• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.533-536
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• 2008

It is on increasing trend to employ H-rolled beams as main flexural members of bridges and of temporary structures owing to their handiness for construction, maintenance, and management. But in the case of applying H-rolled beams to bridges, maximum length of bridge span is around 20m. Therefore, to develop simplified steel-concrete composite bridge having long span using H-rolled beam needs new cross girder system at internal supports, optimization of bridge system without cross beams between supports and steel-concrete composite bridge deck. This study performs mechanical analysis of cross girder system for H-rolled beam steel-concrete composite bridge with long span and verifies its usefulness.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.2
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• pp.157-166
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• 2001

The purpose of this study is to examine the accuracy of the code provisions on lateral load distribution factors of prestressed concrete girder bridges. Most designers in Korea use the lever method or lateral load distribution formula in the existing design codes. However, the methods do not account for the effect of bridge skew or direction of diaphragm. Therefore, this study analysed the prestressed concrete girder bridge with grillage model for various girder spacings, directions of diaphragms, span lengths, and skews, and compared the results with those of existing design code. It has been found that lateral load distribution factors were proportional to the girder spacing while they were not significantly affected by the change of span length, direction of diaphragm, and skew. For bending moments, lateral load distribution factors from the grillage analysis were 60%~68% of those from Korean bridge design code. Therefore, the code provisions result in very conservative design. For support reactions, however, lateral load distribution factors from the grillage analysis were slightly greater than those from Korean bridge design code. Therefore, the capacity of bearings of the bridge with a large skew should be determined by grillage analysis.

• Computers and Concrete
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• v.24 no.4
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• pp.303-311
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• 2019

The depth of superstructure is the summation of the height of girders and the thickness of the deck floor. In this study, it is aim to determine the maximum span length of girders and minimum depth of the superstructure of prestressed concrete I-girder bridge. For this purpose the superstructure of the bridge with the width of 10m and the thickness of the deck floor of 0.175m, which the girders length was changed by two meter increments between 15m and 35m, was taken into account. Twelve different girders with heights of 60, 75, 90, 100, 110, 120, 130, 140, 150, 160, 170 and 180 cm, which are frequently used in Turkey, were chosen as girder type. The analyses of the superstructure of prestressed concrete I girder bridge was conducted with I-CAD software. In the analyses AASHTO LRFD (2012) conditions were taken into account a great extent. The dead loads of the structural and non-structural elements forming the bridge superstructure, prestressing force, standard truck load, equivalent lane load and pedestrian load were taken into consideration. HL93, design truck of AASHTO and also H30S24 design truck of Turkish Code were selected as vehicular live load. The allowable concrete stress limit, the number of prestressed strands, the number of debonded strands and the deflection parameters obtained from analyses were compared with the limit values found in AASHTO LRFD (2012) to determine the suitability of the girders. At the end of the study maximum span length of girders and equation using for calculation for minimum depth of the superstructure of prestressed concrete I-girder bridge were proposed.

• Smart Structures and Systems
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• v.32 no.6
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• pp.371-382
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• 2023

Box girder bridges are now widely used in bridge construction, and it is necessary to perform load rating regularly to evaluate the load capacity of box girder bridges. Load testing is a common measure for load rating. However, the bridge must be loaded by many trucks under different loading conditions, which is time-consuming and laborious. To solve this problem, this paper proposes a load rating method for box girder bridges based on rapid moving loads testing. The method includes three steps. First, the quasi-influence factors of the bridge are obtained by crossing the bridge with rapidly moving loads, and the structural modal parameters are simultaneously obtained from the dynamic data to supplement. Second, an objective function is constructed, consisting of the quasi-influence factors at several measurement points and structural modal parameters. The finite element model for load rating is then updated based on the Rosenbrock method. Third, on this basis, a load rating method is proposed using the updated model. The load rating method proposed in this paper can considerably reduce the time duration of traditional static load testing and effectively utilize the dynamic and static properties of box girder bridges to obtain an accurate finite element model. The load capacity obtained based on the updated model can avoid the inconsistency of the evaluation results for the different structural members using the adjustment factors specified in codes.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.101-104
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• 1990

