• Proceedings of the KSR Conference
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• 2005.11a
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• pp.240-245
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• 2005

There has been a strong demand on more economic and lower depth girder bridges for short and medium span range, PRECOM, which is a new type steel-concrete composite girder, has been developed to realize a more economic bridge system with a lower depth girder. In the PRECOM girder bridge, a steel plate girder is simply supported and then concrete form is hung to girder. Thus, the self-weight of the concrete is loaded to the steel girder. To increase the resistance of concrete in the lower casing against tensile stress, compressive force is introduced by prestressed tendon To evaluate the manufacturability and performances of the completed bridge, four 15-m girders and a bridge specimen with two 20m girders wvere constructed. The camber during the construction and introduction of an appropriate compressive force was evaluated. Dynamic data were obtained through the modal testing of the completed girders. Static loading test was also conducted to examine cracks and evaluate the decrease in stiffness and failure behavior under extreme conditions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.3
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• pp.215-222
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• 2017

In order to evaluate a stress state of concrete according to the change of tensile force of prestressed beam, improved nonlinear resonant ultrasonic spectroscopy(NRUS) method is proposed. This technique is advantageous to evaluate the stress state in initial state because the method shows much higher sensitivity than existing linear ultrasonic methods. The NRUS technique measure a nonlinearity parameter, which is calculated from the resonant frequency shift of ultrasonic wave related to the medium state, and the result is also closely related to the stress state of concrete. In this study, the nonlinearity parameter was measured with the change of tensile force to verify the close relationship between the two factors, and the effect of repetitive load cycle on the change of nonlinearity parameter was analyzed. In addition, sensitivity comparison with the linear ultrasonic pulse velocity method was performed. Through the experimental results, the possibility of NRUS technique for the evaluation of stress state in prestressed beam was confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.75-81
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• 2011

Recently prestressed concrete bridges are generally used instead of reinforced concrete. PSC is more durable than RC because it can reduce crack problems, reinforcement corrosion, leakage and carbonation etc. And also PSC is more effective because there is no crack in tension area, and the entire concrete section is considered in section analysis. And it can reduce section size because vertical component by prestressing force can reduce the shear force. However, using high strength concrete can increase the self weight of bridge because of it's higher density. So the hollowed PPC girder with light weight aggregate can be a alternative. In this study the hollowed PPC girder with light weight aggregate is designed and the performance of hollowed PPC girder is evaluated by experimental tests as well as numerical analysis. As a result, The hollowed PPC girder of light aggregate behaved fully elastically under service load of 110kN, and the plastic behavior was showed after elastic behavior through experimental test, and it can be also estimated by numerical analysis.

• Advances in materials Research
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• v.8 no.3
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• pp.197-217
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• 2019

In this study, the interfacial stresses in RC beams strengthened by externally bonded prestressed GFRP laminate are evaluated using an analytical approach, based on the equilibrium equations and boundary conditions. A comparison of the interfacial stresses obtained from the present analytical model and other existing models is undertaken. Otherwise, a parametric study is conducted to investigate the effects of geometrical and material properties on the variation of interfacial stresses in damaged RC beams strengthened by externally bonded prestressed GFRP laminate. The results obtained indicate that the damage degree has little effect on the maximum shear stress, with a variation less than 5% between the damaged and undamaged RC beams. However, the results also reveal that the prestressing level has a significant effect on the interfacial stresses; hence the damaged RC beam strengthened with an initial prestressing force of 100 kN gives 110% higher maximum shear stress than the damaged RC beam strengthened with an initial prestressing force of 50 kN. The values of shear stress obtained by the analytical approach are approximately equal to 44% of those obtained from the numerical solution, while the interfacial normal stresses predicted by the numerical study are approximately 26% higher than those calculated by the analytical solution.

• Steel and Composite Structures
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• v.23 no.4
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• pp.473-481
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• 2017

Steel plate shear wall (SPSW) system has been increasingly used for lateral loads resisting system since 1980s when the utilization of post-buckling strength of SPSW was realized. The structural response of SPSWs largely depends on the behavior of the surrounded beams. The beams are normally required to behave in the elastic region when the SPSW fully buckled and formed the tension field action. However, most modern design codes do not specify how this requirement can be achieved. This paper presents theoretical investigation and design procedures of manually calculating the plastic flexural capacity of the beams of SPSWs and can be considered as an extension to the previous work by Qu and Bruneau (2011). The reduction in the plastic flexural capacity of beam was considered to account for the presence of shear stress that was altered towards flanges at the boundary region, which can be explained by Saint-Venant's principle. The reduction in beam web was introduced and modified based on the research by Qu and Bruneau (2011), while the shear stress in the web in this research is excluded due to the boundary effect. The plastic flexural capacity of the beams is given by the superposition of the contributions from the flanges and the web. The developed equations are capable of predicting the plastic moment of the beams subjected to combined shear force, axial force, bending moment, and tension fields induced by yielded infill panels. Good agreement was found between the theoretical results and the data from previous research for flexural capacity of beams.

• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.159-175
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• 2024

In order to solve the problem of calculating the reasonable completed bridge state of a self-anchored hybrid cable-stayed suspension bridge (SA-HCSB), this paper proposes an analytical method. This method simplifies the main beam into a continuous beam with multi-point rigid supports and solves the support reaction forces. According to the segmented catenary theory, it simultaneously solves the horizontal forces of the main span main cables and the stay cables and iteratively calculates the equilibrium force system on the main beam in the collaborative system bridge state while completing the shape finding of the main span main cable and stay cables. Then, the horizontal forces of the side span main cables and stay cables are obtained based on the balance of horizontal forces on the bridge towers, and the shape finding of the side spans are completed according to the segmented catenary theory. Next, the difference between the support reaction forces of the continuous beam with multiple rigid supports obtained from the initial and final iterations is used to calculate the load of ballast on the side span main beam. Finally, the axial forces and strains of each segment of the main beam and bridge tower are obtained based on the loads applied by the main cable and stay cables on the main beam and bridge tower, thereby obtaining analytical data for the bridge in the reasonable completed state. In this paper, the rationality and effectiveness of this analytical method are verified through a case study of a SA-HCSB with a main span of 720m in finite element analysis. At the same time, it is also verified that the equilibrium force of the main beam under the reasonably completed bridge state can be obtained through iterative calculation. The analytical algorithm in this paper has clear physical significance, strong applicability, and high accuracy of calculation results, enriching the shape-finding method of this bridge type.

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.577-585
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• 2017

To study the mechanical performances of prestressed steel-concrete composite box beam under combination of bending-shear-torsion, nine composite beams with different ratio of torsion to bending were designed. Torsion was applied to the free end of the beam with jacks controlled accurately with peripherals, as well as concentrated force on the mid-span with jacks. Based on experimental data and relative theories, mechanical properties of composite beams were analyzed, including torsional angle, deformation and failure patterns. The results showed that under certain ratio of torsion to bending, cracking and ultimate torsion increased and reached to its maximum at the ratio of 2. Three phases of process is also discussed, as well as the conditions of each failure mode.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.381-386
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• 1999

The member with external unbonded tendon has two remarkable characteristics, i.e., eccentricity variation and slip by friction force at deviators, compared with internal bonded or unbonded member. An efficient numerical procedure for the nonlinear analysis of prestressed concrete beam with external unbonded tendon considering two remarkable characteristics is formulated and corresponding computer code is developed. On the basis of statistical process of parametric study results, strain compatibility method, eccentricity variation predictor and tendon stress predictor at ultimate state are proposed and verified with test results and existing Codes, which can evaluate flexural behavior at ultimate state. Finally, the proposed procedure and predictors can be efficiently used for the realistic and accurate analysis of prestressed concrete members with external unbonded tendons.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.293-300
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• 2004

A new earth retention system(Innovative Prestressed Wale System) has been developed and introduced. IPR earth retention system provides an economical benefit, construction easiness, good performance and safety. IPS is a prestressed wale by using a steel wire, which provides a high stiffness to resist the earth pressure. In order to investigate the applicability and the safety of new IPS system, field tests were performed. A new IPS system applied in a trench excavation performed successfully. Basic principles and mechanism of IPS system and measure performance were presented and discussed.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.3-11
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• 2000

In pretensioned concrete structures, bond between prestressing steel and concrete is an essential component to ensure the integrity of a pretensioned member. The anchorage and development of the prestressing force depend exclusively on bond. The purpose of this study is to investigate the characteristics of bond and development length between pretensioned steel and concrete. To resolve the controversy over the adequacy of the current code provision on development length of prestressing strands, a comprehensive test program has been scheduled and twenty four rectangular prestressed concrete beams have been tested to determine development length. Major test variables include diameter of strands (12.7mm, 15.2mm) and concrete covers (3cm, 4cm, 5cm). The test results indicate that the development length based on the bond stress-slip relation. The proposed model can evaluate realistically the development length of pretensioned prestressed concrete members and can be the good basis for the future basis of code equations on development length of PSC members.