• Computers and Concrete
• /
• v.29 no.3
• /
• pp.161-168
• /
• 2022

Bridges using double-tee (DT) girders from 12 m to 15 m are one of the good choices to improve accessibility in rural areas of the Mekong River Delta. In this study, nonlinear finite element method (FEM) analysis was conducted with different constitutive laws of materials. The FEM analysis results were compared to experimental results to confirm the applicability of the constitutive laws of materials for DT girders. A parametric study through FEM analysis was then conducted to investigate the effect of span lengths, top flange depths, and a number of prestressing tendons on the capacity of DT girders in order that propose DT girders for rural bridges. Parametric results showed that the top flange depth of a DT girder for rural bridges could be 120 mm. The DT girder with a span length of 12 m or 13 m could be used 16 tendons, while the DT girder with a span length of 14 m or 15 m could be set up with 20 tendons. The prestressed concrete DT girders based on FEM results can be suggested for the construction of rural bridges.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.268-273
• /
• 1995

In recent years, precast prestressed concrete segmental box girder bridges have been increasingly constructed Expansion disphragm segment of this type bridge transfers forces from the superstructure onto bearing or column, and plays an important roll of anchorage zone for longitudinal prestressed forces. Non-linear stresses occur inside of diaphragms by these extensive concentrated forces. In this study, the strut-and-tie models are proposed to design an expansion segment rationally. A formula to determine the effective transverse prestressed forces is proposed on the basis of these models. The present study is expected to provide an effective tool to design expansion segment of prestressed concrete bridges rationally.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.2
• /
• pp.77-89
• /
• 2004

This study was carried out to find out the reasonable optimum design method for the design of prestressed concrete structures. The optimum design problems were formulated and computer programs to solve these problems were developed. To test the reliablity, efficiency, possibility of application and reasonablity of optimum design problems and computer programs, both continuous optimization method and mixed-discrete optimization method were applied to the design of prestressed concrete composite girder and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of prestressed concrete structures.

• Smart Structures and Systems
• /
• v.15 no.4
• /
• pp.1159-1175
• /
• 2015

In this study, the effect of temperature variation on the wireless impedance monitoring is analyzed for the tendon-anchorage connection of the prestressed concrete girder. Firstly, three impedance features, which are peak frequency, root mean square deviation (RMSD) index, and correlation coefficient (CC) index, are selected to estimate the effects of temperature variation and prestress-loss on impedance signatures. Secondly, wireless impedance tests are performed on the tendon-anchorage connection for which a series of temperature variation and prestress-loss events are simulated. Thirdly, the effect of temperature variation on impedance signatures measured from the tendon-anchorage connection is estimated by the three impedance features. Finally, the effect of prestress-loss on impedance signatures is also estimated by the three impedance features. The relative effects of temperature variation and prestress-loss are comparatively examined.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.04a
• /
• pp.18-25
• /
• 2001

Analysis of prestressed box-girder bridges using the spline finite strip method is presented. In the present study, the spline finite strip method(FSM) is modified using the non-periodic B-spline interpolation. In the analysis of the prestressed box girder bridges, each tendon force is evaluated by summation of the adjacent segment forces. Once the equivalent forces acting on the structure at the tendon points are found, they are transformed into statically equivalent forces at the adjacent node or joints. Several examples were analyzed to verify the performance of present method using the non-periodic B-spline FSM. Good agreements were obtained when compared with the previous study.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.40-43
• /
• 2004

A new design method for prestressed concrete girder is proposed in this study, which steps for manufacturing are; (1) the bottom part of concrete girder is placed and pretensioned by the first post-tensioning performed on the tendons located in the bottom part of concrete girder, and (2) the next step which consists of concrete placing and post-tensioning operation is followed by the previous step if required. This indicates that sufficient compressive stress can be effectively introduced at the bottom face in stepwise manner, when compared to conventional PSC girder. Two specimens are prepared and tested to investigate the short-term behavior of the PSC girders manufactured by the proposed method. Section Analysis results exhibit good agreements with the test results in terms of strain distribution across the girder section. In addition, flexural strength obtained from the tests is found to be similar to the expected based on Code(Korea). These demonstrate that the method proposed in this study is applicable to the design of PSC girders.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.701-705
• /
• 1998

The objective of this study is to develop the practical program which can check the constructible possibility of prestressed concrete box girder bridges for design. Checking constructible possibility is defined as checking the interference of each elements in a PSC box girder bridge and computing the distances of each elements. To check the constructible possibility of a PSC box girder bride, bridge must be modelled using solid in three dimension. By using a 3 dimensional solid modeling system, engineers can get the photo realistic 3D viewing images of the bridge and produce FEM analytic model of it. Users can manipulate their drawings easier and take off quantity of the whole structure and its elements as well as check the constructible possibility of their PSC box girder bridges.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.389-392
• /
• 2006

A In this paper, a new prestressed concrete girder system is presented which is designed using a detensionable and retensionable system. Experiments were carried out in order to comprehend the behavior of detensionable and retensionable prestressed concrete girder system. Tension control tests were performed for the detensionable and retensionable system followed by the static loading tests to check the applicability of the girder system. The test results were found in good agreement with the analytical results which clearly indicates the reliability of the concept of detensionable and retensionable prestress concrete girder with projected flange.

• Structural Engineering and Mechanics
• /
• v.17 no.6
• /
• pp.879-898
• /
• 2004

A method of making simply supported girders continuous is described for bridges with spans of 30-45 m. The splicing method takes advantage of an induced secondary moment to transform the self-weight stresses in the precast simply supported girders into values representative of a continuous girder. The secondary moment results from prestressing of continuity tendons and detensioning of temporary tendons in the girders. Preliminary sections are selected for spliced U-girder bridges with a range of span lengths. Use of the proposed technique results in girder depth reductions of 500-800 mm when compared to standard simply supported I-girder bridges. The flexural behavior of an example bridge with 40-m spans is examined to illustrate the necessary considerations for determining the optimum sequence of splicing operations.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.965-972
• /
• 2011

Unlike metallic materials, the importance of fatigue performance of concrete has been ignored. However, it is reported that environmental effects, if it cause deterioration, may increase the risk of fatigue failure under repeated loadings. In case of railroad bridges, the risk may increase due to highly periodic, repetitive, heavier nature of train load, which runs through the fixed passage called the track. Especially, when new material or structure is implemented for a main bridge member, experimental validation should be performed to avoid damage or failure due to unexpected behavior. In this paper, the fatigue performance of an IT girder is examined via a repeated loading test. The IT girder is a new type of a prestressed concrete (PSC) girder with two prestressed H-beams in the top of the girder, which provide additional sectional capacity, and it can be applied to the span longer than 30m which is a typical limit for a usual PSC girder. To obtain the fatigue performance, a 10m IT girder specimen is designed, and a repeated load test is performed by applying the cyclic load two million times. The fatigue performance of the girder is examined according to the Japanese and the CEB-FIB design codes. The fatigue test result shows that the IT girder satisfies both design codes.