• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.707-717
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• 2006

As an alternative to conventional prestressed concrete (PSC) girders, various types of PSC girders are either under development or have already been applied in bridge structures. Incrementally prestressed concrete girder is one of these newly developed girders. According to the design concept, these new types of PSC girders have the advantages of requiring less self-weight while having the capability of longer spans. However, the dynamic interaction between bridge superstructures and passing trains is one of the critical issues concerning these railway bridges designed with more flexibility. Therefore, it is very important to evaluate modal parameters of newly designed bridges before doing dynamic analyses. In the present paper, a 25 meters long full scale PSC girder was fabricated as a test specimen and modal testing was carried out to evaluate modal parameters including natural frequencies and modal damping ratios at every prestressing stage. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer is applied, in order to obtain precise frequency response functions and the modal parameters are evaluated varying with construction stages. Prestressed force effects on changes of modal parameters are analyzed at every incremental prestressing stage. With the application of reliable properties from modal experiments, estimation of dynamic performances of PSC girder railway bridges can be obtained from various parametric studies on dynamic behavior under the passage of moving train. Dynamic displacements, impact factor, acceleration of the slab, end rotation of the girder, and other important dynamic performance parameters are checked with various speeds of the train.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.433-442
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• 2013

This paper presents experimental research work for the evaluation of one-dimensional and two-dimensional acoustic source locations with 50m length of a precast prestressed concrete box girder. Acoustic events are generated by the impacts of Schmidt Hammer and the impact signals are detected by acoustic emission sensors mounted on the concrete web surface of PSC box girder with the average spacing of 9.34m. Based on the amplitude of detected acoustic signals, considering the noises developed in PSC box girder bridges, the arrival times of acoustic signals are estimated by the first arrival times of 0Volt, 0.5Volt, and 1.0Volt amplitude in each signal. Using Least Square Method, the velocities and the source locations of acoustic signals are evaluated. Based on the test results, the spacing of AE sensors and the AE sensor networks are discussed to reduce the source location errors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.135-146
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• 2008

In this paper, a hybrid damage monitoring scheme for prestressed concrete (PSC) girder bridges by using sequential acceleration and impedance signatures is newly proposed. Damage types of interest include prestress-loss in tendon and flexural stiffness-loss in a concrete girder. The hybrid scheme mainly consists of three sequential phases: damage alarming, damage classification, and damage estimation. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the type of damage is classified into either prestress-loss or flexural stiffness-loss by recognizing patterns of impedance features. In the third phase, the location and the extent of damage are estimated by using two different ways: a mode shape-based damage detection to detect flexural stiffness-loss and a natural frequency-based prestress prediction to identify prestress-loss. The feasibility of the proposed scheme is evaluated on a laboratory-scaled PSC girder model for which hybrid vibration-impedance signatures were measured for several damage scenarios of prestress-loss and flexural stiffness-loss.

• Magazine of the Korea Concrete Institute
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• v.20 no.3
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• pp.34-39
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• 2008

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.117-118
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• 2009

A systematic procedure is proposed that can be used to assess the span of PSC girder bridge for a given condition. The proposed scheme adopts a graphical approach that represents a relationship between the number of prestressing tendons and the span, and is derived on a basis of safety assessment equations of the girder in each stage of fabrication and in service.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.235-242
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• 2001

An optimization algoriam for the optimum design of prestressed concrete (PSC) box girder bridges is proposed in this paper. In order to optimize the tendon profile efficiently, a reduced basis technique is introduced. The optimization algorithm which includes the tendon profile, tendon size and concrete dimensions optimization problem of the PSC box girder bridges is verified on the Genetic algorikhm (GA) from the numerical examples. it may be positively stated that the optimum design of the PSC box girder bridges based on the new approach proposed in this study will lead to more rational and economical design compared with the currently available designs.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.143-144
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• 2009

This study is a development of new PSC girder overcomes weakness of the existing PSC girder and has advantage of construction mark, economical efficiency and maintenance. The gole of this study is reducing dead-load and long-span as HWPC girder has same section through hole and multi-prestressing.

• 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.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.83-90
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• 2008

A vibration-based monitoring system is newly proposed to predict the loss of prestress forces in prestressed concrete (PSC) girder bridges. Firstly, a global damage alarming algorithm is newly proposed to monitor the occurrence of prestress-loss by using the change in frequency responses. Secondly, a prestress-loss prediction algorithm is selected to estimate the extent of prestress-loss by using the change in natural frequencies. Finally, the feasibility of the proposed system is experimentally evaluated on a scaled PSC girder model for which acceleration responses were measured for several damage scenarios of prestress-loss.