamic force coefficients due to geometrical shape of girders, incidence angle of flow, wind directions and turbulence intensities were studied by static section model tests. In the second stage, the dynamic section model tests were carried out to investigate the relativity of static coefficients to dynamic responses. And finally, the two-dimensional (lift-torsion) aerodynamic derivatives of three bridge deck configurations were investigated by dynamic section model tests. The aerodynamic derivatives can be best described as a representation of the aerodynamic damping and the aerodynamic stiffness provided by the wind for a given deck geometry. The method employed here to extract these unsteady aerodynamic properties is known as the initial displacement technique. It involves the measurement of the decay in amplitude with time of an initial displacement of the deck in heave and torsion, for various wind speeds, in smooth flow. It is suggested that the proposed aerodynamic force coefficients and flutter derivatives of bridge girder sections will be potentially useful for the aeroelastic analysis and buffeting analysis.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.84.2-84.2
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• 2010

본 연구는 소수주거더 교량에 적용된 I-거더에 고강도 강재인 HSB800 강재를 사용하였을 때, 휨 연성 R값을 이용하여 AASHTO LRFD(2007)의 조밀단면기준에 대한 경향성에 대해 수치해석적으로 수행되었다. 복부판 세장비, 플랜지 세장비, 비지지 길이를 변수로 하여 휨 연성 R값을 구해서 기존의 AASHTO LRFD(2007)의 조밀단면기준에 적용하여 휨 연성에 대한 경향성을 나타내었다.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.289-299
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• 2020

The composition of convergence cross-section of the material is a technique that provides reasonable design and construction of structures. It is frequently used in medium-sized bridges and architectural structures. However, the structural behavioral spare capacity enhancement of the structure by the application of the convergence cross-section is still limited by the expandability due to the limiting state of each material. In order to overcome these limitations, this study reasonably analyzed the construction stages before and after the convergence cross-section constructed and developed a technique for forming multi-point boundary conditions using struts, which are compression members. Based on the existing cases, a reasonable construction step for forming the material composite section of the entire structural system of the structure was derived, and a numerical analysis model for a specific part was constructed to analyze the behavior of the strut application. As a result of this study, the effect of reducing the sectional force of 7.40% in beam-column joint and 6.31% in the center of girder was derived, and the deflection, which is a measure of the serviceability of the structure, improved by 54.41% from the installation and dismantling of strut members at each construction stage.

• Journal of architectural history
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• v.26 no.2
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• pp.7-14
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• 2017

Rafter is a member for roof and plays a role in protecting shaft members under rafter such as pillar, beam and girder from natural environment and to fix by supporting finished materials of roof. It is common in the Korean architecture that rafter cross-section is paired with circular form and Buyeon cross-section is paired with the square shape. However, while there are not many, some architectures have rafter end header in the square shape. The aim of this study is to examine the square shape cases of rafter end header with special reference to stone structure. As a result, among stone structure related to Bangyeon, the majority case is seen at Palgakwondang type Seungtap. It was shown in the Seungtap of monk of Gusanseonmun school in the later Unified Silla to the early Goryeo period that succeeded Seodang Jijang.