The program which could determine cross-sectional dimensions of the box girder bridge at tile stage of preliminary design was developed using the optimal technique in this study. It could minimize the cost and time required in the design of box girder bridges and the construction with the prestressed precast segmental method. Objective cost function consisted of four independent variables such as widths and depth of the cross-section. The Nelder-Mead method was used to solve the nonconstrained nonlinear problem like this.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.839-844
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• 2000

The research was conducted to investigate the effects of intermediate diaphragm in concrete girder bridge. The analytical variables consisted of various types(reinforced concrete and steel) and locations of intermediate diaphragm, slab thickness, girder spacing etc. Finite element analyses of the bridge model assuming simply support condition. The Vertical load distribution was determined to be essentially independent of type and location of intermediate diaphragms. Also, it is found that the practical design of intermediate diaphragm may be revised.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.288-293
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• 2008

The standard prestressed concrete I-girder bridge (PSC I-girder bridge) is one of the most prevalent types for small and medium bridges in Korea. When determining the member forces in a section to assess the safety of girder in this type of bridge, the general practice is to use the simplified practical equations or the live load distribution factors proposed in design standards rather than the precise analysis through the finite element method or so. Meanwhile, the live load distribution factors currently used in Korean design practice are just a reflection of overseas research results or design standards without alterations. Therefore, it is necessary to develop an equation of the live load distribution factors fit for the design conditions of Korea, considering the standardized section of standard PSC I-girder bridges and the design strength of concrete. In this study, to develop an equation of the live load distribution factors, a parametric analysis and sensitivity analysis were carried out on the parameters such as width of bridge, span length, girder spacing, width of traffic lane, etc. Then, an equation of live load distribution factors was developed through the multiple linear regression analysis on the results of parametric analysis. When the actual practice engineers design a bridge with the equation of live load distribution factors developed here, they will determine the design of member forces ensuring the appropriate safety rate more easily. Moreover, in the preliminary design, this model is expected to save much time for the repetitive design to improve the structural efficiency of PSC I-girder bridges.

• Journal of Korean Society of Steel Construction
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• v.22 no.6
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• pp.543-551
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• 2010

The end-reinforced composite-beam (eco-girder) system was developed that has characteristics of the existing composite beams such as reduced floor height and increased strength. With it, less use of steel is expected. In the eco-girder system, only both ends of the steel-frame beam, which are vulnerable to the ultimate moment, are reinforced with steel plates so that the steel frame beam design will be based on the moment at the beam center. This study used fiber element analysis, which is a simple representation and numerical integration of the principles of the detailed Finite Element Method(FEM), to predict the hysteretic behavior of reinforced composite beams under cyclic loading. The validity of the numerical method was verified by comparing the results of this study with those of previous studies. In addition, the hysteretic behavior of the eco-girder was compared with that of the existing composite beams.

• Land and Housing Review
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• v.2 no.2
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• pp.183-188
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• 2011

Recently, the depth of tunnel constructed is getting deeper, which increases difficulty in construction works. Deliberate tunneling techniques are needed as the span and length of tunnels are increased. As one of the technical developments for tunnel, U-shaped and reinforced spider lattice girders are developed by optimizing the spider used in 95mm lattice girder as tunnel steel ribs. In order to evaluate the load bearing capacity of the lattice girder, the 4-point flexural tests are carried out. For the laboratory tests, straight specimens are made for the existing lattice girder and the new lattice girder. The results of the flexural tests showed that the maximum load bearing capacity of the new lattice girders was higher than the traditional one. The load-displacement behavior of the test specimens showed the elasto-plastic behavior in the existing lattice girder and the stress softening behavior in the new lattice girder. It was found that the load bearing capacities are changed depending on the location of the loading points.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.349-352
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• 2008

IPC girder is more prestressed and has smaller sectional area than the conventional PSC-I type girder due to incremental prestressing along the construction process. The continuous IPC girder bridge may have problems in serviceability and stresses at internal supports because it is very flexible. In this paper, The long-term behavior of the continuous IPC girder bridge is studied through long-term structural analysis and monitoring the deflections. The long-term behavior is monitored right before the introduction of 2nd prestressing that is the construction process different from the conventional PSC-I type girder bridge. The total station of high-precision was used in measuring the deflections. According to the monitoring result so far, the continuous IPC girder bridges does not show remarkable long-term behavior like severe camber or deflection and the measured deflections are very similar to the results of long-term structural analysis.