• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.725-732
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• 2006

This study has been started for the development of a refined live load distribution formula that has safety and precision toward I type prestressed concrete girder bridge. This type of bridge is mainly applied to short span bridges that are $25{\sim}40m$ in length. Based on various structure analysis models that are currently being applied as preceding studies for the development of live load distribution method. an analysis of flexural stiffness ratio for barrier and diaphragm has been performed. As the result of parametric analysis for the changes in flexural stiffness ratio, the effect of barrier on load distribution showed as insignificant in all structural analysis models while analyzing the deflection distribution. Also. the deflection distribution of the models with stiffness of 25% in which the diaphragm eccentricity is accounted for as same as the models with stiffness of 100% in which the diaphragm eccentricity is unaccounted for. This results are verified through the comparison with a experimental data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.227-234
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• 2009

Recently, a knee brace is usually installed in connection between cross-beam and main-girder of steel box-girder bridges. The knee brace is installed as a structural stiffener and mainly aims to relieve stress at joints and to prevent main-girder from lateral deformation. However, research on the knee brace is insufficient to obviously evaluate the necessity. The stiffened effect of knee brace is determined by using finite element analyses. Stress distribution, stress level of members and deflection of the cross-beam are evaluated by parametric FE analysis for the installation of knee brace and the depth ratio of cross-beam/steel box girder. It is seen from comparison of numerical analysis results that the knee brace installed in cross-beam of steel boxgirders bridges is not efficient as a structural stiffener with respect to stress relief and stiffened effect.

• Steel and Composite Structures
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• v.20 no.4
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• pp.813-832
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• 2016

This research deals with the behavior of Composite Box Girder Bridges (CBGBs) subjected to environmental effects such as solar radiation, atmospheric temperature, and wind speed. It is based on temperature and thermal stress results, which were recorded hourly from a full-scale experimental CBGB segment and Finite Element (FE) thermal analysis. The Hemi-cube method was adopted to achieve the accuracy in temperature distributions and variations in a composition system during the daily environmental variations. Analytical findings were compared with the experimental measurements, and a good agreement was found. On the other hand, parametric investigations are carried out to investigate the effect of the cross-section geometry and orientation of the longitudinal axis of CBGB on the thermal response and stress distributions. Based upon individual parametric investigations, some remarks related to the thermal loading parameters were submitted. Additionally, some observations about the CBGB configurations were identified, which must be taken into account in the design process. Finally, this research indicates that the design temperature distribution with a uniform differential between the concrete slab and the steel girder is inappropriate for describing the thermal impacts in design objective.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.283-294
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• 2011

The variation of temperature in the steel girder bridge by air temperature is measured. A correlation between the daily temperature range, the maximum and minimum temperatures of the day, and the temperature of the bridge are analyzed. With the statistical data from the Korea Meteorological Administration, the temperature correlations analyzed in this study is able to predict temperature variations between the upper flange and the lower flange which calculates the realistic displacement values of a movable support and an expansion joint in design.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.91-98
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• 2008

Curved bridges are important components of a highway transportation network for connecting local roads and highways, but very few data have been collected in terms of their field performance. This paper presents two-years monitoring and system identification results of a curved concrete box-girder bridge, the West St. On-Ramp, under ambient traffic excitations. The authors permanently installed accelerometers on the bridge from the beginning of the bridge life. From the ambient vibration data sets collected over the two years, the element stiffness correction factors for the columns, the girder, and boundary springs were identified using the back-propagation neural network. The results showed that the element stiffness values were nearly 10% different from the initial design values. It was also observed that the traffic conditions heavily influence the dynamic characteristics of this curved bridge. Furthermore, a probability distribution model of the element stiffness was established for long-term monitoring and analysis of the bridge stiffness change.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.302-305
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• 2006

The temperature difference of deck and girder is one of the major factors that affect the stress distribution of a section, and therefore, the design of a composite girder bridge. However, domestic design codes of highway and railway bridges, respectively, present different shapes of design equations regarding the temperature difference, which may induce some confusion to the designers. In this study, each design equation is investigated on a theoretical basis and compared together. Some other methodologies such as finite element method and other equations from a different point of view are also taken into account for further comparison. An example of a railway bridge is presented to verify the result of each scheme.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.211-218
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• 2000

Many bridges are severely damaged by the overloaded heavy vehicle and the trend will become more serious because the traffic volume is continuously increasing. Currently, the vehicles with gross weights over 40 tonf or axle weight over 10 tonf are not allowed on the public road. However, this regulation is not based on a systematic study on the bridge capacity and assumed to be much too conservative depending on the vehicle types and bridge types. In this study, the permit weights of heavy vehicles of diverse axle spacings and axle load distribution are calculated considering the structural characteristics of bridge superstructures. In order to consider the various load effects of heavy weight vehicle crossings, three conditions are considered in the calculation of permit vehicle load. From the results, the permit vehicle weights of the simple girder bridges are calculated.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.2
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• pp.55-60
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• 2004

This paper describes the estimation method of hull girder response of ships due to springing. To this aim, nonlinear springing effect on the hull girder is evaluated including vertical, horizontal, and torsional deformation of the hull. The Timoshenko beam model is used to calculate the stress distribution on the hull girder. The quadratic strip method is employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, 'rigid lid'is adopted on the hull free surface level and hydrodynamic coefficients are interpolated for asymptotic values. The results of example calculation show a reasonable agreement with previous results for both symmetric and anti-symmetric responses.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.47-56
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• 2009

The first diagonal cracking and ultimate shear load of reinforced girder made of ultra high performance fiber reinforced concrete (UHPFRC) were investigated in this paper. Eleven girders were tested in which eight girders failed in shear. A simplified formulation for the first diagonal cracking load was proposed. An analytical model to predict the ultimate shear load was formulated based on the two bounds theory. A fiber reinforcing parameter was constituted based on the random assumption of steel fiber uniform distribution. The predicted values were compared with the conventional predictions and the test results. The proposed equation can be used for the first cracking status analysis, while the proposed equations for computing the ultimate shear strength can be used for the ultimate failure status analysis, which can also be utilized for numerical limit analysis of reinforced UHPFRC girder. The established fiber reinforcing theoretical model can also be a reference for micro-mechanics analysis of UHPFRC.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.47-53
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• 1998

Many kinds of methods have been developed to carry out transverse analysis of prestressed concrete(PSC) box girder bridges. However, most bridge engineers only use the simple frame model to analyze PSC box girder in transverse direction because of its simplicity and easy usage. But, this frame model has many problems such that it can't consider warping, distortion and longitudinal load distribution. In this study, the results from simple frame model and 3-dimensional shell model with UIC load are compared to show its validity. The results from frame model are slightly larger than those of shell model in symmetric loading case. But, positive bending moment of top slab is larger in shell model than frame model in case subject to anti-symmetric loading. It shows that simple frame model can't always give conservative results, so a practical tool whose treatment is easy and whose product is reliable shall be developed as soon as possible.